Removing Secondary Vacuum System questions.

[DScott600]

I have a chip from the ZR1 Specialist for my 91 and decided to get the option for the chip that eliminates the need for the secondary vacuum system. According to Marc I can remove all of the secondary vacuum lines and just leave the sensor under the ECM exposed to the atmosphere. My question is after removing the vacuum lines, the solenoid and canister what should I do with the line that runs into the drivers side of the plenum? Does this line now need to be plugged? Also is there a better way to tie the secondaries open besides just using wire ties? Or is there a good way to remove the throttle plates with the injector housings still in without dropping anything into the engine? Later I am planning on getting the top end ported and removing the shafts and all.

[Paul Workman]

I have a chip from the ZR1 Specialist for my 91 and decided to get the option for the chip that eliminates the need for the secondary vacuum system. According to Marc I can remove all of the secondary vacuum lines and just leave the sensor under the ECM exposed to the atmosphere. My question is after removing the vacuum lines, the solenoid and canister what should I do with the line that runs into the drivers side of the plenum? Does this line now need to be plugged?

Yes, it has to be plugged.


Also is there a better way to tie the secondaries open besides just using wire ties? Or is there a good way to remove the throttle plates with the injector housings still in without dropping anything into the engine? Later I am planning on getting the top end ported and removing the shafts and all.

Dom tied his throttle plates open w/ a tie-wrap.

As for removing the plates, you might be able to stuff some foam into the IH to catch anything that might be dropped. In my case, I used one of those telescoping magnet thingies and placed the magnet on top of the plate next to the screws. that worked well - gave piece of mind.

You'll like running w/o the secondary hardware. I promise!

Parts not used seldom fail, and they don't cost much!

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1009.jpg

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1008.jpg

P.

[DScott600]

Thank you for the info, I will plug it and tie the secondaries open. I might attempt to remove the plates using the magnet trick as well. I should have it all back together by Wednesday night if I get my plenum gaskets I ordered Saturday by then. I'll report how she does when I do.

[Locobob]

I think you'll have a tough time accessing the screws on the secondary throttle plates with the injector housings still on, save yourself the grief and just pull em.

[XfireZ51]

I think you'll have a tough time accessing the screws on the secondary throttle plates with the injector housings still on, save yourself the grief and just pull em.

:thumbsup:

BTW, I removed the throttleplates themselves and then tie wrapped the throttle mechanism open so the shafts presented the narrowest side to air flow.

[John Boothby]

Does tying open or removing the secondary throttle plates effect the emissions? I remember when I first got my car a few years ago the first time I had it smogged I forgot and left the power key on full power. The car failed the test with high HC. I went home depressed. I thought about this overnight, and the next day I went back with the key turned off and it passed with no problem. It has never failed since. Someone said this should not matter, however it did in my case. The car runs great and always has.

[DScott600]

Well I already have the plenum gaskets ordered from Jerry and I would like to get it back together by Wednesday if they come in. I don't want to have to order the injector housing gaskets and wait on them. If I went that far I would probably replace the breather gasket and loctite the bolts so they want back out (even though it doesn't leak after I pulled the plenum the first time and tightened the bolts.) I plan on having the money to go ahead and do the full top end porting and powder coating with stainless steel bolts and all early to mid next year, if all goes well. So I suppose I will just tie the linkage open for now and then take the plates out when I pull it all apart to do the porting along with a better clean up and replacing the breather gasket too. For now I'll put the 30 or so dollars I would have to spend on injector housings gaskets toward my c5 brake upgrade. Does this sound reasonable to you guys?

[DScott600]

Oh and in response to John Boothby I'm sure that running without the secondaries would effect emissions. Marc told me that the main reason GM did the secondaries is for emissions. But I'm sure the experts may chime in on this one.

[John Boothby]

I understood that the main reason for the secondaries was for fuel consumption so that a buyer would not have to pay the gas guzzler tax.

[Pete]

Here is the answer to emissions 2 chips.

One for emissions,one for performance.

Marc should know what to do.

Pete

[32valvZ]

So what exactly would be a good reason to do this if everything is working properly? :icon_scra

[rudolph schenker]

So what exactly would be a good reason to do this if everything is working properly? :icon_scra


:happy1:

[XfireZ51]

Oh and in response to John Boothby I'm sure that running without the secondaries would effect emissions. Marc told me that the main reason GM did the secondaries is for emissions. But I'm sure the experts may chime in on this one.

Could have been for gas guzzler tax with the drive cycle performed using primary runners only. 2nd Gen LT-5 was eliminating secondaries.

[Paul Workman]

So what exactly would be a good reason to do this if everything is working properly? :icon_scra

Reliability, simplicity, and more air flow!

After alcohol-sensitive injectors, or injectors in general, it would be my observation that issues with the secondary control system is the second (if not the first) issue related to LT5 reliability - a WAAAAY over engineered solution to a "problem" that might have been overcome (and was on the GEN-II LT5) another way.

For example:

There are 4 separate signal lines from the ECM controlling 4 separate relays each controlling (yet) a second pair of injectors; 24 connections in all, not counting the relays themselves.**
There is the vacuum pump that initially charges the system and maintains vacuum as the secondaries are opened and closed (in spirited driving).
Then there is the check valve and (old) rubber connections, plastic lines, the reservoir, solenoid, and let's not forget that the actuators should to be balanced to work in unison.


In my case, I concluded that
the air flow disruption was a consideration in the quest for HP,
throttle response is improved w/o all the stuff that needs to be actuated, espcially when all injectors are working all the time - no lag,
and since all the vacuum "stuff" could be eliminated and removed along with all the stumbling, and high idle, crap that goes along with something failing in the vacuum secondary system
the KISS principal.

So, except for a NCRS car, my question was why keep all that nonsense and the potential for complicating the troubleshooting aspect of maintaining the LT5?

The one item left to be eliminated (by me) is electrical. It stems from the way chip I have installed operates. The engine now depends on all injectors to be running - each injector sharing the load demand. If for any reason, and there are several, that the ECM should turn off the secondary injectors, some serious leaning would result and one would have to "limp home" until the problem was corrected.

So, the solution would be the equivalent of latching the secondary relays closed all the time or connecting the primary and secondary injectors in parallel - so they work as "one". The jury is still out on this - but I think Marc H agrees it may remove some potential for harm should some or all of the secondary injectors suddenly quit.

All that said, I couldn't find a reason NOT to remove the secondary actuation system. Of the 6 of us sitting at the table last week, I believe only one of us still was using the stock secondary system. The rest had removed all of the hardware, or tie-wrapped them open. As to how we liked running w/o the system, it was unanimous that we did prefer NOT having the secondary system installed.

Looks tell the story: Simple is a good thing!

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1009.jpg

FWIW,

P.

[tpepmeie]

So, the solution would be the equivalent of latching the secondary relays closed all the time or connecting the primary and secondary injectors in parallel - so they work as "one". The jury is still out on this - but I think Marc H agrees it may remove some potential for harm should some or all of the secondary injectors suddenly quit.

Or, disable the program logic which would ever cause the secondary injectors to shut down.

Or, implement a substantially lower rev limit (say 3000 rpm) in the event the secondaries are commanded shut down.

Different ways to skin this cat.

Todd

[DScott600]

When I read about and look at the LT5 it is a marvelous engine. The only thing that really bothered me was the secondary system. It looks like a last minute cobbled together idea and it is way over complicated. In the late nineties I had a 1996 mustang cobra. They had secondary throttle blades too that opened up at 3250 RPM. They were used for low end torque. The system was much simplier, they had plates between the intake and heads that were operated from a control box under the intake. It was a compact design and if you wished to eliminate it you pulled the intake to do so. In 99 Ford changed the design of the heads so that the system was no longer needed and they haven't used it since. My point is the system could have been similar to fords and we would have little to know issues with it. And everyone who has done it says that you notice no torque loss and even Marc says that it was for emissions. The Ford design was for low end torque but even they went away from it when they redesigned the heads to promote better low end torque.

[32valvZ]

I see the pros to the removal of all the secondary components if theres problems with it. However, I may be in the minority here, but I believe my secondary system is working just fine. When I did my injectors and coils etc., I replaced both the vac cans with new, tested units turned the right way of course. In addition to that, I silicone sealed any questionable vacume connections and zip tied all the others with the appropriate sized ties.

My secondary engagement is just about seamless. I guess if I start experiencing problems with it, I might want to do the removal procedure. For now, I'm happy with the whole set up as it is.
:cheers:

[xxxscimitarxxx]

I have got vaccum problems now so was looking to replace all my secondary gear ....'all of it' on the basis that lm in the UK and knowing my luck the one part l wouldnt order would be the part l needed ( and there arent corvette spares on every corner in UK.....so

if l go the secondary actuator delete route...l more or less dont buy anything apart from plenum gaskets and l get a more reliable and simple fuel injection system....so

a couple of Qs

is it as simple as ripping out the vac plumbing, jumping the power and signal wiring from the primary injectors to the secondary injectors, tying open the secondary throttles

If not....then is there a 'step by step with pictures' available for this job....or can someone please send me a napkin schematic

what happens to the ECU outputs....codes, CEL other nasties that the ECU might do to the cars performance

are other engine data sensors affected which then provide bad signals to the ECU

But all in all....this sounds good to me....and Im a firm believer in KISS

(so why did l buy a ZR1 .....:icon_scra)

Oh yes I know why:sign13:...they go great....sound great....look great....and have lots of interesting moving parts (some of which it seems l will now remove)

Any additional help to the above would be appreciated :cheers:

Dave:hal:

[secondchance]

I see the pros to the removal of all the secondary components if theres problems with it. However, I may be in the minority here, but I believe my secondary system is working just fine. When I did my injectors and coils etc., I replaced both the vac cans with new, tested units turned the right way of course. In addition to that, I silicone sealed any questionable vacume connections and zip tied all the others with the appropriate sized ties.

My secondary engagement is just about seamless. I guess if I start experiencing problems with it, I might want to do the removal procedure. For now, I'm happy with the whole set up as it is.
:cheers:

I am in the same boat. I finally got everything sorted out. I have this fear of something going awry due to removal. Also, VA emission test.:dontknow:

[Paul Workman]

I have got vaccum problems now so was looking to replace all my secondary gear ....'all of it' on the basis that lm in the UK and knowing my luck the one part l wouldnt order would be the part l needed ( and there arent corvette spares on every corner in UK.....so

if l go the secondary actuator delete route...l more or less dont buy anything apart from plenum gaskets and l get a more reliable and simple fuel injection system....so

a couple of Qs

is it as simple as ripping out the vac plumbing, jumping the power and signal wiring from the primary injectors to the secondary injectors, tying open the secondary throttles

If not....then is there a 'step by step with pictures' available for this job....or can someone please send me a napkin schematic

what happens to the ECU outputs....codes, CEL other nasties that the ECU might do to the cars performance

are other engine data sensors affected which then provide bad signals to the ECU

But all in all....this sounds good to me....and Im a firm believer in KISS

(so why did l buy a ZR1 .....:icon_scra)

Oh yes I know why:sign13:...they go great....sound great....look great....and have lots of interesting moving parts (some of which it seems l will now remove)

Any additional help to the above would be appreciated :cheers:

Dave:hal:

It IS as simple as removing the secondary vacuum pump associated hardware, actuators, and even the friggin throttle plates too!

You don't need to be jumping anything. I Just pluged in a Marc Hiabeck chip programed for cars sans secondary "system". Marc's chip also provides programming to better control the cooling fans, fix the high idle, optimize engine performance for higher operating temps, anti-backfire when using long tube headers. I'm VERY pleased with how the car performs now with the new calibration, as compared to stock. Smooth and very responsive, and no change in my fuel mileage...except maybe 1/2 a mile better w/ cruise control running! (28.5 mpg).

P.

[xxxscimitarxxx]

Thanks

will drop Haibeck a line

does the chip have a specific programme reference and how much is it?

To use the American venacular....''this is a no brainer''

lm driving mine, not going in for concours shows. I want simplicity and reliability....and this is a good move.

Any other suggestions for stuff to rip out that give you more grief than gogo?

Dave

[Paul Workman]

Thanks

will drop Haibeck a line

does the chip have a specific programme reference and how much is it?

To use the American venacular....''this is a no brainer''

lm driving mine, not going in for concours shows. I want simplicity and reliability....and this is a good move.

Any other suggestions for stuff to rip out that give you more grief than gogo?

Dave

There are a few options, depending on what all ya want. Mine was a "feature-rich" version tuned for an additional 50 hp coinciding with the top end porting.

As for your question re the two plenums (other post): Plenum design is a balancing act with volume, harmonic frequency, and air column velocity being the major factors - simply put as I can. Smaller engine displacement benefit from smaller runners, and bigger engine displacement need runners with more volume. However, if you mix the two, you can come out loosing instead of gaining. Put a big siamese plenum and IHs on a 350 ci and you could loose low end as well as high end performance. Put a stock plenum on a (stroked & sleeved) 441 motor and you'll choke it to death. It's all in the tuning, and books have been written on this very subject.

P.

[xxxscimitarxxx]

Thanks for the haibeck info.....lm guessing about $250......

and re the plenums, l was just curious.

I have had the question on my mind for some time since seeing one and was thinking that the siamesed runners were for a performance application

as for other plenum designs ....the one on DRM's web site with the downdraft ram pipes being an example of the dropped plenum

beautiful engineering indeed

[xxxscimitarxxx]

as lm going to be pulling a plenum or two this weekend lve got this secondary delete project in mind

But.....

1)If l delete all the secondary plumbing and tie wrap the secondary butterflies open without the prom being modded (haibeck).....what is the effect likely to be.....driveable or not

2)also as lve not ordered my plenum gaskets in time to get them shipped....if my plenum gaskets come off in OK condition.... is it OK to reuse them with a little jointing compound

I know its not the way :redface:....but as you know my nearest parts stores are over 2000 miles away.

[John Boothby]

Order your gaskets from Jerry. He is very good at getting them out. Excellent service. Order the thicker gaskets that he offers and if you need to R/R the plenum again you should be able to reuse them, no sweat. Also, I reused my gaskets once, and they were perfect. Just be sure that they are in good shape and reuse them on the same side, don't flip them. I do not believe you need to use any sealant on them, I didn't. Torque the plenum screws according to the FSM (20 foot pounds) and in proper sequence.

[Pete]

1)If l delete all the secondary plumbing and tie wrap the secondary butterflies open without the prom being modded (haibeck).....what is the effect likely to be.....driveable or not



It will drive just fine maybe better,you will have to make sure power key is always on.




2)also as lve not ordered my plenum gaskets in time to get them shipped....if my plenum gaskets come off in OK condition.... is it OK to reuse them with a little jointing compound


That is also OK.

Pete

[xxxscimitarxxx]

Thanks guys

there are two reasons to own a ZR1....one of course is the car it self.....the other is the help you get from the people who own them in this registry

Thanks again......:worship:

[xxxscimitarxxx]

well l did the secondary actuator plumbing removal on my yellow92

and........

OMG what a difference......its like day and night :dancing

and considering its been running without operational secondaries since the day l had it (and l didnt know it) its like a different car......

also considering its got muffler deletes, and l discovered its running a fidanza flywheel and a modified prom

Jeeeeeeeeeeeeeeeezus

I was physically numbed by the difference.....l got out of the car after giving it some WOT feeling something l cant put into words

wouldnt have considered this job without the previous comments from you guys

:worship:

Thanks

David

PS....now l have to work on something to keep the nose on the ground.....steering now feels way to light when l floor it....maybe too much squat

my red 90 also has secondary vac probs and driving it now clearly shows that the secondaries dont work......slowwwwwwwwwww

[Pete]

well l did the secondary actuator plumbing removal on my yellow92

and........

OMG what a difference......its like day and night :dancing

and considering its been running without operational secondaries since the day l had it (and l didnt know it) its like a different car......

also considering its got muffler deletes, and l discovered its running a fidanza flywheel and a modified prom

Jeeeeeeeeeeeeeeeezus

I was physically numbed by the difference.....l got out of the car after giving it some WOT feeling something l cant put into words

wouldnt have considered this job without the previous comments from you guys

:worship:

Thanks

David

PS....now l have to work on something to keep the nose on the ground.....steering now feels way to light when l floor it....maybe too much squat

my red 90 also has secondary vac probs and driving it now clearly shows that the secondaries dont work......slowwwwwwwwwww


Can you tell us how much low end power you lost and how many times your car backfired and how badly it chugs in traffic. :)

Some like having the power key,for those that really don't care for it and don't wanna pay big dollar parts,this is the way to go.:thumbsup:


Pete

[xxxscimitarxxx]

seemingly l have gained in all areas.......low end was like a rocket.....and no chugging....and l never drive with power key off

why should it have have been as bad as you suggest if all the previous comments said l would never miss it

[Pete]

seemingly l have gained in all areas.......low end was like a rocket.....and no chugging....and l never drive with power key off

why should it have have been as bad as you suggest if all the previous comments said l would never miss it



Just a little humor with a mix of sarcasm.
Was just trying to make a point for those out there who think it will loose and drive like crap.


Pete

[jonszr1]

sound lie a winter project for me .pete was there much difference i fuel milage on the freeway ?. i do have to have the prom redone when i do this ,correct?.ps hope you get that 10 sec .run on the 26th:thumbsup:

[Pete]

sound lie a winter project for me .pete was there much difference i fuel milage on the freeway ?. i do have to have the prom redone when i do this ,correct?.ps hope you get that 10 sec .run on the 26th:thumbsup:


Brad i have not checked the feul economy but i would think if the car holds 14.7 AFR at cruising speeds i don't see why MPG would change.

Thanks Brad i will surely give it my all for that 10 second pass.
I'm using a friends 4.10's i hope the extra shift won't hurt my ET.
I'm still getting used to the 4.10's i admit they suprised the heck out of me at BG, how fast it was going thru gears.
BG was the first time i ran the 4.10's.
Ran 11.1 @128 1.69 60ft it was 80+* and very humid.

Pete

[jonszr1]

410s are kinda fun when you get used to them. ajust in case tip ,if the track is a little slick past the 60ft mark .i found when it is . if i short shift1 to 2 @6000-6200 i gained almost .2 tenth because she didnt spin .somethin tellme your going to do it on the 26th,juat a feelin . sure wish i could be there .you guys knockem dead :thumbsup::thumbsup:

[bdw18_123]

Too bad I can't remove my secondary system, since California emissions are very strict. :mad: I probably wouldn't pass emissions test if I did this mod. Same with long tube headers, Californians can't have 'em. :mad:

[tf95ZR1]

Same with long tube headers, Californians can't have 'em. :mad:

:-D

[tccrab]

Too bad I can't remove my secondary system, since California emissions are very strict. :mad: I probably wouldn't pass emissions test if I did this mod. Same with long tube headers, Californians can't have 'em. :mad:

Ben:

While this is technically true, there are NO "CARB Approved" long tube headers (or short, or any other kind of header) available for the ZR1, nor has there ever been any.
But.....
However....
In accordance with Kalifornicate law, you cannot buy a "Used" catalytic converter. Period.
It's against 'da LAW.
Do not pass go, do not...well you get it.

OK, Ok, now were getting to the good part....
There are no NEW '90-'92 ZR1 exhaust manifolds with the catalytic converter integrated available from GM.
Zip. Nada. Big "0".
Haven't been any for years and years.

While you still must have all the original smog equipment, (air pump, tubes, blah blah blah), you can have headers and aftermarket cats, as long as the cats are 50 state legal and the headers have the air injectors in place.
You will need to make an appointment with the SMOG "Nazi" Referees and be prepared to PROVE that there aren't any more "NEW" exhaust manifolds/Catalytic converters in the GM inventory. (a note from a local GM dealer will suffice).
Be prepared to spend some time and that it likely will take at least three trips to the Naz....er...."Referee" until you finally get the waiver.

The '93 -'95's have removable Cats, and so they are screwed.
/Soup Nazi/ NO HEADERS FOR YOU!!! /Soup Nazi/.

TomC
"Crabs"

[bdw18_123]

... The '93 -'95's have removable Cats, and so they are screwed.
/Soup Nazi/ NO HEADERS FOR YOU!!! /Soup Nazi/.

TomC
"Crabs"

Lol! :mrgreen: Ahh yes, the satisfaction of finding a loophole! Thanks Tom, I'll keep that info in mind... :thumbsup:

[jonszr1]

or you can live in inyo county. where we only have to smog our cars when we buy them/ . so we smog them then mod them .if we sell a car we just put it back to stk:mrgreen:

[xxxscimitarxxx]

I dont envy your smog laws in US....but here in UK l think we have tougher general standards, pretty much like all of europe these days

checks for foot brake and park brake efficiency
checks on all lights fitted, operation, alignment etc
chassis and panel corrosion
wind screen conditon
wiper condition
screen wash operation
seat belt securement and operation
seat securement
tyres
brake pipes
bearings
bushes
battery securement
horn operation
door latches
mirrors
exhaust leaks
exhaust securement (if cat required after certain year of manufacture it must be present)
ad finally CO2

you can be pulled over and checked for any of these things and busted

the trick for US car owners in UK is to find a freindly test station.

from my trips to US l have seen some pretty rough cars on the road that might pass smog tests but are a threat to all other vehicles or pedestrians anywhere near them

where l am now in Ukraine.....its much worse...the older cars are death traps..and all the drivers really need is enough cash to bribe the cop that pulls them over...

point in question.....last week l had about 2 shots of cognac at 6-7pm in the evening......8am following morning l go fishing.....drive down road.....pulled over....cop 'says' he smells alcohol.....breath tested.....positive (really....after 13 hours....breath tubes have previously been found to have been dipped in vodka by the police....but on the other hand they do have a zero alcohol tolerance in Ukraine and there could have been a trace left).....so choices?

do the protocol...ukrainian paper work....car taken...3 months later go to court get $500 fine....get car returned etc etc

or

come to an agreement with the cop where he follows me to an ATM and takes $100......

no contest :-D

there is something about corruption here in Ukraine that l like.....its manageable.

[bdw18_123]

I dont envy your smog laws in US....but here in UK l think we have tougher general standards, pretty much like all of europe these days

checks for foot brake and park brake efficiency
checks on all lights fitted, operation, alignment etc
chassis and panel corrosion
wind screen conditon
wiper condition
screen wash operation
seat belt securement and operation
seat securement
tyres
brake pipes
bearings
bushes
battery securement
horn operation
door latches
mirrors
exhaust leaks
exhaust securement (if cat required after certain year of manufacture it must be present)
ad finally CO2

you can be pulled over and checked for any of these things and busted

the trick for US car owners in UK is to find a freindly test station.

from my trips to US l have seen some pretty rough cars on the road that might pass smog tests but are a threat to all other vehicles or pedestrians anywhere near them

where l am now in Ukraine.....its much worse...the older cars are death traps..and all the drivers really need is enough cash to bribe the cop that pulls them over...

point in question.....last week l had about 2 shots of cognac at 6-7pm in the evening......8am following morning l go fishing.....drive down road.....pulled over....cop 'says' he smells alcohol.....breath tested.....positive (really....after 13 hours....breath tubes have previously been found to have been dipped in vodka by the police....but on the other hand they do have a zero alcohol tolerance in Ukraine and there could have been a trace left).....so choices?

do the protocol...ukrainian paper work....car taken...3 months later go to court get $500 fine....get car returned etc etc

or

come to an agreement with the cop where he follows me to an ATM and takes $100......

no contest :-D

there is something about corruption here in Ukraine that l like.....its manageable.

Wow, I didn't know the UK required checks of all that non-engine stuff. Sheesh, that would really suck. :thumbsdo: I guess the moral of the story is, it could always be worse.

[blackjack]

sooooooo.....
is it possible for somebody to sum it up for me? (secondary plates removal)
is there a step by step procedure in the archives?
just want to make sure i dont have to remove the plenum 5 times..
also,is a reworked chip a necessity?
if one is to remove the shafts too,what do you use to block the holes?
car is suffering from vacuum leaks-pump running most of the time-and ive got those nice van deventer heads in the basement
thanks
bj
91/1735

[rkreigh]

for sure the chip changes are needed, and Marc just revised the programming so he can eliminate another sensor. some considerations for those considering this (I took the plunge)

the car will run JUST fine with the right chip programming and no secondaries, the program changes to the memcal are down pat and Marc and others can make it work just fine.

there is NOT a big HP increase as the secondaries when open really don't restrict the flow much. mark showed me the injector housings and the estimates are in the handful of HP range. I did notice improved throttle response but much of that is in Marc's better programming. didn't pick up any top end HP (that was a surprise) but I didn't lose any bottom end and picked up just a bit of mid range torq. to really take advantage of removing the secondaries, it would be best to port the heads to take advantage of it.

emission, yup, there is the problem. but you can probably do OK. Graham confirmed that was of the reasons for the secondaries was to decrease emissions. think about it. it increased the "swirl" and flow veloticy when the engine is just cruising. the LT5 due to the combustion chamber and piston (crevice volume) design is a bit dirty on HC, especially when you just put around all the time.

there is where I'm having troubles. I have a 390 with the big valves and cams, and VA cut the emissions standards from 98 HC to 48.

BEST I could do with the old setup was 98 on a 98. I'm now up around 138 HC and this is with a closed loop chip. not sure what to do next go around. when I talked to marc about an "emissions chip" he stated that if the chip monitors the O2 and calibration is good, not much more can be done.

but I'm not going to pass next time. Marc recommended fresh cats, as I likely poisoned the last set running the car so rich. that's probably what I'll try.

the biggest thing I love about no secondaries is the immediate throttle response and lack of complexity. a few less things to go wrong and worry about and I was able to help out some members with some much needed parts *(that I sold way too cheap!!)*

for a stock displacement car, with the secondaries working well, it's probably much more hassle than it's worth. even on the big strokers it's really not worth much unless you are enlarging the ports in the heads at the same time.

but as said (my fav saying) "parts left out don't break or cost much":mrgreen:

[Aurora40]

emission, yup, there is the problem. but you can probably do OK. Graham confirmed that was of the reasons for the secondaries was to decrease emissions. think about it. it increased the "swirl" and flow veloticy when the engine is just cruising. the LT5 due to the combustion chamber and piston (crevice volume) design is a bit dirty on HC, especially when you just put around all the time.
I'd *guess* the main problem is that the cam profile on the secondary intake is much more aggressive, and overlaps more with the exhaust.

[billybaloneey]

Reliability, simplicity, and more air flow!


Looks tell the story: Simple is a good thing!

http://i185.photobucket.com/albums/x220/6PPC_bucket/tech%20files/ZR-1009.jpg

FWIW,

P.

Paul - I noticed you removed the secondary shafts...according to the picture. How did you get the bearing out...they are staked (the term used in the FSM), or another way to describe it, a punch was used to dimple the IH in three places around the bearing? What did you use to fill in the holes once occupied by the bearing?

[VetteVet]

I removed my shafts and used 16MM freeze plugs made by Dorman. I got them through Rock Auto.

[billybaloneey]

I removed my shafts and used 16MM freeze plugs made by Dorman. I got them through Rock Auto.

Ahh...16mm...is the hole size...good to know.

Thanks

[Paul Workman]

Paul - I noticed you removed the secondary shafts...according to the picture. How did you get the bearing out...they are staked (the term used in the FSM), or another way to describe it, a punch was used to dimple the IH in three places around the bearing? What did you use to fill in the holes once occupied by the bearing?

Sorry it took so long to get back to ya!

Per Pete's suggestion, I slipped a short socket over the shaft and bearing, and put a fender washer over the shaft. Then I screwed the nut from the throttle plate down on the washer (with some grease under the nut) and the shaft pulls right out!

In my case, there is a machined relief around the bearing. Finding a socket that would stay inside that flat relief circumference and not impede the bearing's coming out, I took my die grinder and ground the inside of the socket down enough to allow the bearing to clear the socket as it was drawn out. Piece o' cake!:thumbsup:

Hope this helps.

P.

[billybaloneey]

Sorry it took so long to get back to ya!

Per Pete's suggestion, I slipped a short socket over the shaft and bearing, and put a fender washer over the shaft. Then I screwed the nut from the throttle plate down on the washer (with some grease under the nut) and the shaft pulls right out!

In my case, there is a machined relief around the bearing. Finding a socket that would stay inside that flat relief circumference and not impede the bearing's coming out, I took my die grinder and ground the inside of the socket down enough to allow the bearing to clear the socket as it was drawn out. Piece o' cake!:thumbsup:

Hope this helps.

P.

What did you use to cover/fill the holes left by the bearing once they were removed? VetteVet posted a reply that he used 16mm freeze plugs.

[billybaloneey]

I removed my shafts and used 16MM freeze plugs made by Dorman. I got them through Rock Auto.

Is this the one you used?
15.78mm is real close to 16mm


http://i128.photobucket.com/albums/p194/billybaloneey/LT5%20Engine/16mmfreezeplug.jpg

Dorman Cup Type Expansion Plug: Steel; 15.78mm; 10 Per Package 555011

(Dorman - 555011, B001C0F6Z6)



Description:

Nominal Dia. : 15.78mm
Metric Dia. : 15.78mm
Type : Steel
Height : 0.232"
Closed End Dia. : 0.615"
Open End Dia. : 0.630"

[Pete]

If the 555-011's go in too loose.
Try the 555-108 freeze plug.

I have used the 555-108's on about a dozen heads with no issues.

Nominal Dia.: 5/8"
Metric Dia.: 15.90mm
Type: Steel
Height: 0.220"
Closed End Dia.: 0.633"
Open End Dia.: 0.642"
Brand: Dorman - AutoGrade - Boxed


Pete

[Paul Workman]

What did you use to cover/fill the holes left by the bearing once they were removed? VetteVet posted a reply that he used 16mm freeze plugs.

I used the Dorman 555-011s, but I had to splay them with a socket to make them fit snug. Then, just to be on the safe side, I coated the plugs with JB Weld before installing them to make sure they sealed perfectly.

I tried the 555-108s that Pete suggested, but I couldn't get them to work. It probably was due to the fact I was using a socket (to drive the plugs in) that just fit inside the rim of the plug and wasn't allowing the plug to be swagged into the bearing recess. Had I used a smaller socket, or just a socket extension, then they might have fit better (according to Pete).

P.

[VetteVet]

I pulled my receipt and it was definitely the 555-108's that I used. They were a snug fit, but that's a good thing. ;)

I used red Loctite to seal and used a socket that filled most of the cup, but allowed the sides to flex when driving them.

[billybaloneey]

I pulled my receipt and it was definitely the 555-108's that I used. They were a snug fit, but that's a good thing. ;)

I used red Loctite to seal and used a socket that filled most of the cup, but allowed the sides to flex when driving them.

I picked up 8 of the 555-011's at O'Rielys yesterday...they were only $0.49 each. I'll do a test fit/installation, and if it's to loose I'll try one of the 108's. If I have an odd size secondary bearing hole, I'll try Paul's approach...JB Weld.

NOTE THIS DAY IN ZR-1 HISTORY: a part used on a ZR-1 only costing $0.49

[ZR1 MK]

It IS as simple as removing the secondary vacuum pump associated hardware, actuators, and even the friggin throttle plates too! P.
Paul
Are you stating you removed the the whole system and the engine runs fine?

I have the throttle plates and linkage removed plus the holes plugged, but the vacuum pump, vacuum canister, solenoid and most of the vacuum tubing is sill connected. My engine builder told me this part of the system still needs to be in place, but Id like to remove it all.

What do you know that he doensnt? Is there hope?

[XfireZ51]

Mike,

Some of us have a bypass for the ECM/Diff MAP signal.
=Jeff= or myself can make you one. Pretty simple mod.

[ZR1 MK]

Mike,

Some of us have a bypass for the ECM/Diff MAP signal.
=Jeff= or myself can make you one. Pretty simple mod.

Simple sounds good.

Whats involved? Cost? Does my current chip program stay the same?

[XfireZ51]

Mike,

I still have my throttle plates in the bores and attached to the actuating mechanism. However, the vacuum canister is zip tied open so plates are perpendicular and open at all times. The prom is modified to have secondaries open from throttle tip in. At TPS = Idle, secondaries are off.
Anywhere over that, secondaries are on in my cal. For me its easier to tune one set of VE/SA tables rather than two. VE LOW (Port Throttle Closed) is the one I use for idle conditions. All other driving conditions use the VE LOW and HIGH (Port Throttle Open) tables. Spark Tables are setup the same way. MPG isn't really affected because in either case, the motor uses x amount of fuel. It'll just be delivered by 2 sets of injectors rather than one.
As for the bypass, its the cost of the correct male connector for the Diff MAP harness. I already had one, so I would need to check on cost.
BTW, we tried my cal with Lgaff's 92 and it ran fine at the track. His secondaries are still operational.

[Pete]

Mike
Doms,plug will elimanate vacuum pump,vacuum canister etc, the only part you need to keep electric solonoid needs to be pluged in (no vacuum).

That's it.:thumbsup:


If your prom cal was done for no secondaries then your good to go with Doms part, plug and play.

Pete

[Paul Workman]

I opted to remove everything. Marc Haibeck provided me with a prom designed to satisfy the ECM that everything was "OK", even with everything removed except the vacuum senor located under the ECM (on a 90), which must remain and be left open to the air (as Pete said).

I'm sure the refinements in Marc's chip have more to do with how it runs w/o the secondary stuff than simply running without it. But, the drivability with Marc's chip in it is supurb: quicker throttle response, smooth transition from light to moderate to full throttle (or any combo thereof:thumbsup:), and fuel economy remained essentially unchanged, far as I can tell.

In summary, I'd have to say there have been no down-sides to eliminating the secondary system from a driving point of view: if anything it is improved! In some states emissions testing may put a wrinkle in things - IF anyone would know what to look for and be able to see it if they did.

Hope this helps

P.

[ZR1 MK]

Mike,
I still have my throttle plates in the bores and attached to the actuating mechanism. However, the vacuum canister is zip tied open so plates are perpendicular and open at all times. The prom is modified to have secondaries open from throttle tip in. At TPS = Idle, secondaries are off.
Anywhere over that, secondaries are on in my cal. For me its easier to tune one set of VE/SA tables rather than two. VE LOW (Port Throttle Closed) is the one I use for idle conditions. All other driving conditions use the VE LOW and HIGH (Port Throttle Open) tables. Spark Tables are setup the same way. MPG isn't really affected because in either case, the motor uses x amount of fuel. It'll just be delivered by 2 sets of injectors rather than one.
As for the bypass, its the cost of the correct male connector for the Diff MAP harness. I already had one, so I would need to check on cost.
BTW, we tried my cal with Lgaff's 92 and it ran fine at the track. His secondaries are still operational.

Im a bit confused, but Im guessing you sell a custom made electric MAP connector?

Mike
Doms,plug will elimanate vacuum pump,vacuum canister etc, the only part you need to keep electric solonoid needs to be pluged in (no vacuum).
That's it.:thumbsup:
If your prom cal was done for no secondaries then your good to go with Doms part, plug and play.
Pete
That sounds good. Thanks for the clarification.

[DScott600]

I should have wrote this sooner but I deleted the secondaries shortly after I started this thread and I am very happy with the results. I purchased a chip from Mark, removed the entire secondary system except for the sensor under the ECM and wire tied and safety wired the secondaries open. I didn't notice any difference at low speed and Marks tune has improved the idle and gave it more power. In the future I plan on getting the injector housings and plenum ported and powder coated and while I have it all apart I will remove the throttle plates. It's so good to not have to worry about a secondary vacuum leak area under the plenum is much nicer looking without the rats nest of hoses. Thank you for all the advice.

[tccrab]

What about us unfortunates who live where the dreaded SMOG Nazis prowl?
Would removing the secondaries affect emissions to the point of failing our bi-annual inspection?
I would love to be able to ditch them, one less thing to go wrong.

TomC
"Crabs"

[Paul Workman]

What about us unfortunates who live where the dreaded SMOG Nazis prowl?
Would removing the secondaries affect emissions to the point of failing our bi-annual inspection?
I would love to be able to ditch them, one less thing to go wrong.

TomC
"Crabs"

Just an opinion, but it seems to me that as long as modifications are limited to how many injectors are operating (in closed loop), i.e., no other mods are done except for porting, it seems logical that a prom with the appropriate tune should be able to operate two (instead of one) injectors and maintain the proper air/fuel ratio. Two injectors instead of one does not spell emissions failure; only the air/fuel mix would do that (all else being the same such as cam profile and timing, etc.).

But, this would be a question for Dom or one of the pro tuners out there. However, I'll be comfortable placing most of my "chips" on the square marked "won't affect emissions".

So, what do some of the tuner experts say?:happy1:

P.

[ZR1 MK]

What about us unfortunates who live where the dreaded SMOG Nazis prowl?
Would removing the secondaries affect emissions to the point of failing our bi-annual inspection?
I would love to be able to ditch them, one less thing to go wrong.
TomC "Crabs"
It shouldnt matter.

FWIW, NY emission standards are high and cant be far from CA standards. My 427 with larger than stock cams passed well within the limits.

Reliablity is my main concern and why Id like to eliminate as much as possible. I do bring an extra solonoid to track events just in case, but id be nice to not even need it.

[XfireZ51]

Just an opinion, but it seems to me that as long as modifications are limited to how many injectors are operating (in closed loop), i.e., no other mods are done except for porting, it seems logical that a prom with the appropriate tune should be able to operate two (instead of one) injectors and maintain the proper air/fuel ratio. Two injectors instead of one does not spell emissions failure; only the air/fuel mix would do that (all else being the same such as cam profile and timing, etc.).

But, this would be a question for Dom or one of the pro tuners out there. However, I'll be comfortable placing most of my "chips" on the square marked "won't affect emissions".

So, what do some of the tuner experts say?:happy1:

P.


Paul,

You're on the right track. I have a WB on my car and motor idles and runs at 14.4 to 15.1. BLMs are between 124-131. With secondaries operating the pulsewidth for each set of injectors drops depending on where in the VE table you are. Essentially the aggregate pulsewidth for idle and part throttle cruise will be the same regardless if one or two injectors is (are) feeding the cylinder.
I wonder if it isn't better to have both injectors operating in terms of reliability?

[Locobob]

If the 555-011's go in too loose.
Try the 555-108 freeze plug.

I have used the 555-108's on about a dozen heads with no issues.

Nominal Dia.: 5/8"
Metric Dia.: 15.90mm
Type: Steel
Height: 0.220"
Closed End Dia.: 0.633"
Open End Dia.: 0.642"
Brand: Dorman - AutoGrade - Boxed


Pete

Went to NAPA today and asked for the Dorman 555-108 - they came up with nothing??? What gives???

[Pete]

Went to NAPA today and asked for the Dorman 555-108 - they came up with nothing??? What gives???


I don't know why Napa couldn't find them.

I know the Dorman Part # is good.

The only thing i can say is try a different parts store or i can send you a set as a Christmas gift,will have to wait till next week,i'm out of town.

Pete

[Jeffvette]

Went to NAPA today and asked for the Dorman 555-108 - they came up with nothing??? What gives???


http://www.summitracing.com/parts/RNB-555-108/

[Locobob]

Found them at Baxter :thumbsup:

[Paul Workman]

Paul,

I wonder if it isn't better to have both injectors operating in terms of reliability?

Good question. There are a number of things that will result in the secondaries being shut off. My concern is that all the secondary 'stuff' controlling the secondary injectors is still used. If for any reason the ECM turns off the secondaries, suddenly the aggregate injector dwell time is cut in half:jawdrop:.

So...it shouldn't be a biggie to bypass the control and activate the secondaries or "latch" the secondary system to always be on. It will (in the case of Marc's chip) require a modification (by him) to accommodate the second injector being on at idle (Marc's chip runs only one injector at idle).

P.

[VetteMed]

When the secondaries are removed, does the purge solenoid (the one with the red connector) need to remain under the plenum, or can it be removed with the other solenoids?

[oricale]

How much is the chip required for the secondary change???

[Pete]

When the secondaries are removed, does the purge solenoid (the one with the red connector) need to remain under the plenum, or can it be removed with the other solenoids?


No,does not need to remain.
or
Yes,it can be removed.

Pete

[VetteMed]

How much is the chip required for the secondary change???

It's not cheap... I think I remember paying $350 or so?

[GOLDCYLON]

On the 91 what exactly can be removed? The spide,r the purge solenoid obvisouly the vaccum secondary actuators. Does the 91 require the underside ecm plug?

[VetteMed]

I am still running the purge solenoid, since I don't like a car that smells like gas on a hot day... But if you wish to remove it I don't think the ECM will care.

The sensor under the ECM just has its vacuum line unplugged/removed, the electrical connection remains.

Under the plenum, the vac storage canister, the secondary solenoid, and of course all the secondary hardware, is all removed. Vacuum pump is also removed.

[sammy]

corey did mine different . i have a rubber vac line from map sensor under the ecm to my vac pump . said they did thid on the bonniville car so the secondaries didnt shut down on the long bonniville runs .4 miles in think

[LancePearson]

Does an emissions chip retard the timing substantially?

[Kevin]

How much is the chip required for the secondary change???

i think it's around $250 if you have marc do it

[XfireZ51]

How much is the chip required for the secondary change???

Depends on what else you want done and if you want the cal on your current memcal or for a piggyback chip.

Dominic

[XfireZ51]

BTW, If you're removing 2ndaries, I am looking for hose that connects to passenger side vacuum fitting, mid plenum.

[XfireZ51]

Thx, Dyno. If anyone has a spare let me know. I may be pulling the plenum in the near future and would like to replace it then. The hard line broke and its cobbled together right now. I HATE vacuum leaks so I'd like to make sure I don't get one.

[sammy]

i might have one i will ck tomorrow and let you know

[XfireZ51]

i might have one i will ck tomorrow and let you know

Thx Brad.