New ZR1 owner

[Mitsumark]

Hello ladies and gents.I am the new owner of a 91 ZR1 #170.From what I've been told,and basing on the huge portfolio of documents the car came with,it belonged to a former member here named Rick Minson..The car seems to be pretty well modified from what I can see,and from the documents.It seems Mr Minson spent a ton of coin at The Vette Doctors in NY somewhere around 93.That receipt consisted of a 368 Ci engine build that cost 18k alone..That doesn't include the other massive amount of mods done to the suspension,exhaust,cooling system,ect..The kicker is that it seems the car was built and it must of sat for years as mileage is only 9k more now than it was back in 95 according to Carfax and maintanence records..I've listed a link to the car below as if anyone here knows Mr Minson or the car,I'd love to hear about it..The reason why Im posting is the car seems to have developed a slight misfire.I have a document that states the coils were replaced in 2010.I also have confirmed the injectors were replaced with FIC SS injectors just last year..I know a spark misfire when I feel it and Im suspecting the coils were replaced with Chinese junk and not Delcos as the car sat at a small car dealer before it came into my possession..I've already installed a current EPROM for my build by Marc Heibeck.Ive also confirmed there are absolutely no vacuum leaks.That includes the PCV valve connections,and the MAP to Plenum hose..I'm convinced I have a bad coil,thus requires removal of the plenum..Here's my dilemma..I plan to remove the plenum to replace the coils with Delcos..During this time I'd like to totally eliminate my secondaries and it's components..I will send my chip back to Marc for a recalibration..Is there any members local to the NJ area as I am not confident doing this myself the first time around..I would love to watch,help,and learn the first time around..I would also be happy to pay somewhere for there time..I can even come to you..If anyone is interested,please email me.Id really feel better knowing someone with an experienced LT5 hand was there..Thanks..

http://cgi.ebay.com/ebaymotors/NO-RESERVE-1991-CORVETTE-ZR-1-RX500-Vette-Doctors-ZR1-Race-SCCA-/321151682704?_trksid=p3984.m1438.l2649&ssPageName=STRK:MEWAX:IT&forcev4exp=true#ht_49605wt_1021

[efnfast]

Welcome to the forum, sounds like a nice find. I can't imagine you'll have any trouble finding help with the plenum pull.-Steve

[PhillipsLT5]

WOW!

[ZZZZZR1]

Congrats!!!

Great car and lots of documentation!!!

Have you ever been to Corvettes of Carlisle? If not, our club is one of the largest @ the event!! Great way to meet people and learn about your car if you are interested.

It's in Carlisle PA and there are quite a few coming from New Jersey.

Event is August 22 thru 24

http://www.carsatcarlisle.com/ce/events/corvettes/

There will be over 100 ZR-1's there and likely 200+ owners over 3 day's of the event.

Any questions, feel free to post up or send me a PM.

Congrats on your purchase and hope you meet you @ this great event.

:cheers:

David

[msorenso]

I am new to the forum this year and also a new owner to a nicely modified 91 ZR1. It has been my dream car since high school which in those days it was the KING!!!! My Jr year was the ZR1 last:cry: With that there are alot of great people here and TONS of help with anything! Welcome and enjoy this incredible forum!!!:cheers:

[XfireZ51]

There's a couple of ways of "eliminating" secondaries. You can do it physically by removing everything, or you can leave the mechanicals in and tie wrap the secondaries open, which is what I did initially. The calibration for either is essentially the same. Up to you how much u want to do.

[jimmy b.]

Congrats Mitsumark on the Zr-1, is this your first corvette? Where in New Jersey do you live? there's a few of us here. I live in Northwest NJ just off x-25 RT80.

First if you don't have a factory service manual (fsm) get one. When I had a miss I followed mine and it helped me fine a bad 5-8 coil. Lots of info in them. Also just cause some parts are new don't rule them out check em too.

There's a lot of great people on this forum, don't be afraid to ask questions thats how we all learn more about the car we love.

Some of the guys put on repair clinics in their areas and some of them are not too far from us.:thumbsup:

[Mitsumark]

Thanks for the warm welcome guys..Ive been a car guy my whole life..However,this is my first Vette..I've been trying to do as much reading as possible to avoid asking what I'm sure has been answered a million times..It sure sucks being the new man in class..Anyway,yes..I do have a few drivability issues..For one,the car does have a stumble at low-mid throttle.It will break up a bit before it clears up and takes off..Also,even once it gets going,I can hear pre-ignition(pinging) and sometimes even slight detonation.I immediately take my foot out of it as I'm scared to hurt it..This happens with or without the power key on..Being this car was specifically Dyno tuned back in 93 right after the build,I figured it was tuned on old fashioned gas and could really benefit from a new tune..After reading about Marc H great rep,I spoke with him and I went with him..So far I've done his chip along with checking for any vac leaks.I have discovered that my secondary vac pump is innop as is will not cycle on.Ive confirmed this by connecting direct voltage.However from what I've read,this pump failure should have little or no effect on driveability,especially with the power key off..My problem occurs weather on or off.So although I have full documentation of a new Marc H chip,new NGK TR71X gapped at .50,new GM wires, and new FIC injectors.I have also checked for vac leaks and can't find any.Map sensor hose is new and attached at both ends.As stated earlier,this car sat on a used car dealer lot for a short span before I got it..Imcluded in the documents was full coil replacement from an outside source.I know they were changed as I can see the hand written #s on each coil from the previous installer.What I'm guessing is that non factory cheap coils were probably used.So my conclusion is I'm almost 100% positive I have a defective coil.Upon changing them I would love to rip out the secondary system as it seems to be a complex system with many fail able parts..Besides the miss,,I have a dyno sheet (vin specific) that says this car was making 423 rwhp..I know what 423 rwhp feels like and this car is not making anywhere near that now so something definitely isn't right.Im located in S.Plainfield NJ which is right in the middle of the state..Again if any knowledgable local members are close,provide me with a list of what parts I would need to fully remove my secondary system,plugs,seals,gaskets,ect and I will be happy to pay for your time.Im sure I can handle the plenum pull myself.What I'm a bit Leary of is removing all of the secondary parts and buttoning up all the loose ends..

[Dynomite]

What I'm a bit Leary of is removing all of the secondary parts and buttoning up all the loose ends..


Do NOT be Leary.......just post up and Learyness disappears ;)

And.......do NOT try to avoid asking what you are sure has been answered a million times because we do not learn from your experience in that regard.....so ASK AWAY

I always Change All Fluids (I add the Differential Drain Plug) and eliminate TB Coolant as the first step to cleaning the Valley and reconditioning the starter, coils, vacuum system and vacuum canisters.

Oh...and Jerry's Gaskets Jerry's Gaskets (http://jerrysgaskets.com/store2/root/) has every bolt and gasket you will ever need in any type of restoration you decide on. Also.....It is amazing what a can of Rustoleum can do (I have Powder Coated other Restorations).

http://i287.photobucket.com/albums/ll142/dynomite007/A%20Corvette%20LT5%2090/49b05cc4-bb84-4449-af48-80241b98e38a.jpghttp://i287.photobucket.com/albums/ll142/dynomite007/A%20Corvette%20LT5%2090/37cdb647-2dda-449e-8d0d-57905f95ecfd.jpg
http://i287.photobucket.com/albums/ll142/dynomite007/A%20Corvette%20LT5%2090/8e46b8a0-fd42-44c0-b89b-e3e8f15bab7f.jpg

Before Top End Restoration but with Carter Bling
http://i287.photobucket.com/albums/ll142/dynomite007/A%20Corvette%20LT5%2090/LT52m-1.jpg

After Top End Restoration (with Secondaries NOT eliminated on this one)
http://i287.photobucket.com/albums/ll142/dynomite007/A%20Corvette%20LT5%2090/f1e67ee1-dca6-4b7e-b799-feb1ba5026d5.jpg

[Mitsumark]

Thanks Dynomite..Really appreciate the hospitality.Fortunetly for me it seems the original owner spruced up the engine bay quite nice already.Ok gents..Since my last post,I've verified the old fashion way that I have atleast 1 weak coil.I used the old removing the wire method as I don't have a spark plug tester on hand.I'm getting very strong arching sound to ground on 6 cylinders.The other 2 sound very weak with spark noise coming and going..The coils are definitely in order.I feel it in my gut that there's cheapies in there.The car probably came in on trade with driveability issues and the dealer sent it out to a private garage where they put in new coils(per the receipt).Now onto the secondaries..In your honest opinions,do you guys recommend replacing the faulty vac pump and retaining the secondary function?Or is failure imminent being the car is an old lady.Im not sure if it matters but I forgot to mention before..Pumping air into the hose via the passenger side of the plenum,there are no leaks.it held vacuum for 3 hrs rock solid before I removed the gauge.I also have absolutely no trouble codes through this whole ordeal.Besides my faulty pump,does it sound like my secondary system is fully operational?

[Dynomite]

Thanks Dynomite..Really appreciate the hospitality. In your honest opinions,do you guys recommend replacing the faulty vac pump and retaining the secondary function?Or is failure imminent being the car is an old lady.

Short answsere........failure is NOT imminent being the car is an old lady.....that car is definitley NOT an old lady

I kept the secondaries on a 90' and removed the secondaries on a 91'.......just because.......because I like experimenting and both the 90' and 91' perform peeeeerrrrrfectly ;)

[Mitsumark]

I just think I would benefit from removing the system as it seems it has many occasions of failure in some way.I sure dont want to be removing the plenum everytime there is a drivabilty issue.I would be able to automatically rule out all those associated parts.ive also read on this very site of very rare occasions of secondary port parts(linkage & hardware) being ingested into cylinders and jamming valves.If I have the option to avoid that its a no brainer.I guess Im answering my own question as Im typing.If I do decide to temporarily keep secondary operation,anyone here have a working vac pump or know where to get one?

[Dynomite]

I just think I would benefit from removing the system as it seems it has many occasions of failure in some way.I sure dont want to be removing the plenum everytime there is a drivabilty issue.I would be able to automatically rule out all those associated parts.ive also read on this very site of very rare occasions of secondary port parts(linkage & hardware) being ingested into cylinders and jamming valves.If I have the option to avoid that its a no brainer.I guess Im answering my own question as Im typing.If I do decide to temporarily keep secondary operation,anyone here have a working vac pump or know where to get one?

That happened to Daryll (Goldcylon) and that was extremely rare. Actually there are NOT hardly any occasions of failure of secondaries once they are maintained and it is just as much fun to leave them as it is to remove them :p

Also rare are broken timing chains which I have heard of two.

There are more failures associated with injectors but once replaced they last a very long time (That applies to almost every part on the LT5....once replaced if required....they last a very long time). As far as pulling the Plenum......I can pull a plenum in less than 10 minutes if you do not have to mess with coolant ;)

It is the first time cam cover removal (Torx 40s) with engine in car that is a BEAR :censored:
I had five Torx 40s that WOULD NOT come out without considerable encouragement which I found the secret medicine.

http://i287.photobucket.com/albums/ll142/dynomite007/Maintenance%20ZR1/c8db244c-9a15-4253-b644-064d00579b8c.jpg

TOP END RESTORATION
Post 29 - Plenum Pull (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581458206)
Post 30 - LT5 IH, Fuel Rails, Plenum Install Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581458207)
Post 31 - Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581460752)
Post 32 - Eliminated IH Housing and Throttle Body (TB) Coolant system Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581460754)
Post 33 - Eliminated Secondary Throttles/shafts Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581460759)
Post 34 - Stainless Steel Air Box and Air Filter (L98 and LT5) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581460762)

Post 63 - Removing Plenum (including the 10 minute Plenum Removal) (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-4.html#post1581663365)

[PhillipsLT5]

When you get the issues sorted out, this motor should pull 540 HP aprox. at crank depending on tune, porting etc. it should really scream

[LancePearson]

I didn't read each post but since the engine was re sleeved to bigger and perhaps ported and relieved it's possible you will find the secondaries are already out....

[We Gone]

Congrats and Welcome is about all I can add.....:cheers:

[XfireZ51]

Just a quick observation. I noticed you mentioned NGKs gapped at .050".
When did the miss start? I would either try re-gaping the plugs to .035" or just get another set of regular plugs like the NGK BKR6E at .035" and try that.

[Mitsumark]

Ok now that I have the car running again,I pulled the plugs back out and regapped them at .35..The misfire still persists..The secondaries are still in place as I see the vac pump and associated parts when peering through the plenum runners with a bright LED..I'm going to go ahead and order new coils.I take it the plenum gasket is not reusable?The car has quite a bit of porting so it looks like I'll be needing the Jerry's Gaskets plenum gasket kit also as they are already cut for ported plenums..I'm gonna throw in a new MAP sensor too just to rule that out..Maybe even a new knock sensor..Be patient with me guys..I have 20+yrs of catching up to do with you boys..If any of you Jersey guys are planning one of these repair/get together days I keep hearing about,please lemme know:-D

[LGAFF]

Did you check to make sure the MAP sensor under the ECM is plugged in????

[Mitsumark]

Ok boys.I did some more troubleshooting on the car today to try and track down my misfire and low rpm stumble..I started with checking for vac leaks,and operation of the secondary system.I used a vac pump to pump air into the plenum itself,vac gauge held solid..No leak..Next proceeded to put the vac pump on the small hoses on each sides of the drivers side and passenger side that control the cruise and HVAC,,and the other side that controls the secondary system..Both held perfect vacuum.No leaks found..Lastly I did a smoke test just to be 100% sure that there are no leaks.Passed with flying colors.So we have ruled out vac leaks which I was almost sure I didn't have anyway before I began.Next I tested the spark.Now remember as of now I am working with minimal ameatur tools and no FSM.. Here's where I'm stumped.I pulled of each spark plug wire one at a time and arched them to ground..Surprisingly each and every cylinder has what looks like weak spark to me.The arching is orange and small..My experience with healthy firing coils in the past tells me the spark should be bright blue and very thick..I was even zapped at one point while grounding the plug and it barely hurt..Although I have a receipt that says the coils were all replaced in 2010,what are the odds of every coil having weak spark.I wanna pull the trigger and order new coils and pull the plenum.However I don't want to waste $250 on parts unless I'm sure.What else could cause weak spark across the board?Heres a bit of history..I picked this car up in VA last month and drove it all the way back to NJ..It drove and pulled like a raped ape.The tune it had in it was from 2003 when the motor was built..It figured it was outdated and ordered a new tune..So from last month,these are the only things that have changed..Marc Heibeck 500HP chip,8 new NGK Iridium plugs, and I moved the IAT sensor to under the front bumper as the chip was calibrated for an external AIT...Since these changes, the exhaust smells very rich, a low RPM stumble/bogging,idles surging from 500 to 1200 rpm when pulled out of gear quickly,weak spark,pinging at low RPM,, and I just pulled all 8 plugs after 200 miles and they are loaded with dry carbon..I don't have the old chip to see if there are any changes as the tune was an exchange.Any of you LT5 guys have any clues for me because I'm lost.I forgot to mention I did disconnect the battery when I changed the chip as instructed..The car also has a new IAC valve and Delphi MAP sensor.The TPS has been reset.The car has yet to throw a CEL..