New ZR1 owner

[Dynomite]

Originally Posted by Mitsumark

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]

Originally Posted by 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?

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

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
I had five Torx 40s that WOULD NOT come out without considerable encouragement which I found the secret medicine.



TOP END RESTORATION
Post 29 - Plenum Pull
Post 30 - LT5 IH, Fuel Rails, Plenum Install Tricks
Post 31 - Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC)
Post 32 - Eliminated IH Housing and Throttle Body (TB) Coolant system Tricks
Post 33 - Eliminated Secondary Throttles/shafts Tricks
Post 34 - Stainless Steel Air Box and Air Filter (L98 and LT5)

Post 63 - Removing Plenum (including the 10 minute Plenum Removal)

[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.....

[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

[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..