95 lt1 engine.......symptoms....

Erratic idle at times (goes down to 500, up to 1000, stays usually at 750)
Misfires when revving it in neutral (cannot hold a certain RPM, it will misfire and fluctuate RPM's).
Misfires when driving around 1800+rpm's
At stoplights in gear it will bog down real low, then come back up, then go back down.

What I have done lately (last 500 miles):
Holley 52mm TB (adjusted TPS voltage back into spec)
Relocated IAT sensor into the end of the K+N conical
Replaced MAF with a polished stocker I got off ebay
Replaced coil with a MSD blaster, and used another ICM and bracket I had laying around
Added a MSD 6a ignition (plug and play)
Changed plugs to NGK TR55's (did not gap them, as I didnt have the feeler gauge, just stuck em in right outta the box).

Motor has been in the truck for about 3000 miles.
Taylor 8mm wires have about 5000 miles on them, look brand new.
Optispark was brand new 3000 miles ago
IAC was brand new 3000 miles ago

Any other questions, just ask. I have a feeling it may be the plugs not gapped right, but I dont want to pull them unless I have to.

Also, I cannot run a diagnostic right now on it since I do not have a ALDL port wired up into my truck yet.

Any help is much appreciated, sorry it was such a long post, just trying to be complete.

 

What is the status of the EGR?

 

It's blocked off and deleted out from the computer (s+p billet block offs and gaskets).

Also, air pump is gone.

o2 sensors are new within 2000 miles (only front two, rears are deleted, no cats)

Also, lt4 hotcam kit with cam, springs, 1.6RR's, have all been installed since the motor was installed about 3000 miles ago.

LT4 knock module, knock sensor has been deleted from the computer, herter programming on the pcm.

Ran great, but truck sat for about 5 months without being driven because of a bad tranny. I did crank it up once a week or so though. Added a new tranny and 3500 stall about 300 miles ago also.

 

Check your fuel pressure, coil wire for corrosion/connection, look for tears in the intake, vacuum leaks, leaks at the TB. Run it in the dark and look for a light show around the plugs/wires.

 

Check out my post from the other day about my problem....sounds very similar:

http://web.camaross.com/forums/showt...7&page=1&pp=15

My LT1 in almost completely stock and still in a 95 Z28 M6. Still have yet to find the problem....I took out the EGR and cleaned it and haven't run it yet...that's my last step before taking it to get a diag at a shop.

 

Fuel pressure is at 42, fuel pressure regulator is dry. Coil wire, coil are brand new, no corrosion and are connected well. TB is new, all new gaskets, no leaks. No vacuum leaks anywhere, have already tested that. No light show at night either, looked for that last night.

I did have a bad waterpump driveshaft seal, and it leaked alot of oil....but I dont think it messed up the opti. I think it is something recent I did.......I am gonna try changing out the MAF and ICM with another one, and redoing the IAC back in the original spot and see if that does anything.

 

Alright.......tried 3 known good MAF's, swapped the ICM, and swapped IAT's. Nothing helped. It will run PERFECT for about a minute or less, then it starts idling really erratic, then it stumbles when it is revved.

Also, I can rev it to 3000rpms at startup, and it will stay pegged on 3k. I can do this in about a minute when it starts acting up, and it will not hold it, it will go down to about 2600 or so.

 

Since you don't have a way to scan it, you don't know what temp the PCM is seeing. You might have a bad sensor in the water pump or a problem with that circuit. There are instructions for testing temp sensors on my Tech Page, but I have seen some people post that the sensor tests good at one temp and not at another. Just something to consider.

 

Hmm, I happen to have an extra one of those, I can try it out......just have to do it quick so that all the coolant doesnt leak out.

 

Replaced the ECT in the waterpump, didnt hurt, didnt help. Still is stumbling all over itself and not wanting to hold a RPM in neutral at all. I tried revving it to about 3000 again, and it just goes to almost 2200, and stumbles, then goes back up to about 2600.

 

Started it last night in the dark. I could see the spark around each spark plug (is that normal, it was not arching to the block, just a ring around the plug), but I could also see some arching by the coil bracket. When I touched the coil wire, where I touched it got white and looked like it was trying to arch to me.

 

Try checking your TPS. When we first got my car back it was acting very similar to yours, not wanting to idle or anything, and as it turns out the TPS was fried, I'm talking 0 volts at idle or any other setting.

 

TPS is perfect, .65 volts at idle, 4.9 at WOT.

 

I just noticed that blurb about your plugs. Start there. I just threw a new set of TR55's into my car and the gap on them was anywhere from .35 to .60. It may not fix the problem, but it may help smooth things out some.

 

I know it gets blamed for a lot of things, but my vote goes for the Opti. You said you had fluid leak on it. Also the car sat for a while then problem cropped up. I've had similar, oil leak, taken apart and not started for a while.

What I found was that the elec harness going into the opti had corroded. Enevitably ended up costing me the cost of another opti and harness. This time I dielectric greased the connector and did my best to further seal the opti case and haven't had problems in the past year. Might be worth checking that harness at the miniumum as it isn't to hard to get to.

Other than that, one other thought comes to mind is, did you use thermal compound on the bottom of the ICM, between it and the bracket? Seems it could be somehow heat related since it does it after short warming period. Just another thought anyway.

Good luck getting it sorted out.