All 95's are OBD1, and it will not detect misfires. It also has a OBD2 plug. I re-read your problem description, and it really sounds like you have a intermittent vaccumm leak. Most likely a sticking EGR valve.

 

hmmm....thanks...after I tested the IAC I started to look for the EGR....it's on the backside of the intake right? do you have a pic or know where to find one showing it? I checked all the vacuum lines I can find and all look and feel ok.

 

All 95's are OBDI. They have the OBDII connector because GM was getting ready for the switchover to OBDII in 96, but the scan tool communication only takes place on 1 wire. If a diagnostic connector is only for the ECM(not ABS or body or anything else) it will have 3 wiresower, ground, and communication. Actually, many newer cars communicate through the DLC via only 1 wire coming out of the PCM. I believe some Mercedes' have upwards of 80 computers and modules, all communicating through one data bus.

 

Search for "Shoebox", he is a member on this board. He has a link with pictures to most of the LT1 components. I believe he even has a testing procedure on it.

Anyways, EGR's usually fail when carbon deposits hinder the valve's ability to properly seat back into place. You can take it out and clean it with engine cleaner. It is worth a try. GM has a recall issued on this.

 

the egr is on the passengerside rear of the intake. 2 nuts hold it on.

 

ok found the EGR...what a PITA...I've replaced other EGR's and they've all been in the FRONT under the intake....what the hell...the more I work on this car the more assinine the engineering I find...

I knew they were hard to work on when I bought it but damn it's like GM TRIED to put every part in the worst place they could find on LT1's

 

Opti. When i let my car sit for more than a few mins the oil seal from the WP DS would leak down onto my opti and drench it in oil, although it looked it was originating from the front seal. BTW, it also revved at idle before and after starts, but worst on a start after it was running. My opti didnt set a code, but on scans while it revved it was showing the pcm the motor was turning 6700 rpm at a fast idle

When I took my opti apart the little optical eye had an oily film on it, and the bearing was messed up BAD. When it had run at at higher rpm it was spinning fast enough to "clean" itself of oil by flinging it off, and therefore not reaching the optical eye.

EGR is a no, it doesnt function at idle, and you said the car is running good.
IAC maybe, it opens to about 130 at startup and possibly could be getting stuck, you would have to scan to find out.
O2's are a no, since you said they the car works fine before shutoff, which is when the car shoud be in closed loop, but for the first 20 or so seconds after a hot startup, they should be fine.

I am telling you- opti opti opti.

 

Is it loaded up after sitting(black smoke from exhaust)? If it sets longer(2-3 hr's) does it do the same thing?How is your fuel pressure? Is the hose on the fuel pressure reg.dry?

 

nope not loaded up...no smoke ever (from anything on the car ) don't know about fuel pressure...have advice on how to check any of that? I do know I replaced the fuel filter a couple months back and when I pulled the lines off it sprayed good, so I must have good pressure. no fuel leaks of any kind either that I can see or smell.

 

ok...the oil seal where? WP DS? waterpump driver's side? I know the intake seal leaks on the car, but I would say 99 - 100% of the leaking is from the back of the intake, down the back of the block, onto the flywheel/clutch/trans. I had everything off the front just above the opti when I did the plugs - intake hose, alternator, all the coil and all that rat's nest of wires and I got a good look at the top of the opti and the block around it and it has typical seepage but nothing leaking bad enough to get inside the opti...I even pulled out the coil wire and the other connector and both had a clean connection inside. any more thoughts?

 

Try cycling the pump,by turning the key off and on,2-3 times before cranking.Let the pump run through its prime cycle-2-3 seconds each time.See if that makes a difference.
Does it do the same thing after setting for 2-3 hr's?

 

I'll try that...going to let it sit for another 1 1/2 - 2 hours and see...if I get the problem again then I'll try the cycling bit...this is ridiculous...I like doing the work myself but if I do it, then I hate having to even take it somewhere and drop cash to have someone diagnose it....plus I'm not leaving my car with any yahoos and give them a problem that lets them have an excuse to drive it....

 

I hear you.

 

the fuel pressure can be check at the back of the fuel rail under a small plastic cap. you have to have a tester to plug into the line though. i dont personally think it could be the fuel pump, i would test the opti theroy.

(note how he says test the opti theroy so causally knowing deep down inside that it is a MOTHER FU CKER)

 

Ok...let's go back to square one....this car is OBDI....is there a way to scan this car and figure out what is causing the problem....I've already changed/tested enough stuff and I COULD change the opti, but even testing will require taking it out and apart, and I REALLY don't want to do all that work and then find I still have the problem. So anyway...if I take it to a shop, what could they do with it?