1992 Z28. Bought it from one of our fellow TGO members, and it ran like a top. Had a "mechanic" friend take it to drop a cam in it, upgrade the heads, etc... He had it for 4 months. Found out he got locked up, went to get my car. Appears the only work he did to it was stomping the gas pedal at the Quarter mile. Anyway, the night I brought it home, it ran like a champ on the highway, but would sputter a little when you came to a stop. Cut off once, but I assumed it was because it had been sitting.

I changed the plugs and wires, replaced the coil, TPS, IAC, CTS, cap, rotor, and the starter (because it died). The intermittently throws codes 15, 22 and 42, and I adjusted the TPS to within normal limits.

Here's where I get lost... To start the car, you have to push the pedal all the way to the floor (flood mode) and after about 7-8 seconds it starts in a burst, RPMS go way up, then drop to a stall. If it doesn't stall, then it idles extremely rough, exahaust pops like crazy, and it sounds like it's missing. Then it smooths out, but if you take your foot off the pedal and the RPMS drop below 2500-2750, it stalls. If that doesn't kill it, and you maintain a smooth idle for 15 minutes or more, then put it in gear, it dies, right after spitting carbon out of the tailpipes. I changed the oil, and it smells like straight gasoline. I have replaced the PCV, checked for vacuum leaks, checked connections, and done the Kabuki dance in the rain, and I am at my wit's end. Putting a new EGR on tomorrow. Someone, ANYONE, WHAT GIVES? Has this guy ruined my car? If not what do I need to look at? I just need a direction, though a solution would be welcomed. Hell I'll freeze a beer in a block of ice and FEDEX it to you...

 

check air intake for ha ha's, check MAF sensor.

also check fuel pressure, fuel pressure regulator, EGR solenoid, fuel pump and fuel injectors.

double check what each engine code means and go from there. i'm no expert just have my own trans am i've been improving and bringing back from slight death.

the RPM definately sounds like an air intake inssue somewhere or fuel inssue, check your gaskets and like i said fuel pressure.

also have your ECM checked. you could have a bad car computer and that controls the air fuel mixture.

so it actually jsut might be a bad ECM

let us know

 

Replacing EGR tomorrow. Even with the Intake assembly off, using just the TB, it still does the same thing. Fuel pump is new. Fuel Filter is new. Have an AFPR and going to set it to stock level. Timing is dead on 0 degrees.

 

then let us know after the new EGR is in. The EGR has a solenoid on my 86.

becareful with the EGR
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you need to get the dealership one to replace it. aftermarket wont cut it. the EGR has a number on it and the dealership can help you replace it if not an auto store liek NAPA.

 

I will. thanks for any help you guys give.

 

Change #10. Pulled off the plenum, the runners, EGR, valve covers, got a new ECM, and working on getting a chip from TPICHIPS. The last one I got from Brian made a big difference in the "butt dyno".

By the by, the EGR was completely seized. Diaphragm would not budge. Could that be the cause of my above listed agonies?

 

test the car once the new EGR is in. If you have no vacuum you may have to change the EGR solenoid. but the EGR itself fails because of no vacuum or normally it gets clogged with carbon build up

 

Woo HOO!!!! Got her running. Did 120 without sweating. The ignition control module and EGR were both bad. Now for the part where I should be kicked in the head. A friend of mine was helping me set the timing. I assumed (that evil word) he tighend down the distributor bolt, he thought I did... We were both wrong. I also had the vacuum hose on the heater bypasvalve disconnected and didn't notice it... She's hot to trot now... Off the subject, what is the correct torque for the rocker studs?

Thanks for pointing me in the right direction

 

did Ur cars idel jump around on its own while in trafic.... Mine jumps from 400-1500 rpms all by it self. It never just idols like it used to. Before I started racing it.....My cars only happy at full throtle....... I was wondering if my problem could be the same as yours...Thought I'd ask you before I wast everybodys time with a simular qustion.

 

check for vacuum leaks and inspect your throttle body sensors blades, hoses etc... and then go from there. also after that check stuff like fuel pressure etc..

 

good to hear you got it runnin dude, what you gonna do with it now?

 

For right now, just get her tuned properly.... Then I'm gonna clean up the engine compartment, get a better chip from Brian Harris, tighten up the rear end, and run her in 1320 ft spurts, ha ha! Have a friend who has a 400 block, So, with no experience, and a lot of mechanic friends, I'm going to try and build my first engine from scratch! Wish me a ton of luck on that one...
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It only surged on starting... wouldn't stay running long enough to fluctuate on idle. I think you have a different problem. The last time I had a problem like that it was a vacuum leak.

 

Just to clarify some things, first off this is a 92 TPI system, it runs off the MAP system, hence it has NO MAF sensor. The ECM rarely will ever just die, and the PROM if it is the same as when it was handed should be fine. Also if it is throwing out black smoke, more than likely its getting enough fuel for its needs. EGR valves are a dime a dozen, there are direct replacements at a reputable parts store.


Good job on the ignition control module, sounds like he ran her wet and left it to dry. When you pulled off the EGR valve was there a lot of carbon buildup underneath the valve? IF you do have anybody do work on it (I.E. replacing heads, cam, ect.) then you should know that they will have to get a new PROM burned to compensate for the changes due to it being a MAP system. It sounds to me like it is more of a timing issue than anything else, just remember to unplug the brown wire on top of the AC/heater unit in the engine compartment before adjusting and set the timing correctly. After setting it turn the car back off, plug the wire back in, restart the car and check timing again.

 

yea ResurrectingZ is right. thansk for seeting me straight i didn't know it was a 92. i had my 86 in my head. but yea i only suggested the ECM since i've known someone screw one up while probing and testing wires trying to install a few car systems. jsut incase his car had any electrical work done jsut figured it was worth mentioning. anyways let us know how your car does after checkin a few things.

 

Yep... It's a 92. I set the timing to 0. It has new plugs and wires, plus a new cap and rotor, and there is still a slight miss. The guy I bought it from put 1.6 rockers on it, and I'm not sure if they are all torqued correctly. What is the correct torque for the rocker studs?