Background... The vette was a surprise B-day gift from my better half, so i didnt get to check it out before hand. Needless to say the PO should be beaten! The wiring under the hood is HORRIBLE, and the fuse panel/dash wiring isn't much better! Right off i knew it was going to be a LONG road so I just told my lil lady thank you with a smile, and that we would make it our project. Anyway, to the details...

From day one it was very hard to start but once started it ran fine. I figured the pump was going? Well i drove it to work one day and everything was same same but when i went to go home that afternoon it died 3 times. I ended up having to "2 foot" it home. Since that day it has still had the hard starting problem, but now it didnt want to idle. I could start it (eventually) then it would idle around 2-4 sec then die. If i gave it any throttle it would cut out and die instantly. Once i finally got it to stay running, after about 20 min of trying, it would idle around 1200. Now if i VERY SLOWLY applied throttle it would rev up but if u just blipped the gas it would fall flat on it's face then go back to idle @ 1200. I actually got it to drive around the block but it ran like crap and tried dieing again. Well I replaced the fuel pump, strainer and inline filter but it did nothing to help. I decided to take it to our Community College because my buddy teaches their auto tech class and they have always taken care of me on any of my other vehicles.

Well they found MANY issues with the engine harness. Fixed 3 injector clips, replaced cold start switch, fixed 3 "other" wires that had also been chewed through, Fuel pump would not energize (found and fixed 2 hots to ECM to fix this) and fixed no power to ALDL and 2 wires were swapped. im sure i missed something. Well they have gotten to where the car will start and run now but there's more.

In order for them to get the car to idle they have to advance the distributor (CCW) a lot. They verified #1 TDC comp/ballancer 0*/rotor pointing to #1 pin and all was good. They checked timing chain slack to be 6*, maybe hair less. Now with the connector out and base timing at 8* it should run but it wont??? Mechanically it should be in time and run right??? They have tried new cap, coil, ign mod, new a/c plugs, checked PU coil, but still have to advance the **** out of it to run. By run, it will idle ok but if u try and rev it up it stumbles and pops like a timing issue?? Now i should say their scanner (dont know what they have) wont communicate with the ECM. They also tried the A/B jump to pull codes but it flashes nothing, not even 12. They ohm'd out the pins to the ECM and they both showed good though?

So now I'm here asking help cause we are both pulling our hair out on this one. Im sure with all the vette knowledge here someone has to have some good advice/ideas/solutions?? I'm about at my wits end here lol!

On a side note, does anyone know if the Painless 60102 engine harness will work on the 85'? I searched but didnt find much? I know it has no emissions but if it will work on the 85 (with the 165 upgrade im assuming?) that would solve my rats nest of an engine harness, and its issues.

Thanks guys.

 

I have an 84 so not sure how much help I'll be.. Some things that come to mind are IAC'S (might need cleaned), possible vacuum leaks, is your TPS set to .54 volts?
If nothing else it gives you a bump to the top..

 

Sounds like my 1988 acted like it was out of gas, no code 12, 95% chance ecm took a dump . Get a factory service manual it has step by step instructions and flow charts my ecm did go out

 

I think the first thing I would do is to take off the driver's valve cover. Pull out @1 spark plug. Put 5/8" six point socket on the center bolt of the balancer and slowly turn the crank with a finger over the #1 spark plug hole. When you feel compression...then watch for BOTH valves to close on #1 cylinder. Now check the timing mark on the balancer....is it at * degrees or close to 0??? If it is way off then the outer ring of the balancer has slipped and the entire balancer needs to be replaced.

Then proceed to the TPS as noted above and check for .54 volts. Follow that up with IAC. Check the ECM....as noted above....you should be able to get a code 12 out of the of the connector when you connect A & B. Are you sure that you are grounding the correct pins??

Check fuel pressure regulator (looks like a top hat on the rear of the fuel rail. Pull off vacuum hose and see if there is fuel in the hose. Have you checked fuel pressure? With the key on and car NOT running you should have some where between 36-42 PSI.

 

Go invest in a good scanner not the cheap $79 one and spend some time here. Time to break your teeth learning early EFI it isnt bad at all.

Look at the bright side
At least you got a reason to stay out of the house now.

 

If you invest in a scanner....BE SURE that it will work on the 85 Corvette with the 870 chip. This is the only year with this chip and many scanners will not work....IE the Auto-Xray will NOT!!!!!! Damn...money spent without any results.

 

The ECM was replaced with a new 870 last year. Idk if they have checked the IAC or TPS voltage, I'll ask tomorrow. No fuel in FPR vac hose and they said FP @ rail was good. I believe he said they fixed a vac leak also but I'll have to double check with him tomorrow. As for the no code 12, he said they were grounding the correct pins (a/b) but its possible to be wrong considering the wiring mess. They have found wires swapped in a few places/connectors. Idk if they pulled the VC to check both valves closed or not. He did say they made sure #1 was at TDC comp when checking the balancer though. And yes I made sure to give them my FSM with the car.

 

Anybody have any input on the Painless #60102 harness I mentioned above? Im starting to wonder if my main problem isn't the hack job cluster mess the PO did under the hood?!? If it will work on the 85' it might be worth it to just replace the entire mess with a new harness. We have been planning on doing an LS swap down the road, when/if the l98 ever takes a dump. But the more money goes into this the more im wishing we would of just said enough and went with the swap now lol! But the ol' l98 runs damn good...when it runs...ugh.

 

My thought; got that tee shirt.

I recommend a call to painless and totally agree with your inclination to replace the hack job. Their site, as you already know, doesn't offer an exact, nor did I find another.

Aging issues (corroded contacts, cracked insulation, broken connectors) on modern cars are hardly confined to Corvette. Atop the amateurish 'fixes' you describe, it could make or totally break your experience and might save you money as you needlessly throw other parts at it.

J & D or another Corvette salvage place my have one, tho it'll be old if unhacked. I have bought from Jaime; the J &D staff is knowledgeable.
Yeah, one can make an L98 LOTSA of fun.

 

The SES light comes directly from the ECM. Assuming the bulb is OK (it does light when the ignition is on, engine off) then there is either a wiring problem or the ECM is bad.

That said, you can't communicate with the ECM if you can't get it into diagnostic mode. That means a scan tool or cable to computer won't work. They both use the ALDL A-B connection, so THAT has to be good before anything else will work.

 

Called painless today. The 60102 will "work" I would just have to do some integration at the bulk head, or splicing at the ECM directly. Plus the 165 upgrade. But it is a viable solution if it comes down to it.

 

SES bulb is functioning (KOEO) but no diag mode jumping A/B. They ohm'd A and B back to the ECM (pins 9 & 12 iirc but i could be wrong?) and they were good. With the condition of the wiring on this poor car its hard telling, especially since I just put a new 870 in late last year...

 

Found some new info on the mechanical side of things. We got to talking about the ideas from here, then started going over what all they have done and/or found along the way since they have had the car. When they first got it they found the fuel pump relay was not energizing and fixed it first. Once fixed the car would start right up and idle...albeit not 100% right, but it ran. Then one of the guys found the firing order was off on the cap. Going back over this part, and me asking what * they have to advance the distributor now made something click in his head. Come to find out the firing order was off 1 post all the way around (1 was 8, 8 was 4, and so on all the way around). Once the guy fixed the firing order is when it wouldn't run, even on base timing. And to get it to idle at all now they have to rotate the dist CCW the same distance as between pins on the cap. This discovery didnt happen till after they were closed so Tue they are pulling the valve cover to verify valve positioning at TDC to quick check cam position.

With not knowing any history on this car, and only having the mess i can see before me, it wouldnt surprise me...