luvmy88

1988 convert with 96K all stock. I've had poor running condition for several weeks. It does start and run, but sputters and misses. Checked codes and got 42 & 43. After chatting with fellow corvetters and reading online, and checking a few things... and replacing a few of the cheaper parts (coil, plugs, wires), and learning how to use a multi-meter... this is where I'm at.
Some fuel injectors seem to pulse weaker than others. Doing a resistance test, they all check from 16.6 to 16.8, I still need to do a noid test. My electric fan will start as soon as I start the car, even after setting all night. Car will start and run fine for about 10 sec then try to stall. SEC light comes on and seems to be linked to the electric fan.
I had a suspicion of a possible bad ECM. I can touch or wiggle the wires or ECM its self and cause the car to quit. I have it pulled from under the dash but still plugged in so I can easily move it... and it doesn't have to move much to make the car sputter or quit.
Is this a bad ECM? How can I tell for sure?

aklim

Define "weaker". How did you determine that? If they are Multec injectors like the picture below, I'd toss them before they fail from the ethanol. They are bank fired so if one is getting a signal, that side is getting the signal to fire. How crudded up they are is not recorded so there is the only question.

Was the AC on? I can't remember if you have a switch that activates the fan or not. That could be bad.

Ask around. Someone in your location might be able to lend you their ECM for a test. Otherwise, you may have to just throw a part at if or further diagnose.

luvmy88

With a screw driver touching the top of the injector I can feel the pulsing in several of the injectors on each side. And the others it's just not as pronounce and on one, not at all. But the car seems to run alright, and by that I mean the engine isn't shaking like its only hitting on 5 or 6 cylinders.
The AC is not on and there is no external switch to turn on the engine cooling fan.

Kevova

If you can move wires in ecm connectors and engine tries to or stalls. You should look at connectors first. If terminal pins wiggle in ecm, it needs replaced. I would concentrate on your trouble codes verses going off on a tangent. You have codes related to ignition system not fuel system.

luvmy88

I've had an issue with getting spark arcing across wires. I've replaced wires, plugs and coil and had my ignition module check and it checked good. In the dark the arcing issue is still there. Battery is good and battery ground was just checked. Any suggestions would be appreciated.

Dt86

There is specific wire routing in the FSM. Do you have your wires set up accordingly?

luvmy88

By this next question, you can assume that I don't have them routed correctly. What is FSM?

Dt86

FSM = Field service manual.

ddahlgren

Check the plugs if fouled badly and not shorted all bets are off where spark energy might go.

The ohm test on injectors only offers that the coils are not open or shorted and does nothing to tell you if they are mechanically ok or flow correctly.

rblakeney

Check that the eprom is fully seating in its slot. With the ecm plugged in, turn on the ignition (dont start the engine) and gently press the eprom cover plate with your thumb. On my 89 I could literally cycle the cooling fans on and off. I fixed the issue by placing a piece of cardboard on top of the eprom and screwing the cover plate back into place. Im guessing that the eprom carriers bow or warp after years of being in a hot car.

C409

..... The engine cooling fans will come on when the ECM is in limp home mode ... generally caused by a major engine control sensor fault or failure .....

luvmy88

My routing job is not as neatly done as some of the pics I've seen on this sight. I admit I need to take the time and do a better job, but I didn't think the actual path the wire takes was that important as long as they were not laying on the manifold. I was hoping that the new wires would take care of the arcing issue, and if it did, then I would make them pretty. I purchased additional wire separators that I plan on installing.

luvmy88

The cooling fan issue seems to be sporadic and seems to cause the SES light to come on SOMETIMES.
I'm not sure what it would feel like if the car was in limp mode, but it seem to run "OK", but not terrible.
Little history... occasionally my SES light would come on as I felt a slight buck, for just a few seconds and then it would smooth out and SES light would go off. I thought it was dirty fuel injectors so I took it to local mechanic for a Fuel Injector Flush. I've had that done every couple of years for 20 yrs. Drove home (30 miles) car ran great. It sat over a rainy weekend and on Monday morning drove it back to work. I missed a few time, SES light came on for 5/10 sec and when out. I stop at store and 10 minutes later restarted and it ran like it was hitting on 7 and SES light was on and stayed on. I drove about 8 mile to work and had my local mechanic read the codes 42 & 43. He was booked up and couldn't do more. So I drove home (30 miles). It didn't sound right and missed but still drove at 50-55. I parted it and started digging into it and found a spark plug wire OFF. Reconnected and drove it for 1/2 or so and it was better "of course", but it still sputters. So that's what led me to where I'm at. It still codes 42 & 43, fan runs when it shouldn't, spark plug wires arc, ECM freaks out if you touch it.

luvmy88

I will check that tonight, thanks

xrav22

Clean the connections on the ecm with electrical contact cleaner for sure.

chagger32

if it is indeed you're corvette unplug the battery fully remove it and bring it to autozone 79.99 for them to send it in for you and fix it you just will be out of a car for 2 weeks but buying it on ebay i done that 3 times and never works out i believe it needs to be refurbished to you're vin since autozone asks you there what it is

aklim

:confused 2:

Punctuation helps us understand what you are trying to say.

go help your uncle jack off his horse

vs

Go help your Uncle, Jack, off his horse.

chagger32

Not sure if my comment was made towards you or the OP ?
Looking back I was able to understand the text wrote.
But have a goodnight champ.

aklim

Are you asking or telling?

I'm sure you were able to understand it since you wrote it although it was a total run on paragraph. Ask any HS English writing instructor if you don't believe me.

You would need a "," between the "goodnight" and "champ".

luvmy88

Thanks, that sounds like a good option.
But I do have to admit, not using proper sentence structure makes your comments hard to understand. It's a shame we, as a society, are loosing that... mainly because of cellphones.