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Hey everyon . I chasing a gremlin on a 92 RS V8 car. It's not wanting to idle and throwing a code 15. Its exhibits all the standard behavior of a code 15. Wont idle, runs rough etc. Well while chasing it the car decided it didnt want to throttle up. When you push the throttle it chokes and struggles to rev up. That's a new problem. So I've changed both the sensor and the plug itself. I've chased the wires and I cant find anything. I've checked grounds for the ECM, they look fine too. So now I'm curious if my ecm is bad. So I pulled it out and looked at it while checking the wires there. And it looks rough. I hate to just toss parts but I dont have a datalogging cabl . Here is some pictures, it clearly has gotten wet. If you look at the speedometer board on the outside of the ecm, its clearly gotten wet. What does the community think? Extra info, the speedometer doesnt work but the output shaft inside the transmission that interacts with the VSS at the transmission is MIA. I'll have to get into that at another time. Right now I'm trying to get her running right. Outside of the wee devil. The bracket is awful rusty Inside the ECM. Lots of crud around the ports. One side of the speedometer boards casing. Other side.
Hey everyon . I chasing a gremlin on a 92 RS V8 car. It's not wanting to idle and throwing a code 15. Its exhibits all the standard behavior of a code 15. Wont idle, runs rough etc. Well while chasing it the car decided it didnt want to throttle up.
Interesting. Check the ECM harness connector pins. See if any, including the CTS input (pin C10) is corroded. It may also be a bad terminal in the harness connector (C10, yellow).
As for the ECM, not even close to being correct for a '92 RS. That ECM is an '8062 truck ECM with a DRAC attached to it.
A '92 RS should have a '8746 ECM in a slide mount, and no DRAC. With a separate 4-out buffer box mounted under the dash.
Rbob,
. So the mystery continues. I know the car has had an engine swap . I checked the numbers on the block, it's a chevy 305 tbi engine. I assume the wiring harness is the one the car came with, but now I have no idea. Would all the plugs be the same, I know chevy put alot of the same parts in different vehicles. I guess first thing is check those pins and get the proper ecm. Thanks for the info.
Got it, thanks. I found that some makes a vats bypass that emulates the key ok signal. So worst case I'll need that as well. Hopefully this fixes the issue .
Ok so update, been busy with the holidays and work. Finally got the correct ECM and a vats emulator. Well the car is super hard to start and once it starts it wont hardly run. At first it will fire up, rev up to about 2k RPMs, then as it idles down it will chug and die. Then after that when i restart the car, it wont want to start back and I have to flutter the throttle to start it and to keep it running.
So on a hunch, I flipped the wires on the coolant temp sensor, the one that was throwing a code. Well that caused it to stop throwing a code. But this still did not make the car run correctly with the correct ECM. For fun I put the S10 computer back into the car, it fired right up and idled quite smoothly for a long while until the car got warm. Then it began to idle up and down. I drove it up the road and back and it was capable of going, but the power was off and cut in and out. Not so much it wouldn't go, but like you could feel the push in the seat then you wouldn't. The RPMs though wouldn't change, only the feel. Kinda hard to explain, but I could feel it.
All of this feels like it creates more questions. I purchased a ALDL to USB cable and got Tuner Pro set up. I'm gonna data log the two computers. Would someone be able to look at the data and assist? I'm not especially knowledgeable when it comes to that area.
Ok so I did some data logging with both ECM's. The 8062, S10 computer still idles quite well. The idle was very erratic with the 8746 computer for a couple minutes then it normalized and finally settled down. I did not drive the car, I was worried it would die out on me. Also the 8746 threw a code 42 and 44. Here is the data if someone could give me some insight. I logged data twice with the 8746.
