Help on a 90 Riviera... ECM?
06scooby
10-08-2007, 04:08 PM
Hi all,
I just helped one of the high schoolers in our youth group find a cheap car. We ended up finding him an immaculate 1990 Riviera that is in prestine shape (owned by an elderly couple) and only has 65,000 miles!!! Long story short, we knew it had a couple of glitches when we picked it up this weekend. We took it on a 10 minute test drive and the only things we could notice was a really high idle (2500 rpms or so) and the usuall flakey digital instrument cluster. We found a cluster for $100 bucks or so no big deal. The SES light is also on. So we picked up the car for $1200 bucks so not so bad.
Yesterday we were driving around in it to get a cheapy GM Scanner and Haynes Manual and after about 30 min of driving (temp outside was much warmer too) the idle settled down but now it's trying to idle to low and will start misfiring and die. Also the tach and coolant guage on the digital would go dead then come back on intermittently while you are driving. Once you give it some gas it sputters a second but then runs beautiful until it falls back down to idle. This car is so smooth and runs really good except for the goofy idle. We pulled the codes and we got a 14,16, 43, and 47. I believe 14 was ignition module & 16 was dealing with the coolant sensor. but 43 & 47 were ECM Error Codes. A new ECM is only $140 bucks here at the dealer. Is it likely it would flake so easily and will it give failure codes that it itself is failing? I'm not getting any Air Flow Sensor codes, and the alternator and battery are normal.
Any Ideas?
I just helped one of the high schoolers in our youth group find a cheap car. We ended up finding him an immaculate 1990 Riviera that is in prestine shape (owned by an elderly couple) and only has 65,000 miles!!! Long story short, we knew it had a couple of glitches when we picked it up this weekend. We took it on a 10 minute test drive and the only things we could notice was a really high idle (2500 rpms or so) and the usuall flakey digital instrument cluster. We found a cluster for $100 bucks or so no big deal. The SES light is also on. So we picked up the car for $1200 bucks so not so bad.
Yesterday we were driving around in it to get a cheapy GM Scanner and Haynes Manual and after about 30 min of driving (temp outside was much warmer too) the idle settled down but now it's trying to idle to low and will start misfiring and die. Also the tach and coolant guage on the digital would go dead then come back on intermittently while you are driving. Once you give it some gas it sputters a second but then runs beautiful until it falls back down to idle. This car is so smooth and runs really good except for the goofy idle. We pulled the codes and we got a 14,16, 43, and 47. I believe 14 was ignition module & 16 was dealing with the coolant sensor. but 43 & 47 were ECM Error Codes. A new ECM is only $140 bucks here at the dealer. Is it likely it would flake so easily and will it give failure codes that it itself is failing? I'm not getting any Air Flow Sensor codes, and the alternator and battery are normal.
Any Ideas?
maxwedge
10-08-2007, 05:35 PM
Welcome to AF. Idle issues can be the coolant temp sensor, I'd clean the throttle body, iac and passages also. I see 43 as a knock sensor input issue and 47 as a memory loss for the bcm. See this link, http://www.troublecodes.net/GM/88-90_38C.shtml
06scooby
10-09-2007, 12:47 AM
Well this afternoon it was pretty warm outside and the car ran like absolute crap!! We cleared the codes from the computer and then restarted it and the service engine light came back on in about 10-15 seconds and the car wouldn't maintain the idle. I plugged the scanner back in and I only got 2 of the original 4 codes. I got Code 14 and Code 43. 14 is obviously the coolant temp sensor so it is getting changed tomorrow. Code 43 on the link posted above says knock sensor but in the Haynes manual it says it is a Ignition Module error. so is that the unit that all the coil packs are mounted to? We are going to try the coolant sensor first but would that really cause it to run that poorly?
maxwedge
10-09-2007, 02:52 PM
Yes it could.
06scooby
10-10-2007, 12:32 AM
Okay so we changed the coolant sensor. Good news is there is no more code 14. Engine still stalls when it warms up. Now i'm getting a code 16 (Alternator surge) and still code 43 (Electronic Ignition Control Module) I happened to have bought a ignition module too and swapped that out. Not difference. The Haynes manual said the EICM is built into the memory chip in the ECM. Could that be bad? I don't know what is causing the code 14! Help!
maxwedge
10-10-2007, 03:58 PM
You need to do a full scan, not just read codes, to look at operating parameters and sensor inputs.
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