Alchemy333 Posted March 24, 2023 Topic Author Share Posted March 24, 2023 (edited) So I replaced the ECM... still had the rough idle/misfire... beyond 4000rpms became smooth. so I was thinking, ok... its gotta be the ICM, since it looks original and only replaced the coils. Re-tightened all my grounds... no change. Checked my fuel preassure regulator line for fuel in the vac... no change. Tried starting it again later to run codes. No ECM DATA... I did get a B334c though... and heard my cooling fan running which was peculiar. Went to start it... and it acts as if no sensors are functioning. Sounds like the damn engine is gonna jump out of the car... won't even idle. Tried unplugging the battery, all my ECM connection... im stumped. Is it the BCM now? Or did the new ECM malfunction? Ffs🤷♂️😅😅🤦♂️ Edited March 24, 2023 by Alchemy333 Link to comment Share on other sites More sharing options...
Ronnie Posted March 24, 2023 Share Posted March 24, 2023 1 hour ago, Alchemy333 said: so I was thinking, ok... its gotta be the ICM, since it looks original and only replaced the coils. If so, considering all the other work you have done, why wouldn't you just go ahead and change the ICM? I would change the ICM and the Crankshaft Position Sensor to. 1 Link to comment Share on other sites More sharing options...
Padgett Posted March 24, 2023 Share Posted March 24, 2023 This is were an ignition scope is nice but if ECM dies, there is a backup system. What PROM did you put in the new ECM ? 1 1 Link to comment Share on other sites More sharing options...
2seater Posted March 24, 2023 Share Posted March 24, 2023 I would bet the instrument cluster has stuff not working either. If you have no ECM data the chip is not communicating properly. R&R the Prom and see if it is a fluke otherwise, try the old ECM again and see if that goes away. 1 Link to comment Share on other sites More sharing options...
2seater Posted March 24, 2023 Share Posted March 24, 2023 After the go around I had with chips and ECM last fall, I don't install the ECM until it has run and proven to be good, long term. 1 Link to comment Share on other sites More sharing options...
Alchemy333 Posted March 24, 2023 Topic Author Share Posted March 24, 2023 1 hour ago, Ronnie said: If so, considering all the other work you have done, why wouldn't you just go ahead and change the ICM? I would change the ICM and the Crankshaft Position Sensor to. I just did the cam and crank sensors... and the harmonic balancer... no change. I will be swapping out the ICM as well. It just this new issue after replacing the ECM thats got me stuck. @2seater gonna switch with old ECM again... its just that I reinstalled it after it started up fine. Instrument cluster has had no obvious issues. @Padgett I put the PROM from the one I pulled in the new one. 1 Link to comment Share on other sites More sharing options...
Alchemy333 Posted March 24, 2023 Topic Author Share Posted March 24, 2023 Alright... put the old ECM back in again... and it runs as it did. With the new one in, it ran the same... before it crapped out. So its gotta be the ICM at this point. The only difference was in diagnostics. Current one reads "NO E CODES", the new one read "NO E DATA". Unsure if one read right or wrong... or if they are both crap... or something else🤷♂️ Link to comment Share on other sites More sharing options...
2seater Posted March 24, 2023 Share Posted March 24, 2023 No ECM data is lack of communication between the chip and the ECM. It may take a little bit to straighten itself out after a chip or ECM change as it is self learning to a certain extent. No e codes sounds normal. The ECM does not self diagnose. 1 Link to comment Share on other sites More sharing options...
Padgett Posted March 25, 2023 Share Posted March 25, 2023 Is the ALDL cover by the steering column that says "do not remove" in place ? It completes the LAN loop. Someone seriously into pre-95 GM computer cars needs an ALDL scan tool. The OTC 2000 is often on eBay. Just make sure to get a late enough GM, all-in-one, or Pathfinder (think III was latest) cartridge and GM cable. ATYJ is a 90 LN3 but for what car line I do not know. ps the ECM will run just fine laying on the passenger footwell. 1 Link to comment Share on other sites More sharing options...
2seater Posted March 25, 2023 Share Posted March 25, 2023 7 hours ago, Padgett said: ATYJ is a 90 LN3 but for what car line I do not know. ps the ECM will run just fine laying on the passenger footwell. I have no definitive answer on the source for the above Prom being correct for a Reatta but it is listed in the Prom list in the How To guides in ROJ. Listed as California specific. The parts guide for E Bodies lists an even dozen Proms for 1990 with ATYJ being one of them. Link to comment Share on other sites More sharing options...
Padgett Posted March 26, 2023 Share Posted March 26, 2023 Found it. 2 Link to comment Share on other sites More sharing options...
2seater Posted March 27, 2023 Share Posted March 27, 2023 The broadcast number in the ROJ guides courtesy of MC_Reatta shows 8074 to be the California spec for 1990 Reatta. Confirmed by the chart above, 1 Link to comment Share on other sites More sharing options...
Alchemy333 Posted March 28, 2023 Topic Author Share Posted March 28, 2023 On 3/25/2023 at 9:17 AM, Padgett said: Is the ALDL cover by the steering column that says "do not remove" in place ? It completes the LAN loop. Someone seriously into pre-95 GM computer cars needs an ALDL scan tool. The OTC 2000 is often on eBay. Just make sure to get a late enough GM, all-in-one, or Pathfinder (think III was latest) cartridge and GM cable. ATYJ is a 90 LN3 but for what car line I do not know. ps the ECM will run just fine laying on the passenger footwell. ALDL cover is on. Thanx! I'll look into those scanners. Link to comment Share on other sites More sharing options...
Padgett Posted March 28, 2023 Share Posted March 28, 2023 Dredging now but think California cars had to run leaner and with less advance than the other 48/ 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now