-89 Lingenfelter running real bad, ECU?
Thread Starter
Instructor
Joined: Oct 2016
Posts: 232
Likes: 10
From: Stockholm, Sweden
-89 Lingenfelter running real bad, ECU?
I'm working a 1989 C4 with a lingenfelter engine fitted to it.
It's running really bad, smoking black on startup, and does not want to run. Have to keep the foot on the gas pedal to keep it alive.
Issue started during driving. All of a sudden it just didn't run right, and ever since I haven't found the issue.
One time it actually ran great all of a sudden, with Diagnostic tool installed and while scanning
If I have understood correct, with diag tool installed, it bypasses some functions and locks timing etc?
I've changed coolant temp sensor, MAF, spark plugs, wires, fuel pressure is OK, diaphragm OK.
No error codes while reading with diag tool nor via jumping the OBD connection.
Could it an ECU issue? Or distributor issue?
Any ideas are welcome!
It's running really bad, smoking black on startup, and does not want to run. Have to keep the foot on the gas pedal to keep it alive.
Issue started during driving. All of a sudden it just didn't run right, and ever since I haven't found the issue.
One time it actually ran great all of a sudden, with Diagnostic tool installed and while scanning
If I have understood correct, with diag tool installed, it bypasses some functions and locks timing etc?
I've changed coolant temp sensor, MAF, spark plugs, wires, fuel pressure is OK, diaphragm OK.
No error codes while reading with diag tool nor via jumping the OBD connection.
Could it an ECU issue? Or distributor issue?
Any ideas are welcome!
Thread Starter
Instructor
Joined: Oct 2016
Posts: 232
Likes: 10
From: Stockholm, Sweden
Based on the amount of black smoke out the tail when cold starting, I feel it should be a fuel issue. But of course it could be a spark issue as well
And no difference when disconnecting MAF for fueling change
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
When a memcal (the thing that holds the EPROM chip) fails the ECM can go into a limp mode, which on a modified engine is horrible. I had this happen once to my '87 and the ride home was awful.
Does it act poorly on a dead cold start, or only once warmed up? If it only happens once the scanner shows closed loop, then I'd suspect O2 sensor wiring or sensor. If it is also a problem in open loop something more fundamental is wrong.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
I'm working a 1989 C4 with a lingenfelter engine fitted to it.
It's running really bad, smoking black on startup, and does not want to run. Have to keep the foot on the gas pedal to keep it alive.
Issue started during driving. All of a sudden it just didn't run right, and ever since I haven't found the issue.
One time it actually ran great all of a sudden, with Diagnostic tool installed and while scanning
If I have understood correct, with diag tool installed, it bypasses some functions and locks timing etc?
I've changed coolant temp sensor, MAF, spark plugs, wires, fuel pressure is OK, diaphragm OK.
No error codes while reading with diag tool nor via jumping the OBD connection.
Could it an ECU issue? Or distributor issue?
Any ideas are welcome!
It's running really bad, smoking black on startup, and does not want to run. Have to keep the foot on the gas pedal to keep it alive.
Issue started during driving. All of a sudden it just didn't run right, and ever since I haven't found the issue.
One time it actually ran great all of a sudden, with Diagnostic tool installed and while scanning
If I have understood correct, with diag tool installed, it bypasses some functions and locks timing etc?
I've changed coolant temp sensor, MAF, spark plugs, wires, fuel pressure is OK, diaphragm OK.
No error codes while reading with diag tool nor via jumping the OBD connection.
Could it an ECU issue? Or distributor issue?
Any ideas are welcome!
Le Mans Master
Joined: Feb 1999
Posts: 9,922
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
If the CTS is broke, ie the one the ECM uses to determine temperature for running correctly, your car will run like crap. The sensor for the gauge, no biggie.. I think that is on the cylinder head? The CTS for the ECM? Not sure where that is, but it is the critical one
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Thread Starter
Instructor
Joined: Oct 2016
Posts: 232
Likes: 10
From: Stockholm, Sweden
Would images of said scanner during scanning give any insights?
When a memcal (the thing that holds the EPROM chip) fails the ECM can go into a limp mode, which on a modified engine is horrible. I had this happen once to my '87 and the ride home was awful.
Does it act poorly on a dead cold start, or only once warmed up? If it only happens once the scanner shows closed loop, then I'd suspect O2 sensor wiring or sensor. If it is also a problem in open loop something more fundamental is wrong.
WHICH coolant temp sensor did you change (OK...one isn't really a CTS but it senses temp for dash). O2 sensor? You wouldn't think so because open look at startup. Mine wouldn't run (all of a sudden 2-3yrs back. I did two things: O2 sensor AND cleaned the grounds on the ground block behind the batter. Maybe it's the later? TBH, I can't remember which components or sensors are grounded there. Mine got bad enough it would blip off while running too. (Like 2nd-3rd time after symptomm started.
I doubt O2 sensor since it does it on cold start as well. And this problem started whilst driving.
Will have a look at the ground at the battery location.
Last edited by pierrel; May 21, 2026 at 05:47 PM.