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Severe Running Problem

T

TTA#545

Active Member
Just barely got back from a car show about ten (10) miles from my vacation home. On the way to the show my TTA began a mild hesitation at 2K in high gear. The hesitation continued, even at low speed, and when I got to the show the Service Engine Light came on. I left the show about an hour later, the Service Engine Light was off and headed back home. Shortly after getting to 2K in high gear the hesitation reappeared and got continually worse until the car stalled; I got it restarted and filled the tank with 93 octane. The car restarted after fueling but quickly stalled again. I barley made it home and when I restarted in my driveway it began backfiring loudly and would not continue to run. All the while the Service Engine Light would "flash" pretty much in sequence with the stumble and hesitation. The car had been running fine. I changed the oil this week. Early last month, in order to pass DE emissions inspection I put two (2) gallons of isoprophyl alcohol into a small amount of fuel. The car stalled during the inspection and I had to add five (5) gallons of fuel to get it running. I then filled the tank with 93 octane and it had been running fine until all of this. I've tried to give as much info as I can. Any ideas on what to look for? I'd like to get the car to my regular home, thirty-five (35) miles away. I don't have many tools here at the vacation home.
 
I'd say start with the basics, plugs, wires, & coil pack. Where were these last changed and what's the condition of them now? If you can get it started at night you might be able to see if you have a bad wire as it will probably be arcing.
 
Check your hoses. One could have come loose.

Check your MAF. Could have gone bad. tap it with a screwdriver or your knuckle.
 
Started car this morning. Idled fine for a few minutes then began to surge and finally stalled. When I give it fuel in an attempt to keep it running I hear a popping sound in the intake plenum. It will then search for an idle, might backfire, then stall. It ran smoothly for a while; I attempted to drive and made it about a city block. Was able to limp home. Plugs, coil pack and wires are new. The car has a one year old MAF translator with a Corvette C5 3" MAF sensor. I will check that next. Any other ideas are appreciated.
 
You said the check engine light came on. Do you know what the code is? I would start there first, before spending any money on unnecessary parts that might not fix it. It sounds heat related from what you describe. Fine when cold, when warmed up it stalls, could be a number of things, i.e: ign module, crank sensor, fuel pump, maf, tps, etc. Keep us posted.
 
Made an error in my last post; car has a MAF translator with a 3" C4 Delphi MAF sensor. Tapping the MAF sensor had no effect on the problem. I was unable to check for error codes due to time restraints. Have an old OTC 1000 scan tool which I will use later this week to check for code (s). At this point I agree that the problem appears to be heat related as the car starts and runs fine until temp reaches about 140. Will restart at that temp and run for a short time before again stalling. Will also check fuel pressure later this week. I do appreciate all of the suggestions I've received; keep em' coming!
 
Cut and paste...
CODE 42
Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system.
During cranking, the timing is controlled by the ignition module while the ECM monitors the engine speed. When the engine speed exceeds 400 RPM, the ECM sends a BYPASS signal to the ignition module which switches the timing to ECM control. The ECM calculates what the timing should be then "tells" the ignition module via the EST circuit.
An open or ground in the EST circuit will stall the engine and set a Code 42. The engine can be re-started but it will run on ignition module timing.
The conditions for setting this code are:
  • System in BYPASS mode but the ignition module is still controlling timing
    - or -
  • Engine speed > 600 RPM with no EST pulses (ECM controlled timing) going to the ignition module for 200 msec.

Typical causes for this code include:
1) BYPASS line is open or grounded
2) EST line is open or grounded
3) PROM or CALPACK not seated properly in the ECM
4) Poor connections between ignition module and ECM
5) Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise)
6) Faulty or incorrect ignition module
7) Faulty ECM


Return to Chart
CODE 43
Trouble Code 43 indicates that there may be a malfunction in the Electronic Spark Control (ESC) circuit.
ESC is used to sense spark knock (pinging) and retard the timing to eliminate it. A knock sensor (located at the rear of the engine block) sends signals to an ESC module which then signals the ECM that knocking is being detected. The ECM will retard the timing by as much as 20 degrees in 1 degree increments. A loss of knock sensor signal or loss of ground at the ESC module will cause the signal at the ECM to remain high. The ECM will act as if no knock is present, and may possibly result in engine damage, if there is detonation.
Loss of the ESC signal to the ECM will cause the ECM to constantly retard the timing to its maximum. This results in sluggish performance and a Code 43.

The conditions for setting this code are:
  • Engine is running
  • ESC input signal has been low more than 2.23 seconds

Typical causes for this code include:
1) Open or shorted knock sensor
2) Loose knock sensor
3) Excessive mechanical noise within engine
4) Improper or incorrectly installed PROM or CALPACK in the ECM or defective ECM
5) Intermittent open in the EST line to the ignition module
Click to expand...

I would dump the codes first and then see which one comes back first and address it.

Don't be too quick to throw parts at it when it may be a an open wire or bad connection.

Ignition modules do fail but ESC modules rarely fail.


...
 
In the white slots 6Gb 1866MHz the speaker didnt beep, and dont have signal on the display, and the leds are all offOn the blue slots, apears the same problem as the start off this postCan you help me?Regards
 
What is the correct part number for the Ignition Module in the 89 TTA? I have been given any number of incorrect replacements.

AC DELCO
GM
STANDARD
WELLS
 
Cleared codes and after about ten minutes and engine temp at 160 car stalled and reset code #42. I have the Service Manual Supplement for the TTA and I followed the checl list for code #42 on pages 6E3-A-54/55. The "conclusion" is that CKT 423 is shorted to ground. How would one "fix" such a condition? Also I noted that according to the chart on page
6E3-A-8, B4 (EST) from the ECM should produce 1.2VDC while running and D5 (BYPASS) should porduce 4.55VDC while running. A voltmeter reading of both confirms the correct voltage. However, when the engine begins to stumble and the CHECK ENGINE light begins to flicker, both voltages flicker then drop to 0. The engine continues to run, though poorly, while the voltage at both B4 and D5 remain at 0. Any thoughts?
 
Were you able to locate an ignition module? If so did you replace it and it still threw a code 42?

I need to have my manual in front of me so I can see what is shared in circuit 423. I'll have to bring it home.

How does the edge connector look going to the ignition module? Is it strained or loose? Pull it off (1/4" nut driver) and look for sloppy pin connections or bent pints.


....
 
So if I'm reading this right...you're losing the 5V from the (424)tan/blk wire while running.Right?
Either it's getting dropped in the ign module or one of the edge connectors, either at the ECM or the ign module.

But if you're not losing the 5V it's dropping the EST(423) and switching over to ign module control of the timing.

Now, when the codes are dumped and you re-start...and then it sets a code and stalls. Does it restart and run poorly till you shut it off?

If so I'd say it's the ignition module.
 
Actually, it's hard to tell which circuit 423 or 424 drops first. I had a voltmeter on both circuits and it appeared that both dropped to 0 at the same time. I also noted a "hot spot", about 115F, in the center of the module side of the ECM. I can usually, not always get the car restarted and keep it running in order to get back home. It will generally stall a few times in the process, however, I have been able to restart it.
Would it be possible to speak to you? If you supply a phone number and convienent time to call there is other information about all of this that might help. If you prefer to call me, I'd be glad to supply a number and time to call. Your responses are appreciated.
 
For any of you who have been watching, I should say reading this saga, I hope that I've reached a "Happy Ending". After three (3) defective Ignition Modules, two GM and one Standard, it appears that a replacement ECM has thus far, thirty-five miles, cured the problem. My sincere thanks for all of the responses and suggestions. You are a great resource!
 
TTA#545 said:
For any of you who have been watching, I should say reading this saga, I hope that I've reached a "Happy Ending". After three (3) defective Ignition Modules, two GM and one Standard, it appears that a replacement ECM has thus far, thirty-five miles, cured the problem. My sincere thanks for all of the responses and suggestions. You are a great resource!
Click to expand...

Revert back to post #9 :D

I'm glad you were able to get it fixed :thumbup:
 
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