ecu reset = bad running

[JulezSteele]

Everytime I disconnect the battery the car will run horrible afterwards, its really slugish and kickdown goes nowhere. The car seems to learn itself after tons of accelerations and the slugging slowly goes away. Any ideas?

 

[Three Fat Tigers]

It may be because of the +T, my '92 will run fine right away, but a little better after a day or two of driving, little more power and throttle response.

Have you changed your FPR or injectors?

You might want to try a 4bar FPR.

 

[TheJoyOfSix]

Like TFT says I'm guessing because LH 2.4 resets itself to factory settings when disconnected and then has to go through the whole process of learning the car again. This even happens to a mates stock 940 as his car now has over 330k miles and so needs different settings for it to run smoothly compared to when it left the factory.


I'm assuming you have LH 2.4 because a) you say it learns, and b) it's a 93 B230F+T

 

[Al]

You also may have a dying ECU. For close to 1 year I had a hot miss that I could not track down until last week. I must have reset my ECU 10 or more times and although the miss went away for a short time it always would come back. I swapped in a good unit that came out of a salvage yard and the car now runs much better. The miss is gone and the car runs much smoother. You may find getting a good used unit and replacing the one in the car may save you a lot of time, money and grief.
Edit: Let me add that my Indy mechanic replaces on average 8 to 10 of these units per year on the pre-1995 cars. They don't last forever and he recommended that I pick up another unit to keep as a spare just in case the one I just got fails in the future.

 

[JulezSteele]

Yeah its LH2.4, before turbocharging it seemed to have the same deal with the N/A ECU, but I guess its just learning itself or somthing. And about the 4Bar, would that significantly improve the car?

 

[Three Fat Tigers]

It might http://forums.turbobricks.com/showthread.php?threadid=40943

 

[Lazarus]

I myself suspected "adaptive learning" problems in the ECU when I was having rough running problems. TFT correctly pointed out that this function does not cause the engine to go from silky smooth to rough and nasty just because the battery gets disconnected. I soon found my real problem which was incorrect ignition timing (self inflicted). So, my 2 cents worth is that the ECU is trying to compensate for a sensor input that is out of the normal range, and it does so after a period of trial and error.
-Lazarus

 

[JulezSteele]

that sounds very reasonable, because this has only been happening ever since ayear ago when I over revved my engine and a pop stalled it out, and i couldnt restart the car for a day, it ran rough at first, but fixed it self, never the same, ill have to check out my ignition timing and stuff.