Hi, just recently I had to have my alternator reconditioned and a new battery installed, after those installations my car has been running badly, before it used to idle at 800rpm when in drive but now it’s close to 500 and the tyres dont spin anymore when I floor it. I'm thinking it’s the computer so how do I get my car running back normal? Any help would be greatly appreciated. Thanks.

 

i think i'd make sure the battery and alternator were working and the outputs correct. scan the car for codes and make sure the tune up is good. i'd suspect just about anything but the ecm, unless you've doen something to make you think it's the ecm.

 

Yeah I checked for codes and I got nothing, how do I know if the outputs are correct? And and how would I know if the tune up is good? Thanks for helping a beginner out.

 

When you're scanning for codes, do you at least get a "12"?

 

No I had a mechanic have a look at it and he said he didnt get a single code.

 

You should verify with your mechanic that there was not even a "12". If not, either the ECM was not correctly set to diagnostic mode, the ALDL connections are faulty, the SES lamp is malfunctioning, or the ECM is damaged.

 

Ok I'll give him a ring tomorrow, just say it does show a 12 what does that mean?

 

code 12 is just a code everyone gets when scanning the ecm, its completly normal and means nothing... its just says theres no reference pulses going to the ecm... but it should display itself everytime u scan the ecm or something is at fault.

 

If your battery was disconnected for any amount of time it probably reset the ECM & will have to relearn. Sometimes a dirty IAC will complicate the relearning process & have to be cleaned to restore original performance.

 

Hi, how long does it take to relearn? And what is an IAC and how would I go about cleaning it?

 

1. There is no re-learn procedure on an '89 TPI V-8 IAC;
2. You can clear the stored codes and BLMLs in your ECM by disconnecting its power source for a few minutes. It's usually an excellent excuse to remove and clean the battery terminals.
3. A "12" will occur any time the ignition is ON and th eECM is not receiving distributor reference pulses. Usually, that's
   because the distributor is not turning (engine not running) but it can also indicate missed/low level reference pulses when the engine has been running. It should always appear in Diagnostic Mode.
4. Perform a search for "IAC stepper motor" and you should get some ideas.