So i replaced my alternator almost a week ago, since then i have had problems with my car idling properly and in some cases the motor stalls out and dies on me. I've been doing research and i took my car over to FW and found out that more than likely it's being caused by the ECU being reset when i DC'd the battery. I was told to give it time to "relearn" to idle properly, but after six days and at least 800 miles it is still giving me problems. I had paul at FW clean out the throttle body as well....I've followed a couple instructions to attempt to get it idle properly and still have not really had much luck. I found that it seems to idle alright now until the cars fans turn on (not the AC or air) then it sputters like crazy until they shut off then goes back to normal....just wondering if anyone has come across a similar problem and if anyone could offer some advice.

 

Did the alternator check out as working?

 

I recently reset my ECU a few weeks ago and did not have any of those symptoms. My car idled fine and did not hesitate while idling or when the fans turned on. I did have trouble starting for the first couple cranks but that's normal. Make sure the MAF is tight and clean and make sure no vacuum lines came loose or ripped while changing the alternator out.

 

hey Matt..

if it wasn't the throttle or the MAF..how about the fuel pump maybe? you can use some luca injector cleaner too if you haven't tried any of that stuff yet.

 

I think the alternators are different for auto vs manual. Sounds like the car doesn't have enough juice. Check this out. I'm thinking that your fuel pump isn't getting enough juice and the engine isn't getting enough gas to keep the idle steady.

Automatic WRX's have 120amp Alternator? - NASIOC

 

This.

Clean your maf, check any hoses you removed, a pin hole puncture can throw your car off.
Clean you IACV: Cleaning And Reattaching The IACV (Idle Air Control Valve) - NASIOC

However, I suspect your fuel pressure is dropping, your car is probably super lean. Fuel pump is crapping out or filter is clogged.

 

stock injectors?

 

His car is all stock. 90k maintenance was done a few thousand miles ago.


Only thing left to do that I can think of is check fuel pressure and try a different alternator.

 

Have you checked to see if there was a small Ethiopian in your engine?

 

Alright, who let John out of the gimp cage?

 

 

Hmm... After some more research, I've found that it's a common problem with people who tend to pump their gas using their masturbation hand. Try switch hitting and see if that smooths out the idle.

 

^
LOL!

i agree with thejordan.

seems to be an erectrical problem. injectors need power to squirt; fans kick on and reduce available power for the injectors. the latency of the injectors changes with battery voltage
but if you're all stock those values shouldn't have changed.

 

First thing i looked for.....

No difference, but i did meet a friendly stranger in the process.

Yeah all stock.....idk haha at this point i think i am just going to get a diagnostic ran on the car...it's unfortunately starting to give me more problems than just idling funny.

 

Did you ever fix it and if so, what was the problem?