Could a bad alternator cause stuttering under boost at WOT?

[Notstock]

Hey all,

I just finished installing my Aeromotive AFPR and went for a test drive. I set the base FP to 37/38 with the vac line off. I drove for around 20 minutes just fine then all of a sudden, the car started stuttering/backfiring at WOT. I got home (lucky I was close) and shut the car off. I looked under the hood for any fuel leaks from the install and everything looked ok. I got back in the car and tried to start it. It sounded like the battery was drained. I shut it off again, tried to start it and the battery was totally dead. I didn't have time to stay at the shop but what should I start with first? I'm assuming the alternator but wanted to get some feedback on some things I should check.

My car is a 92TSI with a big16g, 3" maft, dsmlink, FMIC, AFPR, 2.5" exhaust, AEM wideband, supporting gauges, blah blah blah.

Thanks

 

[1gDSM4g63]

Dead alternator doesn't cause stuttering. If the battery isn't charging and doesn't have enough power it would completely shut the car down because there is no spark to the spark plugs.

 

[Notstock]

Sounds like I have two separate problems then. I just figured if the battery was slowly draining (because the alternator is going bad) I would lose spark (especially at full boost) and would cause a stutter/backfire. Guess that's not the case.

 

[turboglenn]

Stuttering is usallu either a symptom of an overly rich condition or a worn or fauly product in the ignition system ( I.E. improperly gapped plugs, bad plugs, bad wires, faulty coils etc...etc..)

Not a bad alternator..a bad alt makes your tach jump with your turn signal and other weird electrical issues.

 

[Notstock]

Ok, definitely sounds like I have a bad alternator as well as another problem then. I did notice my egt and electric oil pressure gauges jumping around, especially with the turn signal on. I'll have my alt checked out and check for boost leaks, check my plugs, wires, coils, etc. I must have had really bad luck because it was running perfect, then these two problems started happening about the same time. I just got done fixing an idle surge problem. Does it ever end? ha. jk. I know it doesn't

Thanks guys.

 

[Kevin Jewer]

Bad alternator absolutely can cause stuttering. Real hard for the ignition to fire with low voltage. The fuel pump also suddenly gets real small too, which of course is the biggest risk. When voltage on my RWD dips into the 10s or 11s, the Kenne Bell BAP feeds the pump and saves the motor, but I get a mean ignition misfire.

 

[steve]

First sign that the battery voltage is low is the car breaking up under load. Then the radio display turns off followed by the car dieing when the ECU turns off.

 

[Notstock]

The problem was a dead battery. It finally took a dump on me yesterday and I took it to autozone to have it tested. That was definitely the problem. The car is running great with the new battery. I though it was the alternator because the battery would take a charge at first. Not the case though. A dying battery definitley causes strange issues like stuttering, backfiring, running lean, overheating, etc.. I experienced all 4 of those. Luckily I didn't ruin anything.