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Big T
07-28-2007, 04:10 PM
I had to charge my battery a few times recently. I don't drive my car often. Now it doesn't seem to be running as good. I'm getting some hesitation under boost. I logged my batt voltage and it is dropping to 12.5 and this is at 4300 rpm's. I have never changed my battery since I got the car. Could this be making it run bad? Is the BAP not getting enough juice?

03slidewayzSVT
07-28-2007, 11:59 PM
sounds like a bad alternator:thumbsup:

Big T
07-29-2007, 01:50 PM
I'm leaning towards an alternator problem. I do have a 2# lower and I didn't change the alt pulley size. I also found a code p1233 which is fpdm disabled/off line. My fuel pump duty cycle is in the 20's even under boost when I data logged. It was in the 70's before the problems started. The car will start now but sputters at times upon initial start. I'm going to check my fuses to see if something blew. Any input is appreciated.

blueblazes
07-29-2007, 01:59 PM
check your bap wiring and make sure everything is good there. With the car idling put a volt meter on back of alt where battery cable ties in and see what your voltage coming from it is.

Big T
07-29-2007, 05:11 PM
check your bap wiring and make sure everything is good there. With the car idling put a volt meter on back of alt where battery cable ties in and see what your voltage coming from it is.
Thanks for the info. What should the voltage be out of the alt?

InfamousSVT
07-29-2007, 07:43 PM
With the 2lb lower you shouldn't need a different alt pulley, but it still could be a bad alt or battery. If you decide to swap out batteries go with a Red top Optima, I've never had any problems with mine.

Also check the reset button in the trunk for your fuel FPDM and the wiring on your BAP.

Do you have any "extra" electrics hooked up? Make sure nothing is running off the battery itself, this may cause permature battery failure if you don't drive the car often.

Good luck and let us know how it turns out.

ausie
07-30-2007, 06:59 AM
Measuring off the battery terminals with the engine running should produce 14volts dc. Should be about the same off of the voltage regulator.

Big T
08-09-2007, 11:14 PM
I bought the red top altima $170.00 :eek: . I'm going to put it in and see if it solves my problem. If not, i'll get a new alternator from PA Performance. Still haven't checked the alt voltage. I'm going to do this before the battery install.

Big T
08-10-2007, 08:39 PM
Put the battery in and still have the same symptoms. Must be the alternator. The red top battery looks good under the hood. I'll keep y'all informed on my progress.

Big T
08-26-2007, 05:04 PM
I got a refurbished alt for $70. I put it in and the car starts good now, but is still hesitating when I hit the gas hard. Fuel shut off switch in trunk was not activated. My fuel pump duty cycle is still at 18% and increases to 22% when I turn the BAP setting down to 0% at idle. Like I said before, the duty cycle was about 30% at idle before my issues with the BAP at 40% and the duty cycle was 40% at idle with the BAP at 0%. I think the fpdm is still going offline. The BAP sems to be sending a signal and getting power. Any other suggestions of stuff to check?

blueblazes
08-26-2007, 06:40 PM
try unhooking the bap and see what happens

could eliminate any question about it being the culprit. Work from there. Goto junkyard get a fpdm from car and swap them out make sure its working right.

Big T
08-27-2007, 09:36 PM
Good idea. I'll unhook the BAP this week and see. I've been fooling with it on and off since it's not my daily car.