Can the alternator affect tuning?

[BruceH]

I joined the alternator club today. Replaced the battery too. Alternator was putting out 9v according to the nice parts store lady. Battery was original and over 5 years old.

The new rebuilt alternator puts out 14.2v, all is good.

Has anyone had tuning issues because of a bad alternator? It never threw any codes. I was out datalogging and the values started going screwy, the abs light went on, and the radio was surely posessed. Pulled over and the car wouldn't start. Got a jump and limped home.

I'm wondering how much of an effect a slowly deteriorating battery/alternator would have on things like maf voltage, fuel pumps, frps, etc., and if there are any first hand examples.

 

[hawkeye18]

Bad voltage will absolutely screw with a tune. It will screw with the factory tune too. Many factors in a tune depend on accurate voltages.

 

[FastColt]

100% yes. Never on my mustang, but on a few other cars ive built ive dealt with similar issues. Modern cars just wont run correctly with out proper voltage, too many sensors depend on it.

 

[TurboX]

Yes yes yes. For starters 9VDC is less spark and less fuel vs 12VDC. I cant recall the amount of fuel we took out of the tune when I converted my old race car from 12volt to 16volt. Same thing

 

[Hatchman]

Oh yes, low voltage will jack with all sorts of electrical components.

With a new alternator and battery, you should be good to go.

 

[hamish]

The number one issue with bad sensor readings in industry is power supply problems.
I'm sure it's the same on a car.
All devices will have a minimum power requirement, whether or not 9v is sufficient, I do not know.

 

[itsslow]

I had the same exact issue, just replace the alternator

 

[AutoXRacer]

I had the same exact issue, just replace the alternator

With what? A stocker or an aftermarket?

I bought a PA Performance and I have been having issues with it at idle with a fully loaded electrical system. The stocker does not give me any issues.
I need and want the extra amperage, but its not performing like stock at idle.

Let us know what you go with Bruce.

 

[BruceH]

With what? A stocker or an aftermarket?

I bought a PA Performance and I have been having issues with it at idle with a fully loaded electrical system. The stocker does not give me any issues.
I need and want the extra amperage, but its not performing like stock at idle.

Let us know what you go with Bruce.

I picked up a rebuilt from OReillys. Lifetime warranty. Also got a new battery from NAPA, 3 year replacement and 84 month prorate. They had 10% off on orders placed online and picked up in person. I'm fairly certain it's the same exide battery I could of bought elsewhere but this was a little cheaper and in stock.

 

[SUHleen]

How many amps was the rebuilt unit?

 

[BruceH]

How many amps was the rebuilt unit?

I think it's 130. It's a stock replacement, what's stock? 130 or 135 IIRC. Stock has worked fine for the last almost 5 years so I decided to stay with it.

 

[SUHleen]

Really? I was told by a few people to either get a Boost a Spark, upgrade the wiring going to the injectors, or get a higher amp alternator for a boosted setup to keep spark where it needs to be. Do you have a BAS? Or upgraded wiring (that you are aware of?) How much boost are you running?

 

[BruceH]

Really? I was told by a few people to either get a Boost a Spark, upgrade the wiring going to the injectors, or get a higher amp alternator for a boosted setup to keep spark where it needs to be. Do you have a BAS? Or upgraded wiring (that you are aware of?) How much boost are you running?

That's the first time I've ever heard of it. I've ran over 17psi without any of the things you mention. Right now I'm not sure what peak boost will be. I'm hitting over 16psi before getting to redline.

I do have an 8 gauge wire going to my 40a bap. I've owned the car since new and done all the mods to it except for the gears.

 

[char259]

^ Agreed, I've had to replace alternator and went with stock replacement and have no issues. I'm only running 11 psi though

 

[W3bb3r04]

I replaced mine with an oreilly replacement as well. It was about $100 cheaper than a PA and a lifetime warranty so I'll take it. I can definitely see the voltage messing up the tuning. The diodes in mine went bad so it was still charging but messing with the electrical signals in the car. It kept throwing a code for a can position sensor. I can see that being an issue in tuning as well.

 

[SUHleen]

I replaced mine with an oreilly replacement as well. It was about $100 cheaper than a PA and a lifetime warranty so I'll take it. I can definitely see the voltage messing up the tuning. The diodes in mine went bad so it was still charging but messing with the electrical signals in the car. It kept throwing a code for a can position sensor. I can see that being an issue in tuning as well.

That was one of the codes that I got as well. Not I'm chasing a timing over advanced problem but I know the chain did not skip a tooth and the code for that does not always come up...

 

[W3bb3r04]

It was an intermittent code for me as well. Happened after I installed cams and scared me but I replaced the alternator and no problems with it since!

 

[1sloGT]

Sorry to bump an old thread but with lots of searching this was the closest. I am wondering if I was going crazy here. I had the cam sensor code which everyone here said = replace alternator. The code was coming on frequently, sometimes the car would surge at low RPM, like power would drop real quick when at a low rpm cruise on the hwy or surge forward when touching first. Went with the PA200 amp (big stereo happening soon) and the upgraded wire from AM. Now the CAM code is gone but got a new code P06200 and the battery dash light. Read a few places it will go away with some miles and is common on replacements.

My now long winded question is this...am I crazy in thinking the dying alternator was chewing up power? Because even without going WOT, butt dyno says this feels like noticeably more power. I'm just afraid to really get into it till that light goes away.

 

[86GT351]

MOst important thing to remember is every sensor in the car relies on some form of voltage source. If the Alternator is not doing it's job, then sensor readings can/will be compromised!

 

[1sloGT]

Yeah. On the side of the road now. Gonna be late for work, waiting on a daily expensive tow. Looks like a bad PA alternator. Fml.