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Serious problems with electric and engine

1361 Views 16 Replies 6 Participants Last post by  Pacha
Hi together my name is Fabian and I'm writing from Switzerland.

I have a 2005 Mustang GT with JBA LT Headers, FR Intake Manifold, Saleen Air Intake (looks like stock) and Sultans of Spark coils. The software is from bama.

After I installed all the things I didn't have any problems but now some serious things showed up.

First i replaced the alternator because it smelled. I bought a TYC from and installed at. After that I recognized that my voltage was moving under idle speed (only then). It goes up from the normal 12-14 volt to 16 volt.

Because of that I ordered a new alternator on guarantee but the problem is still there.

Also i have some problems at idle speed with the engine. Sometimes it runs normal but sometimes it has missfires and it shutters. I already took out the BBK TB and put the stock back in. No change. Besides that the car runs totally normal and very good. I was in Germany some weeks ago and drove over 140mph for at least 150 miles (avergage). Some times after I start the engine the P2198/6 shows up. I already replaced the O2 sensors twice. I also checked the Ford Racing Intake for leaks.

My mechanic said that O2 sensors and all other things look normal when he did a diagnosis. He said it could also be the BCM that's broken. He said that while he was measuring the voltage it was always normal but suddently went up to 16 (up and down), independent if radio was on or not or other electric consumers were working.

I'm a member of a german community but nobody was able to help me. I hope you guys maybe have an idea. I'm baffled.

Thanks and kind regards

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for the codes make sure your o2 sensors are motorcraft. most aftermarket sensors seem to be problematic for the fords with a tune.

the voltage issue could be a few things, I would look at the smart junction box, make sure there is no corrosion on any of the plugs.
also check for signs of water leaking on the sjb.
I thought the Swiss considered car modification akin to murder?

Anyway, if you're having rough idle and misfires you should check the other parts of the ignition and intake system. I would expect to see voltage drops if the battery/alternator setup was going bad.

Check your coils. It may be as simple as one of them being loose. I'm not aware of the Sultan's of Spark coils, but the general consensus is that the stock coils are best, and most aftermarket coils have problems. (You can test yours, but just be careful...they can zap the crap out of you.)

It may be time to either re-install your BAMA tune, or get it re-tuned.

Have you changed fuel octane lately? If your tune is set for a certain octane rating, and you put something else in the tank, that will cause rough idle and misfires as well.
I have voltage increases not drops.

What I saw is that the Shaker 500 fuse was broken, but this should make a difference also because I have the shaker 1000.

The TPS and MAF are brand new. Throttle body is clean.
I don't think the coils are bad, because I had the rough idle before I replaced them with new aftermarket ones.

The O2 sensor first were cheap ones from rockauto. The second replacement I did with Bosch O2's.

Could my start button or the aftermarket navi radio be the problem? I had to install a voltage converter to use it with the Subwoofer.

The gaskets of the Ford Racing Intake plus the o-rings of the injectors I already replaced. I also installed a new fuel filter. The spark plugs are also new ones.

I have to check the SJB of course. Could a broken fuse are a lose cable cause this ****?

In Switzerland tuning is almost the same as murder:p But nobody knows what I did.....hahah

In Europe you don't find fuel with under 95 octance (93 in US)

The tune I already changed a few times. I also made a data log for Bama. What was misterious was that I wasn't always able to put it back on stock.
So combine all together it could be the PCM that's broken.
i have nothing to contribute but i think it's cool you're running a modded out gt around switzerland.
that's so:)

There are not so many of these around here and when modded it's somethin very special.

2015 they gonna start to sell the Stand in Europe, then you will see this car as often as a BMW M3 or someting similar.
that's so:)

There are not so many of these around here and when modded it's somethin very special.

2015 they gonna start to sell the Stand in Europe, then you will see this car as often as a BMW M3 or someting similar.
maybe it is a classic case of wanting what you can't have, but i'd rather have a badass m3/m5 over a gt 'stang in almost every circumstance.
If you have the Shaker 1000, I think technically it's the 500 with the added subwoofers in the trunk (there's the woofer plus two additional amplifiers). The rest is the same I believe.

Do you notice that the car behaves badly when the voltage spikes? Can you put your meter on the car and watch it to see what happens?

How's the belt?
So the broken fuse could cause something?

My mechanic put a meter on and he saw that under idle the voltage was always where it should be. But suddently the voltage goes up. Doesn't matter if light is on or off or the radio is on.
bosch o2 sensors are one of the worst I have seen. im tuning a lightning that has one bosch and one motorcraft o2. the bosch sticks lean then sticks rich. it really messes with the idle and part throttle driveability, until it decides it wants to act right.

the radio usually wont cause a voltage spike.

along with the ecm the sjb contributes with controlling the alt voltage.
You have a bad alternator when your voltage spikes like that it will blow the radio fuse every time it has happened to me. I changed the alternator and fixed the problem. Buy a motorcraft alternator. These after market ones are junk.
So I should by motorcraft O2 plus a new alternator. Does somebody have the partnumber for these things?
So I should by motorcraft O2 plus a new alternator. Does somebody have the partnumber for these things?
I'm not sure if a bad o2 sensor would cause a voltage spike. You can test them but it's a little tricky because it's a tight space under there and it's very hot. The chance to burn yourself good is somewhat high.

I'm not sure what stores are available where you are, so I'm not sure where to point you online. I'd say look at and but I don't know if either will ship to your location (the former will only ship to a Ford dealership).

You can get your alternator tested and see if it's causing you issues.

Have you checked for a vacuum leak?

It's stories like these that remind me to never mod my car...
That's pretty defeatist.
I can honestly say modding my car has been a journey but a good one. I've enjoyed the improvements greatly. When things didn't turn out right, it was almost always because I didn't do something right, either because I was just learning how to do something and messed things up, or because I didn't do enough research and bought the wrong parts. The only reason anyone should not consider modding their car is if they don't have the money or patience to do it right.
It's stange because I first didn't have problems. It came up one after another. The O2's I already changed a few times.

I'dont know lets figure out what it is. Maybe the OBD scan finds something.
Hello together

I still have the same problem and defenitely don't what to do anymore.
After I changed the alternator twice I also replaced the voltage regulator inside the alternator. The problem with the voltage ist still there. I also checked all connections and ground cables. Everything sits tight. The connections I cleaned with a electriccleaner spray.

Could it really be the PCM? Or could the SJB cause that problem?

This is a video of what happens. The problem now shows up during idling or while I'm driving. Doesn't matter it the light or radio is on or not.

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You may want to have your mechanic check for any excessive amperage draw simultaneous with the voltage spike.It may help point to a cycling load to the alternator causing rise in voltage.From the video the engine sounds like it reacts with a lower rpm to the rise in voltage suggesting an electrical load on the alternator.If you raise the idle rpm up to around 1500 rpm do you still get periodic voltage rises?
I have it almost at any rpm. The regulator is brand new, 1 day old.
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