So I recently had a Haltech Sprint RE installed on my s4T>s5T swap.

The car starts with a fully charged battery and will run perfect for about 5 min.

Idles at 500 and smooth.

No smoke.

Then all of a sudden the car loses power and stalls and doesn't have enough juice to start again until I charge the battery.

When the car is off the battery stays a steady 12V.

No lights are being left on and killing the battery.

My battery and alt have been tested at Advanced and were both good.

Any ideas or help is much appreciated.

 

Have you already checked your grounds and fuses/relays?

 

Definitely sounds like an alternator...Maybe have it re-checked somewhere else? Ask for it to be tested multiple times or something? Maybe it has a short in it or something that caused it to run for a while and check out good when they tested it but the problem presented itself when it heated up or some such, who knows.

 

Do you have the S4 or S5 alternator? Check the FAQ section for the wiring diagrams to each as they are wired differently. And 500 rpm is too low for a steady idle as it should be somewhat higher.

While running, the alternator output wire should read 14 volts or so.

 

Its a s5 alt. I bought a whole s5 engine and trans together.

When I have my laptop plugged into my ecu it reads 14v while running.

500-700rpms is what I've had all my rx7s idle at.

My ground that goes up to one of the bolts on the intercooler is connected and so is the one that goes to a bolt holding the trans to engine block. I don't know of any others.

I'll test the fuses under the hood. I know the main on is good.

 

But do you have the alternator wired differently than the S4 or the same?

 

I didn't do the wiring. I had a shop do it and they followed the book that came with the ecu as far as I know. Could my alt be draining my battery if its wired wrong?

 

If its wired like your S4 alternator then the answer is yes. The S4 alternator has a B/W wire that runs into the back of the alternator along w/another wire. This wire is powered w/key to on. On an S5 alternator this wire comes 'from' the alternator and is powered w/constant voltage and not key to on power. If its powered w/key to on power then it will drain the battery. This B/W wire should run to the engine fuse box where it receives constant power ( and not key to on power). This is why it was recommended to look at the FAQ diagrams to check how yours was wired as it should be rather easy to tell how your B/W wire is connected.