Hey guys, sometimes when I turn the key to the "On" position I will get a loud "bang", like a backfire sound before I start the car. It only happens once in a while but it scares the hell out of me. I keep thinking that I just blew something up, but everything runs fine after I start the car up.

I have the ignition harness installed so I'm guessing that maybe there is unburnt fuel still in some of the cylinders and the e-manage is firing some of the plugs when you turn the key on, which would cause a backfire if the piston were in the right position. This happens even after the car has sat overnight so I would think that the fuel would have evaporated in the cylinder.

Am I way off on this one, or what could it be?

 

Did you put diodes on your ignition harness? If not..that could be the culprit. I have never heard of the issue you just described.

Good Luck!

 

Yes the diodes were installed!

 

That's wierd, I think your guess is right as to what is happening. It won't damage anything. There isn't the dynamic compression because the engine isn't running. I'd put a Multimeter on the coils and turn the key to see if any voltage is flowing. Do it for each coil maybe only one is doing it.
Good luck
Gary

 

From what I have been told and found out through my own situations is that there will always be current supplied to some of the coils by the e-manage unit if the ignition is in the "on" position and you have the ignition harness installed. I have already burned out 2 coil packs by leaving the turbo timer turned on too long without the car running. It's easy to forget that it is on for me because I had my installed in the glovebox so I can't tell visually that it is on. Say you forget to roll up the windows after you shut the car off, so you climb back in and turn the key to the "on" position to roll them up. As soon as you do that the turbo timer selects the preset cool down period and counts it down. This could be enough time to overheat the coils. Trust me "I know".

Just thought I would give you guys a "heads up" on this problem.

 

I heard that would happen if you didn't install the diodes.I thought that the whole point of the diodes was to prevent that from happening.

 

This was a much bigger problem before the diode pack fix. But you are correct..there is some current supplied at all times..even with diodes. The diodes minimize the excess current, but they dont eliminate it. If I knew how to use a multi-meter...I would check it out myself. Let us know what you find out!

As a precaution, I NEVER leave my car in the on position without the motor running. I dont know for sure if it will fry with diodes installed...but I dont wanna take a risk. I've been driving in hot weather with rush hour traffic for 2000miles with the diodes...no issues.

 

If you notice in the Profec E01 manual it says somewhere when you are programming it that you should unplug the ignition harness because they require you to turn the key to the on position for about 5 minutes while the profec loads data from the emanage. Now I know why they say to unplug the harness.

 

Hey GQ, If you wanna test the didoes grab a multimeter and do this. Set the MM to Volts DC current and connect the black lead to a good chassis ground. Then test the voltage before and after the diode. Before would be on the emanage side, and after would be the coil side.