Hey Guys,
I have a problem. I got my Kenwood 7015 and Nav Installed about 3 months ago. Well last month, my car started misfiring. I took it to Infiniti and they looked at it and couldn't do anything with it, so they reset the codes and sent me on my way. Well last week the same thing happened again. And the stored code was the same as the first, saying that the 4th cylinder was misfiring and they kept the car for a week and could not determine what was wrong with it. So now they have switched the #2 cylinder with the #4 cylinder and say that they think it was the people that installed the stereo, they said that they tapped into the "body control harness" and this directly connects to the "ECM". So now I am about to take it to the Stereo place and see if they can re-wire it. But does any one have any other advice??

 

I would venture to say that the stereo has nothing to do with the engine issues. When a tech can't figure something out and there is aftermarket parts on the car it is easy for them to point the finger. Think about it, what could the stereo installer tap in to that would cause a misfire in one cylinder, let alone two? Also, condsider the car ran fine for three months!!!!!!!!

 

KPierson,
Yeah that is still the way I feel, but then again I don't know what the Stereo place did. So now that my car has acted up twice since saturday, I am taking it to Infiniti to see if, after they swapped cylinder 2 and 4 that if it is cylinder 2 now acting up. If that is the case then Infiniti knows what the problem is.. If not... then I will take it to the Stereo place and take some pictures of how they installed things, and then take it back to Infiniti and challange them to prove, beyond a reasonable doubt that it was the Stereo install's fault.

 

What do you mean they 'switched' cylinder 2 with cylinder 4?

You really can't do that, the block has a set firing order. In order to change the firing order you would have to change your ignition signal (individual coils), your fuel injectors, your crank, and your cams. Otherwise, you will have a MESS of problems.

If you just swap the coil packs on the car (say cylinder 4 and 6) the car WON'T run. I know this from personal experiance (please don't ask).

I would be very suspicious of your dealer right now, and I would have them explain everything they are doing in writing.

The only thing I can think of that they could have changed was the actual spark plug itself, or an actual fuel injector. However, I would like to think that the dealer would replace sparkplugs instead of just swapping them and I think with fuel injectors you would have more issues then just misfires.

Once again, I can't think of any way that the stereo or Nav would integrate into your ECU that could cause problems, unless, of course, your Nav unit has an RPM input!

 

I agree with Kevin. If your stereo shop tapped into your harness to disable/go around the "only viewable in park" safeguards on your head unit or if they tried to tap into the wiring harness for items such as vehicle speed and RPM signal they could have very easily caused shorts in the system. I experienced problems like this with my BMW and many modern cars use a harness that carries signal for a multitude of items, not just pin a to pin a. Even so, the problem with a tap into your harness could be something as simple as a bad tap/improper sized wire that is causing too much/too little resistance on that circuit. I would recommend removing the head unit (PITA) just to be sure. My 2 cents.
Good luck.

 

Thanks for both of you responding. Yeah I am going to request for everything in writing... but as far as tapping into the speed sensor, they did do that. I don't know if that could cause a problem with the way the cylinders are firing. They actually swapped the iginition coils... If I do remember correctly.

 

The speed sensor signal wouldn't effect engine performance. Also, you should be able to verify your speed signal is still accurate using your Navi system.

It would be possible to swap coils IF they unhooked the coil and didn't swap the wiring with it. I was thinking they just unbolted one coil and swapped them without changing the wiring on them.

They must be suspecting a faulty coil.

The coil on the VQ35 is completely self contained - if I remember right they have three wires on them - 12vdc, ground, and signal. The ECU sends the 'fire' signal and the coil creates the high voltage spark completely internally. I would imagine it would be almost impossible to damage the coil with an aftermarket radio!