Aftermarket Keyless Entry causing Misfire???

So I have been having an cylinder 4 misfire for quite some time now. It only happens when the engine is warm and if I turn the truck off and then restart it... Taken it to 2 mechanics now and no one can diagnose the problem.

I started to think about it and right around the time of the engine misfires, I had installed a keyless entry/security system. Not thinking about this at all to cause a problem, I started doing some research and found some weird articles about people installing aftermarket security systems and having engine misfires because its sucking to much voltage from the ignition circuit?

Has anyone installed an aftermarket system on there truck and had this problem?

Dan

 

Off-hand, I don't remember anyone reporting such a keyless-caused problem, but it's entirely conceivable (depending on the keyless system, how it's wired in, and how good or bad the wiring job was).

 

Well I hope it was wired in correctly but im not sure... It was a cheaper system, so it could that. I think I'm going to try disconnecting it and seeing what happens. Hopefully no Misfire, then I will be the only one with keyless entry system causing a misfire, a new mistery to our trucks.

Dan

 

So I took the keyless entry out, the misfire was still there, but it seemed to be slightly better. Is there any possibility that it could be the alternator failing on me...?

Dan

 

I'm having a hard time accepting the notion of a (general) alternator problem (and maybe lowered voltage overall) causing a misfire specific to Cylinder #4 alone.

 

Yeah I was a far reach but one of the last things I thought could maybe in some way cause it. I have checked/changed plugs, wires, coils, many different sensors, fuel lines, fuel filter, keyless entry, and alternator... Not really sure where else to go from there, so I end up taking it in.

Also I went to Autozone be for I took it in and they said it was a Cyl.4 and Cyl.3 misfire from the codes.

Any new ideas?

Dan

 

I had the same issue back in October,
It was a #4 misfire, intermittently. The truck would shake and the engine light would flash. Sometimes it would log a code and some it would not.

I did the new plugs, swapped the coils, and after not making any difference, I brought it to a friends garage, he cleaned the Injector screens, changed an injector seal that looked crappy, and then relocated them to see if it would change cylinders. I also changed the fuel filter afterwards, he said the screens had a little debris in them.

The problem has not come back. Although, it started when I parked it for two weeks while I was in FL, then my GF drove it, and the shake started. It has not sat for any prolonged time since. I have driven it 6000 miles since then.

Good luck.