Got misfires in cylinders 1, 3, & 4. My car is chipped so I replaced the plugs with BRK7E's, )gapped to .028") & changed the coil packs to the Hitachi Rev. E packs. Still getting misfires, but only for a minute or so on a cold start. Other than that my car runs in limp mode and no more misfires till next cold start. Any ideas?

 

How old are your plugs? I generally replace my BKR7E plugs every 5-8k miles.

How old is your fuel pump? You could try cleaning your MAF sensor to see if that would help. Maybe also try swapping one of the injectors from a misfiring cylinder to cylinder 2.

 

Thanks for the reply. Plugs are brand new, got them a week ago. As for the fuel pump I'm not really too sure.. how could these symptoms be caused by the fuel pump?

I also read it could be the ICM, and my coil pack wire harness has definitely seen better days, but I'm trying to exhaust all options before I resort to that.

I'll clean the MAF too even though its only a year or so old so I don't think its that either, and will switch up some injectors. Will post w/ updates after work.

 

Your 2000 doesn't have an ICM, so rule that out. (only AEB engines do)

As far as fuel pump, I meant filter but typed pump lol.

 

Lol I was like hm. That was one of my first guesses as well, changed that about 2 weeks ago too. When I clear my codes and start my car on a warm start (no increased RPM's for a brief period) there are no misfires and no misfires under heavy boost as well. Maybe just a slight hiccup now and then but not nearly as bad as a cold start.

Then once my drive cycle completes the CEL comes back on, and limp mode is back. With a system too lean code as well but I'm sure that my pre-test pipe 02 is shot from all the backfiring.

 

Edit: I just had a thought, I know my valve cover gasket needs to be replaced as I had a small amount of oil on the spark plug in cylinder 2, is there a way that oil could get getting sucked into the intake causing the misfiring?

 

Don't think it would be enough to cause any issues, but if it's leaking then you might as well replace it anyways.

Another thought: have you replaced your CTS (coolant temp sensor) on the back of the head? And how old is your primary O2 sensor?

 

I have not replaced the CTS. Might as well do that this weekend since I'm changing that damn flange back there.

Primary 02 is about 1.5-2 years old.

 

Definitely replace the CTS while you're in there!

Your O2 sensor should be fine, but if you decide to replace during the process of elimination, Amazon has it for $59:

 

That's a really good price. I may have to pick one up. It's the last thing I can think of that would be causing me to average 18mpg on a stock ECU. I get 12mpg in the city.