went from p0301 to p0304

[handcannon44]

i have a 2000 SL1 had the faulty intake gasket problem causing misfire on cylinder 1 ( p0301 ). changed gasket everything was great after that for a month. Now i have missfire on cylinder 4! im stumped drove around all day yesterday just fine. Startedthis morning with ruff idle and almost immediate code.

compression is good all above 180

just replaced plugs and wires when i did the gasket and cleaned coil terminals at the same time did ohm test on coils checked out ok

fuel pressure was good dont remember the exect numbers but i know it was within peramiters at the the time i checked it about 2 months ago

[OldNuc]

Check for vacuum leak or slightly open EGR valve.

[handcannon44]

no vacuum leak and cleaned egr still misfireing

[OldNuc]

Cut up a can and block off the EGR ports. Use the EGR to hold it in place on top of the gasket and keep the EGR plugged in. If that does not show anything the next step is a compression test.

[handcannon44]

compression is good 195 ill try blocking of the egr next

sorry if this a dumb question - why would the egr only affect cylinder 4

should i try swapping the injector with another and see if the misfire moves

[OldNuc]

Listen to the injectors when the engine is running, use a long screw driver. The EGR port in the intake is closest to #4. And #1 and #4 are on the same coil. So an ignition issue is not out of the question. Plugs, wires, coil, ICM are possible.

What brand wires and plugs?

I would swap the coils first, it is easier to do.

[handcannon44]

already swapped coils with no effect

i went ahead and swapped injectors i swapped 3 and 4 to see if the misfire moved. instead it went away completely. i drove it around for 45 min no codes pop up on scanner. could the injector have been stuck and removing it or releasing fuel pressure freed it up ? i did put in some injector clean when i filled it up last (its at half a tank now) could that have flushed something down the line?

it defiantly is not the first thing ive taken apart and put back together to have a problem mysteriously go away. im a little wary of its reliability now though.

thanks for your help ill just have to cross my fingers it doesnt do this again

[OldNuc]

May have been a dirty electrical connection or possibly stuck pintle. Hard to tell. Just be glad it is fixed or isolated to injectors and associated wiring.