Replaced everything, still cylinder 4 misfire

XRYoda · Aug 10th, 2006, 01:03 AM

I'm trying to get my 97' 4cyl. pickup through the smog test, and after replacing the rotor, cap, plugs, plug wires, and air cleaner, I am still getting a p0304(cylinder 4 misfire). I am assuming that I have reset the ECU(cleared previous code), as I unplugged the battery and tried to reset the ECU for good measure. I say I tried to reset hte ECU as the check engine light is burned out and it is a little hard to tell if I was doing it correctly.
What else could it be? Injector? the truck has 138,000 miles on it. Runs great. I guess that I will try a good injector cleaner next, but am at a loss as to what I should try next.

Thanks!!

**88pathoffroad** · Aug 10th, 2006, 02:14 AM

Does it run funny or is it not noticeable?

jerryp58 · Aug 10th, 2006, 06:13 AM

Quote:

Originally Posted by XRYoda

I'm trying to get my 97' 4cyl. pickup through the smog test, and after replacing the rotor, cap, plugs, plug wires, and air cleaner, I am still getting a p0304(cylinder 4 misfire). I am assuming that I have reset the ECU(cleared previous code), as I unplugged the battery and tried to reset the ECU for good measure. I say I tried to reset hte ECU as the check engine light is burned out and it is a little hard to tell if I was doing it correctly.
What else could it be? Injector? the truck has 138,000 miles on it. Runs great. I guess that I will try a good injector cleaner next, but am at a loss as to what I should try next.

Thanks!!

Have you done a compression test on all cylinders?

dvdswanson · Aug 10th, 2006, 08:19 AM

do an ohm test on #4 injector. should be around 80 ohms I think

XRYoda · Aug 10th, 2006, 10:23 AM

I dont notice the misfire at all. I have not tried a comp. test, tht will be next I guess. I'll look at the injector, too. Thanks guys.

lovemysan · Aug 14th, 2006, 10:28 PM

check the intake manifold gasket. Does it burble at idle sometimes? Listen carefully.