ACCELR8

The car is a '98 Sunfire. It started running rough and then the SES light came on. The code was P0303 - Cylinder #3 Misfire Detected. After a couple of days of driving the SES light went off, but the car continued to run rough. Today I ran Autotap and got some information, but I'm not sure what it means. I thought an injector might be plugged or bad so I checked the pulse width of all the injectors. They all seemed to be performing at the same level, so I figured it wasn't a fuel problem. Then I checked the misfire hystory. It showed cylinder #3 only misfired twice, but cylinder #2 misfired approximately 5000 times. That confused me since the DTC said cylinder #3 was misfiring. Then I did what I probably should have done first, I checked the freeze frame that cause the SES and it said the DTC was cause by a MAP reading of 15.4 in Kg. Does this mean there is a manifold leak?

I'm not sure if I went about diagnosing this problem properly, so if anyone has any suggestions feel free to comment.

Thanks,

Jim

wrencher

iTrader: (2)

Go back to your first thought of a plugged injector. It is getting to be so common now a days. 2.2? they also had a wiring issue on the harness's on the J bodies. Need to test that injector while missing/running poor. Another thought if injectors OK, 2-3 are companion cylinders & share an ignition coil also.

ACCELR8

Thanks for the reply!

Yes, the car has the 2.2L engine.

I'm not very proficient with Autotap, is there a way I can test the injector with Autotap or do I have to take the car to a service station? Also, if the injector is OK, what's the best way to check the coil pack?

Thanks,

Jim

wrencher

iTrader: (2)

The injector testing on that 2.2 will require a special injecto pulser/tester, used in conjuction w/ a fuel pressure gauge. That way you can balance the injectors. The 98's I'm pretty sure were still bank fire , they fired injectors in pairs. Important to test them will failure is occuring, common for pintles to stick , & can be intermittant. The coil you can do an ohm test w/a volt/ohm meter. S/B about 5.5 K(5500 ohms)or there abouts, other tests of course involve specialized equiptment.

ACCELR8

Thanks for the info!

I probably start with checking the coil, since I have a multi-meter. If that's not it I may just take a chance and replace the injector.