2005 Saturn ION misfire and it sputters

vikasintl

2005 Saturn ION manual 197k miles

It starts and runs in idle ..does not overheat
I can drive it in neighborhood but I can not go on road ..
i.e. can not go pass 35 mph..

I believe after 20 mph it sputters when accelerator is pressed

recently changed spark plugs and coil pack but no change


Where do you think problem is ?

Do you think its fuel pump or fuel filter or something else?

inuvik

I think you're on the right track for diagnosing the problem. Start with the fuel filter first (it's the cheapest). With almost 200K on the clock a fuel pump could be the culprit.

thecardoc3

What are the long term and short term trims doing at idle, and then under the conditions where the drivability issue occurs? What is the fuel pressure? What other real testing has been done? Any? There are better ways to address this other than continuing to toss parts at the problem.

inuvik

@vikasintl you didn't state whether you had diagnostic tools available to you or whether or not the Saturn was displaying trouble codes that could be read by a OBDII reader. Some auto parts dealers can read codes for no charge.

vikasintl

Well misfire code was p0301 ..seller said he had misfire code so he changed spark plugs and coil pack and wires but it did not fix it and he continued driving it so than it started sputtering ...and now it does not go pass 35 mph ( I believe due to misfire , cat was clogged)

thecardoc3

That of course is a possibility. When driving the car monitor the engine load calculation which should hit 100% at wide open throttle and remain there as the vehicle accelerates, then look at the fuel trims and see whether or not fuel trim correction is being made. If the engine load calculation is low and the fuel trims are not making a correction then some type of a problem that is preventing the engine from pumping air correctly, such as a restricted exhaust is plausible. However if the fuel trims are making a correction and adding a significant amount of fuel (30-40%) then there is a fuel supply issue that needs to be analyzed.