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1999 Pontiac Sunfire rough idle issue?
I have a 1999 Pontiac Sunfire GT, 5 speed standard with the 2.4 engine. While travelling along the carriageway my car dropped RPM slightly, and then began running rough. The check engine light was flashing and when I pulled over I noticed the car ran even worse while stopped and idle. While at idle the check engine light is no longer flashing, but still on. I hooked up my OBD2 and the error code came up "cylinder 1 misfire." I changed my spark plugs and wire plugs but this has failed to resolve the issue. I am unsure as to this being a fuel issue or a sensor issue. Any help would be much appreciated. Thank you kindly!
9 Answers
- KevLv 41 decade agoFavorite Answer
is there an idle sensor on the car? or check the PCV(positive crankcase valve) or the EGR valve(electronic gas regulator)
- Anonymous1 decade ago
This is not a sensor issue because it would affect all cylinders. 99% you are dealing with a bad fuel injector. The easiest way to make sure is to measure resistance of all injectors, and see if the first one is out of line. If I'm not mistaken, the injector for this engine should be in the range 1.9-2.1 Ohms. One note: unlike other gm engines, this one did not have a typical injector problem.
Somebody already mentioned the coil pack - that could be the problem as well, it's just easier to start checking with injector.
- 1 decade ago
If memory serves, your 2.4 uses what are called "coil pack" spark modules. Since your code specifically indicates a "cylinder 1 misfire" I would suggest you inspect and test the coilpack that controls that cylinder. At the very worst case, the timing may have jumped a little, but I am thinking that some other codes would have set if that was the case.
Good luck.
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- nbr660Lv 61 decade ago
Are your plugs gapped correctly? Is this fuel injected? Run a bottle of fuel injection cleaner through your gas tank. Could be a partly gummed up injector.
Source(s): Freightliner Truck Mechanic - AmberLv 45 years ago
The ignition system fires the spark plug in pairs, so if you put a new spark plug in and it did not fix it it's probably not ignition related. Most likely your #1 fuel injector is bad or plugged up.
- 1 decade ago
could be a lifter, push rod or rocker arm. obd2 doesnt tell you specifically what is wrong but tells you where the problem is coming from. if you hear clicking or ticking then those could be the problem and also check your timing- could be out.
- 1 decade ago
check for coolant in the #1 clyinder,or grey milkshake colored oil.possible head or head gasket.
