JCreasy

I started up in "... cold" weather the other day and the car was obviously missing... Vibrating and Rough, High Idle. Check Engine came on. I shut down and restarted. Ran fine for a week.

This morning I turned on and same thing. Shut off and restarted and engine runs fine but Check Engine light still on.

Anyone else have this experience and any insight? By "... cold" I mean about 30 degrees F. Car has 80k. Well serviced and never on track. Late for 75k check up and oil change, but driven pretty gently.

Thanks in advance,

JKC

wross996tt

So get the codes read and report them back here. Also provide Model, MY, last time tuned and other pertinent info.

Then we'll be glad to help. Otherwise we play 1000 guesses and you spend lots of $$$

himself

How much gas do you have? Did the CEL blink or was it steady the whole time?

Without the codes, I would speculate bad gas. Try driving the tank dry, filling up and driving some more. If it was a simple bad gas misfire, the computer will clear itself during its next diagnostic cycle without the "misfire." A number of us were "poisoned" with bad gas when we filled up at the same time the tanker was filling the underground tanks. Apparently, this stirs up the water and particulates in the underground tanks, and can get into your car. The CEL comes and goes until the bad gas is all used up.

But, you should still read the codes and report back, as there are other symptoms that could be classified as a "misfire" when they aren't.

-td

996FLT6

ignition coil packs gone afoul. That happened to me on my old 996. Have dealer check it out. Mike

C4CRNA

You really need to get the code. It will help a lot.

JCreasy

I will take into to the dealer next week. How else can I get the code? Do not really trust anyone else around here.

I doubt bad gas because I have had a few fill-ups. The CEL did not blink. Steady. It is running smooth now but I am wondering if it is ignition coil/packs...

Model straight up 1996, 2003 with the 3.6. Last time tuned 60k by dealer, I am now at 80k. (I know, I am overdue. The economy killed me).

Thanks for input.

JKC

SH || NC

Just about any AutoZone or similar will read codes for free. GL

smshirk

+1 My car did that several times leading up to 60k mile service. Never any other noticeable issues except cold starting in my garage. Same problem.

996FLT6

get a cheapo obd2 scanner from like kragens or similar(i paid like $40 for one-actron)with reset button if need to reset small stuff. Scanner will have book on codes but there a few exclusive to pcars. Check Loren's website renntech.org for the pcar codes if displayed code is not from scanner list. Regards Mike

Macster

gas is a defective coolant temperature sensor. If it over report coolant temperature (at colder temperatures) the engine controller will not enrichen the air/fuel mixture enough and a very rough running engine is the result.

If rough running persisted after secondary air injection pump shut off (engine controller usually goes closed loop around this time) may not be coolant temperature sensor, but a bad/cracked coil.

Would help to know error code(s) and what long term fuel trims are. If you clear error code this clears long term fuel trims so read these first.

An OBD II code reader/data viewer is almost a necessity for anyone attempting to home diagnose engine "troubles". A device that reads DTCs, freeze frame data, and allows you to monitor/view engine sensor inputs and other values like coolant temperature, intake air temperature, long/short term fuel trims, OS sensor readings, etc., is what you want.

Sincerely,

Macster.