Hesitation/rough idle on cold start

07-21-2009, 11:38 AM
Hello all,

I'm having a problem with my '03 Protege5 that is difficult to diagnose. If the car is cold or has been sitting for at least an hour, and I start it up and begin to drive, the idle becomes rough and the car threatens to stall. The strange thing is, it clears up five minutes after driving. So its like the first few sets of lights I approach I have to feather the clutch/throttle to keep the RPM's up so it doesn't stall, but after a few minutes of driving she purrs at a stop. The car only has 120,000 Kms and I have just replaced the spark plugs and cleaned the battery terminals in an effort to clear the problem. Any ideas?

Many thanks.

Doug Tatham
09-03-2009, 04:35 PM
Check your idle stabilizer valve and your fuel back pressure regulator. If you are getting misfires as well, you may want to give your coils a look. I'd also look at the oil and make sure they didn't put in the wrong type.

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