Pulsing power at start up?

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09-25-2009, 11:38 AM

OUR CAT

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Pulsing power at start up?

After a cold start and then a moment or two, the engine seems to hesitate cyclically and subtly. No check engine light.
I clean the throttle body in Spring and Fall (just done). I've replaced the air filter, the O2 sensors (2), the fuel rail regulator, and the fuel filter.

Last thing is the fuel pump, but wondered if the cold condition systems vs. warm condition systems had a part in this. The hesitation dissappears within five minutes of running. Thoughts?
Rob

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09-25-2009, 03:03 PM

sparkenzap

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Idle problems are almost certanly NOT the pump, if it run's OK at full throttle. I would do a trend chart of the fuel trims and temperatures, along with the rpm and see if I could spot something.

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09-25-2009, 04:58 PM

Cadillac

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Sometimes my Jaguar does the same thing too. Not that it throws some code it only lasts for a few secs in P ,even if I press the throttle and rev up the engine during this period , it runs very smoothly