rough idling

Asked by Jan 17, 2016 at 09:39 AM about the 1998 GMC Sierra 1500 C1500 SL Extended Cab SB

Question type: Maintenance & Repair

why does my 98 Sierra idle rough between
1st and 2nd gear,? it's 2wd runs good once
it gets out of 2nd,gears switch right on with
the rpms at 2,500. what could our be.?

3 Answers

71,445

Sounds like it may need a tune-up and a going over.

1 of 1 people found this helpful.

I had someone say a blown head gasket but it hasn't smoked not once, the water isn't milky or anything that shows a blown gasket so I was just wondering. It has a new oil filter on it also.

71,445

No indication of a blown head gasket as long as there is not white smoke coming out the exhaust like steam, oil not going over full, and oil in the radiator or a overheating problem. So is that a 4.3L in there? They have one specific problem which is fuel. You may want to check fuel pressure at the schrader valve, should be 56 to 63 lbs.

1 of 1 people found this helpful.

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