98 4.0 Running rough at cold start

slvr00gt · May 21, 2012

Truck idles rough for a minute or two after cold start. Idle RPM goes over 1000 and stays consistent, but engine vibrates noticeably. When I give it a gas, engine hesitates for a second, spins up and vibration usually goes away. It runs fine from then onwards.

Any suggestions?

Kevery · May 29, 2012

mine does the same thing. Has been for as long as I've owned it (7 years now) you start it up it runs like its misfiring and them smooths out to normal right? Is your engin light on? when I change my spark plugs it stops for a month or so and then starts again. I also replaced some o2 sensors and it went away for a long time until my engin light came on again about another o2 sensor. So my guess is it has to do with the o2 sensor. My buddy's does the same thing. I wouldn't lose sleep over it. It's not much but maybe this will help alittle.

slvr00gt · May 29, 2012

Kevery said:
mine does the same thing. Has been for as long as I've owned it (7 years now) you start it up it runs like its misfiring and them smooths out to normal right? Is your engin light on? when I change my spark plugs it stops for a month or so and then starts again. I also replaced some o2 sensors and it went away for a long time until my engin light came on again about another o2 sensor. So my guess is it has to do with the o2 sensor. My buddy's does the same thing. I wouldn't lose sleep over it. It's not much but maybe this will help alittle.

I don't have engine light on.... May be I should check my spark plugs again... Year or so ago I replaced the spark plugs after getting misfire code. Misfiring cylinder had a spark plug with cracked sleeve.

98 4.0 Running rough at cold start

slvr00gt

15+ Year Member

Kevery

06/2013 OTOTM Winner

slvr00gt

15+ Year Member

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