camnbo

Mates:

The admiral has a 2003 Suburban with a 5.3, 'bout 80,000 on it. The last 20,000 or so, the idle has been funny. At startup, it will lope almost like it has an aggressive cam in it but then will take off just fine. I can live with it but it killed in a busy parking lot the other day and she got a little nervous about it. Nervous admiral leads to trouble for the crew.

croakerpoker

hows your fuel efficiency? ive had o2 sensors go bad on mine and cause bad idle but it burned noticibly more fuel.

billinstuart

Could be a lazy idle air motor..no, I think those are drive by wire so idle is controlled by the digitally controlled throttle plate. Whatever, it's not correct and dangerous. Could be as simple as an air leak, but take it to a COMPETENT technician who understands how the system works. It may require an update to the computer.

centuarynick

IAC. or if the SES light is on and theres a p0171 and p0174 suspect intake gaskets

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1971 Century raven 165HP mercuriser
1990 chevy 2500 pickup
soon to be 240 imperial 210hp mercruiser

scoutman22

Mine does this every so often. Take off the air intake to the throttle body and clean the butterfly front and back as well as inside the intake. Try that first. I should mention that Seafoam works well for this.

rit.05

No codes? Reset computer.

Seafoam first. Air and fuel. Run the highest octane gas you can get with the Seafoam. Clean MAF and throttle body.

If still an issue, maybe plugs, wires, ignition? (If you're going to do the Seafoam, do it before you change the plugs or clean the TB)

brianm333

If its only after start up when engine is warm. It could be the fuel pressure regulator. Take the vaccum hose off when the engine is off. If there is any fuel there the regulator needs to be replaced

fldmax

take the air intake loose and wipe the throttle plate with sea foam and get it cleaned up, I do 2 or 3 a week wthis way,

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2003 Wellcraft 290 coastal 225 Yamaha 4 strokes.
2003 Key West 1720