All right, I get a rough idle around 700 rpm(misfires I'd assume) when I'm below a 1/4 tank of gas.

If I rev it to 900rpm of everything is fine.

If I fill the gas tank, everything is fine

Plugs are OK, just checked them.

Anyone want to give me some hints?

Coldie

 

Coldie,
Do you guys have winter fuel up there? If you do chances are pretty good that you have water in you fuel tank. The ethanol seems to create a lot of condensation in the tank.

 

Yes, we have winter gas up here

So just throw some gas drier in the tank?

Coldie

 

Fuel filter?

 

fuel filter was changed about 1000 miles ago...

Coldie

 

I d/k why a full gas tank makes a difference but a loping idle or an erratic idle can be caused by:

1. Vacuum leak(s) Check by listening with a stethoscope--if it will idle.

2. Leaking EGR valve or a plugged PCV valve.

3. Air filter clogged.

4. Fuel pump not delivering sufficient fuel.

5. The other reasons are because of an internal eng. problem, leaking head gasket(s), timing chains worn, burned valves,

Also could be ignition or PCM related?

Dan

 

It's weird... It doesn't really lope, just occational it misses.

Coldie

 

OK, if it's "missing" then check:

1.. Faulty s/plugs or not gapped properly.

2. Wet or 'bad' coils.

3. Sticking or faulty emissions systems.

4. Clogged fuel filter(you recently changed it) or foreign matter in fuel.

5. Vacuum leaks.

Dan

 

Basically down to coil packs/vacuum leak... There isn't really any way to check coil packs though, is there?

Coldie