ok so the other day I put a quart of 2 stroke oil in my tank which was about half full. today I get almost to where the low fuel light comes on and out of nowhere the trucks idle drops from 800 to about 500 or so and lopes. it shakes the truck too. it does it in gear, or in park, with and without the a/c on. runs fine otherwise. what do I check? overflow valve?

 

Try checking to see how much fuel is actually in the tank..

What colour , if any, smoke was coming from it?

 

I have since filled it up and there was a slight haze but thats normal anyways, and it still does it.

 

Mine did this when the fuel filter needed changed. Does it rev to max rpm and stay there or does it rev then back off. Same with boost pressure. If it does this it is the filter.

 

Lance my truck did the exact same thing and still does. Here is what I have done so far.

I installed 80 HP injectors first. Still had rough idle. Then the overflow valve. Still rough idle. Then I discovered my lift pump was bad. So I installed a new lift pump but it did not change the idle characteristics. My truck runs fine in the upper RPMS.

Are you having hard starts?

Dave

 

Have either of you guys checked timing? sure sounds like it could be a candidate for severely slipped timing...

 

why dont u just raise the idle back to 800 ...maybe ur just panickign and all that happened was ur idle screw loosened and ur idle dropped....let us know what happens after u adjust ur idle?...the truck wont run happily at 500rpms...or am I missign somehting

 

no hard starts, I will check all of the above. it kinda sounds cool with it loping and shaking the truck, reminds me of an old muscle car with a big block and a big cam.
I don't think my timing slipped because it still has the same amount of power above idle

 

These trucks will not run good in the upper RPMS if the timing has slipped. severely. Neither Lance or myself are having issues once the truck is moving.

 

well today I floored it in neutral and it shot up to 3600 and stayed there, also the boost went to about 14 and didn't drop at all, so I guess that rules out the filter
people were looking at me funnay

 

had simular problems with idle at 500 rpm. dying all the time, harder starting etc.

raised idle to 750 rpm in drive with auto tranny. all related problems went away.

 

Lance did you find anything out? I am still have a rough idle and poor performance.......

Dave

 

well I turned up the idle a little and it helped, but I can't get it up any higher otherwise it idles at about 2000 rpm. guess I need to loosten my gov springs a tad