Well this one has got me stumped. I have an 89 runner that is my baby. It has the 3.0 5 speed with 130k on the clock. Recently the idle has been acting funny. When I drive the truck for a while and get it to operating temp and then shut it off for a few minutes, and then start it back up, it barely idles at 100 rpms. It kinda diesels and makes a rough but constant sound. Now while this is happening, I can drive it like normal and just ride the clutch a bit and it goes away in a few miles but it is starting to make me nervous and it sounds like its doing damage when it acts up. Any help would be great. Im not even sure where to begin. thanks alot guys.

 

whens the last time you had a look at your plugs and wires and such? A tune up can sometimes do wonders for your truck.

what exactly is the sound? is it a popping? a thumping? knocking? ticking?

 

Well to be honest I havent had a look at the plugs in a while. I just thought maybe it was a temp sensor (guage seems to be moving somewhat erratically) or something with the intake maybe (maf or tps?). I just dont know man. The noise is a knock from that seems to be coming from the passenger side bottom end? Its weird I know and I havent really stopped and taken a closer look because I usually have to drive right away when it happens. It is also not showing any codes so I guess thats a good thing. Let me know what you think. Thanks.

 

Headgasket.......if its not ignition....

i just fired up a truck that had the same problems before and ended up being head gasket...

 

Well after doing some research on this, I decided that it was the coolant temp sensor. So I replaced it and the problem did not go away. It didnt get any better either. Same symptoms - starts fine when cold, idles VERY low when hot. Other than that the truck runs beautifully and if I never had to stop you would never notice the problem. The gas mileage hasnt changed (about 19 mpg) so I do not believe it is a real rich condition. Any other ideas besides head gasket