My 89 3.0 runner has been running crappy for a while now and i am getting fed up. I replaced the coolant temp sensor and the cat converter but nothing has changed. It is not throwing any codes so I cant really narrow it down. Any ideas? Some have siggested the EGR valve but how do you test it? It runs very low idle (100-500rpms) all the time other than that it runs fine. Thanks

 

i had that same problem on my old motor...i have no idea what it was

 

Have you checked the air filter, the top can be new looking, but if you pull it and look at the bottom, it's dirty.

 

yeah the air filter is good.

 

The only problem is the low idle? I had a #6 plug that had a cracked electrode that cause all sorts of problems, including a low, bouncey idle, and violent shaking when starting the truck cold. Any misfiring or stumbling?

 

Have you checked your coolant level?

 

No misfiring or stumbling when driving. It runs great and is getting 20mpg (which I consider good). The only problem is the very very low idle. It sounds like it may be missing or stumbling at idle. The coolant level is fine.

 

I did a few things that really helped with my 2nd gen 3.0 V6 idle.
changed spark plugs, wires and rotor. Adjusted idle speed by turning the screw (remember- it should be at 800 RPM when warm, not when just starting out. My RPM starts at a little over 1000 and drops to 800 and stays there after driving a bit. I also cleaned the throttle body and finally sucked a can of Seafoam into the engine. I also got an Optima battery (prob. didn't affect idle). This combination of things really did wonders for my idle and it purrs like a kitten, no problems. Good luck!
TW

1992 4runner, Thorley Headers, Jardine Exhaust, Magnaflow Cat, OME Steering Stabilizer, Downey Idler Arm Gusset, FIPK, Optima Red Top, WAAG brush+rear guards, PIAA 520s, TOMTOM GPS on Treo 650

 

Vacuum leak? With your engine on at idle, spray some starter fluid around your vacuum hoses, intake, throttle body, gaskets, and see if your idle drops because of the spray. Could be a vacuum leak.

 

vacuum leaks generally raise the RPMs dont they? Ah well I checked and came up with nothing. I also jsut replaced the plugs, wires, cap, rotor. Also checked the oil and coolant and it doesnt appear to be head gasket problem. so its off to the dealer tomorrow to get checked out. Any last ideas before I shell out an arm and a leg to get it fixed!!?!??!

 

if you spray "starter fluid" the idle will raise id recomend carb or brake cleaner nad see if the idle drops plus its safer then spraying a bomb all over your motor

 

Good call. It was a vacuum leak. It turns out the EGR valve was cracked and was causing a major leak. I replaced it and the truck runs beautifully now. Thanks guys for the input.

 

Glad it is fixed! BTW, I intended to say the idle will smooth out if there is a leak. Sorry for the miscommunication. Starting fluid, carb cleaner, propane, all good.