hot bad idle

i have a 93 runner with 3.0 in it it drives perfact in the mornings at first start idles about 1100 rpm after making long trips (30-45min) or just driving alot around town when its still hot and i go to start it its jumpy? with idle from 300 to 500 and acts like its missing..but when i hold accelorator to about 2000 for a few seconds it runs fine any suggestions??

Reply 1 : hot bad idle

4runneroffroad,



A few things I can think of off the top of my head are,



1) ECT (engine coolant temp sensor) which sends water temp signals to the ECU.

2) Carbon in the throttle body, which causes sticking and rough running.

3) Throttle Position sensor out of adjustment. Which can be checked if you take throttle body off to clean it.

4) EGR valve sticking open

Reply 2 : hot bad idle

Wat do you.think I should start with first? I haven't delt much with throttle position sensor how would I go about checking it

Reply 3 : hot bad idle

t4runneroffroad,



Ok to check the TPS you will need a hand vacuum pump and a Volt/Ohm meter to set the TPS idle adjustment. The best way to do this is to remove the Throttle body first. You should have a gasket available if you damage the one that's on there. The idle adjustment is a feeler gauge setting and I think the setting is .020 open and .032 infinity don't quote me though, look it up.

When was the last time you changed the spark plugs?

You might have a faulty cold start system that allows just a little too much fuel on a hot start to allow it to run rough until you give it enough throttle to clear the system.

Just another thought.

Because it is hot I tend to think it is a sensor that is not sending the right signal when it is hot and causes too much gas at start and runs rough until it is cleared to a normal mixture. I would lean towards the ECT.

Reply 4 : hot bad idle

Awesome I can do that. I haven't changed then in about 6 months but I only average about 10 miles a day. Right now I have Bosch platinum plugs is there anything better that I can put in I plan on changing them soon. With the ECT I have an idea of were its at but there's 4 plugs between firewall and motor I can't pinpoint witch one it is and how hard its going to be to get it out since they are side by side.

Reply 5 : hot bad idle

4runneroffroad,



Get rid of those Bosch plugs! Toyota's don't run very well with those. Get either Denso or NGK. Your rig will love you for that. If you are looking at the back of your engine the ECT will be on the right hand side. It will have a Brown wire with a black stripe and a Green wire with a light Green stripe. Before you look into this ECT I would put new plugs in it and run it to see how it behaves first.

Reply 6 : hot bad idle

Well I went out and got the ECT when I took the old one off it was cracked all the way around I replaced it so hopefully ill figure out today if the problem goes away.I bought the jfk plugs I will also replace this week. Thanks jetwhine. The next thing I would Like to do is run a cold air intake any suggestions besides k&n I'm trying to be cheaper than the kit they have for $255 or I buy the MAF sensor adaptor through them and make my own?

Reply 7 : hot bad idle

4runneroffroad,



I always try to stay as stock as possible. I use the K&N stock filters they work fine. I do like the looks of the K&N filter system.

Good find on the ECT. That might make a difference.

Get rid of those plugs though!

Reply 8 : hot bad idle

I changed the plugs to ngk platinum changed cap rotor not wires there fairly new went for a drive today bout 10 miles and it did it again! Wat do u think about the dashpot?

Reply 9 : hot bad idle

I have encountered the same problem as you have expressed! Truck would run just fine! Shut it off, go to restart it, and it would run rough until I stepped on the throttle! My problem was a leaky fuel injector! Next time it is running rough, while it is running rough, pull the plug wires one at a time and see if one cylinder doesn't drop the RPM's further. If the RPM's doesn't drop on the one cylinder, pull the spark plug and see if it is fuel fouled!

Reply 10 : hot bad idle

t4runneroffroad,



I'm now thinking fuel issues. As stated by the previous post. Could be an injector or the cold start system putting too much gas on a hot start. You also might want to check that system when you get the problem too see if the cold start injector is squirting when it is not supposed too. And as previously stated check each plug while running to see which cylinder is causing the problem.

Reply 11 : hot bad idle

Well yesterday I fixed the cap on the dashpot it had a crack in it I just used a plastic epoxy for temporary fix. I tried to get it to act up today but the most it did is idle about 500 but it wasent jumpy about it. I also took the back line off of the egr valve and had no vac at all. Does that vac line lead to throttle body. I plan on cleaning the throttle body over the weekend and cleaning maybe replacing egr valve

Reply 12 : hot bad idle

The crack in the dashpot would cause a vacuum leak, and not be associated with the symptoms you have explained above. Your EGR valve shouldn't have vacuum to it at idle. You can check to see if it has vacuum with engine above idle. You can check to see if the EGR is functioning by applying vacuum to it,engine at idle, and seeing if the engine rpm's drop/runs rough! this will tell you that the egr valve is working;I.E. not stuck open or closed! The EGR does get its source vacuum from the throttle body, but goes through the EGR vacuum modulator, to the vacuum switching valve, to the EGR. I wouldn't take the approach of throwing parts at the vehicle in order to get it running right. Try to get the vehicle to duplicate the problem, and do a cylinder balance test on it first, as i mentioned above.