High Idle

After giving the MAF Sensor and Throttle Body a deep cleaning, I stumbled upon a high idle which wasn't there before I cleaned them. Before it idled around 650-850rpms when warm but after a good cleaning a high idle ranging from 1000-1500rpms appeared. Its really affecting my gas mileage(lucky it ain't my daily lol) but otherwise runs great but it still really bothers me. Checked for any vacuum leaks and wasn't able to find any. Replaced MAF Sensor, Throttle Body, and IAC Valve gasket. Any help please?

P.S. The previous owner replaced the egr valve, egr solenoid, egr temp sensor, egr vacuum switch valve, spark plugs, and wires. I myself did replace the IAC Valve because the previous one was stuck open and it had a really low cold start idle that made it close to stalling and idling around 500rpms or less, that's why I didn't include it in the cleaning part.

 

Try replacing the throttle positioning sensor (TPS). If it has one.

 

I had a high idling problem a while back. I didn't do anything with the MAS or anything, but it was due to low power steering fluid.

Seems unrelated but I hope it helps.

 

I never heard that before but if it worked then thats good to know.

 

Yeah the high idle bedeviled me for about a month.
Another thing I went through a while back was high idle due to a lose battery connection.

In both cases the engine had to run higher in order to compensate.

Now if it high idles again those are the first things I check.

 

It does have a TPS but it seems adjustable so I might give that a try but I figured if I replace it it needs to be adjusted regardless. I can adjust it be the only problem is you need to apply vacuum in one of the ports near the throttle body which I don't know how to do.

And never woulda thought low power steering fluid or a loose connection in the battery would cause that. Will definitely give that a look.

 

after cleaning did you reset the EFI (or w/e)? pull the EFI fuse (if ithas) or pull the neg(-) battery cable for about 3 minutes

 

It does have a EFI fuse and I did pull it and it looked fine and disconnected the battery for actually 30 min but that wasn't right after I cleaned it. I did that after I read a few forums after but still nothing.

 

how many miles/times run since the cleaning/EFI fuse pull? It can take a few hundred miles to dial in sometimes.

 

The truck isn't my daily so I run it at least 2-4 times a week but I took it fishing on the other side of the island so i'm pretty sure I ran it for at least a few hundred miles already.

 

@jbv808

I have been reading as much as i could for people who are having similar problems as i am having. After reading your issue it had struck some memories of things i might have done to cause a malfunction of my truck. My problem of high idle is not fixed after an engine rebuild so it must have something to do wit sensors in my case.

I have a few questions for you. Have you replaced M.A.F. sensor? How did you clean M.A.F. sensor? Have you tested Idle air control sensor/vale? Does your particular year of tacoma have a charcoal canister? Have you tried replacing canister if you have one? Is your throttle cable to loose? does you tacoma stall or seem to have rich fumes coming out of exhaust when first starting in morning or after sitting for a while? Is your truck set up for California emissions? How old is your exhuaust line from the manifold to the muffler? Is it in good condition? Are your sensors for exhaust good? Does your truck have a difficult time going up hills? Does it want to stall sometimes when on a hill that is somewhat steep?

My problems for my truck had started i think with me cleaning the M.A.F. sensor. I didn't think there to be an issue due to the fact i used the right cleaner and did things as required to the "T". Then the fun to try to fix problem occurred. Now i almost have a brand new 2001 2.4 tacoma, another 3k dollars and it will be for the most part. Hoping to fix problem before then.

I hope to read how you fixed problem.

 

Could be a number of issues, throttle body maybe, if you have a lot of miles on the truck
the throttle body might be worn out. Mine was working fine till I cleaned it. There was a worn ridge
by the butterfly valve on the wall of the TB. The carbon filled in the gap. After I cleaned it there was a gap exposed that was filled in with carbon.
So I had to buy a new throttle body. Look to see if there is a worn gap between the wall of the TB and the butterfly flap.

 

There should be a little slack in the throttle cable where it connects to the throttle bell-crank.
If not, that could cause a high-idle.

 

Fixed the high idle after speaking to a member of LCE Engineering. Happened to be the Engine Coolant Temperature Sensor. Pulled that PITA right below the valve cover right underneath the wiring harness on my 2.7l engine. Had to remove the whole air intake tube so I could move the wiring harness to the side and reach all the way in the back. But anyways, got it to idle at 650-750 rpms with minor adjustment to the throttte stop screw. it kinda takes a while for the idle to settle from a cold start but most likely because the thermostat is sticking a little but otherwise when the engine is at normal operating temp, it idles just fine. Was supposed to change the thermostat with the coolant temp sensor since I had to drain the coolant but the local parts store didn't have the gasket so decided to replace it another time. Now time to spoil my toy @Time41