Stuck High Idle

He already replaced it I believe.

 

Oh, thought he just cleaned it. Well if he is sure the little motor is working then yeah I'd take apart the throttle body and measure to make sure the butterfly is closing the right amount and that the butterfly shaft isn't leaking around it's seals.

 

I had a P0420 recently and it was an exhaust leak just upstream of the sensor at the joint in the exhaust pipe. Tightened the bolts and hasn't come back since..

 

The IAC is brand new, as is the gasket. In fact its the 2nd new IAC ive put on it. Reference the rest of the thread.

 

Ill give that a try, hopefully i can find a new throttle body. Its turning out to be difficult. There are plenty for the 3.4 and the earlier and later models, but the one I need is a difficult one to find.

 

I had a high idle issue after cleaning my throttle body IAC and throttle position sensor. I found that the throttle position sensor after install was barely off. I hooked up my scan tool and look at the % When idle and it was around 14% I loosened it and turned it left and right until it was around 11% and it went down. I would suggest seeing where it is percentage wise and also making sure you have no vacuum leaks.

 

Well this ones gonna be on hold for a while, I blew out my ACL and possibly MCL. Itll be a slow recovery so ill update when i can work on it again. Thanks for the help everyone!

 

Well I finally was able to get a new throttle body and install it. And we have partial success! Ive still only put about 100 miles on it since I put the new TB on. But there is still something going on. It idles now at 1200 RPM, but behaves weird on start. When its cold outside the RPM right after start are low, fluctuating between 500-800, and if you don't give it a little throttle it will generally die if its below freezing. It takes about 30 seconds or so of throttle before its stabilizes at 800-100 and when its warm gets up to about 1200.

The truck also has a little bit of hesitation. The first quarter of the throttle travel it accelerates fine, but if you bury the throttle its not super responsive. Im guessing maybe the fuel filter or injectors.

Additionally i'm also getting a P0300 code, which is multiple cylinder misfire detected. Im going to have to start testing the fuel system to see where the problem lies, multiple misfire could be a bad injector or a couple bad injectors. Im not too worried about this, I can run some tests and figure this out.

Whats weird is the low RPM on start. When I replaced the throttle body I just realized that I did not test the TPS on the new throttle body. I had only tested the old one. Ill have to test it and rule that portion out. Other than that I dont know what would cause the truck to start at such a low RPM. Its not rough or anything either, it runs smooth, just at a low RPM.

Any thoughts on the low RPM?

Thanks!

 

Ok thanks for the advice, Ill have to check that out. I just ordered an OBD-II so I can get a little more detailed info. So once that gets in I should be able to find out a bit more.

 

sorry to revive a semi-dead post, but trying to resolve a somewhat similar issue:

did this issue ever get resolved, or is it still ongoing?

 

Give us an update!!

I’m going nuts with a Similar situation.

Had a burnt exhuast valve. Got the entire head replaced by a shop and they cleaned the TB. They told me the IAC Valave was super dirty and tried to clean it the best they could. I was suppose to have normal idle in about a tank or two of gas (never happened). My truck idles about 1,250 and will bounce down to 1,000 multiple times.

Now I replaced the IAC with a new OEM one and it’s worse. It would idle way above my old OEM one and bounce down to 1k then back to 1,250-1,600. Then steady at 1,800. So I threw my old OEM one back on...

I noticed I have a slight gap on my TB butterfly plate. Not sure if this would be the issue...

Any guidance would be greatly appreciated

 

I’m having a similar issue after installing a K&n cold air intake. I had a throttle body spacer installed at the same time and the truck ran terrible so I took it off and got it running; I have P0171 and P0300 sometimes. I’m seeing if LCE will send me their fuel rail pressure guage kit out of sympathy so I can cross low fuel pressure off of the list..

I wonder if all resolved their issue?

 

have you checked the little stopper screw if yours has it? @what road had a high idle issue and that ended up being the problem

 

Yea, after we checked half a dozen things first lol

 

I had to buy a used TB to partially fix the issue, but my truck still hasnt idled normally for a while.

So I still havent been able to fix this issue, at this point i'm not sure what the problem is. It is still having the issue of essentially behaving backwards when starting. It starts at low RPM and as it warms up settles out around 1,100 RPM. I finally took it into a mechanic hoping enlisting the help of a professional would help, and they said the IAC was the problem. GAH!

Shortly after taking that into the mechanic I started getting an IAC code (cant remember what it is). Im also getting a P0420 code, but thats not surprising considering theres something fucky going on with the EFI.

I currently have another Tacoma in my garage that I'm doing a head on. Same engine and year. So the other day I took the throttle body from that truck and slapped it on this vehicle to see what would happen and ran into the original issue again (idle around 2,000). Looks like the same problem with excessive play around the throttle valve.

I have an IAC im going to put on it again. The mechanic I spoke with said to only use the standard auto parts, so I grabbed one of those. We will see if that does anything. Ive got my doubts.

My next move might be talking to a machine shop here in town and seeing if they could make a new throttle plate for the TB. Maybe a fresh plate that sealed good would help with the issue.

 

I’m still working through my issues; I checked fuel pressure and it was good around 47#; I replaced the fuel injectors this weekend and started are the fuel filter but broke the screw that holds the clamp (it isn’t reverse threaded is it?). So waiting for more parts. I’ll post if the fuel injectors make a difference. By the way I already replaced my IAC, lots of vacuum hoses, mass flow sensor is within reason along with coolant temperature.

seems like cleaning the throttle body seems to be the common theme. I do notice that if I let the truck warm up and let it idle it begins to “chug” oscillating 50-75 RPM.

 

Here is a shot of the throttle body plate.

im going to do a compression test next weekend if I find time to mark that off the list.

 

So there is a stopper screw that can set the throttle plate minimum position, right? My plate is going perpindicular so I don’t think that is the issue...

 

Yeah on mine getting a used throttle body was the best thing and that partially fixed the problem. But being that it is not a new throttle body it only partially fixed the issue.

 

In

seems like the only option for a new one is at the dealership but I haven’t confirmed you can even get one; ones on ebay are going for $400-$500.

If the fuel injector and filter change does not help I will do a compression test and check spark plugs to confirm those are in good order.

then I plan to read up on testing the EGR valve. The EGR valve makes sense if it is stuck half way or stuck closed except that I would expect that the truck would throw a code if it does indeed periodically test the valve using the temperature sensor between the leaving side of the valve and the leaving side of the throttle body. If only the sensor was available on my blue driver app I could easily verify it was working properly (only open under mild to mid throttle)

I’ll keep posting as I work through things.