Excessively High Idle When Warm

2002 Tacoma, 2.7L Manual Transmission

I have been noticing that as the days get colder, my truck's cold start seems abnormally low at around 600-1100 rpm's. As it gets up to operating temperature, the idle speed steadily increases up to around 1800-2000 rpm's. If I rev the engine a little, the rpm's drop down before climbing back up to 1800-2000.

In addition, my UltraGuage indicates the truck is permanently stuck in a open loop. I have one check engine light code, P1135. From what I have read this is for the upstream O2 sensor, which I just ordered yesterday. Would a bad O2 sensor be a realistic cause of the high idle? I also plan to clean out the throttle body and replace spark plugs this weekend. Would cleaning the MAF be beneficial as well?

I've done a fair bit of searching online, but I have not been able to find similar issues to mine, only the opposite (low idle when warmed up).

 

Personal opinion, a defective o2 shouldn't cause high idle. Check and clean your idle air control valve on your throttle body if you got one.

 

Good idea, I will clean that as well.

The odd thing is that I never noticed a high idle like this in the summer, which leads me to believe that it has something to do with air, since colder air is denser and whatnot.

 

Pretty textbook symptoms of a vacuum leak.

 

That's what I was worried about, I will have to check the lines after cleaning the TB and IAC

 

If you have an OBD scanner, you can verify the accuracy of sensors that directly affect fuel trim. I had a high idle on my truck last winter when it was warmed up. Found out that I had a bad coolant temp sensor telling the ECM that my engine was at 90 degrees F when it was more like 180 degrees F. Swapping that sensor out fixed it.

 

This afternoon I cleaned the throttle body and IAC. It was fairly dirty, and the IAC valve seemed to be stuck open a little bit. I gave both a thourough cleaning but didn't have the right screwdriver to get the IAC solenoid/motor off, so if the issue persists I may take everything apart and try again when I do spark plugs.

I did go for a little drive afterwards and I think the issue may have been solved! I will know for sure after my drive to and from school tomorrow.

 

What did u use to clean sensers with ?

 

I used NAPA CRC brand throttle body cleaner. I wanted something specific to for throttle bodies as I read that carb cleaner can take the protective coating off of the IAC and butterfly valve.

https://www.napaonline.com/en/p/CRC092400


In other news, the issue seems to have completely gone away! I'm hoping to see some better fuel mileage, but regardless I'm glad to see a normal idle and warmup cycle.

 

Thanks I'm having similar issues. I shimmed out advanced whatever that's under throttle to get truck home to garage. Runs fine this way for now. Truck was dropping under 500rpm and stalling. First time I have this problem. I have had high idle issues in past briefly

 

I wasn't having any issues until the weather turned colder. If that's the case with you then maybe it's the same issue!

 

Its my dashpot. It was stuck back. Cleaned my EGR filter blew some sensor cleaner into dashpot freed it up. Vacuum systems I find are most over looked area. I'm going to continue to clean and research vacuum system in truck. And yes we finally got some cool air but Its still hot during day and high humidity and night dew point temps here, I got my AC back on now. Couple of days without it and windows open.

 

Good to hear! Glad you figured it out

 

I still have work to do I'm looking at cable springs and all. Truck has 340000 on it runs great. I would would like to get to half million mile on it like I did my 79' Bronco. Little old lady totalled it for me.