Corolla Idling Issues from cold start

[dongsky07]

Hi Experts,

My car has idling issues which I get to experience from cold start (though not everyday). Upon starting, I usually warm up my engine pass the low temp mark before I start driving. For several days now, I noticed that my idle plays at around 1100 to 1400 from cold start even after driving several distance and it is not usual since my normal idle is only between 700 to 900. When I get to experience this, what I do is to turn of the engine and upon re-starting, the idle goes back to normal as if nothing happens. Has anyone have this experience with their ride? What should I do to have this fix? My ride is a 2000 corolla lovelife 1.6 m/t.

Thanks!

[dongsky07]

Additional. At cold start, my RPM is at 1100 which is normal to me and goes down after several minutes. Thanks again.

[dongsky07]

Additional. At cold start, my RPM is at 1100 which is normal to me and goes down after several minutes. But after driving several meters, I can hear the car revving and the RPM plays between 1100 to 1400. Air conditioned is not yet turned on during this time. Thanks again.

[CivicVTi]

Your air filter element may be dirty, have it checked/cleaned. And when was the last tune-up?

[dongsky07]

The sparkplugs were replaced maybe 2 months ago. According to the mechanics, there were no adjustments needed since it is an EFI and the computer will always reset it to its original setting. Is this accurate? What should I do? As with my high idle problem, if I don't experience it after the cold start, the car runs smoothly throughout the day. (Probably since the engine is already hot?)

I was observing it a while ago after a few minutes of driving from cold start, every time I changed gear (full clutch), the rev goes up without touching the accelerator. But after driving for several minutes, everything was already normal. I did not experience the high RPM problem that I had yesterday. I recently had may oil changed using 20W-50 mineral, I used to use a 20W-50 synthetic blend oil. Could this be causing the issue?

Hope you can further help me out. Thanks CivicVTi.

[CivicVTi]

I don't think the recent change of oil has anything to do with the rpm behavior. While it is normal for the engine to have up to 1500rpm while warming up in the morning, it is strange if the rpm normalizes to 750-800rpm and then goes back to 1200rpm while driving. You may want a mechanic to check and clean the IACV and MAF sensor.

By the way, have you recently removed the thermostat from the engine? The one that regulates the flow of coolant?

[dongsky07]

Yes, when I had my radiator cleaned but we placed it back. If my memory serves me right, that happened before I noticed the rev issue. Does this have anything to do with the rev issue?

[CivicVTi]

Yes, when I had my radiator cleaned but we placed it back. If my memory serves me right, that happened before I noticed the rev issue. Does this have anything to do with the rev issue?

Probably not, I was just wondering if it was removed. The absence of the thermostat would result in a longer warmup in the morning (the engine's rpm will take longer to go down to normal). But once it normalizes, its not supposed to go back up while in normal driving conditions.

First priority in your case (IMO) would be to clean the air filter, IACV, and MAF sensor.

[dongsky07]

I did clean a sensor that what inserted on the filter pipe (like a plastic one) when I arrived home this morning but did not find any significant dirt on it (I'm guessing that that was the MAF sensor correct?) I'm using a simota cone filter btw. Do you recommend using other filters or switching it back to stock?

I'll have the sensors clean including the throttle and injections and give you feedback. How much would the cleaning cost me? Any recommended shops?

Thanks again CivicVTi!

[CivicVTi]

You might want to experiment and put back your stock air filter assembly. If the rpm normalizes, then you have found the culprit. Be very careful when cleaning the MAF sensor, it is very fragile and expensive to replace.