Stays at high idle on start-up longer then should

[Posimoto]

RE: 1999 Camry 4 cyl auto

On cold start-up the engine jumps to 1800 RPMs and stays there for about three mins then slowly as the engine warms the idle goes down. The engine won’t come to the proper idle (700) until the temp needle is half way between cold and hot. Occasionally on cold start-ups it barely gets to 300 RPMs and I need to tap the accelerator pedal to keep it running.

I’ve cleaned the TBI and IAC with seaform (on engine). I tested for correct IAC operation using a jumper wire and valve resistance using an ohms meter both test confirm it’s working properly. I removed the coolant temp sensor plug and tested the switch while the engine was running and the ohms meter lowered gradually.

Any help solving this issue would be much appreciated.

[Posimoto]

Anyone?

[garytho]

Did you remove the IAC to clean it? Or was it done while on the car?

Was Seafoam Deep Creep used and left to soak a while inside the IAC?
How many miles on the car?
Was the IAC ever cleaned before?

[Posimoto]

Originally Posted by garytho

Did you remove the IAC to clean it? Or was it done while on the car?

Originally Posted by Posimoto

I’ve cleaned the TBI and IAC with seaform (on engine).

Originally Posted by garytho

Was Seafoam Deep Creep used and left to soak a while inside the IAC?

Yes, deep creep for 20-25 mins

Originally Posted by garytho

How many miles on the car?

130,000

Originally Posted by garytho

Was the IAC ever cleaned before?

I've owned the car for 5 months although the TB didn't look too dirty before cleaning looking from the outside in.

[garytho]

Hmmm,....I'd wait for other members to comment on this. Those IAC valves can get really thick with build up and sometimes need to be removed to be cleaned all the way.
I'm suspecting thats the problem,..but I'd be more comfortable if others would confirm it.

[Posimoto]

Here is a before and after pic.

[garytho]

The throttle body looks clean,....but you cannot tell if the IAC underneath is really truly clean unless you remove it. There is a thread on this by Fenixus. He included pics and procedure and it is excellent if you want to check it out. Just search the forum (IAC).

[Posimoto]

I'm sure the IAC isn't as clean as it can be if removed and cleaned properly, but does the IAC control cold high speed idle?

Also, can IAC be filled with carbon enough where it didn't function properly at the same time the IAC tests confirms it is working correctly?

[fenixus]

I had same clean throttle body after numerous cleaning (including the IAC opening) and this how the actual IACV looked like after unbolting:


go figure where the idle problem was on wife's car ... I actually didn't bother cleaning the old one and shelled out $200 for new stepper motor IAC valve (specific to Calif specs on certain years).
The old one is covered with carbon buildup and crust, still haven't even tried cleaning it ... it's nowhere near a 15 min spray & brush...
I had similar buildup on TB passages and I was NOT able to clean them with sea foam deep creep and toothbrushes... it rather called for some serious solvent and wire brush perhaps...

more pics here:
removed Throttle Body for IAC replacement then re-installed, now questions

one thing for sure, the new valve fixed the idle problems on wife's car.

[garytho]

Hey Fen,....how many miles were on your wifes car before you replaced the IACV? Just wondering how long it took to get that bad

[fenixus]

it's coming from a year 2000 5s-fe motor with 81k miles on it. it had weird idle trouble (a tad too low) since I acquired the car 5 years ago, so I don't know maybe it was half that bad already back then?
recently it started cycling RPM up and down occasionally at traffic lights when car was hot (e.g. after exiting the highway).

the biggest problem however was that this valve likely cannot get close ever, so it causes a sort off a vacuum leak when ECU doesn't expect it, not big enough to throw things drastically off, but it was screwing up acceleration from a dead stop seriously and also the AC idle up was not working at all, car used to idle at 550-650rpm with ac turned on no matter how I adjusted anything (for this probably the IAC valve was unable to open as much as designed for).
driving this car in such condition was very annoying in middle of last Summer.

all these problems are gone now, car also regained the normal acceleration from traffic lights.

Originally Posted by garytho

Hey Fen,....how many miles were on your wifes car before you replaced the IACV? Just wondering how long it took to get that bad

[fenixus]

however, if the car only stays too long at high idle then there is another possibility, two of them actually (even if IAC valve works fine):

a) the Engine Coolant Temperature sensor for Electronic Fuel Injection (in short ECT for EFI) is wrongly reporting too low temperature for a long time and ECU holds the car up in high RPM to keep warming it up (while in fact it could be half way to warm already). ECT for EFI sensor is a primary feed to the ECU, it's unmonitored, so it will never know if it works bad or not.

that sensor costs around $45 OEM from a dealer online, easy to replace on 5s-fe, even without draining coolant, it's a sensor with green plug (2 wires) and golden base (19mm deep wall socket should fit over it after unplugging). it sits on driver side of engine when looking under hood and standing in front of car. right by it is another coolant sensor (sender actually) which is 1-wire only and only feeds the coolant temp gauge on the dash. there is a non-re-usable copper gasket under each of those sensors too, so get it along with new sensor if planning to replace, torque is 14ft-lbs.

you can test the resistance between ect for efi sensor's terminals, but it won't tell you much without knowing the exact coolant temperature at same time. extrapolating the temperature from the resistance when using diagrams like the one below is pointless, because you only translate the resistance into temp degrees and still don't know the real temperature of coolant (same about OBD2 scanner reporting coolant temperature).



you would need to remove the sensor and put it in the hot water bath while measuring the resistance AND checking the water temperature at same time.

b) coolant temperature is in fact cold and stays cold for other reasons (e.g. thermostat is stuck open) and car in fact takes a long time to warm up.

Consider all options to be possible (including a sticky IAC valve too).

[Posimoto]

I'll try the ECT, thanks you.

[Posimoto]

Update: 1999 Camry 4cyl 130k stays at high idle (1800RPM) on cold starts for 3 mins before dropping to 1100 RPM. Runs and idles fine when warm

I swapped in a new coolant senor switch seemed to work for about a week then back to the high idle on cold starts.

I tested the IAC @ 19.5 between the proper terminals.

I then removed the TB and IAC valve and gave it a thorough cleaning. I supplied 12v to the IAC and had movement. I also swapped in another new coolant sensor switch by chance the new one I previously installed was bad. I installed the TB and IAC with new gaskets and torqued the bolts to specs.

The first cold start it jump to 1100RPM then climbed to 1800rpm and stayed there for about three mins before it came back down.

Unlike fenixus’s pic (9th post in this thread) I have some shinny metal in one chamber. I’m thinking this may be more then a case of carbon build up. What would cause metal on metal binding? Thoughts?

[fenixus]

posimoto, yours looks a tad cleaner than mine at ~80k miles ...

also your IAC valve is a federal or pre-2000 type (for 4 cylinder), with a bi-metal (sensitive to temperature) spring on one end. on top of a sticky metal shutter due to carbon buildup it could be something wrong with either the spring (I don't have this piece on mine) or the electrical motor itself.

when car is dead cold and below let's say 45F, it may take a few minutes at high RPM to warm itself up. do you feel, your car is properly adjusting the engine RPM now with a new IAC valve and ECT sensor?