lol, sorry. I only looked in the TEWD for what Nick M mentioned to look for. I should've looked more though. With all of this info, I should definetely be able to figure this problem out. Thanks!
Bad idle when warmed up
- Thread starter Back2Basics
- Start date
3p141592654 said:
Lol, nah. I've bit on this guy's hook before. That and the "find more posts by" function shows some folks simply can't be helped. Feel free to learn this lesson for yourself though
my car is doin the same thing. it jsut started happening after i got it back from paint. its never done it b4. checked codes and got 24 (IAT) and 31 (AFM).
oh sorry if im stealin the thread but i wanna get my car fixed. it looks good but isnt runnin to good.
oh sorry if im stealin the thread but i wanna get my car fixed. it looks good but isnt runnin to good.
24 and 31? Those never happen together.
Start with the easy checks, the connector and wiring. They share a power source, and it is likely the weak link for you.
Start with the easy checks, the connector and wiring. They share a power source, and it is likely the weak link for you.
I'm also having the exact same problem. Good idle when cold, bad when warm/hot.
Want to check the ECT sensor as mentioned here, but the tsrm diagram tells me that I have to measure the temperature to see what the resistance should be.
How do I check the temperature of the ECT?
Do I hold a thermometer to the ect? Or do I get the coolant cap off and put a thermometer in there?
Any thoughts?
Any help will be greatly appreciated.
Want to check the ECT sensor as mentioned here, but the tsrm diagram tells me that I have to measure the temperature to see what the resistance should be.
How do I check the temperature of the ECT?
Do I hold a thermometer to the ect? Or do I get the coolant cap off and put a thermometer in there?
Any thoughts?
Any help will be greatly appreciated.
Just drive the car for 15-20 minutes to get the engine up to normal operating temp. Then unplug the ECT (an OBD-II term btw. CTS is the older term) and see if the idle improves. If it does change the sensor. If you want you can test it while it's out to confirm it's bad. In either case clear the code 22 that'll be set. I doubt it's the sensor as so many other things can cause poor hot idle and they're more common.
Thank you jetjock.
Just went for a drive and when I stopped the car at my house I noticed there was no clicking whatsoever from the ISCv.
So I guess that's my problem while the ecu does not give me an error 22.
Just went for a drive and when I stopped the car at my house I noticed there was no clicking whatsoever from the ISCv.
So I guess that's my problem while the ecu does not give me an error 22.
The ISCV doesn't have anything to do with code 22. That code is only for the coolant sensor circuit. You need to better describe the problem. Idle issues can involve speed or quality. They're not the same thing. As far as the ISCV goes yes, you should hear the motor step open just after the engine is shut down. Course, that doesn't mean the pintle is opening but there's a way to check that without taking the valve off.
Jetjock,
I meant thesame as you described above. Maybe it's because english is not my mother tonque.
I do not get a code 22 so my coolant sensor is most probably not broken. that's what i ment.
Meanwhile i took a spare iscv apart and cleaned it + tested it thoroughly according to the tsrm.
Hope to get to replace this part asap.
I meant thesame as you described above. Maybe it's because english is not my mother tonque.
I do not get a code 22 so my coolant sensor is most probably not broken. that's what i ment.
Meanwhile i took a spare iscv apart and cleaned it + tested it thoroughly according to the tsrm.
Hope to get to replace this part asap.
Droevig
The sensor can still be bad and not set a code 22. However it should set this code whenever it's disconnected. The code isn't my point though. I suggested unplugging the sensor because the ECU will then use a default value of about 90 degrees, the same temperature as a hot engine would be. If idle improved it would indicate a problem with the sensor or it's circuit.
The sensor can still be bad and not set a code 22. However it should set this code whenever it's disconnected. The code isn't my point though. I suggested unplugging the sensor because the ECU will then use a default value of about 90 degrees, the same temperature as a hot engine would be. If idle improved it would indicate a problem with the sensor or it's circuit.
Ah ik begrijp.
I disconnected it yestday and it didn't help. Sorry, I didn't mention that
So it is most probably not the ics that is faulty
I disconnected it yestday and it didn't help. Sorry, I didn't mention that
So it is most probably not the ics that is faulty
Okay, since dark006 doesn't reply to this topic anymore, or so it seems, i'll just continue to hack into this thread
The next thing I did:
I disconnected the ISCV and the idling problem did not change. In fact, nothing changed so it's most obvious that mine is toast.
So the thing I did: I took my spare ISCV out of its housing to clean it. But is was in fact too dirty to slam it on just like that. So I took the whole ISCV apart and cleaned all parts.
But being silly as I am, I forgot to check how far the ISCV should be 'open' by default. I tried putting it waaaaaaaay out (the little penis like looking sensor thing at the longest /most expanded position) and the car immediately dies after starting.
Next stop: ISCV completely in. So I removed it and put it in the most contracted postion. Now the car will idle but it's sputtering. Therefore I think I have to 'set' the ISCV back to its default position (more or less because it expands and contracts a little thru the stepper motor.) to get the engine running nice and clean.
This ISCV is not faulty because the resistance was good and I also hear the clicking noise when shutting down the car.
So if anybody could tell me how to 'reset' the ISCV to the normal position I'd really appreciate it. The TSRM sais nothing about this. Just how to check it, not set it.
The next thing I did:
I disconnected the ISCV and the idling problem did not change. In fact, nothing changed so it's most obvious that mine is toast.
So the thing I did: I took my spare ISCV out of its housing to clean it. But is was in fact too dirty to slam it on just like that. So I took the whole ISCV apart and cleaned all parts.
But being silly as I am, I forgot to check how far the ISCV should be 'open' by default. I tried putting it waaaaaaaay out (the little penis like looking sensor thing at the longest /most expanded position) and the car immediately dies after starting.
Next stop: ISCV completely in. So I removed it and put it in the most contracted postion. Now the car will idle but it's sputtering. Therefore I think I have to 'set' the ISCV back to its default position (more or less because it expands and contracts a little thru the stepper motor.) to get the engine running nice and clean.
This ISCV is not faulty because the resistance was good and I also hear the clicking noise when shutting down the car.
So if anybody could tell me how to 'reset' the ISCV to the normal position I'd really appreciate it. The TSRM sais nothing about this. Just how to check it, not set it.
Thanks man, I appreciate it.Dark006 said:
And hey, maybe we get enough help to solve both yours and my problem :naughty:
There's no manual setting of the ISCV. As you said, the ECU homes it after every engine shut down. The little penis looking thing is called a pintle. Just because you hear the motor step doesn't mean the pintle is moving. Shut the engine down, unplug the ISCV, then restart the engine. Idle should be 1200-1600. I'm assuming you cleaned the boost check valve when you had the ISCV out.
I have tested the ISCV for proper functionality before putting it in, according to the instructions in the TSRM.
The pintle (thank you sooo much for this word ) however can only move so much using the ecu. 4 pins can move it to 4 positions so the difference in min vs max is no more then maybe 0.5centimeters.
(At least, in my perception. Correct me if i'm wrong).
Or can it be set by the ECU to the utmost mininum or maximum setting?
I will test this tomorrow, and maybe post some pictures if my explanation is still not clear (which is very well possible ).
Oh and I did not take the whole housing out. I just unscrewed the black cover and took it off.
The pintle (thank you sooo much for this word
) however can only move so much using the ecu. 4 pins can move it to 4 positions so the difference in min vs max is no more then maybe 0.5centimeters.(At least, in my perception. Correct me if i'm wrong).
Or can it be set by the ECU to the utmost mininum or maximum setting?
I will test this tomorrow, and maybe post some pictures if my explanation is still not clear (which is very well possible
).Oh and I did not take the whole housing out. I just unscrewed the black cover and took it off.
It is a stepper motor. It has 255 positions. See here for the details.
http://www.mkiiitech.com/forums/viewtopic.php?t=826
http://www.mkiiitech.com/forums/viewtopic.php?t=826
What 3p said. Because the ISCV has no positional feedback device on it (an optical encoder for example) the ECU has no way of knowing where it is unless it homes it at every engine shutdown. It does this by stepping the pintle full open just after you turn the key off.
In your car the throttle plate is fully closed at idle. The engine can't run when it's choked like that so the ISC plumbing provides a bypass path around the TB. The volume of this plumbing (it's conductance in engineering parlance) is enough to provide an idle of up to about 1800 rpm when the pintle is fully open. Having it fully open not only provides for a positional starting point but also makes for easier starting of the engine. Think of it as holding some pedal as was done in carbed engines.
As soon as engine speed crosses 500 rpm after start the ECU begins stepping the pintle closed until rpm reaches the target speed demanded at that moment. Target depends on several things but is mainly determined by coolant temperature. The target is always changing as the coolant warms up until it reaches about 175 degrees. At that point the cold idle algorithm ends and warm idle control begins. The system is in full feedback control with a tolerance of +/- 20 rpm even during the rolling target.
In your car the throttle plate is fully closed at idle. The engine can't run when it's choked like that so the ISC plumbing provides a bypass path around the TB. The volume of this plumbing (it's conductance in engineering parlance) is enough to provide an idle of up to about 1800 rpm when the pintle is fully open. Having it fully open not only provides for a positional starting point but also makes for easier starting of the engine. Think of it as holding some pedal as was done in carbed engines.
As soon as engine speed crosses 500 rpm after start the ECU begins stepping the pintle closed until rpm reaches the target speed demanded at that moment. Target depends on several things but is mainly determined by coolant temperature. The target is always changing as the coolant warms up until it reaches about 175 degrees. At that point the cold idle algorithm ends and warm idle control begins. The system is in full feedback control with a tolerance of +/- 20 rpm even during the rolling target.
Thank you for this long and clear information.
This is exactly what I needed to know.
You guys are amazing.
This is exactly what I needed to know.
You guys are amazing.