idle fault

[Shaun]

i have been having problems with my idle for a while now. on first start up it revs up to about 1700 and will slow drop down to about 1000 but then after about a minute it will go crazy. it drops down to below 500 and almost stalls then picks back up to about 1000. it keeps doing that for about a minute and then it will idle normally again.

the check engine light is on constantly and the only code is 24. i have taken the IAC off cleaned it and it made no difference. i bought another one and cleaned it but it made no difference either. i have also put a new gasket on which made no difference either. I tried a reconditioned AFM which made no difference.

i have just replaced all vac lines with silicon hose and taken apart the bov and cleaned it so there are no leaks

someone please help before i do something i will regret

[titian]

possible water temp sensor fault?..Causes idle issues... Although it usually throws a code too

[Shaun]

wouldn't that cause fans to come on when it's cold

[RA_Jay]

use to have similar fault with my car. was the vehicle speed sensor though (code 33), the idiot that owned my car before me had a speed cut defender in when i test drove it and purchased it, but when i went to pick it up it was fine until i started engine breaking down a hill. then the check engine light came on and it brought up code 33 and 24? the idle just went shocking and went into safe mode (couldnt rev over 4500).

turned out the idiot that previously owned my car had just cut the defender out of the car after i put a deposit on it, without connecting the wire back up. look down near your ecu. under your front passenger carpet and look for a green wire with a black strip on in and make sure its not burnt out or cut.

another thing you can try is reseting your ECU. disconnect your negative battery terminal and pump you brakes a few times and then leave disconnected over night. just a thought hope this might help?

[Shaun]

i have reset the ecu about 5 times. when i first start it up after resetting it idles even worse for about 15 seconds and then the check engine light comes on and it idles the way i explained in the OP

[RA_Jay]

definalty look at the wires around your ecu for the green wire with the black strip. make sure theres none cut or burnt out, and have you checked the wires to your icv. and the plug itself?

[Shaun]

checked the wires to the ecu. they all looked good

[hijacka]

I would be replacing intake manifold gaskets then AFM.

[Shaun]

i just had aftermarket intake pipe put on and split feul rails done so the manifold was taken off to do that and gaskets done. and i have tried a reconditioned AFM with no success

[RA_Jay]

how about the plug wires and inside of the plug that clips onto the icv? have you tried adjusting the icv?

[Shaun]

the wires to the ICV look good. i have adjusted it, when it's warm i've set the idle to 850.

(i'm thinking aloud here)

since the adjustment works and the cold start works i'm thinking that there is nothing wrong with the ICV.

BUT the hunting idle only happens when the engine is cold.

Is the ICV the only thing that controls the cold start or is there something else that works with it

[Shaun]

I was having a look around the engine bay today, seeing if anything looked a bit sus and i noticed a wire with the insulation stripped off. the wire connects to the thing that i have circled in the picture below

is it part of the temp sensor

[SWAGGN]

i had this same problem which got so bad i needed a new motor! thank god for insurance!!! turns out it was the oxygen sensor on the exhaust, reading the fuels to rich, try that and see how that goes!

[Eight_dollar]

replace everything or just sell it lol

na prob best to get someone who knows subbys' to look at it

[Stoffa]

Buy a new coolant temp sensor. cheap as. symptoms fit

[gazzy2000]

How r u resetting ecu?

The right way is plug in both green n black plugs, turn key on engine off, push throttle pedal right dwn for 3 secs then bak upto half for 3 secs, release, then go for drive n stay over 11kph until engine check light flashes the all clear or displays a code.

No boosting while doing this, infact i dont think you are meant to go over 40kph.

If an issue is curent the code will show, take note of the code, if all it was all clear... you are sweet. Pull ova turn off engine n unplug plugs, your ECU is now reset. drive away see if problem persists.

This must be done every time u replace a sensor.

[Guest]

how does playing with the throttle make any difference? its just opening and closing the throttle body plate?

[gazzy2000]

 AshtonC said:

how does playing with the throttle make any difference? its just opening and closing the throttle body plate?

lets ECU relearn/recalibrate the TPS signal..

[gazzy2000]

 gazzy2000']

[quote name='AshtonC said:

how does playing with the throttle make any difference? its just opening and closing the throttle body plate?

/quote]

lets ECU relearn/recalibrate the TPS signal..

we just had the exact same prob on qiksti's car.. two man probs 1) a hole in the intake pipe under manifold where they all perish by the turbo.. and 2) the AFM was crook the code was 24 which is actually quite a generic code whereby it cud be a number of things.. but a crook AFM made sense.. although the code was not saying AFM.

But if you chuck another AFM on you must reset the ECU, otherwise you wont know when or if you fixed it, as stated do this everytime you change a sensor so it forgets the old corupt signal settings, this restting allows the ECU to relearn teh new (correct) signal settings

[Shaun]

i have been reseting the ecu by plugging in the black and green. but i havent been doing the throttle thing.

I have been resetting it after i change anything. the only code that comes up is 24 everytime.

I'm going to change the coolant temp sensor this week and have a look at the knock sensor. I'm going to put the stock BOV on once i get a recirc hose.

I just replaced my intake because it split all the way around where it met the turbo

[gazzy2000]

 Shaun said:

i have been reseting the ecu by plugging in the black and green. but i havent been doing the throttle thing.

I have been resetting it after i change anything. the only code that comes up is 24 everytime.

I'm going to change the coolant temp sensor this week and have a look at the knock sensor. I'm going to put the stock BOV on once i get a recirc hose.

I just replaced my intake because it split all the way around where it met the turbo

ahh yip, so you go for a drive withe them connected etc?

(the throttle thing is for the TPS resetting)

[Shaun]

i'll give the throttle thing a go.

I havent reset it when it's cold though and that seems to be the only time the problem happens.

do you rekon it will make a difference

[gazzy2000]

 Shaun said:

i'll give the throttle thing a go.

I havent reset it when it's cold though and that seems to be the only time the problem happens.

do you rekon it will make a difference

the whole reset process resets all the stored signals..the throttle pressing is only part of that process & purely does the TPS

you need to plug the plugs in, do the throttle pressing then go for a drive over 11kph (no boosting) untill light either flashes code or flahes the all clear. That is the TRUE process to reset the ECU for ALL sensors

bettery disconnects have never done it on any car i have owned

[kamineko]

what intake pipe did you fit? the under manifold one? was the fault present before or after the manifold came off?

[Shaun]

i have a silicon under manifold intake. the problem was there before i replaced it.

the CEL has been on for 6 months