strange idle behaviour - ***SOLVED***

[Ajit_mk2_16v]

Hi all

My 1999 1.4 16v polo has been giving me problems!

My car used to idle at 800rpm at standstill, now this has increased to 1000rpm.

When i move away the revs do not return to rest when coming to a standstill. They remain around 1000-1500 rpm

Upon start the revs hit 3000rpm and go between 2000 and 3000rpm and do not settle down to normal. Unless I stop the car and restart when they idle at 1000rpm....

Could it be the temperature sensor ? can someone help!!!! - thanks

[bloomfield_5]

From the sound of it, I think it might be the throttle valve.

Sometimes the throttle valve gets all clogged up with crap and stuff. This makes it stick and not open and shut properly. Try taking it off and cleaning it out with some carb cleaner.

[Ajit_mk2_16v]

From the sound of it, I think it might be the throttle valve.

Sometimes the throttle valve gets all clogged up with crap and stuff. This makes it stick and not open and shut properly. Try taking it off and cleaning it out with some carb cleaner.

Does the ECU need to be reset as well?

[bloomfield_5]

nope it shouldn't need to be. Because your not replacing it with a new one. If you haven't got an engine warning light on then just cleaning it out shouldn't effect the ecu, and it will stop it sticking.

[david burton]

mine does this, or used to. temp sender doesn't fix it. i tried cleaning the butterfly valve and so on, but nothing helped. ecu resets sometimes helped, but now the car seems fine, I think it might just have needed a bit of adaptation to my cleaning.

if you put the engine under load - i.e handbrake on, and let off the clutch slightly, so the revs drop - does it stay at 1000rpm? if so, it's identical to mine. sometimes putting the fan on full returns the revs to normal!

noone else seems to be able to help me tho

going to leave it, putting it down to "one of those things" as it doesn't happen all the time.

[BenMMellor]

Does the ECU need to be reset as well?

nope it shouldn't need to be. Because your not replacing it with a new one. If you haven't got an engine warning light on then just cleaning it out shouldn't effect the ecu, and it will stop it sticking.

I'd argue that this is one of the firs thtings to do as its cheap and free ! You won;t harm the engine doing it..

I had similar issues with my 16v. When it was in having the cambelt changed the battery was off for an hr and caused an ECU clear and reset.
No more idlin problems..

[Ajit_mk2_16v]

I think i'll try and discount the battery for a while to see if the ECU reset works.
Second, i'll clean the thottle body...
and lastly... i take the car to the garage! which probably won't be cheap!

Thanks for the suggestions... keep them coming

[bloomfield_5]

sorry my mistake.
I think I was wrong too. If you have had the battery disconnected or had any faults then resetting the ecu probably would solve it.
If that isn't the problem then you could always try the throttle valve.

[Ajit_mk2_16v]

disconnecting the battery is something i'll try after work tomorrow.

then get the manual out to check out to clean the thottle body!

[Ajit_mk2_16v]

Well,

I took the car to my local independent garage.

I got him to connect his hand held tool to the cars on board computer.

One fault code was displayed 01250 - Injectator Cylinder 2 o/c or s/c intermittent fault.

The garage wasn't concerned about this and puts it down to an electrical error so he reset the ECU and to my surpise the car was running fine! normal revs and in fact so far its running smoother than normal.

I need to go back next weekend to get the logs read again so see if the fault returns, but it looks like an ECU reset was the way to go!

[BenMMellor]

I need to go back next weekend to get the logs read again so see if the fault returns, but it looks like an ECU reset was the way to go!

which is what will happen if you disconnect the battery for 20 mins folks... So use this as the first action.

[Ajit_mk2_16v]

I need to go back next weekend to get the logs read again so see if the fault returns, but it looks like an ECU reset was the way to go!

which is what will happen if you disconnect the battery for 20 mins folks... So use this as the first action.

Agreed! its the way forward!!!!