hunting idle

[slippo]

on tick over what could be the cause of the revs fluctuating quite dramitically? from say normal to 2500rpm? any ideas

[Jay07]

Ive just hosted a long thread on this type of problem;

http://www.e30zone.net/modules.php?name ... highlight=

After all that i had most success by changing the dizzy cap and sparks im still get a slight searching vibe, my next check with be the air flow meter but filter before that!

good luck mate keep posting results!

[FlappySocks]

Check the easy things first - TPS and Blue temp sensor. Then hunt for an intake air leak.

[johnna]

Brown and Blue temp senders/ sensors in Stat housing, dirty Idle Control Valve, holes in rubber boot between afm and throttle body.

[slippo]

hows the car at the moment jay, did you get it sorted?
i have an auto aswell, and ever since i changed the ecu and put a airfilter on it, it hunted a little bit on idle only when it was in gear, and sometimes would stall if you reved it then let them drop.
also when pulling away it wouldnt respond as quickly as it did befor, just a slight delay, so took the air filter of and seems a slight bit better,

[FlappySocks]

Sounds like the TPS and/or air leak. The TPS is easy to check with a continuity checker/multimeter. After installing a new ECU (or disconnecting the battery), expect idle problems for a few days.

[Jay07]

hows the car at the moment jay, did you get it sorted?
i have an auto aswell, and ever since i changed the ecu and put a airfilter on it, it hunted a little bit on idle only when it was in gear, and sometimes would stall if you reved it then let them drop.
also when pulling away it wouldnt respond as quickly as it did befor, just a slight delay, so took the air filter of and seems a slight bit better,

Slippo! Hmmm interesting... mine was doing it in drive or not, The difficulty i was having is that occasionally it would all seem fine and then a few days later back to the same old. After i gave up i took it to a mechanic who was covinced it was the ICV (changed it) but sure enough it started again. The next of checks that i hadnt done was the sparks and dizzy cap. The old arm and cap were messey and to be honest it hadnt been done for ages. So with that in place it hasnt stalled yet!!! but im not speaking too soon, or have i just.... anyway the idle is still uneasy sometimes it will hold sometimes a wavelike continuous bounch at idle.

So i'm not sure anymore, thats why i want to try a new air filter/ test the air flow meter - and if all else fail i will take it to someone who can plug in and read the error codes!!!

Wheres best to do that other than dealer? anyone know of somewhere local??

[E30BeemerLad]

warm the car up and with it ticking over and presumably hunting up and down the revs, spray some WD40 or carb cleaner around the inlet manifold, where it bolts to the head, if normal steady idle is briefly restored for a few seconds then you have a leak on the inlet manifold gasket.

Check the rubber boot for splits on the induction system and that all hoses around the throttle body are secured, you could have disturbed some of this, particularly the rubber bellow when moving the airbox about when changing the filter.

[Jay07]

warm the car up and with it ticking over and presumably hunting up and down the revs, spray some WD40 or carb cleaner around the inlet manifold, where it bolts to the head, if normal steady idle is briefly restored for a few seconds then you have a leak on the inlet manifold gasket.

Check the rubber boot for splits on the induction system and that all hoses around the throttle body are secured, you could have disturbed some of this, particularly the rubber bellow when moving the airbox about when changing the filter.

Nice tip Mate I did check for splits/leak but i will look again when i do the filter - Thanku

[FLEX]

SORRY LADS WHAT IS TPS I DONT KNOW WHAT THAT IS AND WHERE IS THAT.

[E30BeemerLad]

Throttle Position Sensor.

On the bottom of your throttle body (thing with the large butterfly inside) which your throttle cable goes to, there is a small black box. That is the TPS.

With the car switched off open the throttle slightly by using the throttle linkage on top of the throttle body, it should make a very slight "click" sound when the throttle is just opened a fraction, this tells the ECU the throttle is open. I suppose it is possible to still have the "click" sound from the micro switch inside without it working, but searching for the click sound is a start.

[FlappySocks]

If the TPS doesn't make a click sound (or make contact) when the throttle is closed, then the ECU doesn't know when your foot is off the gas. Therefore, the ICV doesn't cut in, and keep the revs steady.

[Jay07]

Flex go to the link in the second post in this thread, there are pictures in there that will show you the TPS