Uneven idle problem, worse in cold
28 January 2006, 06:36 PM
#1
Uneven idle problem, worse in cold
Still got this uneven idle - bounces up and down between 500 and 900 rpm - when cold, worse when very cold recently. Seems better but a little uneven when warm.
Ideas welcome.
MAF seems ok - unplug it and car stalls, AFR shows fine on gauge, volts look OK on Apexi PFC for both.
No oil in inlet pipes / TMIC or breathers, at all!
Can't find air leaks on inlet after MAF, around TMIC or any signal lines etc.
Plugs and coil packs new and fine. New air filter ( non oiled & not stainless steel one! )
ICSV idle valve air hose is afffixed.
What do I clean in the ICSV - I unscrewed the 2 screws and pulled off the plastic top ( the bit with the magnet inside and electrical plug on the outside ) but could only see a post with a magnet on and an o-ring at the base of the aluminium part. The valve ( under the post with the magnet ) turns easily, but should this part come out of the body ... couldn't get it out and scared to force it in case I broke it!!
It could be the cold air sensor perhaps, would this be a symptom of it? Where does that live and what sort of cost to replace?
Something else I noticed on the FC Commander display is that during town driving from cold, the temp increases to say 58, then drops to 42, then slowly climbs to 50 odd, then climbs to high 60's then falls to low 50's ... I thought it was due to the thermostat opening and letting litres of cold water suddenly in ... but not sure now as that should be opening at a higher temp, 70 C plus IIRC.
Also maybe needs a tweak to the cold start settings in the PFC map, as it IS worse in the recent colder weather, almost stalling as cold idle revs bounce from 300 - 900, settling once warm at 900 rpm steady.
Also, some times on lift off / stopping in neutral after using the revs the revs drop to 500 and bounce up and down a bit for a few seconds before stabilising at 900 rom ... is this related?
It's a 94 classic wagon with 3 port boost solenoid, Apexi PFC, cone induction, etc. but was all fine before engine rebuild.
Cheers
Ideas welcome.
MAF seems ok - unplug it and car stalls, AFR shows fine on gauge, volts look OK on Apexi PFC for both.
No oil in inlet pipes / TMIC or breathers, at all!
Can't find air leaks on inlet after MAF, around TMIC or any signal lines etc.
Plugs and coil packs new and fine. New air filter ( non oiled & not stainless steel one! )
ICSV idle valve air hose is afffixed.
What do I clean in the ICSV - I unscrewed the 2 screws and pulled off the plastic top ( the bit with the magnet inside and electrical plug on the outside ) but could only see a post with a magnet on and an o-ring at the base of the aluminium part. The valve ( under the post with the magnet ) turns easily, but should this part come out of the body ... couldn't get it out and scared to force it in case I broke it!!
It could be the cold air sensor perhaps, would this be a symptom of it? Where does that live and what sort of cost to replace?
Something else I noticed on the FC Commander display is that during town driving from cold, the temp increases to say 58, then drops to 42, then slowly climbs to 50 odd, then climbs to high 60's then falls to low 50's ... I thought it was due to the thermostat opening and letting litres of cold water suddenly in ... but not sure now as that should be opening at a higher temp, 70 C plus IIRC.
Also maybe needs a tweak to the cold start settings in the PFC map, as it IS worse in the recent colder weather, almost stalling as cold idle revs bounce from 300 - 900, settling once warm at 900 rpm steady.
Also, some times on lift off / stopping in neutral after using the revs the revs drop to 500 and bounce up and down a bit for a few seconds before stabilising at 900 rom ... is this related?
It's a 94 classic wagon with 3 port boost solenoid, Apexi PFC, cone induction, etc. but was all fine before engine rebuild.
Cheers
Last edited by vulnax999; 28 January 2006 at 06:39 PM.
28 January 2006, 08:07 PM
#2
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Hi mate ive just replied to a similar thread:
http://bbs.scoobynet.co.uk/showthread.php?t=487711
You say you unplugged your MAF and the engine stalled,my old MAF did the same but when cold the revs where all over,now MAF is changed im hoping the new MAF has fixed my problem!
http://bbs.scoobynet.co.uk/showthread.php?t=487711
You say you unplugged your MAF and the engine stalled,my old MAF did the same but when cold the revs where all over,now MAF is changed im hoping the new MAF has fixed my problem!
28 January 2006, 10:32 PM
#3
It may well need more fuel for cold weather and high barometric pressure.
ICVS may need turned up a bit too but only just a touch.
You can use brake cleaner to clean out the ICVS.
Hope this helps mate.
Phone/e-mail Andy F if you want advice on the idle settings on your Apexi.
Regards,
Harvey.
ICVS may need turned up a bit too but only just a touch.
You can use brake cleaner to clean out the ICVS.
Hope this helps mate.
Phone/e-mail Andy F if you want advice on the idle settings on your Apexi.
Regards,
Harvey.
01 February 2006, 09:09 PM
#4
Cheers Harvey.
I think the fueling is OK, used to be, but will contact Andy for ideal settings for water temp correction and cranking.
Think I need to pop off the 4 bolts holding down the ICSV ( thanks for the idea / info STi 69 ! ) and clean out with carb cleaner or similar, in case.
Could it be a dodgy water temp sensor ?? I said AIR TEMP sensor in top post but don't have one fitted!!! Do I ??
As I guess the ICSV was moved from old engine to new is most likely that dirty / damaged / wrongly set, but wouldn't moving the top slightly raise idle at all temps not just the cold temps ( where idle jumps from 300 to 1500 rpm each second! ).?
MAF voltages go from 1050 mV at idle to 5115 mV at full boost/throttle ( actually air flow exceeds MAF limits, hence Z32 MAF awaiting fitment! ) so looks like MAF OK; AFR gauge and lambda volts look fine. Injector duty fine, not a worry on idle though and was fine previously.
I'll see how this goes!!!
I think the fueling is OK, used to be, but will contact Andy for ideal settings for water temp correction and cranking.
Think I need to pop off the 4 bolts holding down the ICSV ( thanks for the idea / info STi 69 ! ) and clean out with carb cleaner or similar, in case.
Could it be a dodgy water temp sensor ?? I said AIR TEMP sensor in top post but don't have one fitted!!! Do I ??
As I guess the ICSV was moved from old engine to new is most likely that dirty / damaged / wrongly set, but wouldn't moving the top slightly raise idle at all temps not just the cold temps ( where idle jumps from 300 to 1500 rpm each second! ).?
MAF voltages go from 1050 mV at idle to 5115 mV at full boost/throttle ( actually air flow exceeds MAF limits, hence Z32 MAF awaiting fitment! ) so looks like MAF OK; AFR gauge and lambda volts look fine. Injector duty fine, not a worry on idle though and was fine previously.
I'll see how this goes!!!
02 February 2006, 10:07 AM
#5
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Check the idle speed as controlled by the ICSV.. the two screws on the top.. loosen and turn clockwise to increase the idle speed.. put the commander on REVs and put it in view from under the bonnet and play until you get required rpm speed etc..
Simon
Simon
02 February 2006, 06:09 PM
#6
Yep Simon.
But would this even out the bouncing idle speed until warm, or just simply raise idle even when warm but still bounce?
When cold and settled for a few seconds between bounces it is steady at 950 ish rpm, and steady when hot at 850 or 950 depending on air con on etc. - as set on PFC revs screen.
But would this even out the bouncing idle speed until warm, or just simply raise idle even when warm but still bounce?
When cold and settled for a few seconds between bounces it is steady at 950 ish rpm, and steady when hot at 850 or 950 depending on air con on etc. - as set on PFC revs screen.
02 February 2006, 10:54 PM
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sometimes if it is set to low the PFC fights it.. and so the idle bounces.. it might not be your problem.. just if you have had the top off and swevelled it, it might not be in the right position any more.. also iirc the engine has been in and out.. did the problem materialise after the engine was refitted?
Simon
Simon
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