Idle on stock s3 304 ute

Holden Delco ECU and PCM Tuning
Posts: 61
Joined: Fri Jul 22, 2016 5:54 pm
Location: Sunshine Coast

Idle on stock s3 304 ute

Postby The J'rod » Fri Jul 14, 2017 10:56 pm

Idle driving me crazy....idle on cold start is mega high can sit on 2 grand plus, once up to temp it settles down, but can be idling at temp and without touching anything the rev's can just rise up to to about 1400 than drops back down again, there is no engine light on, have plugged in car to laptop nothing on there will faults or anything, replaced coolant temp sensor, throttle position sensor, idle air control sensor, vacuum hoses.....oh and it's a manual before people ask that to, I believe it still maybe IAC how can I check it with multimeter to make sure wiring is good to sensor, or any help will be greatly appreciated....I will try anything at this stage

Posts: 2741
Joined: Mon Aug 02, 2010 6:35 pm

Re: Idle on stock s3 304 ute

Postby Dylan » Fri Jul 14, 2017 10:59 pm

Post a log up and see what other's can pick. If it's a sudden rise like that once warm possibly it's dropping out of closed loop idle. Maybe a fluctuating vacuum reading or a short speed input signal. A log will tell more.

Posts: 1963
Joined: Thu Apr 09, 2009 12:31 pm

Re: Idle on stock s3 304 ute

Postby immortality » Sat Jul 15, 2017 12:03 pm

Factory manual or a conversion? Have you cleaned the maf and tb?

Posts: 61
Joined: Fri Jul 22, 2016 5:54 pm
Location: Sunshine Coast

Re: Idle on stock s3 304 ute

Postby The J'rod » Sat Jul 15, 2017 12:54 pm

Factory manual

Posts: 61
Joined: Fri Jul 22, 2016 5:54 pm
Location: Sunshine Coast

Re: Idle on stock s3 304 ute

Postby The J'rod » Sat Jul 15, 2017 12:55 pm

Yeah have cleaned MAF and throttle body

User avatar
Posts: 8910
Joined: Sat Feb 28, 2009 9:05 pm
Location: Tenambit, NSW

Re: Idle on stock s3 304 ute

Postby Holden202T » Mon Jul 17, 2017 10:15 am

is the IAC set correctly ?

Posts: 61
Joined: Fri Jul 22, 2016 5:54 pm
Location: Sunshine Coast

Re: Idle on stock s3 304 ute

Postby The J'rod » Mon Jul 17, 2017 6:55 pm

How do I set it.

Thought the IAC was set by the ecu, I have read that it may a few drives for the ecu to learn it, but it's been months now,

User avatar
Posts: 4962
Joined: Mon Oct 08, 2012 6:41 pm
Location: Kyneton, Vic

Re: Idle on stock s3 304 ute

Postby vlad01 » Mon Jul 17, 2017 7:36 pm

nah, more like 5 sec to self calibrate. There is an issue somewhere.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

User avatar
Posts: 1492
Joined: Fri Mar 14, 2014 8:37 pm
Location: Bacchus Marsh, Vic

Re: Idle on stock s3 304 ute

Postby Biggvl » Mon Jul 17, 2017 9:07 pm

No, the idle speed needs to be set so there are X amount of IAC steps otherwise the IAC will never seat, this needs to be checked.

TPS is a great cause of what is being described, grab a workshop manual and check that the voltages are to spec.
According to chemistry, alcohol is a solution...

User avatar
Posts: 4962
Joined: Mon Oct 08, 2012 6:41 pm
Location: Kyneton, Vic

Re: Idle on stock s3 304 ute

Postby vlad01 » Mon Jul 17, 2017 9:38 pm

Biggvl wrote:No, the idle speed needs to be set so there are X amount of IAC steps otherwise the IAC will never seat, this needs to be checked.

TPS is a great cause of what is being described, grab a workshop manual and check that the voltages are to spec.


That's not the IAC that's set, that's the butterfly stop screw you are talking about and the IAC just reacting accordingly to set idle RPM table in the tune and natural bypassed air.

In terms of the IAC actually adjusting its stop point and calibrating is 0 step position, that's done automatically after a ECU ram reset and a starting the engine, giving it a rev and then the IAC will do its calibration. That's why sometimes if you just blip the throttle on a ram reset the engine just revs and immediately stalls, stall saver just wasn't quick enough to bounce back the IAC. On and restart it will already know the 0 step position and open more to prevent a stall. If you don't let it die on the first reset it learns it all in about 5 sec, otherwise it needs 2 starts to work out where its at.


setting the idle screw just ensures a min about of air for the IAC for a optimal step range. Basically you don't want too much bypass otherwise the IAC is always closed and that can result in high idle so def worth checking, and you don't want to little as the IAC can be maxed out in range and idle still to low, ie Mc stally Mc stall-face
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

Next

Return to Holden ECUs

Who is online

Users browsing this forum: Bing [Bot] and 2 guests