Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

VN High idle and engine light on all the time??

edelbrock1

Member
Joined
Mar 16, 2011
Messages
35
Reaction score
2
Points
6
Location
Adelaide
Members Ride
AllPaw CV8 & HSV Coupe4
Hi guys,

I have a mate with a 91 VN Berlina with some problems.

It has developed a high idle, I would say around 1500 rpm, and with this the engine light is permanently on. We have checked all the vaccuum hoses, so there does not seem to be a leak there

I have tried and tried to do the diagnostics thing with the paperclip but it just does nothing. Car starts and runs as normal. I have definately got the right plug, I have read and reread the sticky on how to do this.

So what am I doing wrong? are there times when the paperclip bridge does not work??

What could be the problem.

We are at our wits end here

Any help would be greatly appreciated.

Thanks
 

Darren_L

Well-Known Member
Joined
May 2, 2009
Messages
1,872
Reaction score
70
Points
48
Location
Toowoomba, Qld
Members Ride
VH SS
could be a stuck IAC. Have you tried adjusting the base idle ?

if you are bridging the correct 2 terminals on the ALDL connector and the engine light doesn't flash, then chances are the ECM has a problem
make sure you are bridging terminals A & B together.

 

edelbrock1

Member
Joined
Mar 16, 2011
Messages
35
Reaction score
2
Points
6
Location
Adelaide
Members Ride
AllPaw CV8 & HSV Coupe4
Hi Darren,

Thanks for the reply. I am definately bridging A and B in that plug. We can not seem to find any other plug, and the configuration is the same has it has to be the right one.

Is it possible to get a new computer from the wreckers and plug it in? Will this work or does the computer have to be matched to the car like in the later models??

Because the light will not flash, does this mean that it could be a faulty computer?

Thanks again for all the help.

Cheers
 

Darren_L

Well-Known Member
Joined
May 2, 2009
Messages
1,872
Reaction score
70
Points
48
Location
Toowoomba, Qld
Members Ride
VH SS
no probs mate
if the engine light doesn't flash in diagnostic mode, then that indicates there is some sort of ECM issue because it should flash a code 12 at the very least when the diagnostic connector is bridged. Assuming of course there isn't an open circuit in any of the wiring between the ALDL connector and the ECM. Back when the series I VN's were released, Holden had a recall on ECM's as they had bad solder joints, causing all kinds of problems. And often the check engine light wouldn't flash on these ECM's. I'd assume yours would have been replaced by now, but maybe it slipped through the recall ??

yes you can use a VN-VP ECM from the wrecker (V8 or V6), just need to swap your memcal over if it's not from the same engine. But don't let the wreckers charge you an arm and a leg for it. There are heaps of them about on Ebay, shouldn't really pay more than $50.
 

Brett_jjj

Well-Known Member
Joined
Oct 16, 2009
Messages
6,805
Reaction score
94
Points
48
Location
Tamworth NSW
Members Ride
vs commodore
The engine cooling fan should also turn on as well as the engine light flashing when the termials on the ALDL connector are bridged.Does the cooling fan turn on when the terminals are bridged? If not,Id replace the ECU with another second hand one.
 

edelbrock1

Member
Joined
Mar 16, 2011
Messages
35
Reaction score
2
Points
6
Location
Adelaide
Members Ride
AllPaw CV8 & HSV Coupe4
Thanks Brett. The engine fan come on if the ALDL connector is bridged or not, as soon as the key is turned to get all the lights on the dash working, the engine fan starts spinning, and it does exactly the same thing when we bridge the connector. So really when we bridge it, nothing different happens.

He also told me last night that the oxygen sensor in the exhaust got the wires melted onto the headers, he cut out the melted bit and joined the wires back together. Could this have caused a short somewhere? Maybe that oxy sensor is not working at all and causing this problem?
I think I will try on the weekend to replace the oxygen sensor and the ECU and see what happeens from there.

Thanks again for all the help guys.
 

delcowizzid

on holiday
Joined
Jul 8, 2008
Messages
6,993
Reaction score
439
Points
83
Location
NZ
Members Ride
в∞ѕтεכ √&
take the cover off the ecu and make sure the memcal hasnt come half out or corroded from water damage
 

edelbrock1

Member
Joined
Mar 16, 2011
Messages
35
Reaction score
2
Points
6
Location
Adelaide
Members Ride
AllPaw CV8 & HSV Coupe4
Thanks guys.

I will go to U pull it and score a new ECU and maybe another oxygen sensor for the exhaust and see how we go.
 

Whiteford88

38PONT
Joined
Jan 11, 2010
Messages
71
Reaction score
1
Points
0
Location
Tamworth, NSW
Members Ride
WH Statesman 5.7L
Hey mate, when my commodore did this it was after I took off the throttlebody and cleaned it, I also sanded it back a little bit to make it smooth and get all the crap off the sides. ANYWAY, when mine did this, I took off the IAC, and the TBS and cleaned it with WD40, and after this it went bug, it would constantly show engine check light and also rev at 1,500 and sometimes even reach 2,000. You need to take EVERYthing off the throttlebody and clean it, install it exactly how it came and make sure all vac hoses ect are on correctly, and in the right spot. The real problem with mine was the gasket had broken in half and was hanging down the centre of the tb and creating a small gap inbetween the two manifolds, causing excess air going into the engine, and thus triggered the computer to go into limp home mode.
p.s the memcal is fine, if the memcal fell out or whatever like a comment or so above stated, it would crank over but wouldn't fire, no fuel would be being injected. Trust me, I've tried it :)
But if you haven't stuffed around with your tb like I did, do what the above said and try a new computer, maf sensor then go IAC...
... those IAC's are C**nts.
 

edelbrock1

Member
Joined
Mar 16, 2011
Messages
35
Reaction score
2
Points
6
Location
Adelaide
Members Ride
AllPaw CV8 & HSV Coupe4
Thanks for all the help guys.

Today we went to the wrecker and stocked up on bits. We got a whole throttle body, various other sensors and another computer. We got home and swapped over the throttle body... Nope no change, still the high idle and engine light on all the time. Time to swap the computer. Suprise here, no metal shield over the computer, not even the holes for it to go. Seems it never had one. I have never seen one without the metal guard.

Anyways, swapped the computer over and she settled into a nice slow idle, took it for a 20 minute drive around the place and it all works perfectly. I was expecting the fault to come back after a certain amount of time, but as yet, it all seems to be sweet.

So thanks again guys for pointing me in the right direction.
 
Top