1990 EFI 2.6L Isuzu Trooper/Jackaroo WON'T IDLE

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1990 EFI 2.6L Isuzu Trooper/Jackaroo WON'T IDLE

Postby bexi » Thu Aug 05, 2010 2:23 am

Hey all,

I'm from Sydney, Australia ... I've just signed up to this forum and am hoping to get a bit of help with fixing an issue i have with my 1990 Holden Jackaroo/Trooper which has the 2.6L Isuzu fuel injected motor in it.

The car will only start if i pump the accelerator pedal and it won't idle at all whether the motor is hot or cold.

If i make the motor idle by hold the accelerator pedal on a little bit, it will only idle if it's at about 1150rpm or higher. As soon as i let the revs go under about 1100rpm, the motor stalls.

I used to own what we call (in australia) a holden rodeo pick up which had the same motor and the motor was really responsive and quite powerful.... the same motor in my jackaroo/trooper is nowhere near as responsive or powerful.

I havn't bothered adjusting the idle screw as i know that there is other issues if the motor requires to be held on 1100-1200rpm just to idle.

I know there are lots of things i can check such as air cleaner, fuel filter, clean injectors, rotor button and cap, ignition leads etc but i'm just wondering if this is a common issue that other people have experienced and might be able to lead me straight to the problem?

Many thanks
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Postby fourzeedee1 » Thu Aug 05, 2010 3:48 am

I don't know about common issue since I have the carb, but I would verify yer fuel pressure and see if you are within spec.
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Postby DigitalDrifter » Thu Aug 05, 2010 4:05 am

Go with the basics first..

Look for bad grounds, charred wires, buildup on the plugs, change the oil filter, check the airways..

Unless it knocks horribly, or does some awful clanging sound when driiving, make sure it breathes, gets fuel, and gets spark.. its basic troubleshooting from there..

You've got a good rig that can built upon, post ups pics/vids of it running!

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Postby bexi » Thu Aug 05, 2010 4:58 am

ok guys thanks
there's no abnormal engine noise... the issue is only with the way it runs.
I will post up some pics over the weekend
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Postby Cavmedic » Thu Aug 05, 2010 8:14 pm

look on the side of the intake there is a very large hose that curves under the intake it goes to the idle control valve mine did the same thing it came unhooked and the trooper would not idle unless you have the gas pedal to the floor
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Postby shooter » Thu Aug 05, 2010 8:20 pm

Cavmedic wrote:look on the side of the intake there is a very large hose that curves under the intake it goes to the idle control valve mine did the same thing it came unhooked and the trooper would not idle unless you have the gas pedal to the floor


I think he's on to something here. When I first read your thread, I did a little looking and the idle control valve itself, if it went belly up or such, would cause that problem. Believe it was a pain to access.
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Postby bexi » Fri Aug 06, 2010 10:12 am

Cavmedic,
I will check it tomorrow but if it was the hose you are talking of, wouldn't you be able to hear an extremely obvious vacuum leak?
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Postby Cavmedic » Fri Aug 06, 2010 12:08 pm

i didnt on mine it did not make any noise
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Postby johnny5ive » Fri Aug 06, 2010 10:41 pm

My first impression would definitely be vacuum leak. Id start there. There are GOBS of vacuums on that motor all over the intake, all over the engine compartment, etc. I also have heard that these are know for Throttle position sensor problems. Chaning the oil and filter is a waste of time so far as fixing your idle issue goes, I am constantly amazed at the level of garbage that I read on here somtimes.
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Postby bexi » Sat Aug 07, 2010 12:25 am

hahaha
yeah i did have a bit of a chuckle about changing oil to fix an idle issue... just trying to help though so i won't get upset :)

I'm not really sure where this idle control unit is but maybe i'll just spray around every vacuum hose i can find with contact cleaner while the motor is running and see if it alters the way the motor runs
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Postby caveman » Sat Aug 07, 2010 9:22 am

If you don't find a vaccum leak, the next step would be to check the adjustment of the thottle position sensor and ignition timing together as they directly affect one another.
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Postby bexi » Tue Aug 10, 2010 7:49 pm

I would have thought that the TPS would be very unlikely to be out of adjustment as people don't usually touch them.
I would have no idea how to check if it's set right or not anyway???

On the positive side, I've got the car idling now - it's still a bit rough and shaky but it is actually idling at about 1000rpm. I fiddled round with cleaning spark plugs and advanced the timing a little ... i then found some sort of valve type thing mounted on the side of the engine bay which had 2 vacuum lines going to it... i pulled off the 2 hoses and blocked them with my fingers for a while to see if it would affect how the motor ran. I then plugged them back onto this valve type thing and that was it.

So i've definitely got an improvement in that the motor will idle now... the only thing is that it's still a rough idle and it does still stall occasionally when pulling up to stop at some intersections but maybe i just deal with it as it was a cheap purchase
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Postby SSM200 » Tue Aug 10, 2010 10:27 pm

i always listen with a piece of hose pointed at different areas in the engine bay. Works quickly. it is a noisy motor to begin with so leaks are tricky to find.

The idle control valve is mounted under the intake and VERY difficult to replace. Replaced it for the same reason. i did it with everything on the motor, but hated it. the vac line to it is rigid, so also difficult to replace.

Good luck.
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Postby bexi » Wed Aug 11, 2010 5:13 am

thanks SSM200

I just took the car for another drive and it's gone back to the way it was and won't idle again.

Seems like it might be this idle control valve which is hard to get to as you say.

From what people have been saying, one of the hardest things is actually getting parts for thing to start with.

Any tips on doing the job?
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Postby stusvend » Wed Aug 11, 2010 3:49 pm

John wrote:I am constantly amazed at the level of garbage that I read on here somtimes.


no need to be an --- about it. people just trying to help. personally I am amazed at the arrogant attitudes I read on here sometimes.
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Postby SSM200 » Wed Aug 11, 2010 10:33 pm

bexi wrote:Any tips on doing the job?


Get under the vehicle and get a good look at the thing. go ahead and get the replacement part first so you know exactly what you are looking for. it is tucked away. make sure you have a swivel socket and a bright flashlight. Disconnect the vacuum hose from the intake first. you will leave this on the IAC valve when you remove it. if there is slack in the wires, it will be easier to disconnect after you have the valve removed.
Install will be reverse, with the hose attached. the only difference is the connector, it will be easy to reconnect the wires after the valve is installed.

Inspect the vacuum hose carefully. a leak here will cause just as big a pain. I could not get a replacement hose, so i had to repair mine.

Hope this helps.
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Postby SSM200 » Wed Aug 11, 2010 10:39 pm

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Postby bexi » Thu Aug 12, 2010 4:11 am

Thanks so much for your help!
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TPS check

Postby bexi » Sat Aug 28, 2010 6:56 pm

Hey does anyone know the details on how to check the adjustment of the TPS on these things with a multi meter?
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Re: 1990 EFI 2.6L Isuzu Trooper/Jackaroo WON'T IDLE

Postby Arlie123 » Tue Dec 02, 2014 8:06 pm

I know this is old....but, curious if TPS fixed this idle issue. Having the same issue among others with my '89 2.6 Trooper.
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