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1988 Holden Jackaroo transmission problem

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1988 Holden Jackaroo transmission problem

Postby KirkW » Thu Dec 19, 2019 8:57 am

Hi

Firstly thank you so much for your help! I've got an intermittent issue that I assume is electrical and we all know how hard these things can be to solve.

If anyone can point me in the direction of what I could check or test. I haven't been able to find much info online.

The below issues can occur independent of each other:

-Only appears to be an issue when the car is warm (but could be coincidence)
-Transmission has displayed a few different issues
--Stuck in low gear
--Dropping to neutral between shifts
--Holding gears longer than it should
--OD light flashing (not flashing like a warning, flashing like a loose connection, this only happened when it was stuck in low gear)
-Idle raises to approx 1200 RPM with in P or D while this issues are occurring.
-Once car has been sitting a while it all returns to normal

Other information:
-Trans fluid looks and smells clean
-Trans not slipping

My thoughts:
-Possible relay
-Possible ECU
-Has had a few oil leaks over the years so maybe a fouled connector
KirkW
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Vehicle: 1988 Holden Jackaroo/ Isuzu Trooper

Re: 1988 Holden Jackaroo transmission problem

Postby geeves » Thu Dec 19, 2019 2:07 pm

What engine?
Im thinking ecu or valve body
Sanding your knuckles before starting work can help. That way you cant skin them
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geeves
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2013 Subaru XV

Re: 1988 Holden Jackaroo transmission problem

Postby KirkW » Thu Jan 02, 2020 10:12 am

Hi Geeves

It's a 4ZE1

The problem really seems to be exacerbated by heat. Thought I had it resolved a few times and when hot weather hit it happened again.

I think I've narrowed it down to electrical or vacuum related, definitely not mechanical.

On the inlet manifold side if I wet this down when the problem is occurring it seems to settle down.

I've tidied up all the wiring, re-taped, cleaned connections and made sure everything has good contact.

I checked vacuum lines for leaks and fixed as required.

It's got an Auxiliary Air Valve from another vehicle fitted, this seemed a bit sticky so that's been cleaned now.

After all that the car has noticeably more power and gear changes are more pronounced, the gear box also kicks down much easier on acceleration.

I'm still not sure if it is 100% fixed but I've definitely made some improvements.

Any ideas of anything else to look at?

Do you know where the ECU is on the vehicle?
KirkW
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Posts: 7
Joined: Thu Dec 19, 2019 8:37 am
Age: 40
Country: Australia
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Vehicle: 1988 Holden Jackaroo/ Isuzu Trooper

Re: 1988 Holden Jackaroo transmission problem

Postby geeves » Tue Jan 07, 2020 8:47 am

Also look at the filter in the trans
Sanding your knuckles before starting work can help. That way you cant skin them
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geeves
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Posts: 8962
Joined: Sun May 10, 2009 1:36 pm
Location: Rangiora
Age: 63
Country: NZ
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Vehicle: 94 bighorn 4jg2
2013 Subaru XV

Re: 1988 Holden Jackaroo transmission problem

Postby KirkW » Fri Jan 10, 2020 1:30 pm

Just an update in case any one ever has similar issues.

It seems there have been a few issues and as we tend to do I grouped them together.

Trans issue seems to be resolved. The TPS only had one of the 2 screws and the second connector that is only on automatics was loose. Added the screw to the TPS and guesstimated adjustment and I've had no further issues.

It had an after market fuel pressure regulator so I returned this to an original product. Made sure all vacuum lines went to the correct places and remounted the AAR (the flow was going in the wrong direction through AAR too). Not sure if this had much affect on the trans issue but it certainly drives better.

The idle issue is to do with heat. The trans is unrelated to the idle, but with the dodgy TPS mount and the loose connection heat still may have been an issue with electrical resistance and TPS adjustment.

The idle issue seems well documented, so I'll take some steps to improve the cooling system.

Trans could probably still do with a service, now I'm paying attention it may have a slight slip into 4th under throttle.

Thanks for your help!
KirkW
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Posts: 7
Joined: Thu Dec 19, 2019 8:37 am
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Country: Australia
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Vehicle: 1988 Holden Jackaroo/ Isuzu Trooper


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