91 Petrol GQ Patrol Tuning Question

Submitted: Thursday, Jul 01, 2004 at 10:07
ThreadID: 14272 Views:3451 Replies:4 FollowUps:4
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I have a 91 GQ Patrol with about 180,000km on the clock. For about the past 6-9 months it has been unable to hold a tune. In this period I have had it tuned four times and on all occasions it has returned from the shop in perfect tune only to start misbehaving in around 3-4 weeks.

The misbehaving symptoms are:
Starts fine on all occasions (cold, damp - you name it)
Once running exhibits low power and misfiring
(Note: If very cold will run very well for about two mins then begin low power and missing)
Once warmed up it stops missing and the power returns to ok but it still seems to be a little rough.
Warm up time is 5-20 mins depending on ambient conditions
Warm up time is less when first tuned but it gradually increases

This is driving me crazy. Anyone had any similar issues and found a solution?
Thanks
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Reply By: Member - Mike (SA) - Thursday, Jul 01, 2004 at 12:24

Thursday, Jul 01, 2004 at 12:24
GeeCee,
How annoying! Loss of power and misfiring after start up, in my case, was caused by the airfilter thermostat failing; this caused carby to ice up giving the symptoms you descirbe. Few minutes at side of road and I would be able to move off again, only for the the process to come back, all over again.
To get a "new" thermostat requires the purchase of the whole housing (approx $190) from wreckers. Problem fixed!
Check it out, it may help?
regards
Mike
Too little time in the bush!
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AnswerID: 65939

Follow Up By: uppy - Thursday, Jul 01, 2004 at 17:40

Thursday, Jul 01, 2004 at 17:40
Hi Mike sa,Im thinking about puting long range tanks on my 4.2 efi gq,I notice that you got 220 lts set up ,could you please advice regarding this set up
regards uppy
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Follow Up By: Member - Mike (SA) - Friday, Jul 02, 2004 at 07:37

Friday, Jul 02, 2004 at 07:37
Uppy,
I have 147L main tank, and 80 litre aux fitted to offside under my seat and to rear. Filler is through a "Y" junction at the normal filler point. System works well but I am aware that I have no protection (Bash plates) underneath. Both tanks required no modifications.
To date one small hole and easily fixed but the extended range (over 1,100kms on available fuel) is very handy.
Hope that helps
regards
Mike
Too little time in the bush!
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Follow Up By: Bryan (WA) - Friday, Jul 02, 2004 at 13:50

Friday, Jul 02, 2004 at 13:50
Hi Mike,
I have heard that to get the 147L tank fitted, you cannot have the nissan/rheese tow hitch fitted? is this correct? as I have also been thinking about fitting a long range tank, but keeping the original 95,and add an 80aux.
also, what brand did you fit?
thanks
regards
Bryan
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Follow Up By: Member - Mike (SA) - Saturday, Jul 03, 2004 at 17:32

Saturday, Jul 03, 2004 at 17:32
Bryan,
Apologies for the tardy response!
I was able to keep my Nissan tow bar - wasn't an issue. As to "make" - haven't a clue I am afraid. Bought second handfrom another club member - vg investment.
Hope that helps.
regards
Mike
Too little time in the bush!
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Reply By: James M - Thursday, Jul 01, 2004 at 18:39

Thursday, Jul 01, 2004 at 18:39
My 2.8td was very simular. Started fine, miss fired when cold and blow a lot of smoke when cold. Once warmed up it ran fine.
Turned out to be the fuel pump.
This is a diesel so I don't know if this is relavent to you.
AnswerID: 65998

Reply By: Brew69 - Thursday, Jul 01, 2004 at 20:55

Thursday, Jul 01, 2004 at 20:55
Hi GeeCee, i have the 4.2 with gas/petrol and was having similar problems. Ended up having to go a heavy duty coil, 9.5mm leads,heavy duty plugs,new ditributor cap and rotor button and to top it off the valve clearances done which i was told needed doing every 60 000 k's. When they checked the clearances they found two were miles out. All oky doky now.......just needed to rob a bank lol. Funny thing is no amount of bloody dyno's would sort it out, but an old fashioned mechanic sorted it for me .

The Brewman
AnswerID: 66049

Reply By: SupaMav - Thursday, Jul 01, 2004 at 21:34

Thursday, Jul 01, 2004 at 21:34
You didn't actually say, but I bet its a carby (prolly understood given the year!). Mine does exactly the same thing. I have converted to electonic ignition and sorted the rest of the spark path out too. From the research that I have done it is probably a problem with the choke overfueling. That is what my mechanic said too, he's got the same truck. I also read threads on other forums that said others have the same problem. I haven't bothered fixing it because I only do about 5000k's a year, and I'm in Queensland so it doesn't get that cold!
You'll probably have to either gas it or get a carby kit put thru.
AnswerID: 66059

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