Gu Patrol exhaust tuning

Submitted: Sunday, Jan 06, 2008 at 19:08

ThreadID: 53179 Views:1922 Replies:4 FollowUps:6

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barney rubble

Gday all the gu 4.2 tdi seems to lack power on take off and in the sand
although once shes wound up goes very well keep the revs over 2000 rpm and turbo working well i couldnt be happier
my research tells me a 3 inch exhaust will fix this
but some adjustments of the fuel pump and turbo are req
my question is can any one tell my what these adjustments are
or should we be not such a tight **** and pay some one to tune her after the new exhaust goes on
and can anyone recomend somewhere in the pilbara to do it
Cheers Barn

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Reply By: Member - Mick O (VIC) - Sunday, Jan 06, 2008 at 19:26

Reply By: Trevor R (QLD) - Sunday, Jan 06, 2008 at 22:01

Reply By: Skinnydog - Monday, Jan 07, 2008 at 00:56

Reply By: Member - Coyote (QLD) - Monday, Jan 07, 2008 at 13:01

Monday, Jan 07, 2008 at 13:01

I have a 4.2 TD GUIV and a 3" exhaust (mandrell bent) fitted. I had it done shortly after buying it new so it's hard to 'compare" but I really don't think it has made all that much difference.. certainly not all that much difference t o it's perfromance around town etc that I could pick up in the 10000k's or so I did before I had it fitted.. Maybe I'm missing something. It was re'tuned after the exhaust was fitted too.

AnswerID: 280259

Follow Up By: Trevor R (QLD) - Monday, Jan 07, 2008 at 21:06

Monday, Jan 07, 2008 at 21:06

Dear Coyote,

Not trying to minimise your opinion because some people validly do have this opinion of the old 4.2 slugs, but I am curious if you had the dump pipe fitted as well as the 3" exhaust. If not, here may be the problem. This dump pipe in standard is quite small compared to the aftermarket jobs and the difference is quite noticable when you drive an unmodified side by side against my worked 4.2 Patrol. I have a dyno printout on my rig pics to give you an idea but essentially I am almost 100% over factory settings and I have been running like this for miles. I currently have 340 000km on the clock and mine was worked on for the first time, pre delivery when brand new so longevity is a non-issue in my opinion.

If you are in Brisbane, Mike Vine turbo's will set you straight and fix any lack of performance issues you have with the 4.2 so long as you understand it is a workhorse and not a racehorse.

Best regards,
Trevor.

FollowupID: 544560

Follow Up By: Member - Coyote (QLD) - Tuesday, Jan 08, 2008 at 09:54

Tuesday, Jan 08, 2008 at 09:54

Thanks Trevor, I am now in Brisbane.. I had the 3" exhaust system fitted in Adelaide early on and I got Dyno rpint outs et and there wa sonly a marginal improvement. I accpet that if there is more improvement to be had it is out of my ignorance in not asking them to do further tuning etc.. addmittedly, I rushed it as I wasn't even iun the statte when my wife dropped the car off and then she picked up inthe arvo and they gave her the rpint outs. they told her a list of stuff they had done and I accpeted it on face value. Thecar now has 70k on it and I drive it like a workhorse not a race horse. I will take up your suggestion and tget the guys you mentioned to check it out and see if there is something I'm missing.. Thanks for the tips...

FollowupID: 544659

Follow Up By: Member - JohnR (Vic)&Kath - Tuesday, Jan 08, 2008 at 16:50

Tuesday, Jan 08, 2008 at 16:50

Coyote, you didn't answer the question as to the dump pipe which is the pipe at the back of the GU turbo. It is extraordinarily restrictive on the 4.2 at about 1.7" diameter. A 3" dump pipe takes a heap more gas out of the turbo.

Mine with a 3" dump pipe gave a 16% improvement in the 0-100kph time. Without a dyno, it was the only way I could quantify the improvement. It made a hell of a difference to the drivability.

FollowupID: 544699