First mechanical(?) problem in 17 years.......

Hi Guys,
I've owned my GQ Y60 manual 4.2 EFI Petrol (203,000km) from new and for the first time, I have a problem.
It has been misfiring (idling rough) and was advised by the mechanic to run it on premium with Nulon injector cleaner which I did on a trip I have just completed (2,000km).......no change.
I was then advised to have the tappets adjusted which I had done today.....it's now idling worse than before!
I am going to have a compression test done next (subject to the feedback I get from here on the forum).
I recently had a new dist. cap, rotor,leads and plugs fitted.......it was running fine before this ( could it be a faulty plug ?)........I'm a bit doubtful about the latter because it would idle normally and then the next time I started it up it was rough and so on.
I had a major service done at 200,000.......when the trouble seemed to start.
HELP AND / OR ADVICE TRULY APPRECIATED.

leads and plugs , thats what I would be checking . Are they a reputible brand these parts ?

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Originally Posted by boots

leads and plugs , thats what I would be checking . Are they a reputible brand these parts ?

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.......yeah, the simple things first, also check the fuel and air filters

Take it back to who did the work and ask them for an explanation. Their parts have caused a problem with your car

I basically changed everything on my 4.2 efi, even got new injectors, but still had running issues. New fuel pump helped alot, but wasn't the cause. Turned out it was the inlet to head gasket. Just dried up and leaked like a sieve. Replaced it(despite being an awful job) and the difference was night and day.

Get the compression check done and if possible have the ignition system checked on an oscilloscope this will find most electrical faults with out guessing or changing parts unnecessarily

Can you still do it the old way?
Disconnect a plug lead one at a time. If one makes no difference its the one giving trouble.
Run the engine at night with no lighting around to see if any leads are showing sparks where they are tracking to the metal parts of the engine.

A couple of things..........1).two mechanics suggested I just drive it as it is !!!!!!!!!!!!!!!!!!!!!! I was "gobsmacked" to hear such inane comments.
2). On my 2000km trip I was towing my 5 metre caravan(1.2 tonnes) and the fuel consumption was the same as it's always been, (4.3km/litre).

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Originally Posted by Parksy

I basically changed everything on my 4.2 efi, even got new injectors, but still had running issues. New fuel pump helped alot, but wasn't the cause. Turned out it was the inlet to head gasket. Just dried up and leaked like a sieve. Replaced it(despite being an awful job) and the difference was night and day.

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I find that interesting as I have been having trouble for a little while now and it might be worth looking into??

Yeah but BA you drowned yours in mud that why its running rough.

I would say leads and spark plug would be your issue IMO


Guns don't kill people, people with mustachios kill people

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Originally Posted by Bloodyaussie

I find that interesting as I have been having trouble for a little while now and it might be worth looking into??

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It's worth checking. I found it by spraying wd40 around the gasket area. Was actually a fluke, because I was checking to see if the brake booster line was leaking, but inadvertently sprayed wd40 onto the gasket and it made the engine rpm rise so I thought it was the brake booster line. Played with that and was very disappointed that it didn't make a difference. So tried replicating what I did before with the wd40 and eventually found that it was around the number 5/6 cylinder gasket was letting air in. Took the majority of a day to replace but I also replaced the collector gasket while it was all apart and it made a world of difference to the performance. The 4.2 efi engine is very smooth and quiet. Starts within the first half second of turning the key. Idles very smoothly.

No this has been an issue for sometime and I have changed leads plugs had valve clearances done and tried swapping sensors.

It is on petrol it bogs down at 2000rpm and the power below that is non existant.

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Originally Posted by megsy

A couple of things..........1).two mechanics suggested I just drive it as it is !!!!!!!!!!!!!!!!!!!!!! I was "gobsmacked" to hear such inane comments.
2). On my 2000km trip I was towing my 5 metre caravan(1.2 tonnes) and the fuel consumption was the same as it's always been, (4.3km/litre).

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Its not the mass weight of the van you have to consider,its the extra wind drag .........
Much higher than the patrol roof,itll be bad on wind
Considering they aren't super efficient on the juice just normal driving, around the 20L/100 K mark your not too far of it, id go maybe wind drag .....

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Originally Posted by macca

Can you still do it the old way?
Disconnect a plug lead one at a time. If one makes no difference its the one giving trouble.
Run the engine at night with no lighting around to see if any leads are showing sparks where they are tracking to the metal parts of the engine.

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Electric ignition mite give you an instant perm, or a mighty jolt ....
But you could drop a lead, start listen for difference that way,dont need to run long to check
Running at night,yep still a simple easy check

Id go over the basics leads,dizzy cap, (if its cracked its shot),check plugs,maybe remove and check for some difference in colours that mite help pinpoint an issue
Make sure all the electrical clips are fully plugged in ,if not it could run ruff
We bumped the plug near airbox, ran ruff till we pushed it right in

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Originally Posted by pearcey

Get the compression check done and if possible have the ignition system checked on an oscilloscope this will find most electrical faults with out guessing or changing parts unnecessarily

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Hi pearcey.......I had the compression done this arvo'......cylinder number 3.....125 psi.....others...200psi
Estimated cost of labour $2,000 plus parts.......I suppose it's not too bad considering I've had 17 years trouble free running

Not sure I want to hear that.

I have not done a compression test on my rig, have the gear just such a pain to get to all the plugs in these things.

Not like my wifes car or a motorbike!

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Originally Posted by megsy

Hi pearcey.......I had the compression done this arvo'......cylinder number 3.....125 psi.....others...200psi
Estimated cost of labour $2,000 plus parts.......I suppose it's not too bad considering I've had 17 years trouble free running

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Good to see you found the problem. I would expect that a total head recondition IE valves, guides,face and pressure test plus gaskets would set you back about $750 then the strip down and reassembly could be around $1000 to $1500 depending who does the job .
Even at $3000 in 17 years isn`t to bad. Best of luck with it mate.