Your thoughts on GQ 4.2 petrol not running well

[muddydigger]

Guys just after some thoughts on thing to look at.
car is a Gq 4.2 petrol patrol

Firstly its has alwasy had a slight miss, ever since I have owned it.
Sometimes, after a tune up it seems to disapear but never for more than a week, then its back.

Latley its has become very bad.
Morning when its cold, it drivers fine, has slight miss, if you rev it other than that goes like abat out of hell. I drive it up the freeway and all is good, accelerate fine and kicks down fine (auto).
However, when its warme up it starts missing badley. After comming of the free way, if it I have stop at lights, then it starts the shit, missing badley at idel, no power when it takes, off. Misses and back fires under excelartion going up small hills. Any time it has to load up, it start missing. In the morning when its cold it will rev freely up to about 3200 rpm, but thats it. When its warm after stop start traffic it will not rev over 2500 rpm.

[adoom]

how long since the plugs and leads have been replaced?

[MitchellBros4x4]

EFI or Carb??

[gumbs]

Assuming its the carby model, its pretty much standard operation.

Everyone I've ever been in has had the miss, you can just ignore it or if you really want it gone this is the list of things to replace.

Plug
Leads
Dizzy Cap
Exteneded rotor button (exchange with your standard or extend it yourself)
Electronic ignition (petronix kits are around $130)
Coil

I've done everything other then the Extended rotor and I now have a perfect idle. Realistically its about $350 - $400 to do the lot.

When was the last time the Leads, plugs and points were changed? If you don't know I'd be doing all of them first (replace points with electronic ignition) and that should fix most of your problems.

I just reread your post, the miss at idle is standard the other stuff isn't I'd be doing the plug and leads asap and ordering a petronix kit aswell.

[billsgq]

check valve clearance

[BadMav]

Could be the condenser, mine did the same thing, new from Nissan about $18.00. But, as already said, put the pertronix in, best thing I ever did. Gets rid of the points (and the need to adjust them), condenser and all the hard starting and stumbles.

[kooter]

mine did that, new air mass meter fixed it,ebay, it was efi

[scott/gqfun]

i think its trying to say put a v8 in me

[rus733]

i reccomend checking your leads and plugs see where that take you one of the leads from the dizzy could be breaking down or the mail lead to the dizzy could be on the way out.

[Nat84]

i reccomend checking your leads and plugs see where that take you one of the leads from the dizzy could be breaking down or the mail lead to the dizzy could be on the way out.

or your coil could be breaking down under load

[lexplay]

mine was doing that i fitted new leads plugs and a bosch gt40r coil and runs better than ever now. mine is a carby.

[muddydigger]

The sagar continues. I baught a new GT40 R coil, and a new set of leads, which made the issue 10 times worse, couldnt even get it to run. It would start, then start back firing and all sorts. I had to put the old coil and leads on to get it home.

I rang an electrision who said its not electrical its carby. So I either need to chase down either a rebuild carby or a good second hand one, so does any one have one? or know where in Brisbane I can get a re built one?

[BadMav]

The sagar continues. I baught a new GT40 R coil, and a new set of leads, which made the issue 10 times worse, couldnt even get it to run. It would start, then start back firing and all sorts. I had to put the old coil and leads on to get it home.

I rang an electrision who said its not electrical its carby. So I either need to chase down either a rebuild carby or a good second hand one, so does any one have one? or know where in Brisbane I can get a re built one?

This may sound like a really dumb question, but did you take the screw out of the rotor button and forget to put it back in?

Failing that, spray about half a can of 'clean r carb' into the carbie, particularly through the bowl vents while it's running. You may need to bump the hand throttle up a bit to do it. There may just be some crud blocking an orifice somewhere.

Be sure your auto choke is adjusted properly as this can be a source of trouble too (or remove it altogether and give it some hand throttle in the morning). There is also the BCDD, this may be another thing to look at, it's located on the engine side of the carb and has a little black grommet in it. pull that out and wind the screw anti clockwise 3 turns. It may not be the problem but it will make your fuel economy a bit better.

[naif]

The sagar continues. I baught a new GT40 R coil, and a new set of leads, which made the issue 10 times worse, couldnt even get it to run. It would start, then start back firing and all sorts. I had to put the old coil and leads on to get it home.

I rang an electrision who said its not electrical its carby. So I either need to chase down either a rebuild carby or a good second hand one, so does any one have one? or know where in Brisbane I can get a re built one?

arnt carbie tb42's non resistor coils/plugs?

ie BP5E plugs apposed to the BPR5E used in the TB42E ?

if so, you baught the wrong coil, you need a plain GT40 not GT40R, the R means resistor.

[bilby]

carb "n" gas at woolloongabba would be the ones to fix it , BUT you will pay through the nose for it .

They are pretty exxey in price but will rebuild the carb , and tune it on the car

They did this with my sisters car and it wasnt cheap from memory

[BadMav]

The sagar continues. I baught a new GT40 R coil, and a new set of leads, which made the issue 10 times worse, couldnt even get it to run. It would start, then start back firing and all sorts. I had to put the old coil and leads on to get it home.

I rang an electrision who said its not electrical its carby. So I either need to chase down either a rebuild carby or a good second hand one, so does any one have one? or know where in Brisbane I can get a re built one?

arnt carbie tb42's non resistor coils/plugs?

ie BP5E plugs apposed to the BPR5E used in the TB42E ?

if so, you baught the wrong coil, you need a plain GT40 not GT40R, the R means resistor.

Anything with points will have a resistor type coil.

[cooki_monsta]

The sagar continues. I baught a new GT40 R coil, and a new set of leads, which made the issue 10 times worse, couldnt even get it to run. It would start, then start back firing and all sorts. I had to put the old coil and leads on to get it home.

I rang an electrision who said its not electrical its carby. So I either need to chase down either a rebuild carby or a good second hand one, so does any one have one? or know where in Brisbane I can get a re built one?

arnt carbie tb42's non resistor coils/plugs?

ie BP5E plugs apposed to the BPR5E used in the TB42E ?

if so, you baught the wrong coil, you need a plain GT40 not GT40R, the R means resistor.

Anything with points will have a resistor type coil.

that is correct, points ignition cant take the 12V and they HAVE a white ballast resistor near the washer bottle, which means it is correct to buy the gt40R and the bpr5es plugs, if its gas its bpr6es

having said that the best mod i did to mine was ditch the points in favour of a pertronix kit they are awsome. Id also check to make sure you got the plug leads right, you may have accidentally swapped 3 and 4 around, which will make it backfire like crazy, check your dissy cap, if its cracked it could be arcing across the wrong point, and also causing it

[CoR]

Hi guys, I'm new to the forums. Been reading here and there but never posted.

Definitely check the Dizzy! Had the exact same problem a week ago (I still have the points version *ouch* did I just say that?).
One other thing, are you getting enough fuel through etc? No blockage or suction leak into the fuel line?
Only ask as this was the exact same prob with the truck at work.

Later.
CoR

[PGS 4WD]

The GT40R is designed for a ballast, the primary resistance of a genuine Nissan coil is different to a GT40R therefore the voltage drop at the ballast is different so you need to run a Nissan coil with a Nissan Balast or a GT40R with the appropriate ballast, can't recall the exact resistance. The carbies are prone to blocking the idle emusion tube, is causes poor idle sometimes requiring that the hand throttle be used. The rotor air gap is rediculously large, get an extended rotor to go with the new plugs and leads, hopefully you bought a good set of spiral core leads not rubbish carbon core. Ideally if you can afford it ditch the points, and fit a Petronix with an ICE module and coil. Massive spark means you can open the plug gaps and significantly improve idle and lor rpm performance. Before all that as mentioned set the valve clearances before undertaking any tuning. First rule of mechanics is you can't make an engine smooth with uneven compressions.

Joel

[Articulator]

Hey mate mine was doing the same .changed dizzy cap problem solved also running pertronics ignition.As for carby the place to go is re-carb on the sunny coast they do rebuilt -exchange ones good luck

[Bigred Gq]

Ok,Ive got electronic conversion Crane fireball,GT40R coil and nippon denso w20es-u spark plugs but still runs like crap( not always though).
Mine still has the resistor fitted though,is this correct as I thought ud get rid of resistor wen goin electronic! Shes also dual fuel so im going to do plugs and leads on weekend.
So the question I have now is,should I run the efi plugs BPR5E's , the standard BP5e's or gas plugs BPR6ES's. I was told I should fit the gas plugs as they run a bit hotter.