GQ Patrol misfire.

[leatherland1]

Hi, this is John.

      I have a 1991 GQ Patrol with a 4.2 petrol engine, 

with a Carby, and a Points and Condenser distributor.

For about 3 years now, I have been getting an  intermitent misfire that I couldn't fix.

It would not stall, but would missfire for about 100 metres, and then was OK for another 60 or 70 kms.

and then more misfiring. 

The first time that it happened, I couldn't isolate the problem,

so I replaced the Coil, the Points, the Condenser, and the Plugs.

After that it ran fine for about 1000km or more. and then started to misfire again.

This time I only had a set of points with me, so I replaced them,

and it didn't missfire for about another 800 or 900 kms. 

About 200 kms. back, I replaced the points again, and it again fixed the missfire.

Although this is not a problem that will leave me stranded somewhere offroad,

I would appreciate any suggestions as to what is causing the missfire.

I have never had any brand of points that would only last for about 1000kms.

and I am wondering if anybody has had this happen to them?

Any advice would be appreciated.

Regards, John.

[cq_tech]

John, although I don't have any experience with that particular engine, many years ago I did have similar issues with the 5.8 V8 in my XC Fairmont GXL and even changing to a CDI ignition system didn't cure it, so in desperation I replaced the only things that I hadn't previously, and it solved the problem and never came back.

In my case, it seems it was the spark plug leads that were the ultimate cause and replacing them with a set of high-performance leads did the trick, although I suspect that even just standard OEM leads would have also worked fine as well.

Having said that, in your case it could also be a cracked distributor cap which is cross-firing at high humidity levels, hence the intermittent nature of the problem. Also, my Ford used to virtually eat spark plugs after a couple of thousand kilometres until I replaced them with Nippondenso plugs, which lasted the rest of the vehicle's life while I owned it - around another 60,000k, but I include that simply as a matter of interest.

Good luck, and I hope you eventually solve the problem. 🙂

Bill

[colic2bullsgirlore]

what do the points look like when you pull them out?

Are they burnt?

how are they burn't?

I would think there may be a problem with the baseplate in your dizzy. Either the contact breaker base is not being

retained exactly square meaning that the point faces do not "meet" evenly or the baseplate is sticking under

mechanical or vacuum advance which ostensibly randomly changes the point gap distance relative to the ignition

timing.

If the points are burnt squarely but for a (mark) ^ that burns wide from base to a point at the arm and leaves the piece

on the base means that the condensor is over capacity. If the opposite impression occurs ie large (mark) v occurs and

the piece is left on the breaker arm then the condensor is under capacity.

So, in short, the misalignment of the contact breaker faces caused by a warped ior damaged baseplate or the incorrect

fitment of a condensor not specced for the ignition system are two common causes of the conditions you describe.

[colic2bullsgirlore]

something to think about

http://www.ebay.com.au/itm/ELECTRONIC-IGNITION-NISSAN-PATROL-GQ-6-CYL-FORD-MAVERICK-PERTRONIX-IGNITO...

ELECTRONIC IGNITION NISSAN PATROL GQ 6 CYL & FORD MAVERICK PERTRONIX IGNITOR. #PRT5836 For over thirty years, the Ignitor has proven itself in applications ranging from race cars to tractors. The Ignitor replaces breaker point and troublesome factory electronic ignitions with a dependable, self contained and maintenance free electronic ignition system

http://www.ebay.com.au/itm/GQ-Patrol-distributor-TB42-/121339204341?pt=AU_Car_Parts_Accessories&hash...

Complete, good condition. Has extended rotor button which itself is worth $75+. Off carburetor model. Still has points and condenser attached

[leatherland1]

 Hi,

    thank you to  cq_tech  and  colic2bullsgirlore for your advice.

The points always look to be in "Fair" condition,  with no excessive burning.

I am going to go with the "Pertronic" electronic ignition system,

as it seems like the best way to go.

I will wait a couple of weeks, till Cameron, of Mountain District Gas, in Montrose,  Melbourne

returns from his trip to The Cape.

It doesn't look too difficult, but I will be happier if he does the installation.

Thanks again for the advice ,

       regards,

                       John.

[xb50gs]

I had a GQ troll with a 4.2 in it, i had an electronic conversion but in this intance it is irrelevant.

When I spoke with one of the gurus, from memory, at crane cams, the problem the GQ's suffer is with the rotor button. I had a misfire in mine (it was due to the gas safety switch shorting out, so not the case in your car) but I did chase a lot of ignition things to solve it before I found it by accident.

Apparently, they require a coversion to lenghten the rotor button. There is a company in SA who makes them but I cant remember who it is, but Crane Cams could steer you in the correct direction and let you know what the problem is.

Cost me about $50 all up from memory. More than double the original one, but if it solves the problem, it no matter.

[leatherland1]

Thanks for your reply 2barkingbeagles.

I still havn't changed to the electronic ignition, as It is not giving trouble right now, but I will do it.

When I do, I will replace the cap and the leads as well.

Moutain District Gas recently replaced the head, (porous and soft), and I now have a good unit again.

I whole heartedly agree "FORDs" forever.

I have had  two 1962s  a 64, a 67, and then bought the brother inlaw's 1965 Galaxie,

and had it for 19 years.

My best ute ever was a 1975 F250 4X4 with a 351ci. motor,

but after 9 years of the worlds heaviest steering, I sold it to the guy 2 streets away.

That was 18 years ago, and now there are plenty of places that convert them to power steering,

but way back then, the only place I could find was in Brisbane, and I am in Melbourne.

Nice to chat with you,

                             regards, John.