The Mitsubishi Pajero Owners Club®

Scamper · Posted: Sun Feb 03, 2019 19:03 Post subject: Shogun 3.0V6 Occasional Misfire

Hi, I'm a newbie on here so please be gentle!!

Just bought a lovely 1998 Shogun 3.0L V6 24 Valve auto, and all is very good with it but for an occasional misfire or stuttering. I know misfires have been covered by many threads on here but mine is only occasional, sometimes when cold sometimes when hot.

It can run without a problem for many miles only to suddenly develop the problem then it will run like a pig, jerking and stuttering. The auto box wil sometimes change down I assume because the revs road speed drop, Then all of a sudden it's fine again. But it does seem to happen almost every day.

My initial thoughts are fuel starvation, filter?

Does any one have any thoughts?

Thanks in advance

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Craig-SM · Posted: Sun Feb 03, 2019 19:18 Post subject:

Failing coil?

Scamper · Posted: Sun Feb 03, 2019 22:40 Post subject:

OK thanks! That's one of the 3 pairs on top of the engine?

Craig-SM · Posted: Mon Feb 04, 2019 20:39 Post subject:

It will be. Get a single replacement and try it in each of the positions until you find which is faulty.

Scamper · Posted: Mon Feb 11, 2019 10:51 Post subject:

Unfortunately not a coil pack. Swapped a new one in and exchanges with all 3 but problem still there. Whilst at it I replaced the online fuel filter under the rear left passenger seat. Looked like it had never been changed still had underseal waxy stuff on it.
Loads of brown tea coloured fuel came out. But since then it is now running rough all the time coughing and spluttering now even on tickover which it didn't before. Is there another filter I should be looking at.
I will do the cleaning of the maf and the throttle body as I've read in other posts.
One thing I do notice is that when it's idling and I'm in the engine bay if I rev it quickly with the throttle cable a definite brief intake chuff comes from the manifold area towards the bulkhead on the left side (battery side) of the bay.
I'm thinking of replacing plugs and leads whilst I'm in there, so that I assume will mean lifting the manifold off the engine maybe there's a gasket or hose problem?

jods101010 · Posted: Mon Feb 11, 2019 12:17 Post subject:

If its worse after changing the fuel filter that is perhaps where you should be looking, rather than plug leads or exhaust? The symptom of occasional cutting out could well be fuel blockage of some sort. So given dirty fuel in the filter you could check out the in tank pump and the metal pipe connectors on the top of the tank. The connectors can corrode bad and could need replacing (make pipes up rather than trying to use dealer parts). I remember also replacing the fuel line from tank connector down to filter as well. There is also a basic filter at the bottom of the pump in the tank. While all thats out you could inspect inside of the tank and see whats there - could need removing and flushing if theres a load of carp in there

re your other points: exhaust manifolds do split (and can be welded) as well as splitting the small metal pipe that comes up from the rear of the ns manifold (I tend to just use exhaust gunk on that). Gaskets tend to be ok as they're metal. None of this is likely to be your problem. Let us know how you get on

Scamper · Posted: Mon Feb 11, 2019 14:09 Post subject:

Many thanks for that, I'll follow your instructions as soon as I can get onto it.

Scamper · Posted: Mon Feb 11, 2019 15:58 Post subject:

Ok well I've got the pump out and it looks immaculate inside the tank and the pump filter is like new although the return hose was just rust when I pulled that hose off. I suppose it would be worth replacing the hoses as you say?

Scamper · Posted: Mon Feb 11, 2019 17:58 Post subject:

As for the return hose at the tank being dry and rusty does that point to a blocked return pipe further back then? The inside of the tank is shiny like new not a sign of any contamination there. Looking at the state of the return pipe I would assume that if it was running then it would have deposited some rubbish into the tank.
I assume a blocked return pipe would surely cause running issues?
Anyway I need to look at a way of replacing said pipework.

Thanks again for the help.

jods101010 · Posted: Tue Feb 12, 2019 12:42 Post subject:

just check all those rear hoses and pipes carefully where you can (and blow through where you can) and replace if anything looks dodgy. Check those pickup pipes round the fuel pump inside the tank as well - I think I remember replacing the whole pickup/return pipes with copper pipe - (I was tempted to use stainless but its a b***d to bend properly). The return pipe goes straight to the tank so crud could have worked its way towards the front of the car? maybe disconnect the return at the front and blow it through?

jods101010 · Posted: Tue Feb 12, 2019 12:44 Post subject:

just use copper pipe and compression fittings to replace the pipe (8 or 10mm - can't remember)

Scamper · Posted: Wed Feb 13, 2019 17:01 Post subject:

Well I've installed a lovely section of 8mm copper pipe back to the tank and it's flowing fine all the way into the stack and into the tank. Rather a lot of return fuel like a really high flow. Is that OK? Anyway no difference to the lumpy stuttering running. So where to go now I'm not sure.

Scamper · Posted: Thu Feb 14, 2019 7:38 Post subject:

Also you'll have to excuse my ignorance on this but I do have good fuel flow to the engine compartment from there it goes to an injection pump or direct to an injector or injectors?
I'm just wondering if there is some rubbish that got up there and has maybe blocked something there?
I don't know much about injection systems but I'm assuming that mine has only one injector which is in the throttle body? Sorry if I'm sounding thick I'm just trying to get my head around it and this is my only means of transport.

assassin · Posted: Sat Feb 16, 2019 4:24 Post subject:

Have you checked the plug leads if you have them, or the connectors on the coil packs if they connect directly to the plugs.

Scamper · Posted: Sat Feb 16, 2019 11:10 Post subject:

Well that's probably my next task removing the top intake manifold and doing plugs and leads, just haven't had the time to do that as it appears to be a long job.
I did try a new coil pack on it and swapped it around but still the same on each try.

Symptoms are now starts first time every time no problem. as soon as you pull away it begins to stutter and if you then drive up a hill, and we live in a very hilly area, it gets worse. If you drive it hard on a flat road it will pass through the misfires and almost clears itself at around 110kph (70mph ish) but slow back to to 50mph at around 2,000 rpm and it's horrible lurching and spluttering. Makes no difference if it's hot or cold. But it will occasionally drive perfectly OK for a few minutes only to falter again. That's why I wondered if it was more likely fuel starvation. When I checked and renewed the return pipes to the tank I left the return pipe off at the tank and put it into a container and started it and it was literally gushing out. Should the return be that much?