Intermittant fault (Mitsubishi) - Jools
I inherited a G reg Mitsubishi Galant (4WDS 4WS) 2.0 DOHC from father in law (would not be my first choice) but it has served remarkably well for two & a half years recently however it left us stranded twice with an intermittent fault.
It runs fine for a variable period (5 to 20 miles) then starts to hesitate & miss (producing clouds of smoke (not steam) when it momentarily picks up) & eventually stops all together.
Leave it an half hour or so and it drives fine until it happens again. Currently I can use it to go to work & back but obviously long journeys are not worth the risk.
It feels very frustrating suspecting it's a £100 (if I'm lucky !) part but that if I can't trace it I'll have to scrap a good car. I keep my motoring costs down by maintaining &
fixing things myself but this car is too complex for me and Mr Mitsubishi is far too expensive (probably three hours of his time would exceed the car's value !)
Anyway I have been told unless it presents the fault to the garage they can't trace it anyway.
Does anyone have any ideas as to what it might be & how to eliminate the various suspect components.

I realise it's a total nail but one which is good to drive and has been V reliable until now.

Intermittant fault (Mitsubishi) - Adam Going (Tune-Up)
Jools,

Is this engine carburettor-fed or fuel injected ?

Adam
Intermittant fault (Mitsubishi) - Railroad
The first thing to do is as soon as it cuts out altogether, open the bonnet and check for an HT spark by removing a plug lead, and wedging it close to but not touching earth. Crank the engine and see if there is a spark. This at least will narrow you down 50/50 to an ignition or fuel problem.

Post again when you've done this.
Intermittant fault (Mitsubishi) - Jools
Ta

Will try when it happens
Intermittant fault (Mitsubishi) - Jools
Thanks for the interest

It\'s fuel injection - with all the associated trickery I love to hate on \"modern\" cars.

Jools
Intermittant fault (Mitsubishi) - joe
~I had one of these, albeit not the 4WS version, but i think it would have had the same engine (2.0l, DOHC, 16v)
i never had this problem,and found my car fantastically reliable and almost abuse proof.

Thie timing did slip out from time to time, and I also had the HT leads replaced. I am no expert, but it sound like a spark problem of some type. have you checked points/plugs etc?
Intermittant fault (Mitsubishi) - Jools
sounds like the same engine & yes it has been V good & yes I had to replace the leads a little while ago but this one is electronic fule injection & no points to check (at least none that I can find !)

I wouldn't expect plugs to show up as an intermittant fault tho' ?
Intermittant fault (Mitsubishi) - joe
Don't fuel injected cars still have points? If not, I wonder what I have just cleaned on my Primera!!

Think you are right about the plugs.

I suppose it might also be a fuel feed problem. I sympathise with you, as my local franchised dealer cost the earth. Maybe a trip to a tuner might be a good idea?
Intermittant fault (Mitsubishi) - Jools
I'm kind of guessing as I can't get a manual for this car but I think it's got distributorless ignition with everything done via ECU, ignition module and coil pack.

I was wrong about the smoke when it presents the fault (as it happened to me twice today!)it is in fact blue (not grey) and smells like burning oil so I reckon the fault has to do with oil finding it's way into the head and cause a misfire - maybe burning the oil off allows it to re-start and off we go again - INFURIATING tho' potentially less expensive to fix I suspect (with, for example, an airflow sensor assy at over £500 anything electronic going down would instantly scrap the car)

Anyone suggest how oil gets into the head in an intermiitant fashion ?
Intermittant fault (Mitsubishi) - Adam Going (Tune-Up)
Jools,

Sorry for not getting back to you sooner - busy, busy, busy !

Reason for asking was it carb or injection was that, had it been carb, it could have been a carb icing problem due to failure of air intake temperature control system. Less likely on injection, indeed, you may not have a warm air intake system at all, but worth checking out if you do.

Blue/grey smoke does indeed suggest oil getting into the cylinders. Assuming sump is not over-filled, most likely reason is a blockage somewhere in the crankcase breather system. Check all pipes, and replace the Positive Crankcase Vent (PCV) valve
(usually a push-fit into a grommet somewhere on the cam cover, connected by rubber tube to inlet manifold).

Distributor problems are not uncommon on Mitsubishis, and unburnt or partially burnt fuel could be what you are seeing at the tailpipe, but such faults are indeed hard to diagnose until they become permanent, or car is tested on a rolling road facility (but the faults does still need to occur under test).

Joe,

I have never seen a Primera with points ignition in my life, so I would be most interested to know what it is you have "cleaned". Please describe.

Regards, Adam
Intermittant fault (Mitsubishi) - Jools
Thanks for your interest Adam

What with the good weather and all I'll give the breathers a going over this W/E - if it works it'll be a cheap fix

Don't recall seeing a PCV before - will have to look more closely - does it function as a non-return valve or does it do other things ?

Ta

Jools
Intermittant fault (Mitsubishi) - Adam Going (Tune-Up)
PCV valve is a spring-loaded shuttle valve, shut when vacuum is low (ie on acceleration), opened by vacuum acting against spring when vacuum high (ie cruise or over-run). If spring goes weak it allows crankcase fumes / oil to be drawn into manifold under power.

Regards, Adam
Intermittant fault (Mitsubishi) - Jools
Thanks Adam,

found the PCV valve (Mitsubishi parts said the car didn't have on !)

The valve was gunged up and I cleaned it out & refitted it BUT alas it didn't work - i.e. same fault (maybe with a bit less smoke) - seem to be able to drive thro' the missing (when it looses all power) by flooring the throttle but the missing soon comes back - stop for a while and you can get another 5 miles or so before a repeat performance.

This valve is my sort of thing (Hydraulics Engineer) so I took a good look - the poppet is permanently connected to the spring and this whole assy rattled around inside the body such that there was no spring preload on the poppet holding it shut if you blew from the r'box end it allowed flow & if you sucked it closed almost completely. I guess that means it would be open all the time when fitted to the car unless the r'box pressure goes lower than inlet manifold (unlikely ?)

Loathe to buy another one (good money after bad - approx £25 - mind you that's not bad compared to the £52 + vat they wanted for a r'box gasket !) but was trying to work out if I can test to see if it's present condition is causing the problem - what about running the car with the PCV out of the circuit and the r'box open to atmosphere and the PCV tube to inlet manifold blanked ?

Could this little blighter r eally bring the whole thing to a halt ?

If this doesn't work it's time for something horribly sensible like a mondeo

thanks

Jools








Intermittant fault (Mitsubishi) - Adam Going (Tune-Up)
Jools,

Should be no problem running without the PCV valve. As you say, you need to blank the tube into the inlet manifold, and fit a length of pipe without the PCV valve from the r'box either open to atmosphere or, prefferably, into a vented catch tank (old screen washer bottle etc.). If your problem still occurs it does look like something more serious. Could be difficult to pin-point at kerbside, but a good rolling-road invetsigation could be helpful.

Regards, Adam
Intermittant fault (Mitsubishi) - joe
Oh crikey, well they looked like points..

The ht leads all go to what looks like a distributor cap. When you unscrew it, inside the cap are 4 metal contacts set 90 degrees apart, and these are plainly in contact (when all screwed together) with what looks lie a rotor arm.

What on earth have I cleaned?
Intermittant fault (Mitsubishi) - Matt At
The distributor cap contacts! not a bad idea if corroded!

Intermittant fault (Mitsubishi) - Adam Going (Tune-Up)
Hi Joe,

As Matt says, keeping the distributor cap contacts (and the rotor tip) clean is a good thing. But when we say "points ignition" or "contact ignition" we mean a system using low-tension contact breaker points. These open and close as the distributor cam rotates, thus switching the earth side of the coil to create a high-tension coil discharge. First generation electronic ignition systems still had distributors, but the contact breaker points were replaced by electronic pulse generators which sent a signal to an amplifier module, which in turn switched the coil. Next came electronic systems with crankshaft sensors to signal the module, but retaining the distributor cap and rotor, solely as a means of directing the spark to the right cylinder. Next came the distributor-less systems where the coil(s)were connected directly to the plugs by HT leads, and finally the "coil per cylinder" systems where each plug has a coil fitted directly above it.

Regards, Adam.
 

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