View Full Version : Mitsubishi gto problems!!
Well got to pick your brains on our naughty beast. Almost put this under electrical but not 100% sure.
OK our Mitsubishi gto 3.0 v6 twin turbo 1991. Has been mostly very good, had a bit of the odd problem with hot start but otherwise good until recently. It had a hunting problem (two occassions) and then stuck at 2000 revs. Stuck in traffic not funny, had to actually put on as many electrical items as poss as the only way it reduced the revs. It sometimes brings the revs down and sometimes up?!
Sometimes it drives fine. The car is misfiring and causes the CAT to overheat in about 5-10 mins and then the car shuts down until its cold. Engine check light came on twice during playing up for about 1 sec and went out, car ran fine. Engine check light on when it conked out last, it turned over fine but not starting (a definite car protection/engine protection mode).
James has replaced the plugs and checked ecu for any corrosion (a common problem), found a nice bonus in that it is chipped, mines. Managed to get the ecu fault code flashing mode, no faults came up. James generated a fault that was deliberate so that showed up ie although running crap no fault code??
In between these problems it has been running a blast? Any ideas would be really helpful?
macca
10-12-2009, 11:13 PM
Sounds like more than one problem to be honest.
Idling sounds like some kind of idle control system. It will most likely have an idle control valve that bleeds air in to the system to control the idle, these often fill up with soot and other crud and need a disassemble and good clean in carb cleaner.
The ICV will often control the idle depending on load, and depending on when and where it is sticking could affect whether it idles up when you put stuff on (as it should to compensate, such as with the AC on) or down.
If the cat is overhearing then it's running lean, so be very careful as this could cause major damage. Check/change the fuel filter to make sure there's not a blockage, also depending on mileage and fuel used and whether the tank has been run very low there could also be crap in the injectors causing fuel starvation and a lean condition. Lean running could also be a timing issue, not sure on how the GTO deals with timing, but could be a duff sensor advancing the timing too much and making it run lean?
Either of these could also cause increased boost and the shutdown you describe could be a fuel cut due to too much boost, often this will show the check engine lamp but not actually store a fault code.
Just ideas, but worth a look at!
macca
10-12-2009, 11:14 PM
And hot start seems to be a common problem with Jap cars, mine doesn't like hot starts as much as cold and my old Mk3 Supra's were really hard to start when hot.
The cause? The fuel rail runs too close to the engine and when it's been standing the fuel in it gets very warm, which is harder for the engine to ignite!
Thanks Macca for all the help I will pass it on. James felt that it was throwing too much unburnt fuel down the cat that caused it too overheat. Do feel it is all related though as it has run amazingly well and all the problems come together. Well we will plod on and see what's happening! I dare say he will get there soon enough, hope so!
As we find more will pop it up and see if anyone has any ideas?
macca
10-14-2009, 10:57 PM
Unburnt fuel won't burn in the cat unless it's already hot. Unburnt fuel will feck a cat up but not through overheating it.
Being jap and complicated, it's probably some stupid little sensor somewhere throwing everything out.
Be good to keep us updated! :)
The car seems to run for a bit and then really overheat, stinks of too much fuel. Has had a couple of days of running and then messed up today. I think, personally, the worst bit came after me having a hack in the flood waters :innocent:. Can you think of any sensors low down in the car? I know sounds silly but with a car like that it's a nightmare.
macca
10-17-2009, 10:45 PM
Only sensor likely to be low down could be a crank position sensor if it has one? That has the possibility of messing with the timing and causing misfiring.
Looks like an ecu fault. ECU looks fine inside but does anyone know anyone good for testing it in the South?
macca
11-16-2009, 11:16 PM
No ideas I'm afraid Ang. I reckon your best bet would be to see if there's anybody friendly on the GTO forum that would try it in their car for you?
Well 3 capacitors out and James wanted to try the ecu without to test, it ran and seemed to run pretty reasonable and the ecu isn't shutting down :). Now just getting some more capacitors................... they hadn't leaked but smelt fishy.
God I hope this is a cheap and easy fix. Fingers crossed.
As stated above, a replacement ecu worked a treat. The old mines one is being sent for repair.
waynem
08-28-2010, 03:23 AM
Hi Guys.. I have a GTO that doesnt seem to want to start.. Been told possible crank sensor but also have noticed that when I remove the oil filler cap,it smells of petrol... Any1 got any ideas cuz the engines in these r RIDICULOS lool...
Thanks
As you can see been there but first port of call would be the ecu. What year and type of gto have you got. If you are local may be able to assist by swopping ecu and seeing if that works. If not see if you can borrow one. My replacement ecu was an ebay one, got it for around £100 and it worked well. Shame head gasket has now gone.
The capacitors can leak. Not much fun.
waynem
08-30-2010, 08:26 PM
errr i believe burgess hill is bout 60 miles away from me. Im in Chingford, Essex. Are the ECUs a common fault with these cars???
errr i believe burgess hill is bout 60 miles away from me. Im in Chingford, Essex. Are the ECUs a common fault with these cars???
Early GTOs have a common problem with leaking capacitors. It was a manufacturing problem with sub standard capacitors. I am sure it just affects 1st generation cars. Ours didn't appear to be leaking, we did replace them but that didn't resolve the problem.
We took the risk and got a replacement ECU and it worked straight away. We have kept the other ecu to send off for repair as it has a mines chip in it. Major difference with that in. Ours used to stink of petrol also.
Like I said though is it manual or auto? Is it turbo or not? Year? If you can check the code for your ecu I will keep an eye out. You can get the ecu sent off for checking or you can beg to borrow one from someone to see if yours is faulty.
Looking on ebay there seems to be people with good feedback with ecus available, check the coding and make sure the spec matches. They seem to be going from about £50 - £300 (with warranty)
:) Good luck with it, they are lovely cars.
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