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Greg
Greg, All import japan models
Category: Mitsubishi
Satisfied Customers: 7144
Experience:  All Japan made models
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hi I have a mitsubishi gto 3000 v6 na mk1 ran lovely till

Customer Question

hi I have a mitsubishi gto 3000 v6 na mk1
ran lovely till one day parked up for 5 minutes engine running went to set off and she started misfiring almost like on 5 cylinders then cleared.
now everytime I come to a stop say at lights or roundabout same thing happens.
I have to feather the throttle till clears.
usually accompanied by a backfire but through the air intake not the exhaust.
its not the mass air flow as have changed it.
no engine code from ecu thats showing no problem.
ive noticed it only happens under load ie pop into drive or any gear while stopped and I get a miss (automatic).
it also doesn't miss when engine cold.
once upto speed no problems it pulls like a train
starts first time half revolution and fires up
any ideas??
Submitted: 3 years ago.
Category: Mitsubishi
Expert:  Greg replied 3 years ago.
Name is***** goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back,

Please do a compression test one cold and ones hot on all cylinders with all spark plugs removed ..

Then please give me the readings .

When misfiring did you notice the check engine light come ON or flash .

I'm thinking this is a mechanical issue if no check engine light or flashing light .

Regards Greg
Customer: replied 3 years ago.

no engine check light comes on or flashes.

check light does work as goes out after ignition switched on.

compression check not able at moment.

what you thinking?

do you not think could be one of many sensors like O2, tps, or even bad ecu

Expert:  Greg replied 3 years ago.
Hi .Michael

No Michael i was thinking more on the lines of a timing belt streached or a bad valve spring .

If you had an issue with the sensors you would have a code in the system and check engine light ON when the engine is running .

This is going that as you said plug wires are good, coil is good, and that you don't have Bosch spark plugs fitted .

Pull plugs and compare with the others,with a good running engine all plugs will have the same colour .

Greg
Customer: replied 3 years ago.

engine does run rich always has done.

would that explain why at cold it runs fine and only when warm does problem start to occur


Expert:  Greg replied 3 years ago.
Its possible but to be sure would be batter to do a compression test and even though no check engine light check for codes (history codes)
And a good scan tool with live data to check the fuel trims , this could be a vacuum leak

Greg
Customer: replied 3 years ago.

engine does run rich always has done.

would that explain why at cold it runs fine and only when warm does problem start to occur


Expert:  Greg replied 3 years ago.
Hi Michael

Is the exhaust tail pipe black.

Greg
Customer: replied 3 years ago.

yeah internally it is.

its just been for MOT and passed its emissions on that

Expert:  Greg replied 3 years ago.
Hi Michael .

If it passed the MOT then it can't be running rich, or they did not check the emmission specs.

Rich running engine will run good cold until warm will run a bit ruff . check the bank 1 and 2 1st O2 sensors .

This could well be your problem if the map is good .if the engine has over 100.000 miles replace the O2 sensor .

Regards Greg