Need hel0

Asked by Mar 19, 2016 at 03:21 AM about the 1991 Mitsubishi 3000GT 2 Dr SL Hatchback

Question type: Maintenance & Repair

Well i got a 3000gt sl 1991 and i have just replace
the egr valve beacouse it was serging when driving
i smoke test it and the egr was leaking badly so i
replace it n also replace the valve cover gasket as
well the back spark plugs since i didnt have
enough money i bought gasket material n cut
some for the throttle body gasket n the intake
manifold.. I turn it on and still missing fire worst
than before and i dont k ow what could it be help

16 Answers


Most likely the gaskets you made are not sealing properly as it is running worse than before. Why didn't you change all the spark plugs?

We smoke test it to see if they seal and they do wise but ill buy the other spark plugs today


After those are replaced then see how it runs.

Ok but its weird because it only misses fire at idl. But once i put it to drive or reverse it doesnt .. It keeps serging while driving tho


Could be a injector restriction At idle when the plusewidth is small it might not be injecting fuel but when you put it in gear the plusewidth increases and over comes the partial restriction.

Best Answer

Might be i ve been runing with low tank which could of pick up the trash on the botton of the pan n plug them up?... I put new spark plugs it runs a lil better but still serging n missinfg fire


Only the extremely fine particulates can get through the filters and into the injectors but yes it can happen. Also never run less than 1/4 tank of fuel, the fuel pump uses fuel as a coolant and if you run below 1/4 tank you are exposing the fuel pump and allowing it to run hotter than normal shortening its life. HTH


when you fill up next time put either Chevron or Texaco fuel in it and add a bottle Techron and run it down to 1/4 and refill with another tank of Checron or Texaco fuel, if it runs noticeably better then you know it is injectors, you can at that point either keep running that kind of fuel or bite the bullet and replace the injectors. I can tell you that the Techron is amazing stuff, I had a Tahoe that would develop a low speed misfire and I knew it was an injector but if I ran nothing but Chevron fuels after the first tank full it would go away, if I couldn't get Chevron fuel I always carried a bottle of Techron with me and would put it in with the other fuel. So now Chevron or Texaco fuels are my fuel of choice. HTH

Ok ill try that im honna have to enty out the tank tho i got full tank from cosco .. N ill buy the techron see what happens..

So just to keep it updated it turn on to be the ignition timing control that is off so it sparks before it reaches top dead center n it running lean


Base timing should be 5 degrees +or - 2 degrees, {make sure you do this procedure correctly or the timing will still be off} and the computer handles the rest of the advance, so if it is over- advancing that much it should have pinged like mad, over- advanced timing can show lean on the O2 readout, reset or repair the over-advance problem and recheck the O2 readout before replacing the O2 sensor. HTH

Well ignition timing is good ones you by pass the computer so im trying to see whats messing with it when you dont by pass the computer

Also the timing belt has a line on one side n idk where it it hitting or whats making it smell like burn rubber when its running


Could be an idler or tensioner pulley, or something got in the timing cover and is rubbing on the belt, probably will have to remove the cover to find it. Did you find out how far the computer is advancing the timing running?


It should be around 21-27 degrees.

It was like 30so it was the injector control module so I changed it I replace it with a new one afterwards I found out that the mass flow sensor was messed up as well so I did some researchand a tow me to check out the computer I checked it out on the computer looks best up to so I guess I have to get a new computer but I don't know where to buy at any ideas?

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