engine surge under acceleration

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bossler - 20 Jul 2005 22:45 GMT

recently my friend bought a 1993 mitsubishi ecliple 5 speed non-turbo. It had been sitting for roughly 10 years, but only had 50000 miles, and the price was right. Anyways, we drained out the old gas and put in some new gas. With this gas we put in fuel injector cleaner, and fuel system conditioner. The car started, and had a hard time idling, but eventually after being run enough would idle and rev. We took the car out for a ride, and upon reaching a hill and flooring the car, the engine would lunge on and off, enough the chirp the tires ever half second or so every pulse. It seemed to me that the car was still not getting enough fuel, or something was wrong with the computer. The car's gauges showed no errors or check engine lights. We then installed new plugs, plug wires, and a new fuel filter. doing this the car ran better, but still would lunge while accelerating. I was thinking of maybe of replacing the oxygen sensor, and removing the injectors and thouroughly cleaning them. I have no idea where else to look after this. Any help would be much appreciated
Thank

--
bossler

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simpleton - 22 Jul 2005 01:06 GMT

The oxygen sensor will have no effect here as it controls air/fuel ratio at
part throttle. When you accellerate you move into what's called open loop
mode and are running off of fuel maps in the ecu.
Ten years is a long time to sit, you very well could have varnish in your
injectors. The ecu's on these car are prone to have the electrolytic
capacitors leak and cause damage. This is normally something you can detect
visually by removing the cover on the ecu and looking around the base of
each of the three capacitiors.( black, cylinder shaped components.) The
leaking electrolyte will corrode the board leaving icky residue.
http://www.tmo.com/howto/ecu1g/caps.htm

> recently my friend bought a 1993 mitsubishi ecliple 5 speed non-turbo. It
> had been sitting for roughly 10 years, but only had 50000 miles, and the
[quoted text clipped - 12 lines]
> else to look after this. Any help would be much appreciated.
> Thanks

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Stewart DIBBS - 22 Jul 2005 01:50 GMT

> mitsubishi ecliple 5 speed non-turbo ... sitting for roughly 10 years, but
> only had 50000 miles

Soaking the injectors in cleaner will help.

Pull off the Throttle body, and CAREFULLY clean all the krud out of it.
Check esspecially the air idle jet. This is the big Phillips screw under a
10mm black cap on the top front. It will turn, don't try top remove it.

On the rear is the air idle control motor with little gears under a plate.
These gears can strip. The air idle control motor is controlled by the ECU,
and is the most likely cause of the surge.

Replace any of the little vacuum hoses that attatch to the throttle body
that have hardened or cracked. Make sure the main intake hose clamps are
tight. Check the vacuum hose to the brake booster for cracks, and replace if
necessary. Follow the connection diagram sticker on the inside of the hood.

Check the cam belt alignment. Take of the top cam belt cover, turn the CRANK
(not the cam sprocket) clockwise). At top dead center, both #1 valves will
closed, the marks in the sprockets should be facing one another and parallel
to the top of the head, and the cam sprocket keyways should be on top. See
next paragraph.

Last, and most important, if this car has really been sitting for 10 years,
change the cam belt and balance belt. Belt will last 100,000 km on a
running engine, but unused for 10 years it will have hardened. If it breaks,
or jumps a couple of teeth (a very real possibility), you'll be facing 8
bent inlet valves or worse, and a BIG bill to fix it ie about 4 times the
cost of replacing the belts now.

While you are at it, replace the rad hoses too.

Stewart DIBBS
www.pixcl.com/lancerproject.htm

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