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94 mirage skipping/bucking after plug change
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trackjunkie
New User
Jan 15, 2008, 1:24 PM
Post #1 of 6
(1567 views)
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94 mirage skipping/bucking after plug change
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I'll keep this as short as possible: 94 Mitsubishi mirage, 1.5, auto, 151,000 miles
Car ran perfectly, then would not start one day. The plugs were fouled and had deposits. Changed them and everything was perfect for about 30mi.
Now it skips/bucks and hardly accelerates at low speeds/rpms. It's perfectly fine right off the bat, but the problem develops within a couple miles. At highway speeds/high rpm its almost perfect still. I've lost about 5 mpg. Plugs still look great. Timing was at correct factory setting. Engine light comes on occasionaly, but it always has. I changed the plugs again; no effect. Changed gas and added water remover;no effect. Changed plug wires; no effect. Tried high octane gas; no effect. Cap and rotor fairly new and look great.
I can mask the problem mostly by advancing the ignition. I advanced it till it pinged, then backed off alittle. It's drivable now but still skips and bucks some. Holding high rpms helps too, but getting away from stops can be tough.
Lastly, without the ignition advanced, if I floor it quickly at low speeds, sometimes the motor feels like its shut off completely, and stays that way till I back off and open the throttle again more slowly.
It's one of those problems that gets better and worse. I'm baffled and pissed off. I just need this to get through the winter...help please...
(This post was edited by trackjunkie on Jan 15, 2008, 1:25 PM)
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trackjunkie
New User
Jan 18, 2008, 9:56 AM
Post #2 of 6
(1543 views)
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Re: 94 mirage skipping/bucking after plug change
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Really? Nothing? Don't feel bad i'm stuck too, or I would not have posted...I'm thinking of installing a new (junk yard) distributor, since advancing the timing helps, maybe the timing curve is messed up. That would be a $100 shot in the dark for a car that's worth about $200 with a full tank of gas. Sound kind of stupid to me.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 19, 2008, 7:43 AM
Post #3 of 6
(1539 views)
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Re: 94 mirage skipping/bucking after plug change
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Ok: I don't know either?? Some ideas though: Rule out and fix vacuum leaks. Get a code reading anyway - see if that helps at all. Dist shaft bushings may be worn which causes erratic timing and the computer can't adjust out of that. What I do to test for that is look at the timing with a light and see if it jumps around. Most distributor engines cay still get you a "dwell" reading and if that changes more than 5 degrees or so with revving the engine the shaft bushings could be at fault.
Hey - there's a lot of could bees. That's just a couple that come to mind,
T
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dave284
Enthusiast
Jan 19, 2008, 7:55 PM
Post #4 of 6
(1533 views)
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Re: 94 mirage skipping/bucking after plug change
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Tom, What about a deffective plug ,I have seen new ones go bad, 
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jan 20, 2008, 12:59 AM
Post #5 of 6
(1532 views)
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Re: 94 mirage skipping/bucking after plug change
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"Defective Plug" Yup - they do happen new out of the box. I have a habit of marking the cyl# of any new plug that even comes out of a damaged box. You usually can just move a bad one to a known good one and if the problem follows it's like domestic light bulbs and lamps if you ever dealt with that as it's easier than going crazy to diag the whole engine if something just cropped up,
T
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bryan_kilco
User
Jan 29, 2008, 6:34 PM
Post #6 of 6
(1498 views)
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Re: 94 mirage skipping/bucking after plug change
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while im not a mechanic, but i have seen these similar symptoms leading to a plugged catalytic converter!
hesitant, sputtering pulling from a stop or up hills.
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