Mechanics

IT SEEMS TO BE MISFIRING

1992 Geo Prizm

Engine Performance problem
1992 Geo Prizm 4 cyl Front Wheel Drive Automatic 198, 00 miles

now that ive changed the plugs and wires and made sure I had a good connection to them, it still sounds bad, dies when left to idle or when stopping, and just doesnt want to move even when flooring it. What comes next in my process of elimination?And how?
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Avabella6308
December 13, 2009.



Check for an excessive exhaust backpresssure due to a clogged-up catalytic converter.

Engine misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.

Rasmataz
Dec 13, 2009.
Was there a rotten egg smell?

Tiny
Bigjim79
Dec 14, 2009.
No rotten egg smell. Fuel filter and plugs replaced and still the rough idle, stalling easily if im not giving it some gas, and a lot of power lost. I could put the pedal to the floor and was not getting anywhere most of the time. Car will gain speed but very slow and it sounds bad.

Tiny
Avabella6308
Dec 14, 2009.
Sounds like it may have jumped time! Did it backfire or anything before rough idle?

Tiny
Bigjim79
Dec 14, 2009.
Check base timing by shorting Te1 and E1 on diagnostic link. Set mechanical timing to 10 degrees BTDC.

Remove valve cover and inspect timing belt for missing teeth.

Other possibilities are fuel pressure, fuel pressure testing on this car requires a special tool set. Could also be a bad ignitor.

And as Raz mentioned, the convertor could be clogged. The CAT is bolted on, so remove bolts and inspect interior. If you see any melted material, chunks, then CAT is bad.

Mmprince4000
Dec 14, 2009.