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1997 Pontiac Grand Am Repair Question


Topics covered: Fuel pressure, Compression, Spark.
Mileage: No information provided.

Asked on August 6, 2009

Misfiring

1997 Pontiac Grand Am 4 cyl 173000 miles

i have replaced the cam sensor, crank sensor, coil, timing chain plugs, tested fuel injectors, changed the plug boots and it still misfires 1 and 3 everything ive done it still misfires 1 and3
Avatar Asked by webangel

Answer

Replied on August 6, 2009

Hello, a misfire can be caused by just about anything. Did you visually check for spark at the plugs? Fuel pressure ok, use a gage?

Tiny Answered by JDL (expert)
14,457 answers provided
Replied on August 6, 2009

yesi have visually checked spark have it 1 and 3 still misfieing

Tiny Response from webangel
2 questions asked
Replied on August 6, 2009

What was the fuel pressure spec? Are the injectors pulsing?

Tiny Answered by JDL (expert)
14,457 answers provided

Replied on August 6, 2009

the fuel pressure was good and the injectors are pulsating could the lobes be worn or valves burnt how do i find out

Tiny Response from webangel
2 questions asked
Replied on August 7, 2009

You can't check proper fuel pressure without using a gage. Do a compression test on the cylinders.

Tiny Answered by JDL (expert)
14,457 answers provided
Replied on August 7, 2009

compressioncheck is 180 lbs we did a leakage test and 1 and 3 misfires 2 and 4 has a 25% leakage

Tiny Response from webangel
2 questions asked

Replied on August 9, 2009

Maybe I misunderstood your post. To do a cylinder leak down test, the engine isn't running. The cylinder your checking, you bring the piston up to tdc compression stroke, pump in air through the spark plug hole, shut the air valve off, watch for a leak-down. Right now, I'm not sure why the misfire.

Tiny Answered by JDL (expert)
14,457 answers provided