Nick1994
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Catalytic converter
2001 Chevy Malibu WOT power loss
- Thread starter SilverFusion2010
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I hollowed out the cat today. Same behavior.
Not the cat
Not the cat
I think it's an ignition timing issue. The timing chain could be stretched, due to coolant in the oil for however long the LIM leaked before I got the car.
Bad knock sensor retards timing, so under load when timing needs advance it doesn't. More Rpm needs more timing.
Ignition Module could be out of whack.
Car has 83k miles. Revs fine in park with no load.
If you rev for a few minutes, say 5 min at 2k, the coolant temp does jump up about 15-20 degrees but does not get to the danger zone.
Thoughts? Things I can test?
Bad knock sensor retards timing, so under load when timing needs advance it doesn't. More Rpm needs more timing.
Ignition Module could be out of whack.
Car has 83k miles. Revs fine in park with no load.
If you rev for a few minutes, say 5 min at 2k, the coolant temp does jump up about 15-20 degrees but does not get to the danger zone.
Thoughts? Things I can test?
Originally Posted By: Colt45ws
Ignition? If you're losing spark on one cylinder that would be 25% of your power. You'd feel that.
You would get a misfire code if it were that bad and the car would be shuddering if you lost one cylinder.. Connect a scan tool, check the data the sensors are sending as well as the fuel trims.
Ignition? If you're losing spark on one cylinder that would be 25% of your power. You'd feel that.
You would get a misfire code if it were that bad and the car would be shuddering if you lost one cylinder.. Connect a scan tool, check the data the sensors are sending as well as the fuel trims.
Last edited:
Originally Posted By: SilverFusion2010
I think it's an ignition timing issue. The timing chain could be stretched, due to coolant in the oil for however long the LIM leaked before I got the car.
Bad knock sensor retards timing, so under load when timing needs advance it doesn't. More Rpm needs more timing.
Ignition Module could be out of whack.
Car has 83k miles. Revs fine in park with no load.
If you rev for a few minutes, say 5 min at 2k, the coolant temp does jump up about 15-20 degrees but does not get to the danger zone.
Thoughts? Things I can test?
Don't worry about the timing chain, you would wipe out the bearings before that. As stated, with the scan tool and going for a drive, you can answer all your questions. Diagnose, don't go assuming and spend your money on parts which may not help you.
I think it's an ignition timing issue. The timing chain could be stretched, due to coolant in the oil for however long the LIM leaked before I got the car.
Bad knock sensor retards timing, so under load when timing needs advance it doesn't. More Rpm needs more timing.
Ignition Module could be out of whack.
Car has 83k miles. Revs fine in park with no load.
If you rev for a few minutes, say 5 min at 2k, the coolant temp does jump up about 15-20 degrees but does not get to the danger zone.
Thoughts? Things I can test?
Don't worry about the timing chain, you would wipe out the bearings before that. As stated, with the scan tool and going for a drive, you can answer all your questions. Diagnose, don't go assuming and spend your money on parts which may not help you.
I'd think fuel pressure dropping off could cause it but everytime I've had that happen I get a lean condition code.
Could be a bad MAF. Really need a scan tool to see what everything is doing when it happens.
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Originally Posted By: mightymousetech
Could be a bad MAF. Really need a scan tool to see what everything is doing when it happens.
With a GM, can you do what you can with a Ford or BMW, which is unplug the MAF and see if the power comes back (base table only) ? If so, that'd be an easy test.
Could be a bad MAF. Really need a scan tool to see what everything is doing when it happens.
With a GM, can you do what you can with a Ford or BMW, which is unplug the MAF and see if the power comes back (base table only) ? If so, that'd be an easy test.
Fuel filter? or pressure?
Ok hooked up a scantool. Ignition timing is being retarded under WOT.
And it's not the knock sensor. WOT shows no knock event but under light acceleration 2-3 degrees of retard can show. Timing advances and retards normally under light throttle.
Any idea what would cause ignition timing to be retarded because you floor it?
When it is bogging it's capping advance at 24-25 degrees
Any idea what would cause ignition timing to be retarded because you floor it?
When it is bogging it's capping advance at 24-25 degrees
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Bump
OVERKILL
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Originally Posted By: SilverFusion2010
Bump
Have you tried it with the MAF unplugged?
Bump
Have you tried it with the MAF unplugged?
I have not. I thought unplugging the MAF meant a dead engine
OVERKILL
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Originally Posted By: SilverFusion2010
I have not. I thought unplugging the MAF meant a dead engine
See my earlier post. I'm not 100% on how it works for a GM, but Ford and GM it puts the engine in base table only.
I have not. I thought unplugging the MAF meant a dead engine
See my earlier post. I'm not 100% on how it works for a GM, but Ford and GM it puts the engine in base table only.
Ah. Well I can try that tomorrow
Anybody? Timing retarded under WOT
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