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1990 ls 400 ? nocand pings?

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Old 06-26-03, 02:23 AM
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elclassico
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Thumbs down 1990 ls 400 ? nocand pings?

about 150,000 miles, still using the best gas, recently getting knocks and pings. used fuel treetment the last time i changed the oil too. any thoughts , suggestions? please help, thanx!
Old 06-26-03, 02:39 PM
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GA400
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how many miles since the plugs were changed? spark plug wires? throttle position sensor? fuel injector cleaner may not be strong enough if there is a lot of build up on the back of the valves, it may need a throttle body cleaning as well.

Positive it is not valve tapping? it is a clicking sound which is sometimes mistaken for engine knocking.
Old 06-27-03, 02:21 PM
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elclassico
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Arrow real good info thanx!

well its been a while sence the plugs were changed. it only pings when im gassing it just alittle, and especially up hills. i will check up on all the thingsyou said, thanx! also, recently the check engine light came on. i checked it out, reset the ecu by un plugging the battery. now the light is gone, for now. i will post a follow up, any other thoughts?? thanx to all!
Old 06-30-03, 05:19 PM
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chliansh
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My guess is carbon build up in the cylinders....... this in turn gives you lower volume in the cylinders. With less volume your compression increases creating extra heat which fires the piston at the wrong time before the spark plug can. Could also be bad timming or possibly even the knok sensor itself could be bad.
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