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Pinging Cadillac

I have a '94 Cadi w/4.9L engine and 66k miles.

I am having a problem with pinging. Between 35 and 50 the engine pings. Its worst right around 45 when the tcc engages, but present even if I manully select a lower gear. New plugs/wires/cap/rotor. Timing set on spec. Fuel system cleaning by my mechanic.

This pinging is bad enough that I am afraid to drive the car.. My regular mechanic doesn't know and Santa says this isn't a good time to take it to the dealer.... I'm thinking intake manifold gasket leak. Anyone here have experience with this problem? Any suggestions appreciated.

Steve B.

Reply to
Joe
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Reply to
Dave J and Lynne J Shepherd

I don't know a huge amount about the Cad 4.9 from that era, but for many many years the Cad 4.1 and 4.5 (both close realtives of the 4.9) were INCREDIBLY sensitive to a failed or clogged EGR system causing pinging. The old TBI 4.1s would knock like someone pounding a piston with a sledgehammer, and many wound up in the junkyards just from severe detonation damage due to a clogged or failed EGR.

I know that isn't a firm answer, but if you're groping in the dark already its a pretty good place to start.

Reply to
Steve

Thanx to the two guys who suggested EGR problems. Turned out to be a bad EGR valve. $75 later I have no pinging!

Steve B.

Reply to
Joe

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