bdiamond Posted April 15, 2004 Report Share Posted April 15, 2004 1988 DeVille, 4.5L engine noise On cold starting, the motor runs perfect, smooth, quiet, excellent throttle response. After reaching closed loop, it continues to run the same. But after, 10-15 minutes of driving, or after shutting it off, and restarting, it starts a slight “chauga-chauga” sound. Almost like a rod knock, but, I believe the block is tight. Even when making this noise, it still runs very good. At ¾ to 4/4 throttle, it disappears. Here are the ECM data parameters after the cha-cha starts, KOER, in drive, parking and main brake applied: P.O.1 Throttle position -0.6 P.O.2 Map 31 P.O.3 Computed baro. 102 P.O.4 Coolant temp. 94 P.O.5 Mat 91 P.O.6 Injector pulse width 1.2- 1.3 P.O.7 Oxygen sensor .67 - .69 P.O.8 Spark Advance 12 P.O.9 Ignition cycle counter 36 P.1.0 Battery voltage 12.8 P.1.1 Engine rpm 6000 - 6300 P.1.2 Car speed 0 P.1.3 Oxygen sensor cross cts. 28 - 36 P.1.4 Fuel integrator 121 P.1.5 Transmission temp. 75 P.1.6 E-Cell 1 P.1.7 ECM prom id 850 Anyone have an idea where I should start looking for the cause of the noise. Bill Link to comment Share on other sites More sharing options...
KevinW Posted April 19, 2004 Report Share Posted April 19, 2004 6000+ rpm??? Was it idling very fast? The ECM receives a speed signal from the distributor. Assuming the reported RPM is invalid, there could be a temperature sensitive problem in the ECM hardware, distributor pick-up coil or module. ___________________________________________________ Link to comment Share on other sites More sharing options...
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