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View Full Version : Knock in a 496mag?? Bogus temp sender alarm??



NJgr8ful
12-02-2009, 07:19 PM
Looking for some help ... I had a 2002 Formula 330SS surveyed today with twin 496mags and the port motor had a knock. Computer diags confirmed 157hrs. and no other codes worthy of note. It is not a motor knock, but a popping more like misfire or wires were crossed kinda pop/knock, but bottom line it prevented us from running at speed. Motor starts and idles fine.

The only other clues are that a warning alarm is sounding throughout while running on that motor and doesn't shut off. When checking the Smartcraft codes there are none present indicating an issue, but yet one manifold shows temperature is reading 257* on the Smartcraft and the temp is NOT 257* (prolly a bad sender?!) ... we confirmed this false temp reading through multiple means:

1) infrared gun - reads 78*.
2) temp gauge at the dash reads perfect and consistent with other motor at 165*.
3) coolant temp is on the money does not elevate ... lastly,
4) by touching with hand and it is cool (not 257*). It feels the same temp as the other 3 risers and manifolds.

So that said, Question: Could this ecm Smartcraft reading of 257* be throwing off the computer on the 496mag and not allow it to run at specs and possibly causing the knock?? The knock is not at idle, but only when trying to get up on plane.

Any input or experience with these symptoms, please offer them! Thanks Chris

NJgr8ful
12-06-2009, 10:43 AM
Thanks!!!! :D :D :eek: