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4.9 Detonation


Cad1

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Well after reading the post below about the EGR valve I guess I have the true solution to my problem. I have had this detonation problem once the car warms up for years. I never really correlated heat and ping together until recently so I dropped a 180 degree stat in there. It almost never pings with the 180. I'll still look into the EGR though.

Cad1

92 Deville w/210k miles

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Do searches on Detonation, there is a lot of into on it for the 4.9. It took me a year to get rid of it. If you have a problem getting rid of it come back and let us know. You WILL get rid of it if you read up on detonation here and follow the recommendations. In a nut shell, rod out the two egr ports with a hanger, when you open the TB you will see two tubes clean them out push a hanger in and out as far as you can. Pull the EGR and clean the pindle and seat as best you can, tap with hammer, read precautions in you search, replace EGR gasket with new one, and check all EGR hoses for cracks. Check codes you are probably getting an E048 check engine code. Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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One more thing, the engine is designed to run with the correct thermostat, 180 is not the correct stat. I can't remember if its 190 or 195, but the computer expects to see at least 195, at 180 the computer could be altering the timing, etc. I would put the 195 back and fix the detonation.

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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