| Cad 500 backfire through TB [message #371501] |
Sat, 28 October 2023 09:56  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma:
|
Senior Member |
|
|
This is just an FYI to all in case it happens to you.
We attended the fall GMCMI conference in Corunna Michigan and had a great tlme. Following the conference we toured Michigan State Campgrounds for about a 2 week period of time. We went from one State Park to another and during that transition from one park to the next I began to notice a backfire through the TB (I am running a FiTech TB). It would happen at RPM's over 2500 with throttle pressures lower than 7 inches of vacuum. Over the 60+ years of being a mechanic, I recognized the symptoms as possible intake valve that was either not seating properly or a actual beginnings of a burned intake valve. Sounded/acted just like it. So following our Michigan trip, I feathered the throttle and made it home with anticipating that I may have to pull the heads for a valve job. The Cad 500 has about 45K miles on this rebuild. Not really looking forward to this as I do not have indoor storage and would be completing the task in approaching cold weather. I decided to check some easy things first. Check things like plug wires, distributor cap, rotor, Petronix pointless ignition, Fitech programing.......etc...etc. So, I made a list and started with plug wires first. I began with plug wire #8, drivers side back of the engine. I found it just barely hanging on to the plug, almost falling off. I pushed the plug wire back on and took the coach for a ride up the Irvington hill. The Backfire is gone. Before we left for Corunna I had changed out the transmission governor which is located directly below plug wire #8.
Lesson learned, sometimes it is the simplest things that get ya. Check the simplest first!
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
