Pinging in E350 Motorhome

If this happened after the "tune-up", you might check and see if the shop adjusted the timing during the tune-up. (It might have been put to "factory specs" which isn't always the best set-up.)

Try a tank of 89 octane and see what happens too.

Matt

the 460 needs high octane fuel. as long as you use 87 octane, you will get detonation, and eventually ruin the motor

The 460 Absolutely DOES NOT "need" high octane fuel!

A properly tuned 460 that is running well with all system function properly can run on any of the standard commercially available grades of gasoline with no detonation.

The original posters detonation problem is not an octane issue! Something has changed from before his "tune up".

Please explain how you can make such an absurd a blanket statement about this engine? Oh, I would be interested in hearing how you think detonation will eventually ruin his engine.

Changing fuel octane from a lower octane to a higher octane, at best would mask the true reason for his relatively "new" detonation problem, possibly compounding the original problem.

check for vacuum leaks re check the timing. john

It's not a big problem if you don't mind a hole in the top of a piston.

I would hope that he gets detonation, no matter what fuel he is trying to burn. Without detonation, the engine will not run. If he increases the octane rating, he will still get detonation. However, hopefully by raising the octane rating, he will eliminate pre-ignition of the fuel and the accompanying ping.

My 85 F250 w/460 runs better on regular than premium grade, go figure...

David Jones djonesLSidaho.com

The only normal ping is that associated with engine lugging when the tranny is just about to downshift and YES, excessive ping can cause damge and should not be tolerated. The 460 motor is designed for 87 octane. Using a higher octane is just an expensive bandaid.

Does the spark knock diminish at wide open throttle ( pedal to the metal)?

- If so then check the EGR system ( the EGR valve is supposed to close at WOT and the PCM goes into open loop strategy). A code tester will come in handy. This is a good time to clean out the throttle body area.

-If not then the ping is likely misfire related. Check all those "tune up" items such as ignition wire connections, wire routing , PCV valve installation etc... Perhaps this problem was maintenance induced ( a very common cause of car trouble nowadays). An exhaust gas test will likely reveal high HC and NOx levels. Are there any other symptom such as rough idle, high idle , lack of power , hesitation, poor fuel milage etc..?