When cruising in overdrive at 1500 - 2000 RPM and applying pressure to the pedal for light acceleration, I get a pinging like noise. Is this detonation? Short of turning off overdrive for anything but highway driving, how do I get rid of it?

The engine is very smooth at all other conditions.

 

Resevoir is full. Using 93 octane. I don't even think that the water injection is coming on at that point since boost theoretically hasn't built up yet.

I know my information is vague so I'll try to get some more details and post them.

Thanks for your help.

 

sounds like tip-in pinging. Are you running a chip. Most chips will advance timing during tip-in and cause it to ping.

 

I've been trying to reproduce the pinging but haven't had much luck. Any time I get into overdrive at low rpm I try to put light pressure on the pedal to get it to ping but the last few days it has been pretty quiet. I have heard enough of it in the past to be concerned so I'll keep trying.

I've noticed that I also get just a quick rattle at different times during shift patterns. One such instance that can be recreated at will is at full throttle during the rollover from one gear to the next. It will rattle for about a quarter second just before the engine rpm is pulled down (or possibly while it is pulled down) to meet the speed of the next gear. I'm guessing that the shift characteristics are the same for Expeditions and F150's. At around 5k rpm (shift point set by KB chip) the shift begins and the engine does the "mushy" pull down to the next gear and just before or as it starts to lock into the next gear I get pinging.

Other times I'll get just a single knock or two when depressing the pedal while the transmission is downshifting.

How concerned should I be about this noise? On hard acceleration the engine runs very smooth. Do these short bursts or single instances of detonation have a cumulative detrimental effect on the engine or does it take a continuous, several second rattle to cause damage?

Also, what is "tip-in"?

Thanks for your help.

 

I chased after a detonation problem on the Stang, turned out to be a plug! I installed new Edelbrock heads, new plug, had the same problem you describe. I pulled the plugs and found one that was grey on the insulator. Changed it out, problem solved.

 

Hey skyhook8,

What do you think of the Aquamist Water Injection system? I looked around the Internet for more information and discovered the product is made in England. Sounds nice for cooling the Kenne Bell, hopefully, my next upgrade. Where did you get it and do they have good pricing. What model and part number if you don't mind me asking.

Thanks!

 

So far so good. The pump is solid and seems to be a high quality product.

Do a search on Ebay for "aquamist". If you don't get results make sure that you also search "completed items". There's a dealer from Austin selling them for much less than others. Right now another person seems to be letting them go even cheaper.

I installed the "1s" system. It's the basic one and turns on and off based on the amount of boost. I thought about the "2c" system since it can "vary" the injection by tagging onto one of the fuel injector signals. You'll have to search for more info on that.

Check this thread for details on my installation:

https://www.f150online.com/forums/sh...threadid=97238

 

Very good article on pre-ignition and detonation:

http://www.streetrodstuff.com/Articl...e_Basics_I.php