Detonation problems in OD '92 4WD

[Ranchero]

Ok, Ive read all the posts on this, but I still need help. My '92 is used 95% in town. When we take a drive and the truck hits overdrive it will detonate under load between 45 and 65mph. Drop it into drive and it goes away. It really does it climbing mountains, but again get it above 65 and it goes away. The truck has 96,000 miles and runs great otherwise. Any questions, tips or hint are appreciated in advance.

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'68 Ranchero GT
'68 Fairlane 500 Fastback
'69 Mustang Fastback
'92 Explorer XLT 4WD

 

[Ranchero]

Come on, any tips or questions? I need to get this thing figured out, it's bugged me since I got the truck. Please reply

James Sollenberger
Jsollen@aol.com

 

[jhayes]

Check your transmission fluid level. Mine had a modulator valve leak which allows the transmission fluid to be drawn into the engine via the vacuum line. Caused mine to ping very badly, the tranny fluid really messed up the engine sensors. Looong crank starts went away also.

JHayes