Join Date: Mar 2000
Location: Moab, Utah
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Detonation, open air filters & high air temps
1982 CJ-7, manual trans, 4.56 gears
1990 XJ 4.0L (pre-HO) engine, original manifolds, fuel rail, injectors
Mopar MPI harness, sensors (everything other than the intake manifold and fuel rail/injectors)
Will an open element air filter (Rock-It tube/K&N filter) drawing superheated under hood air aggravate detonation? I have been fighting a pining/detonation problem for some time now and I have read a lot of posts on the subject but most seem related to the MPI conversion on 258 not a 4.0L conversion. One post recommended an adjustable pressure regulator but at $200+ I want to eliminate other problems first.
Fuel pressure is within specs according to the FSM (34 to 40 #.) I even road tested with a pressure gauge attached and the pressure was 38-40 # at 1/2 to full throttle, ping or no ping. Engine temp runs 200 Ė 210 depending on load (195* stat). For curiosity I checked for trouble codes, there was a 23 (low/high inlet air temp) and a 54 (no cam signal) I donít know why the 54 as I havenít had any starting problems. A DVM shows the temp sensor to be within specs although I havenít checked it at operating temp yet (FSM says it should be < 4k ohms). Finally, can I clear the codes by pulling the fuse for the MPI system and for how long? Any thoughts or suggestions?
Thanks in advance,