Detonation, open air filters & high air temps - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 09-05-2002, 12:37 PM Thread Starter
Journeyman
 
gmoabrim's Avatar
 
Join Date: Mar 2000
Location: Moab, Utah
Posts: 199
Thanks: 0
Thanked 0 Times in 0 Posts
 
Detonation, open air filters & high air temps

Background info:
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,

GaryM
gmoabrim is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 09-05-2002, 01:48 PM
 
Join Date: Jun 2001
Posts: 1,705
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Detonation, open air filters & high air temps

One thing you could try is to move the Intake Air Temperature (IAT) sensor onto the air tube just behind the stock box. This fools the computer into thinking that cooler, and therefore more dense air is being fed into the engine. The computer will compensate by supplying more fuel, which may help with the detonation problem. The best part is that this mod is free!
AllLockedUp is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome