Can Timing be adjusted on a '93 4.0? [Archive]

dorfs

09-26-2001, 05:34 PM

Yea and no. Ignition timing is determined by the crank angle sensor, which is rigidly mounted on the bell housing. Mopar does sell an offset crank angle sensor. This sensor is designed for high atlitude, and is offset 8 degrees. This will advance the timing 4 degrees. You must cut the dist. indexing tab off, and set the "sync signal" for proper operation.

Sometimes, there is a function in the computer that will allow you to retard the timing up to 6 degrees, 2 degree at a time. All of the mpfi kit's have this function, but very few of the YJ's had it. The only way to find out is to hook it up to Chryslers DRB scanner.

Older 4.2's and 4.0's were notorious for combustion chamber deposits. I would go by your local Mopar dealer and pick up a can of Mopar Combustion Chamber Conditioner. This stuff is basically 80% water, and comes out of an aresol can as a foam. Run this stuff down your throttle plates on a hot engine until the can is empty (with the engine running). Then drive it down the highway until it stops smoking. Then dump a can of 44K injector cleaner in the tank. By morning you should be fine!

[ 09-26-2001: Message edited by: dorfs ]


Pirate4x4.Com > Brand Specific Tech > Jeep - Hardcore Tech > Can Timing be adjusted on a '93 4.0? PDA : Can Timing be adjusted on a '93 4.0? DanH 09-26-2001, 02:11 PM My engine is knocking Bad!! Like constantly over 2500 rpm's on the highway. Could it be the timing? dorfs 09-26-2001, 05:34 PM Yea and no. Ignition timing is determined by the crank angle sensor, which is rigidly mounted on the bell housing. Mopar does sell an offset crank angle sensor. This sensor is designed for high atlitude, and is offset 8 degrees. This will advance the timing 4 degrees. You must cut the dist. indexing tab off, and set the "sync signal" for proper operation. Sometimes, there is a function in the computer that will allow you to retard the timing up to 6 degrees, 2 degree at a time. All of the mpfi kit's have this function, but very few of the YJ's had it. The only way to find out is to hook it up to Chryslers DRB scanner. Older 4.2's and 4.0's were notorious for combustion chamber deposits. I would go by your local Mopar dealer and pick up a can of Mopar Combustion Chamber Conditioner. This stuff is basically 80% water, and comes out of an aresol can as a foam. Run this stuff down your throttle plates on a hot engine until the can is empty (with the engine running). Then drive it down the highway until it stops smoking. Then dump a can of 44K injector cleaner in the tank. By morning you should be fine! [ 09-26-2001: Message edited by: dorfs ] Littlex 09-26-2001, 07:59 PM There is also a updated piston that is coated to control piston slap.