'82 CJ7 Misfire

[galaxyk5blazer]

Finally got my jeep running. I've converted to Howell Fuel Injection and a GM HEI distributor. I noticed a misfire at acceleration and normal driving speed. I have replaced all the distributor components. Timing set at 6 degs. BTDC. With the vacuum advance disconnected, using a timing light, I noticed that the firing mark moves to zero degs. as I increase rpms, then as I continue to increase rpms the timing advances normal. Also during this I noticed that the spark is not consistent. Runs ok then I have a misfire and there's no spark for that brief second. Then it repeats. Any help would really be appreciated.

Thanks, Mike

 

[RockScar]

Loose timing chain or worn timing gears?

 

[galaxyk5blazer]

Engine just rebuilt. timing chain and gears new, no slack in chain, 15 pins between timing marks. When I first ran it, it ran great even passed smog. After driving for a couple of days started missing.

 

[dslywalker]

do you have at least a #12 wire operating the HEI? What engine do you have and what brand HEI did you buy?Also a extra ground wire on the HEI attached to the module helps.

 

[josh94yj]

not real familiar with HEI, is the COIL built in the dist or no? and the coil could be breaking down, i bought 2 screamin demon coils and BOTH were pieces of crap (this was a few yrs back though not sure if they've improved any) and would idle fine but break down while driving and reving the engine up. but regardless of the ignition sys if you dont have approriate voltage (wire size and connection types play a huge factor in this) then the coil will not fire the way it should bc it wil not get enough voltage to be able to build up the spark. ANd running with too little voltage will kill the coil (how long it takes depends on how short you are on voltage)

 

[Robert_Stephens]

not real familiar with HEI, is the COIL built in the dist or no? and the coil could be breaking down, i bought 2 screamin demon coils and BOTH were pieces of crap (this was a few yrs back though not sure if they've improved any) and would idle fine but break down while driving and reving the engine up. but regardless of the ignition sys if you dont have approriate voltage (wire size and connection types play a huge factor in this) then the coil will not fire the way it should bc it wil not get enough voltage to be able to build up the spark. ANd running with too little voltage will kill the coil (how long it takes depends on how short you are on voltage)

Good post and good reply and you are correct. Ran into this with VEX and normally have huge wiring for everything including two 1000 amp batteries and 2/0 welding wire for wiring w/200 AMP alternator. With the new coil upgraded to 4 gauge battery cable and 3 grounds to battery, frame and engine block--hummed like a hemi and that was the fix.

Hope our friend follows and checks out. The coil should last for years if it has to not labor against resistance (tiny wiring, light grounds and tiny connectors).

Robert

 

[galaxyk5blazer]

Thanks for all the information. The Jeep is in the shop, been there for 3 weeks. They still can't figure out the miss and low kv's. I'll run it by them tomorrow.

Mike

 

[dslywalker]

I had a miss in mine in the high ranges.It turned out to be the plate on the throttle body where the throttle linkage was bolted to was on wrong.
Once we positioned the plate on the throttle body correctly it went away.Is Howell working with you on this?I would sure get their input.

 

[galaxyk5blazer]

The misfire is electrical. Originally the throttle body regulator diaphragm was ruptured, that was fixed. Now if you remove power to the distributor the engine cranks normal. As soon as you re-connect power the engine will crank normal then all of a sudden stop as if the distributor fired on the piston up stroke. When I first checked the spark (one cylinder at a time) #6 had a blue-white spark all others was a yellowish color.

 

[dslywalker]

Has anyone checked the distributor gear since install?Some of the HEI dizzys had hardened gears that would eat a cam up on startup.Especially on the 258.That would throw everything off.

 

[dslywalker]

Did you ever find your problem:???:

 

[galaxyk5blazer]

Problem was resolved. Replaced the distributor. Jeep fired up like a champ. Been on the road for a week with no problems. Thanks to all who replied to my post. I'll try to get some pics up soon.

Mike

 

[dslywalker]

Problem was resolved. Replaced the distributor. Jeep fired up like a champ. Been on the road for a week with no problems. Thanks to all who replied to my post. I'll try to get some pics up soon.

Mike

Good to hear.Did it have bad internals or gear.?That was about the only thing it could have been was bad Dizzy