2006 4.0 Spark Knock

[chad]

I have a pretty good spark knock going on when it gets under a load. I’ll start with things that I have tried. Clean by putting water down the throttle body and replaced spark plugs. The motor is quite the rest of the time and isn’t throwing any codes. Even premium fuel doesn’t seem to make much of a difference. Do you guys have any suggestions any help would be appreciated.

 

[AndrewLJR]

Try using a small amount of water as you did already as it may take several attempts. Don't be afraid from hammering down and pushing the motor. Probably some carbon build up from not pushing the motor enough. May sound crazy but a simple "Italian tune-up" should help.

 

[chad]

Try using a small amount of water as you did already as it may take several attempts. Don't be afraid from hammering down and pushing the motor. Probably some carbon build up from not pushing the motor enough. May sound crazy but a simple "Italian tune-up" should help.

I put 2 16 Ounce bottles of water through it and have been running it hard for about a week. So far no change at all. I’m kinda at a loss what to do for it.

 

[Rubicon John]

Mine did this when I bought it but premium fuel did mask it. I figured I had carbon at that point and did a BG intake cleaning service. Then I took some Mopar Combustion Chamber Cleaner and sprayed onto the tops of the pistons while warm. Let sit and took for a spin. Then replaced my plugs. My 4.0 runs 10x better and doesn’t ping anymore.

Maybe you didn’t knock off the carbon with water? Worth a shot to try a chemical treatment.

 

[AndrewLJR]

I put 2 16 Ounce bottles of water through it and have been running it hard for about a week. So far no change at all. I’m kinda at a loss what to do for it.

Next step would be trying done cleaner and see what happens. Will have change plugs most likely. Do you have you old ones? Were they in decent shape? Toss them in if you have them, then run the cleaner

 

[chad]

I put a can of seafoam in the gas and then gave it the full seafoam treatment down The throttle body. Then beat the hell out of it for about 20 miles or so. Now I would say it’s about 95% gone or at least something I can live with.

 

[Steel City 06]

Are you using the cheapest gas, or a name brand?
Consider buying only gas from a Top Tier supplier when possible. Top Tier is a voluntary standard set by both automakers and gas corporations on the minimum amount of detergents required in the fuel. (The EPA requirement for detergent is very low compared to the Top Tier fuel.)

Here is the list of suppliers:
https://www.toptiergas.com/licensed-brands/
The higher detergent fuel has been proven to clean out carbon and prevent buildup much better than cheap gas. Most automakers recommend its use. The TJ FSM doesn't call out Top Tier by name, as it was likely written before the adoption of the new standard. It does recommend the "Reformulated" standard fuel, which is a standard that precedes Top Tier.
Here is the call out in the FSM:

Lower carbon deposit amounts means cleaner combustion and prevents pre-ignition (ping or knock). It also prevents valves from getting stuck or burned because of improper seating due to carbon buildup.

I have attached a research report to back up these claims. It's an interesting read.

 

[chad]

Yep according to the list I should have be good. I normally use BP or Chevron.

 

[chad]

I thought I would give you guys an update just in case someone else has the same problem. After attempting to remove carbon,replacing plugs and a Italian tuneup technique. Nothing still had a bad spark knock. So I decided to start changing parts. I replaced the MAP,ACT sensors and at the same time I replaced the fuel pump module the OEM Bosch unit. Also fixed the fuel overflow problem while I was in there. And now it runs perfectly the problem must have been going on a while because the motor seems to have a lot more power than it did before and it even seems to run cooler than before. The problem must have been getting worse over time and I didn’t really feel the power loss. It wasn’t in till I heard the spark knock that I realized that there was a problem. It never did throw any codes. If I was going to guess I would say that it was probably the fuel pump. I guess I should have changed them one at a time. But the OEM wasn’t that expensive and I figured it was good preventive maintenance anyway.

 

[Daryl]

I thought I would give you guys an update just in case someone else has the same problem. After attempting to remove carbon,replacing plugs and a Italian tuneup technique. Nothing still had a bad spark knock. So I decided to start changing parts. I replaced the MAP,ACT sensors and at the same time I replaced the fuel pump module the OEM Bosch unit. Also fixed the fuel overflow problem while I was in there. And now it runs perfectly the problem must have been going on a while because the motor seems to have a lot more power than it did before and it even seems to run cooler than before. The problem must have been getting worse over time and I didn’t really feel the power loss. It wasn’t in till I heard the spark knock that I realized that there was a problem. It never did throw any codes. If I was going to guess I would say that it was probably the fuel pump. I guess I should have changed them one at a time. But the OEM wasn’t that expensive and I figured it was good preventive maintenance anyway.

Thanks for updating your thread. I hate when people never follow up with the fix. Again,

 

[Rubicon John]

I’m wondering which of those 3 things fixed it.

 

[Daryl]

I’m wondering which of those 3 things fixed it.

Unfortunately we’ll never know, but it’s narrowed down.