Is that carbon or oil, or a mixture of both?...I know this might be a stretch but that almost looks likes a head gasket leak...hoping its not, but I would not like to see that on my rig.

 

X2 on this...

 

I'm going to dealer tomorrow see if they can diagnose the problem

 

Let us know what they say...

 

Well, I was following your lead until I read your commentary that Techron was junk, now I'm not sure what I'm reading here...

It's a known fact and documented by all the Hemi tuners that excessive crankcase oil making its way into the intake does cause inefficient combustion. However, I'm reading your comment to say crankcase oil acts as an octane booster.. are you a chemist as well?

The guys that are building motors, programming tunes and making Cherokee SRT8's go 9 seconds in the quarter will say to install catch cans and stop allowing contaminated crankcase oil to enter the intake... why do this if the oil is acting as octane booster?

LKlad posted factual information and it appears your analysis is the contrary...

 

It is coming from the PCV breather.... a catch can is designed to remove the oil before it enters the intake.

You're not pinging because your fuel, ignition and timing system is working correctly.

 

I read through most of this thread and i didnt see anyone mention the third heat shield that almost got me a new motor.

My motor at 15000 miles started pinging under load intermittently, right after putting in the superchips tune. Well that lasted a week of tryin to figure that out. Different fuel brands and octanes seemed to change the problem but really not fix it. The dealership checked both manifolds for cracks and rattles but could not reproduce at idle or sitting still tapping on the throttle. They checked all the skid plates for rocks boucing around since that is a common complaint for weird noises here. Nothing....

Did not ping as bad on cold days.

I took it back on a hot day with the top and doors off and superchips back on stock tune. Tech rode with me and agreed the motor is pinging under load and there are no codes being thrown. They said it may need an engine replaced.....poop!

I left it with them all depresed and got a ride home.

they call me back next day laughing.

They had one of the techs drive down abandoned road with another tech hanging out accross the back door seals leaning head under vehicle( only in texas!) and they found the pinging noise. Didnt sound like a safe way to troubleshoot this issue but hey, thats thier call huh.

It was the heat shield that goes on the pipe acrross the jeep from one side to the other. One of the welds had broken and the two pieces were tapping each other during hi vibration moments when under load, not at wot or idle. One tack weld later and i am noise free. Superchips reinstalled and no issues on any level.

Its too easy and cheap not to check it out. Good luck.

 

Okay bubba, I'm on the same page again...

I agree with your Techron assessment. I've never used Seafoam and never will... I've read a lot of guys use it for various remedies, but didn't know about the effects on parts. I'm always cautious when it comes to cleaners and was concerned about the effects of BG44k on fuel-lines, etc. ... but since I've never heard about it I'm open to listening to a SME that has tested and used it with good results.

My thoughts regarding Techron is purely from a long term use perspective.. it won't solve an immediate problem and is more for the fuel system, which is why I suggested it in the first place. Also, its safe because it was developed by Chevron and used in their blend.. which goes through extensive testing and validation.

I didn't know the OP only has 15K miles (55,000KM... I'm not Canadian) on this motor and have a hard time understanding why he would have enough carbon build up to cause pinging, primarily due to the ignition system's ability to compensate for nominal increases in carbon build over time.

I still believe however that his problem is fuel, sensor or ECU related, if in fact it's actually pinging. I also don't advocate installing a CAI and opening the exhaust without installing a good CMR or Dyno tune - although, one may argue adaptives would compensate for the change. I don't know enough about the system to really make that judgement - I do know you typically re-jet a carb when you help a motor breathe better, otherwise it will run lean.

Thanks for the claification and education ... can't learn this stuff in a texbook.

 

haha ... where were you 100 posts ago?

Everyone has been chasing this and speculating the root cause and you drop a heat shield bomb.

Classic !

 

The PCM doesn't always function in closed loop. It is not a completely dynamic system. Under load and heavy acceleration it runs in open loop. Open loop is table based for proper A/F mixture and spark advance. It's a safety mechanism that runs a pretty fat fuel mixture when your engine is most vulnerable. Change mechanicals, the tables are off. Denser air from an intake, more/less cylinder evacuation from the exhaust and potential shrinking of the combustion chamber with build up.

We are also working with a Speed Density system where MAP (Manifold Absolute Pressure) sensor and airflow is reliant on a large lookup table. We do not have an MAF (Mass Air Flow) sensor that lets us know how much air is actually being pulled into the manifold.

Back on topic, personally I am not tracking any of this down if a bump in octane addresses things, especially if I changed mechanicals.