The good and the bad of a roots supercharger.

[DC3]

I did not realize there was a TSB for the right intake cam. It looks like the bulletin was updated in May this year. This may be old news to everyone else, but I am posting here anyway.

I renewed my Mopar tech subscription so if there is any information someone is looking for, let me know sometime in the next 30 days.

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[DAVECS1]

Be nice to know about Throttle body related stuff. I think we are going to see a wave of these fail too if my in box is any indication

 

[ShadowsPapa]

Since this version of the 3.6 was first used in the 2016 Grand Cherokee before it was used in any other Jeeps, have WK2 owners had camshaft and follower/rocker problems?????????
We've had two Grand Cherokees with 3.6 since 2016 and zero engine troubles (except the spark plug issue for which there's a TSB)
If WK2 owners have not seen these troubles - why not?

 

[DAVECS1]

I wonder the same. Do the cars, minivans, and other SUVs/trucks have this same rate of attrition? I have not gone looking, so I do not know. I have noticed that there are a number of these vehicles not tied to this operating system. The solid axle Jeeps, sprinter Van, and trucks seem to be tied to this OS.

That puts us back to a software issue possibly over or under utilizing a feature. I would be willing to fall on the sword and say it is my software, but 20 to 30 percent of the people I have helped have not even had a supercharger or tuning. I have helped 3 dealerships! 6 different independent shops. The data for the failure looks the same supercharged or not. The factory pulls no timing or makes no cam adjustments when the airflow messes up from cams or carbs, tries to blow right through it, at least early versions. The new stuff is doing something with the throttle, that has totally messed with my tune. I don't know if that throttle change was for a throttle body issue or the cams, but I have a fair number of people emailing me about throttle stuff.

The JL and JT use a closed loop feedback on NRatio (calculated drivetian load) to manage airflow. I think the intent was to manage wheel tire combos, and off road low speed situations. Unfortunately the model is not tolerant to big changes, and just messes up when there is an issue with the engine or you go to crazy with a combination. The throttle looses control, and the cam timing goes into a catalyst reserve

 

[SteveInOrlando]

Be nice to know about Throttle body related stuff. I think we are going to see a wave of these fail too if my in box is any indication

only way I found to get one right now it used out of a junk yard.

 

[cmb396]

only way I found to get one right now it used out of a junk yard.

I ordered a new one from my dealer, and had it the next day. Didn't fix the issue I was having tho, so a waste of $250.

 

[DC3]

@DAVECS1

Could this be related to your throttle body issues? Besides the MIL light, the TSB mentions no symptomatic behavior.

 

[ShadowsPapa]

@DAVECS1

Could this be related to your throttle body issues? Besides the MIL light, the TSB mentions no symptomatic behavior.

There may not be obvious symptoms. It would likely just throw the fuel mix off - it would likely be running rich if I recall the high and low of the O2 sensors correctly.
COULD be a less than smooth idle, engine may run a bit rough.

 

[DAVECS1]

@DAVECS1

Could this be related to your throttle body issues? Besides the MIL light, the TSB mentions no symptomatic behavior.

My tb has been fine so far but I am constantly working to find away to make it less erratic for my customers so it never is in the same place for more than a week. The problem I have found is in the stock location. The throttle Control model cannot consistently hold the small opening and it causes jump starts and slow tip in. Turning up the idle used to help but the new operating system is rejecting that change. So it becomes a game of mm to tune in many jeeps

 

[DC3]

My tb has been fine so far but I am constantly working to find away to make it less erratic for my customers so it never is in the same place for more than a week. The problem I have found is in the stock location. The throttle Control model cannot consistently hold the small opening and it causes jump starts and slow tip in. Turning up the idle used to help but the new operating system is rejecting that change. So it becomes a game of mm to tune in many jeeps

If you want, I can flash the update to my ecu and then send you the file.

 

[DAVECS1]

I wouldn't do it, it changes something, I believe HP does not have mapped, and it is stuck like that even if you role it back.

 

[RIPP Superchargers]

I wonder the same. Do the cars, minivans, and other SUVs/trucks have this same rate of attrition? I have not gone looking, so I do not know. I have noticed that there are a number of these vehicles not tied to this operating system. The solid axle Jeeps, sprinter Van, and trucks seem to be tied to this OS.

That puts us back to a software issue possibly over or under utilizing a feature. I would be willing to fall on the sword and say it is my software, but 20 to 30 percent of the people I have helped have not even had a supercharger or tuning. I have helped 3 dealerships! 6 different independent shops. The data for the failure looks the same supercharged or not. The factory pulls no timing or makes no cam adjustments when the airflow messes up from cams or carbs, tries to blow right through it, at least early versions. The new stuff is doing something with the throttle, that has totally messed with my tune. I don't know if that throttle change was for a throttle body issue or the cams, but I have a fair number of people emailing me about throttle stuff.

The JL and JT use a closed loop feedback on NRatio (calculated drivetian load) to manage airflow. I think the intent was to manage wheel tire combos, and off road low speed situations. Unfortunately the model is not tolerant to big changes, and just messes up when there is an issue with the engine or you go to crazy with a combination. The throttle looses control, and the cam timing goes into a catalyst reserve

To provide some data we can confidently say the LX, WK, WD, RAM, JK platform engines definitely don't exhibit any notable number of issues like this. We've sold and teched over 12,000 kits for those models and not once has something like this happened. If anything the rocker arm issue for that engine is so well known we never even hear about it from a customer if it happens.

Meanwhile we have seen cam failure over and over again on JL and JT models. With that + your data we started to ask every Jeep dealer tech on the phone how often they change JL/JT cams. So far it's been the same "all day everyday" response. Great work collecting all this info here, Dave.

 

[jsalbre]

Turns out (due to needs the Jeep can't meet) that I'm going to have to trade my JT in for a 2500 in the near-ish future. The longer this thread gets the less bad I feel about it.

 

[DAVECS1]

Depending on how long your cams get run bad, you can expect a follow up converter replacement. I am living that dream at the moment. Luckily magnflow makes factory replacements that are better price.

 

[mghoodlum]

The JL and JT use a closed loop feedback on NRatio (calculated drivetian load) to manage airflow. I think the intent was to manage wheel tire combos, and off road low speed situations. Unfortunately the model is not tolerant to big changes, and just messes up when there is an issue with the engine or you go to crazy with a combination. The throttle looses control, and the cam timing goes into a catalyst reserve

Dave I emailed you this as well but hoping to get to the bottom of this ASAP because I have a road trip coming up to the Rockies in which I plan to take and off-road the Jeep and trying to figure out if I just need to uninstall the SC for now or of there is something I might be able to do to get this running right.

As I read this I’m wondering if this is where my issue is? Can you describe what one would observe when the throttle losses control, and the cam timing goes into a catalyst reserve?
As you describe the control system being used this sounds very much like what is happening after my install. I know I am running a recent firmware as I had to install a new PCM after an electrical issue in which my original one got fried.

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