The good and the bad of a roots supercharger.

[DAVECS1]

I believe what you are saying is that this sneaks up on you............ they can tolerate a lot of wear and not "misfire" - but I'd bet the trim tables would have to be off? I mean, if you aren't letting in the air, or letting out the exhaust, aren't you going to see the thing trying to compensate by changing the fuel going in? Intake lobe badly worn, valve not opening like it should, less air going in so the normal injector spray would be too much for the air that did get in - and the PCM would try to trim it back?
Time for another coffee - maybe it doesn't work like that - but if you can't get the exhaust out (in cases of worn exhaust lobes) or in these cases, the intake valve isn't opening and letting enough air in, won't that trigger a mixture change? The O2 sensor readings would have to be off.
On old engines if there was a badly worn lobe or the lifter caved, it would pop - BANG - back through the carburetor.

So here is the issue. The only part affected is high RPM on the intake valve. The lobe in the middle you are seeing worn down, is the high lift lobe. As your engine crests 2800 RPM a solenoid shuts off the oil sent to the rockers to activates a valve in the rocker that deactivates the high lift lobe. Then the rocker and intake cam run on the outside skinny lobes from idle to 2800. ingesting fuel and air as it normally would. Once you crest 2800 a solenoid in the head shuts off the oil and the the rocker spring loads the center lobe and locks it out, to ride on the center of the cam. If that lockout does not happen, because the solenoid will not close or the rocker is broke, then the center lobe does no lockout and it rattles around making noise and messing up the lift profile for that valve, as it is a mix of bouncing high lift lobe and riding on the low lift lobe.

Also how do you flag a diagnostic on a solenoid that has shut off but not closed?

SOooooo basically the intake cam is the only cam affected
It is only affected above 2800
It still opens at high RPM but the profile is drastically altered and erratic
The VVL solenoid may work sometimes, but if your cam is wiped now your just grinding your cam.

SO anyone could have this issue right now and you may never know until you drop the hammer in your truck and it makes some weird noises and possibly trips a misfire light.

You will chalk it up to bad gas or a hiccup and continue to drive grampa style, as metal courses through your engine.

I am slowly talking myself into a hemi swap.

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[ShadowsPapa]

I am slowly talking myself into a hemi swap.

Dibs on your SC and parts!! ?

The good - you can't blame this on any mods
The bad - no need to explain that part

 

[Rusty PW]

Reading this thread reminds of the 5.7 Hemi MDS problems causes by bad solenoids that controlled the oil flow for the lifters. That it wiped out cams and lifters too.

 

[DAVECS1]

Reading this thread reminds of the 5.7 Hemi MDS problems causes by bad solenoids that controlled the oil flow for the lifters. That it wiped out cams and lifters too.

Luckily the hemi crate engines do not utilize this solenoid

 

[Rusty PW]

Luckily the hemi crate engines do not utilize this solenoid

Thank god. Just wish Chrysler would learn from some of their screw ups. Because most of it carries over from model line to model line.

 

[DAVECS1]

This one makes me upset, because it is like they almost intentionally tried to hide it.

 

[WK2JT]

I am slowly talking myself into a hemi swap.

As I was reading through this, this is exactly what was going through my head.

 

[DAVECS1]

Really sucks. I have spent so much time getting this to run fantastic. I love the power, the response, the whole package. I just drove my mustang the other night and I like this performance better. But this cam thing is a ticking time bomb

 

[ShadowsPapa]

Really sucks. I have spent so much time getting this to run fantastic. I love the power, the response, the whole package. I just drove my mustang the other night and I like this performance better. But this cam thing is a ticking time bomb

But you know what's up, and you can fix it. Think of the odds, the tens of thousands of 3.6 engines that are doing fine, some with massive miles on them.
You know that your mods didn't break this so there's certainly no risk to any engine out there that uses your tune or this equipment. It's the core engine that's the issue and most of us don't even ever see a hiccup.
If I translate this into the blown #5 on 1970 AMC 390s - I'd have been afraid to even take my car out of the garage. I've personally known many people who lost the top piston land on those engines, I was one of them - and it happened to mine TWICE (once before I bought it.
And yet those same engines are out there getting thrashed almost daily. (different, of course, because we figured out the issue and have now decades later, resolved it)
Should I trade my truck or park it, afraid to ever drive it again and heaven forbid, hit 3,000 RPM while towing? Which is what I did over and over and over my last tow with this truck - it spent a lot of time at 3,300 RPM.......

 

[DAVECS1]

The problem is you may never know when it fails until it fails catastrophic. If you drive normal most of the time you are not in that rev range very long. Who says it is not my harness or ECM drive not working well with the solenoid. Maybe I have low level stand by current or EMI than hangs it open.

Honestly there should be a pressure sensor after that solenoid to confirm it is functioning correctly. Otherwise it is a roll of the dice!

 

[ShadowsPapa]

Here's my take, and possible solution -
Jeep hires you.
Problem solved.
Their tunes stock from the factory would be better, there would be better/more testing and a better understanding of "what went wrong" if something does go wrong.
You could be QA.

Due to my troubleshooting and working with Symantec years ago on obscure problems, they called out of the blue one night (yeah, they got my home number!) and literally said "we want to fly you out to Cupertino to talk to you about our QA position.

A friend who was a volunteer support person when I was for Symantec had actually reverse-engineered a lot of the code in Windows 95 and was working with Symantec as a volunteer to make their Windows utilities better. Microsoft caught wind of that and hired the guy, and paid him quite well.

You need to be inside - fixing things for them.

 

[DAVECS1]

I worked with Chrysler in 2000. One of the reasons I am familiar with the issues here. Go drive a Plymouth Neon. I mapped that car ?
Anyway I imagine they are just as convoluted as the company I work for now. These days the management engineering has run rampant and it is concerning to say the least.

 

[ShadowsPapa]

I worked with Chrysler in 2000. One of the reasons I am familiar with the issues here. Go drive a Plymouth Neon. I mapped that car ?
Anyway I imagine they are just as convoluted as the company I work for now. These days the management engineering has run rampant and it is concerning to say the least.

We had a Stratus for a couple of years. Liked the car, the color was fantastic but was really glad it was one of those rare times we bought an extended warranty....... that engine had head problems. Second time we said that's enough - and went back to Jeep.
We had super-low income for a while and figured we couldn't afford the payments on a Cherokee or Grand Cherokee. That car convinced us we could and we've not looked back since.

 

[NachoRuby]

I worked with Chrysler in 2000. One of the reasons I am familiar with the issues here. Go drive a Plymouth Neon. I mapped that car ?
Anyway I imagine they are just as convoluted as the company I work for now. These days the management engineering has run rampant and it is concerning to say the least.

That's really cool! Too bad you were not around for the srt4!

 

[DAVECS1]

If you have a rattle STOP driving your truck. It is a bad cam!!!!

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