(Engine experts needed) Chirp, Vibe, Pop (What is Wrong?)

[toximus]

That is a bad suggestion

Do you mind expanding on why? After talking to Mark we were discussing what will happen when pressurizing the intake and if it's even possible or if it'll blow by one of the valves or the cylinder rings and blow out the RMS. I don't know enough about this topic.

I had a distinct conversation with Mark in the past about a topic I do know about to say that I don't trust him.

 

[k-huevo]

Assuming one is wearing an oven mitten, and can hold pressure greater than 200lb, the engine will stall or will not start (probable), backfire (less likely, but try holding that back), or the exhaust tubing will separate at the weakest connection (rare, but history provides examples). Thus putting an end to the create-excessive-back-pressure-while-listening-for-exhaust-leaks test.

 

[toximus]

I pressurized the intake. I couldn't get it up to a full 14psi, but holding 5ish didn't reproduce the sound. Considering that the sound starts as soon as 1psi is reached I don't see any reason to go higher?

 

[toximus]

Also, these are awesome:

https://www.amazon.com/dp/B000AYN7LU/?tag=wranglerorg-20

 

[toximus]

I could bolt a plate with a valve stem on it to check for leaks on the intake manifold but I'm not really sure what I'd be looking or listening for since BoostedTech said to listen for the chirping, vibrating, or popping when pressurizing the intake. I'm also not sure how much leakage would be considered normal if any leaks past the rings, valves, or RMS.

 

[toximus]

Shooting air up the tailpipe isn't really effective since the muffler is designed to drain through a small hole (I assume so it doesn't ice up in the winter). The stock muffler is the same way...

I don't really have any direction to progress further down this path and I don't know enough about engines if I take apart the 4.0 to know what's within tolerance or not or what parts to even look at. Similarly with the supercharger I have no clue what's within tolerance and what's not. The consensus on this forum and my boosted 4.0 guy is that the SC is most likely the issue although we don't know how. The only person adamant that the SC is fine is Mark from BT. I'm not sure which it is and I'm at a dead end on both.

Someone was kind enough to send me their BoostedTech SC off the same year, model, and color of LJ as mine for testing. Without blindly "fixing things" this seems to be my only course of action to figure out which end is the problem.

 

[Daryl]

I could bolt a plate with a valve stem on it to check for leaks on the intake manifold but I'm not really sure what I'd be looking or listening for since BoostedTech said to listen for the chirping, vibrating, or popping when pressurizing the intake. I'm also not sure how much leakage would be considered normal if any leaks past the rings, valves, or RMS.

BoostedTech seems to be giving you bits & pieces of a procedure. Either give you the entire procedure or hire someone who can (BoostedTech).

 

[Daryl]

Someone was kind enough to send me their BoostedTech SC off the same year, model, and color of LJ as mine for testing.

Barring BoostedTech coming up with an exact procedure this sounds like a good option.

 

[toximus]

BoostedTech seems to be giving you bits & pieces of a procedure. Either give you the entire procedure or hire someone who can (BoostedTech).

Just to be clear, every test and replacement part that has happened so far has come out of my own pocket.

 

[toximus]

Barring BoostedTech coming up with an exact procedure this sounds like a good option.

I'm willing to do more tests but I can't think of any more tests to do that make sense.

I was hesitant to borrow the SC and spend even more money shipping it back and forth since I'm not sure what it means if I figure out which end is causing the problem if I don't know how to fix an engine problem and BT isn't willing to fix a SC problem. But at least I'll know in good conscience which is the problem.

 

[toximus]

I just had a realization. How can BoostedTech, or us, know that the rotors aren't deflecting underload (which could be evidenced by messing up the machining) if this is as much as we can see without taking the unit apart?

I'd guess there's 40% more rotor that we can't see.

 

[BuildBreakRepeat]

I just had a realization. How can BoostedTech, or us, know that the rotors aren't deflecting underload (which could be evidenced by messing up the machining) if this is as much as we can see without taking the unit apart?

I'd guess there's 40% more rotor that we can't see.

View attachment 165088

Only if they ran it on the bench and checked for vibrations. Which they didn’t do.

 

[Daryl]

I just had a realization. How can BoostedTech, or us, know that the rotors aren't deflecting underload (which could be evidenced by messing up the machining) if this is as much as we can see without taking the unit apart?

I'd guess there's 40% more rotor that we can't see.

View attachment 165088

They can’t. I can’t believe they wouldn’t take it apart for inspection. They’re so simple to work on.

 

[Apparition]

I just had a realization. How can BoostedTech, or us, know that the rotors aren't deflecting underload (which could be evidenced by messing up the machining) if this is as much as we can see without taking the unit apart?

I'd guess there's 40% more rotor that we can't see.

View attachment 165088

I think it’s ridiculous they won’t open it up and take a look.

 

[toximus]

I was asked if the boost could be blowing out between the supercharger and the tub which my pressure test wouldn't have shown.

This picture was taken immediately after I removed the SC and does not seem to show any indication of that happening as there's a distinct line where the oring contained the spray from the 7th injector:

 

[Daryl]

I was asked if the boost could be blowing out between the supercharger and the tub which my pressure test wouldn't have shown.

This picture was taken immediately after I removed the SC and does not seem to show any indication of that happening as there's a distinct line where the oring contained the spray from the 7th injector:

View attachment 165513

View attachment 165514

I agree. If it was leaking that o-ring would be deformed at said leak.

 

[Apparition]

This may or may not be useful, popped up in my YouTube feed.

 

[toximus]

Just a small update... I heard back from another (very large and seemingly reputable) multiple manufacture certified supercharger sales and repair shop and they don't work on M90s anymore.

This may or may not be useful, popped up in my YouTube feed.

I'll watch this.

 

[toximus]

BoostedTech is rebuilding/replacing the supercharger.

 

[jesseshoots]

BoostedTech is rebuilding/replacing the supercharger.

Woah, that was a complete change in their stance. How'd this come about?