[YoungBlood]

I've asked this a couple times in the MHD master thread, gotten zero answers.
How does the MHD rattle fix work? Is it like menu 10 on the JB4? What about menu 12? Just curious, as this fix, is part of the reason I am drawn to the JB4. I actually ran a JB4, for about a week, courtesy of a friend, and was able to adjust out 90% of my rattle using menu 10, and I absolutely loved map 1, although I had a bit of lag, it was only a hair more than stock, and it pulled so much harder after that I could care less. Does the MHD rattle fix work the same way? From my understanding, menu 10 just adjusts how far the WG is held open off throttle, and low throttle, this is the only time I get rattle, none on acceleration. Yes I know it's just a band-aid, but I'm not planning on buying new turbo's til the rattle get's real bad or the turbo's die.

Summary, how does MHD rattle fix work?

[hellokitty]

sub

[fatjoez]

Originally Posted by YoungBlood

Summary, how does MHD rattle fix work?

master thread someone replied to you
http://www.e90post.com/forums/showpo...postcount=5068

"I suggest looking at YouTube and seeing how an external wastegate works to better understand rattle. Tons if you type in n54 rattle."

[JustDriveIt]

All MHD does is control how open the wastegate is at idle/low throttle. No fix = shut.... this causes rattle in some turbos due to the actuator rod being too long (from loosening over time) so the wastegate is bangint rapidly against the metal creating the rattle instead of being tight against the bypass exhaust outlet. The more fix (more lag) you do, the further it tells the wastegate to be away from the outlet. Some people are able to pull it out so that it doesn't bang against metal and the rattle goes away. Mine goes away at about 20% on the MHD slider (80% lag) but it is pretty laggy obviously and even through 30FF underboost codes.

I fixed my rear turbo rattle by tightening the actuator rod. The front is terrible, and I'm hoping to tighten the actuator somehow (probably by adding washers under the mounting bolts to extend the length).

[YoungBlood]

Thanks, I was wondering if that's how it worked, the extending of the wategates that is. Only my rear turbo rattles. Tightened the rod and it got rid of quite a bit but once in a while the rattle is horrid, other times it's not there.

[cstmx_ryder]

hmm.....So I was told that the DME controls the WG. My issue is that the WG will stay 'open' during cold-start (while oil temp warms up), then when the car warms up, the WG should 'close'. Not the case, I'm positive of it, as I've been observing that for the past week or so.

My car is 'super' loud and backfires and gurgles like a mf, but like I've been observing, this is happening at random times now, whether the car has warmed up or not. I would think that the 'Rattle Fix' in MHD has something to do with fixing this issue? Haven't tried, but would like to know if anyone has experienced the same using MHD? If so, what is the fix?

TIA

[ferocity02]

Here's how I think it works...

When disabled (box unchecked), it will use the tune's WGDC values as is. When enabled, you can then select a value from 0-80%. I think this value is a simple multiplier on the tune's WGDC. So let's say the tune is commanding 50% WGDC and you have rattle fix enabled and set to 20%, the WGDC will instead be 0.5*0.2=10%.

You cannot select 100% when rattle fix is enabled just because this would be the same thing as it being disabled.

Someone please correct me if I am wrong!

[YoungBlood]

Originally Posted by ferocity02

Here's how I think it works...

When disabled (box unchecked), it will use the tune's WGDC values as is. When enabled, you can then select a value from 0-80%. I think this value is a simple multiplier on the tune's WGDC. So let's say the tune is commanding 50% WGDC and you have rattle fix enabled and set to 20%, the WGDC will instead be 0.5*0.2=10%.

You cannot select 100% when rattle fix is enabled just because this would be the same thing as it being disabled.

Someone please correct me if I am wrong!

Wish MHD would shed some light on it, because I'd like to know what I'm actually doing messing with that setting..

And is a higher % or lower % wgdc more open or closed?

[ferocity02]

Originally Posted by YoungBlood

Wish MHD would shed some light on it, because I'd like to know what I'm actually doing messing with that setting..

And is a higher % or lower % wgdc more open or closed?

The higher the setting (%) the more closed the wastegates are.

Generally speaking, fully open (0%) should produce the least amount of rattle. Mine rattles the worst at 40%, and both 0% and 100% (disabled) rattles the least.

0% is nice because it will make the exhaust louder and burble more on decel. But it tends to rattle my interior more. I need to try 20% next. At the lower % you'll notice more turbo lag.

[YoungBlood]

OK, thanks! You have to reflash the map each time you change the % used, correct?

[ferocity02]

Originally Posted by YoungBlood

OK, thanks! You have to reflash the map each time you change the % used, correct?

Correct.

[Sgop335]

Originally Posted by ferocity02

Here's how I think it works...

When disabled (box unchecked), it will use the tune's WGDC values as is. When enabled, you can then select a value from 0-80%. I think this value is a simple multiplier on the tune's WGDC. So let's say the tune is commanding 50% WGDC and you have rattle fix enabled and set to 20%, the WGDC will instead be 0.5*0.2=10%.

You cannot select 100% when rattle fix is enabled just because this would be the same thing as it being disabled.

Someone please correct me if I am wrong!

i think your settings etc is correct and i would like to try 20%. But the multiplier seems incorrect, if that was the case would be hard to produce boost since at load wgdc is 80% and higher w tune.

Its mostly a setting for idle, decel., may be coast, meaning (more) open under those conditions. Im getting my new turbos installed and think a 20% setting would be better.

[ferocity02]

Originally Posted by Sgop335

i think your settings etc is correct and i would like to try 20%. But the multiplier seems incorrect, if that was the case would be hard to produce boost since at load wgdc is 80% and higher w tune.

Its mostly a setting for idle, decel., may be coast, meaning (more) open under those conditions. Im getting my new turbos installed and think a 20% setting would be better.

I think the multiplication theory is correct, but only at lower load. So under higher load either the tune uses a different table which is not multiplied, or the multiplication is only done on the low-load part of the table. I'm just guessing here as to what seems most feasible.

But you are right, WGDC under high load is not affected by the rattle fix setting.

[JustDriveIt]

Originally Posted by cstmx_ryder

hmm.....So I was told that the DME controls the WG. My issue is that the WG will stay 'open' during cold-start (while oil temp warms up), then when the car warms up, the WG should 'close'. Not the case, I'm positive of it, as I've been observing that for the past week or so.

My car is 'super' loud and backfires and gurgles like a mf, but like I've been observing, this is happening at random times now, whether the car has warmed up or not. I would think that the 'Rattle Fix' in MHD has something to do with fixing this issue? Haven't tried, but would like to know if anyone has experienced the same using MHD? If so, what is the fix?

TIA

Have you tested to see if you have a vacuum leak? I had one which helped a little, but I still need to find out how to tighten the front actuator rod.

[YoungBlood]

I still need to test, it very well could be

[cstmx_ryder]

Originally Posted by JustDriveIt

Have you tested to see if you have a vacuum leak? I had one which helped a little, but I still need to find out how to tighten the front actuator rod.

The dealership did a leak-down test about 3 months or so ago. They said they didn't find any leaks.......Not sure if I should trust them?

[ferocity02]

Originally Posted by cstmx_ryder

The dealership did a leak-down test about 3 months or so ago. They said they didn't find any leaks.......Not sure if I should trust them?

A leak down test won't reveal a vacuum leak.

[cstmx_ryder]

Originally Posted by ferocity02

A leak down test won't reveal a vacuum leak.

Ok, so I would have to manually test for vacuum leaks? Like using the Mityvac like some others have mentioned? But not sure what the proper steps are in diagnosing vacuum leaks using Mityvac.

Care to shed some light on this?

TIA

[JustDriveIt]

Originally Posted by cstmx_ryder

Ok, so I would have to manually test for vacuum leaks? Like using the Mityvac like some others have mentioned? But not sure what the proper steps are in diagnosing vacuum leaks using Mityvac.

Care to shed some light on this?

TIA

You just get a vacuum gauge and look at pre and post solenoid with the car running. Here's a pdf of what the values are supposed to be.

http://www.e90post.com/forums/attach...6&d=1264862759

[cstmx_ryder]

Originally Posted by JustDriveIt

You just get a vacuum gauge and look at pre and post solenoid with the car running. Here's a pdf of what the values are supposed to be.

http://www.e90post.com/forums/attach...6&d=1264862759

Thanks for the link. But I'm not sure I'm getting this, lol.