Under boost errors after disabling JB4 / MHD

[BadgerDog]

So I need to get my car smogged... as such I disabled JB4 from the steering wheel (map 0), and flashed back to stock for MHD. Actually did the full stock flash because flashing the map messed up somehow and killed my ECU...

Since then I have been getting occasional 30FF Boost Under Target errors. Cant say I can figure out how to reliably create them. At least once it happened shortly after being heavy on the throttle and at least one other time it happened while gently accelerating. I did get one single boost -over target error early on (not long after disabling the tune, and it was the first error I saw of this type).

Im wondering if there is any chance there is some self-adjustment to the car (adjusting the map perhaps, or wastegate position, or...) and it got 'used' to having the JB4 / MHD tune in there and now its expecting more boost than its getting which causes issues (though the one over boost error makes me wonder). IF that is the case I assume it will self-adjust over time and chill the heck out on these error codes.

I have read that wastegate problems can cause these errors, and I DO hear a wee bit of rattling on startup (for a second or so then dont notice it again). Car has around 43k or so miles on it so its not that old.

I dont know, any thoughts guys? This is preventing me from getting the car smogged because you cant do that with a CEL light on, and resetting the codes resets SMOG readiness... its starting to frustrate me.

 

[BadgerDog]

I should add that I ALSO swapped the DCI that I installed for the stock breather box at about the same time. Turns out that while the DCI I bought are C.A.R.B. (california SMOG approval process) they arent for my specific model year. Serious PITA. So it IS possible I have a leak somewhere causing under boost, but I dont think so. Its a pretty simple install, and I visually checked the two connections, as well as feeling around with my hand for any moving air.

 

[Chippie]

I’m no expert but it does sound like a boost leak, I’d suggest doing a smoke test and then go from there.
Sounds like hydroelectric lifters on startup as the oil pressure builds. waste gate rattle is when you lift off the throttle and the play in the turbo linkage rattles

 

[Argyll Andy]

Faulty Turbo Boost Solenoid(s) can also cause this error if the the vacuum is weak/compromised.

 

[BadgerDog]

I’m no expert but it does sound like a boost leak, I’d suggest doing a smoke test and then go from there.
Sounds like hydroelectric lifters on startup as the oil pressure builds. waste gate rattle is when you lift off the throttle and the play in the turbo linkage rattles

Good to know, thanks. I will try to do a smoke test sooner than later.

Faulty Turbo Boost Solenoid(s) can also cause this error if the the vacuum is weak/compromised.

Interesting. I somewhat doubt thats my problem as it started right as I changed all these other things. Not impossible, but its far from the simplest explanation. Ockham's razor and all that.

 

[R.E92]

Probably a boost leak or problems with the vacuum lines. With the JB4 installed you wouldn't get the code as it just masks the problem.

The vacuum lines are easy to check so do those first, then move onto checking the charge pipework, common leaks are around the intercooler. The chargepipe on the Z4 is bulletproof so not normally an issue but easy enough to check.

If I were you I'd remove the JB4 completely, if you already have MHD then there's no reason for it.

 

[sumotan]

Does MHD have a program for Z4 ??? I wrote to them & NO was the reply .

 

[BadgerDog]

[ref]R.E92[/ref], [ref]sumotan[/ref], I am not using the full map that MHD offers. I'm doing the backend map only, that JB4 provides to work with it. Even if I were running the full map there would still arguably be use for the JB4. It offers some nice information with the wireless connection to my phone as well as gauge hijacking and the like. The company is absolute trash, though, as I've come to find out. I may one day decide to fork out the cash for the full map capability of MHD and not bother with the JB4 for anything BUT the fancy I/O interface...

 

[R.E92]

You don't have to pay the full cost for MHD to upgrade from the backend maps. They offer a separate license for €20. https://mhdtuning.com/products/n54-jb4-bef-upgrade-to-full-flasher

I suppose you would then need to add the OTS pack on top of that so the cost does add up. Good time to buy any licenses though as they have a black Friday 15% sale.

Does MHD have a program for Z4 ??? I wrote to them & NO was the reply .

They support the Z4 but only the N54 models.

 

[sumotan]

Thanks BadgerDog, btw why is the company trash thought JB4 has a huge following with good tech support ?

Sorry R.E 92 forgot to mention that mine is a 28i

 

[BadgerDog]

[ref]sumotan[/ref], I'll get around to creating a long post sometime with my experiences, but the owner is a POS that doesnt stand behind his products, and refuses to honor his own terms and conditions. Had to go through a big thing with my credit card to fix another situation (unrelated to the JB4). Their products are kinda iffy on quality as well.

 

[sumotan]

Hi BadgerDog,
Do you mean from the US or a dealer in the UK ?

Thanks

 

[BadgerDog]

Hi BadgerDog,
Do you mean from the US or a dealer in the UK ?

Thanks

Was dealing directly with the company and its owner. I am in the US.

 

[sumotan]

Oh ok got it Badger.

Thanks