[bmwarg]

Hi everyone,

I NEED HELP!

I'm having some issues with my 335i. My father drove my car for the past few months and called one day to say that the engine check light went on when he was accelerating and made a sharp lane change. The engine check light has not come back since.

However, upon getting the car back I noticed that it lacks significant power (feels like it is limp mode). I used Bavarian Technic and saw the 30FF shadow code come twice during the time my father had the car. I also used JB4 to log and there is 0 boost. Also, when starting the car, a ton of what seems like oil spits out from the back (see image). Additionally, I had the oil changed this past Saturday at 6K miles and the mechanic said it was very dirty. No codes are being thrown.

Things done to the car recently:

1. Mechanic adjusted the charge pipe and the downpipes because it was rubbing just before my father took the car.
2. new fuel injector about 4k miles ago
3. new spark plugs about 4k miles ago
4. Vacuum lines and turbos were replaced by BMW 1 year ago.


What could it be? How bad is it? Could it be a blown gasket that is causing no boost and oil from being spit out from exhaust at start?

No CEL but I have a BMS backend flash and so may affect code triggers?

[bmwarg]

bump

[pits200]

You need to find the root code. The 30ff is just a safety features to cut boost till the main problem is resolved. Stop pushing the car at this point, check all turbo connections at the ic and chargepipe. If it truly is oil you're seeing out of the tailpipe you would be getting more codes than 30ff.

[bmwarg]

Originally Posted by pits200

You need to find the root code. The 30ff is just a safety features to cut boost till the main problem is resolved. Stop pushing the car at this point, check all turbo connections at the ic and chargepipe. If it truly is oil you're seeing out of the tailpipe you would be getting more codes than 30ff.

Thank you. Maybe it is just carbon deposits being spit out. I'm going to try to remove the BMS backend flash to make sure that it isn't disabling some codes from being read.

[bmwarg]

Turns out that it was the JB4 interfering with the electrical signal that controls the vacuum that moves the turbo wastegate actuators. When I removed the JB4 the boost came back. I read another thread where they had the same problem and they fixed the problem by crossing the wastegate wires in the harness. Does anyone know what crossing the wastegate wires means?

[bmwarg]

Turns out it was the JB4 boost transistor that needed to be upgraded / replaced.

[maddmatt02]

can you give me some more info on that? I tried to google jb4 boost transistor but got 3 links to burger tuning sales for jb4s for different applications, 4th was this thread, then some stuff about the DME mosftets. bought a used jb4 that all the cool little features work but it builds 0 boost, and based on the deformed plastic case and slightly discolored board you can tell something has gotten hot before.

might be worth a shot before I just give up and toss it.

[maddmatt02]

ok, didnt find anything related to the jb4 transistor problem itself but googling in geeral I found the part, and found how to test it with my DMM, and found a replacement.

if this works I owe you for setting off the litle light bulb in my head!

[Flex68]

Wow first I heard of this issue ... Glad I went with Cobb

[maddmatt02]

Originally Posted by Flex68

Wow first I heard of this issue ... Glad I went with Cobb

if its the first you heard of the issue, then its probably not a common issue... and its not necessarily my problem and I got mine used so who knows what its been through as far as previous (possibly faulty) installations.

my other one is used as well and I havent had a problem for 5 months with it. and 2 friends bought theirs used as well and one has at least a year on it and another even more than that.

[bmwarg]

Originally Posted by maddmatt02

if its the first you heard of the issue, then its probably not a common issue... and its not necessarily my problem and I got mine used so who knows what its been through as far as previous (possibly faulty) installations.

my other one is used as well and I havent had a problem for 5 months with it. and 2 friends bought theirs used as well and one has at least a year on it and another even more than that.

Sorry, I wasn't checking the messages. I sent the JB4 back to Terry and he replaced the boost transistor free of charge. It happened after owning the JB4 for about 3-4 years. Problem fixed.

[maddmatt02]

no big deal, I just sent it in the other day. I am paying for it but its a very reasonable price and since I bought it used I couldn't expect them to do it for free.