[6speed]

Originally Posted by JamesM3M5

$50 for a look-over and diagnosis is cheap. Always best to have an experienced mechanic check the car out every now and then anyway to catch issues before they become problems.

thanks you're right. I'm gonna get it checked out. but i do have a few noob questions tho. what is a DME and what is TMAP? oh and btw i have my jb4 on auto clear, could that have solved the problem?

[bootay]

The car will throw codes that do not indicate a crisis. It is a very good idea to get the USB cable in there so you can hookup a laptop to it and log data, update the JB4 software, etc.. And be sure you hit n54tech.com or ping Terry directly (that is where the JB4 tune is from), he'll get you straight.

[bee-yum-uu]

Here is a snap shot of the limp home section from the BMW engine management document. Though there are several faults that can trip limp home mode it seems to be due a airhandling related issue due to the charge pressure sensor fault. There are two charge pressure sensors on the N54. One upstream of the throttle called the TMAP (temperature and manifold air pressure sensor) and the MAP (manifold air pressure sensor) sensor in the intake manifold. The TMAP is easy to access without having to remove anything. You might have to remove the airbox to get more working room to reach the MAP. Its one of these two sensors thats malfunctioning causing the sensor fault. I would recommend getting rid of the JB4 and doing a couple of key cycles. Usually the way diagnostics are designed is to clear fault codes after mutiple" no fault decisions". Good luck

[bootay]

Originally Posted by 6speed

btw i have my jb4 on auto clear, could that have solved the problem?

Yes, the codes, once cleared, will regenerate if the problem continues to be seen, but auto-clear will keep removing them. If you think there's an issue, it's good to remove auto-clear so you can capture any codes and ping Terry with them to diagnose.
Don't Panic!

[6speed]

Originally Posted by bootay

The car will throw codes that do not indicate a crisis. It is a very good idea to get the USB cable in there so you can hookup a laptop to it and log data, update the JB4 software, etc.. And be sure you hit n54tech.com or ping Terry directly (that is where the JB4 tune is from), he'll get you straight.

yeah i emailed terry. what a great guy. he emailed me back telling me to send him a picture of my install/dme box and to check the TMAP. i dont know what a DME is so it will be hard to take a picture of it

[bootay]

Originally Posted by 6speed

yeah i emailed terry. what a great guy. he emailed me back telling me to send him a picture of my install/dme box and to check the TMAP. i dont know what a DME is so it will be hard to take a picture of it

DME is where the JB4 is installed, in that white box. If you read the install guide (which has TONS of pics, even videos), it'll show you all about how to get in there and how it should be hooked up.

[bee-yum-uu]

DME refers to digital motor electronics. In layman terms it just refers to the ECM (Engine control module).

[JamesM3M5]

DME = Digital Motor Electronics (ECU). It's a Bosch term, but the N54 uses a Siemens ECU. We use DME because BMWs have had Bosch for decades - ever since fuel injection was installed in the 70s.

TMAP = Temperature and Manifold Absolute Pressure sensor. It's the pressure sensor that tells the ECU how much load the engine is seeing, and measures boost pressure on forced induction cars. TMAP also reads intake air temperature (IAT or AIT) in the same unit. The N54 has 2 TMAP sensors - one in the manifold and one in the elbow pipe that leads up to the throttle body. It's call Absolute Pressure since it's measuring pressure from absolute zero pressure (perfect vacuum). 1 bar / 14.7 psi is atmospheric pressure at sea level. Our sensors go to 2.5bar absolute, or 1.5bar (about 20.7psi) above atmospheric pressure.

[6speed]

ok i just disabled auto clear. what I'm gonna do is go to the shop in a few hours and have him check my TMAP and my MAP, because I've also been having another problem with the car that may be TMAP related. I started a thread on it, if you are interested just go to my stats. anyway, ill keep you posted on what happens when i get back. besides that, thank you to everyone who contributed. every post was helpful. i feel so much better. you guys are awesome, and again, i really am thankful to everyone who posted. you guys are the ish

[MCoupeInsanity]

Take it to Neil at Oceanside Motorsport -- they are legit BMW pros and handle plenty of modded bimmers. I almost feel tempted to drive down there from LA to let him do my routine maintenance. Always had great experiences with them when I was living in SD.

And they may handle other brands, but I only ever see BMW literature in their waiting room, and bimmers in their lot. Beautiful, sexy, modded up bimmers.

[Chrisred]

Originally Posted by RambleJ

Did you have the same codes?

Honestly I didn't even check the codes. They went away after i restarted car. Once i retightened the charge pipe. I knew it was my charge pipe cause I had problems installing it. But then I figured it out.

Btw I'm talking about the charge pipe I use with my meth kit.....so I don't know I we in same boat...

[Tony135]

It's happened to me before when I changed maps whilst under hard acceleration lol. It just went into limp mode but after it was fine. I'm sure your car is just fine but get it checked out anyway.

[abhishriv]

probably too late for my input but sounds like what happend to my car last week.. it was logged as a misfire in one of my cylinders.. the spark plugs and coils turned out to be all fine.. and they they found that my chargepipe was leaking. they fixed the chargepipe and the problem was solved. but i had all the same symptoms as OP did the limp mode twice and would go away without any errors when car was turned off and restarted. Thought it was a huge problem at first but turned out to be an easy fix.

[E92murdered]

good news, did you have a stock chargepipe? also OP any news??

Originally Posted by abhishriv

probably too late for my input but sounds like what happend to my car last week.. it was logged as a misfire in one of my cylinders.. the spark plugs and coils turned out to be all fine.. and they they found that my chargepipe was leaking. they fixed the chargepipe and the problem was solved. but i had all the same symptoms as OP did the limp mode twice and would go away without any errors when car was turned off and restarted. Thought it was a huge problem at first but turned out to be an easy fix.

[Chadd]

Keep in contact with terry bro he helped me with the same exact codes the other day. I think my jb4 got fried from my body shop jumping my car after they killed the battery. We switched out jb4's and problem solved.

Terry helped me out big time.

[abhishriv]

Yup, stock chargepipe, they kept the car overnight though and changed out the chargepipe. All was done under Certified warranty and i didnt have to pay a cent

Originally Posted by E92murdered

good news, did you have a stock chargepipe? also OP any news??

[335(EX)(EYE)]

i would check for boost leaks/turbo issues also..

[6speed]

Originally Posted by E92murdered

good news, did you have a stock chargepipe? also OP any news??

nope, I've been busy this week, so I'm can't do anything until next week comes. But so far the car has been fine, i keep checking codes since i disabled auto clear and there haven't been any. Ill be sure to let you know by next week, that is if i even find out haha