[Chief Orman]

As one of those who wanted to tap the last 20% of performance from my 335d, I spent a hell of a lot time trying to figure out what tune I wanted to use. Moreover, since I own a 2010 335d CPO with an extended warranty so I felt like I needed to keep the car as stock as possible, e.g., no cold air intake, non-OEM rims and tires, etc. This consideration only became more important as more and more mechanical issues have emerged for 335d owners over the past 12 months.

Based on all my research I finally decided on buying both the JBD and the DTUK. To be honest it was impossible to get a clear view of which tune was superior in a head to head comparison from reading these boards. Ronin provided a great overview but seems to have gone mostly silent since his car had the meltdown. Worse almost all the board threads are now mostly full of the various carbon deposit emissions systems issues we are all having.

Back to the tuning boxes…both DTUK and BMS provid great sales and support. In fact, I have learned more about tuning boxes from Terry's (of BMS) posts than from any other place. Andrew at DTUK was also very helpful when I purchased my box. That said, DTUK provides little written detail on the four tuning maps in their box. This is annoying as hell. Yes, you can call Andrew day or night but the mapping schematic they provide is literally unreadable. Why? You'd think they were trying to protect a state secret or something given DTUK unwillingness to provide written descriptions of exactly what their maps do.

In any event, I ran both boxes back to back over several weeks. In fact, I pulled the acoustic engine cover so many times I had to buy a new one since the foam fell apart. I changed the boxes and as well as the individual settings on the boxes to try and discern the differences. Given the relative similarity of operation (i.e., more fueling) of both tunes it was really surprising how much difference there was in feel and performance between the two boxes. FWIW, I also developed a major attitude about the need to unscrew both boxes to be able to change the settings. In fact, on both tuning boxes I had to swap out the screws because they quickly became stripped. JBD and DTUK…make the damn box easier to adjust the settings!

JBD Overview
Simple, intuitive tuning box that a pet monkey could install. Two plugs connect it to the fuel rail. Power adjustment is made via turning a tiny dial inside the box from 60-100%. Other than the cheap casing and screws, it is really hard to say anything bad about the amazing simplicity of the JBD box. I got to the point where I could install the thing in less than 10 minutes. The box is small and easy to zip tie out of the way under the hood.

Like everybody else on this board, it is hard not to want to dial the box immediately to 100% after a few runs. On anything but 100% the performance increase, in my view, was just not enough to really transform the car. With the box turned to 100%, my car just pulled so much better at through the higher end of the rev range. The bizarre dead spot in the high end is just gone. The JBD has a sort of "on cam" pull at the high end for anyone who was born before 1970. Finally, the JBD, for whatever reason, worked seamlessly with the car's transmission, i.e., shift points and rev ranges did not get squirrely. More on this later.

DTUK Overview

Unlike the JBD, the DTUK CRD T connects to both fuel rail and turbo sensor to provide modestly more boost (JBD only changes fueling) if you choose map 1, 2, or 3. The DTUK has a multitude of different setting (28 in total, i.e., 4 maps X 7 different jumper voltage settings) that break down as follows:

4 major maps:

Map 1 = increased fueling and increased boost
Map 2 = increased fueling and even more turbo boost
Map 3 = even more fueling and increased boost
Map 4 = increased fueling only

Each map has seven different voltage power settings that you can change via jumpers that require you to have hands the size of an infant to change. These voltage power settings are available for each map as follows:

+30 +20 +10 0 -10 -20 -30

The DTUK box ships with the power jumper set at the zero position. You can then set the voltage up 3 setting or down three settings. I am not sure why anyone in the US (looking for speed not economy) would use one of the three down voltage settings but who knows. Those of us looking for more power can crank the voltage up in 3 increments +10 +20 +30.

As a practical matter the +30 setting is unusable. You'll throw a limp code immediately. For that matter, +20 is too temperamental. Push too hard before the engine warms up and the car you will always throw a code. (I never threw a code using the JBD box…a testament to BMS work on their tune.) Moreover, I would not trust driving at +20 in hot conditions >70 degrees. Bottom-line…I felt like it was too much on the knife's edge code wise to use +20.

So in my view the you really have only eight different truly usable settings on the DTUK, i.e., the four maps running at default zero or +10. For my money, and those of you who are looking for substantial performance gains, you are always going to want to run the four maps at +10. The car does not throw codes and you feel a significant increase in performance. With the four maps at +10 you have now reduced the box down to four very usable and very potent maps.

To cut to the chase, I liked map 2, disliked map1 and 3 and LOVED map 4. While experimenting with the various maps on the DTUK, as well as using the JBD, I really began to realize how much I hate the off the line/low end drivability of the stock 335d. The stock throttle response of the car just sucks in comparison to what the DTUK tune does to the car's day to day drivability. The other consideration beyond increased performance is how the transmission behaves and shifts. On balance I thought the JBD did a better job of integrating with the transmission. On some of the DTUK maps I felt like the transmission hunted and lagged. This was not a big deal but made me worry about the transmissions ability to integrate with a few of the DTUK maps.

In any event, know that I really wanted to like map 1, 2 or 3 because of the increased turbo boost those maps provide, unlike map 4 which only increases fueling. In fact, why the hell would one buy the DTUK and spend the extra $200 over the JBD if not to utilize its increased turbo boost feature? That said, after test every map extensively map 4 +10 was just unbelievably fantastic and in my view clearly superior to the other maps. My car goes like hell at low RPM and high RPM. I would feel perfectly confident racing an M3 to 100 mph using this tune.

The car with the DTUK feels MUCH more powerful off the line. This is the primary difference vis a vis the JBD. Moreover, with the DTUK I would estimate that I have picked up 60-70 hp over stock. The car just pulls like a freight train Moreover, I have to think that somehow the DTUK's (tuning box is actually made by DTE in Germany) experience with their pedal box product has somehow made its way into the DTUK CRD T. In any event, huge performance gains and drastically improved drivability via better throttle response and modulation.

To recap, here is why I think the DTUK CRD T is better than the JBD... First, I can't say anything bad about the JBD…it is a a great deal. However, the JBD, in my car, did not provide significantly improved drivability around town. Sadly this is where I spend most of my time driving. You need to be on the freeway, accelerating from 40 mph to 100 mph, to really feel what the JBD can do. Moreover, and I know this sounds strange, but when I used the JBD I could smell a noticeable but very faint diesel/exhaust smell that just was not there with the DTUK.

Like I said, the DTUK on map 4 +10 makes you always aware that you have much more power on tap. Just moving in out of traffic around town is easier thanks to the improved throttle response. You also get even more of the great torque pushing you back in your seat. The power is easier to modulate all the way around. When you open it up the car pulls and sounds like a race car. It is fantastic and a total transformation of the car.

Let me close by saying that I sweated bullets about the warranty, mechanical issues, detection etc. However, after reading about all the myriad problems that have cropped up with the 335d over the last 18 months, I just said to myself "screw it…this car is going to have mechanical issues with our without the tune." Well I have been running a tuned care for 5,000 miles of damned hard driving and I have not had an issue. Fingers crossed. I have not gotten any indications that the car is being pushed beyond its mechanical limits.

I hope this helps those of you considering a tuning box.

[Bicax]

Excellent reviews, exactly what I've been looking/asking for!

Would be perfect with dyno runs comparing both boxes, but I don't want to push it

I have the DTUK CRD-T and I fully agree with your comments regarding the box in general, and also regarding Andrew's responses. I was totally lost regarding the maps when I got it, asked a few questions about the differences between each of them, and was diplomatically told to have a look at the charts included in the package... which for me are really not self-explanatory.

I've been running the box for over a year, and have done probably over 40.000km with it without any issues.

I actually managed to run it at 20% for 5-6 months, and then a sudden increase in temperature made it start throwing codes so I had to lower it to 10%. With 10%, it never throws any codes, except sometimes after 5-6 hour drives at fast-ish speeds. It really doesn't like the heat.

To be honest, I haven't had the patience to try more than 2 maps so far: map 2 (++ fueling, + boost) and map 3 (+fueling, ++ boost). According to my charts, map 4 provides only a very slight increase of boost and fueling (so this would be your map 1). Or at least that's how I understand it. If you could post a scan of your charts to compare them with mine, I would appreciate it. I'll try to check mine when I get home.

In any case, for me map 3 has been the best so far throughout the entire range. Map 2 is quite strong down low, but loses momentum and doesn't feel as strong when you're in the higher revs.

[135i_vs_]

Thanks for the review.
With either of the tunes, did you experience LIMP mode, when the tuning boxes are operating at 100%?

[crugeman]

I have a DTUK and been mainly running 3 +10. I think today I am going to switch out to table 2 and see how she handles.

Thanks for your write up!!!

[sergiy'd]

any USA vendors for DTUK

[BB_cuda]

Thanks Chief orman. That was over the top information. Yes, it has been a long while since we heard from Ronin after his DPF meltdown. I wonder if he has his D anymore? I wanted to use my last year's tax refund to buy a DTUK but decided spending money on trying to prevent CBU was a higher priority... waiting on Ecotune.

[taibanl]

Great writeup

[Chief Orman]

Originally Posted by 135i_vs_

Thanks for the review.
With either of the tunes, did you experience LIMP mode, when the tuning boxes are operating at 100%?

I got limp mode with DTUK at +20 and +30...took about five seconds to clear the code.

[WreckerX5d]

I wonder if having the DTUK with addition to a Wagner IC would help prevent the limp mode issue. According to your results it's a heat related cause.

[Chief Orman]

Originally Posted by MonkUSMC

I wonder if having the DTUK with addition to a Wagner IC would help prevent the limp mode issue. According to your results it's a heat related cause.

I would be worried about being in a hot environment with the tune. On the other side of it, one's car definitely needs a few minutes of running time before you can really romp the accelerator.

[AzureHaze]

Great write-up. Now I'm strongly looking at the DTUK and trying it out!

[konvict]

great write up!

i have the DTUK CRD-T box- but its been off the car for a long long time since all the carbon issues since its been at dealer more than my house lol

i have no idea how to change the settings on the DTUK tho- never thought about opening it up tho... do you just unscrew the casing?

[FastFour]

I have a JB+ on my mini and have really considered it for the 335d. 0 problems with it and it really woke the mini up.

[Bicax]

Originally Posted by MonkUSMC

I wonder if having the DTUK with addition to a Wagner IC would help prevent the limp mode issue. According to your results it's a heat related cause.

I've been wondering exactly the same thing. It's definitely heat related, however I'm thinking more and more that it's the DTUK box itself that cannot take the heat generated under the hood, especially since I live in a relatively hot climate.

If that's the case, then maybe the IC wouldn't help with that specific issue.

But again, this only happened a couple of times, and both times it was after 5-6 hours driving at enthusiastic speeds. In normal use, I never get a limp mode on +10.

[Puerto Rican 335d]

Chief great reviews but we needed dyno runs to solidify your review. Me on the contrary I opted for RENNtech falsh NEVER gone limp mode. Yes its expensive but like I state I never have to b worried I go limp. And as of last week when we dynoed it at 318 whp and 425 lbs torque I cant say much that I hv a better product on my hands. Again I thank you for your review in helping other D member but I'll stick to my flash. Fair winds and following seas SHIPMATE.

[Bicax]

Originally Posted by Puerto Rican 335d

Chief great reviews but we needed dyno runs to solidify your review. Me on the contrary I opted for RENNtech falsh NEVER gone limp mode. Yes its expensive but like I state I never have to b worried I go limp. And as of last week when we dynoed it at 318 whp and 425 lbs torque I cant say much that I hv a better product on my hands. Again I thank you for your review in helping other D member but I'll stick to my flash. Fair winds and following seas SHIPMATE.

Heya PR, a flash isn't necessarily more expensive. My DTUK cost me at least as much as a lot of flashes I've been seeing.

The advantage of the DTUK, and the reason why I didn't get a flash, it's the possibility to remove it without a trace when needed for warranty purposes.

IMO two different products that really can't be compared since they have different targets.

[Puerto Rican 335d]

Amigo Bicax my flash is ecrypted. My friend from Poland tried to look it up and couldnt find it when he entered my ecu.

[finnbmw]

Thank you for the detailed review! What caught my eye was your experience with DTUK in day-to-day driving with map 4 at 10%. That is exactly what I am looking for in a tune for my X5, power from get-go, i.e. more power between 1000 - 2000 rpm, where I spend over 90% of the time in city traffic.

Tunes like JBD, Renntech, the power boost comes on after 2,000 rpms. I'd rather have something that gives me that extra boost already at 1000 - 1200 rpm's for everyday drive-ability.

[Puerto Rican 335d]

Finn mines has been programmed to perform from 1500 to 5000 rpms lol

[finnbmw]

Puerto rican, interesting. Do you have to request it from Renntech? I was going by what Lenny told me and with the dyno graph I found on the internet

[Puerto Rican 335d]

Give me a call after 12pm

[Chief Orman]

Originally Posted by Puerto Rican 335d

Amigo Bicax my flash is ecrypted. My friend from Poland tried to look it up and couldnt find it when he entered my ecu.

PR that kind of changes everything...like Bicax the only reason I turned to tuning boxes is the warranty issue and the prospect of having to remove the ECU. In other words, I have no doubt a well engineered flash beats a tuning box but convenience and warranty issues were the only thing I worried about. Once I am out of warranty I will probably pursue getting a flash. I'd do so know if I had 100% confidence it was undetectable.