SLK250 CDI DTUK Map

[bmv900]

Hello

I have recently fitted a DTUK CRD-T tuning box to my SLK 250 CDI and so far I am impressed with the results. Has anybody else used this tuning box on the SLK 250 CDI or any other Merc variants that use the same 250 CDI engine? What is the optimal map that you finally settled on?

 

[elbarry]

Haven't settled on one setting as yet as pretty much all settings trip limp mode. Either instantly or eventually at steady motorway speeds.
E250 but same engine I believe.
Was very impressed with map 4+1 for performance but again limp mode eventually.
Map 0 0 did not trip limp mode but increases in economy only, torque increase hardly noticeable.
What setting are you in and any limp mode engine lights yet.

 

[bmv900]

Hi there, I have tried map 1+0 (default configuration) and I did notice a moderate increase in torque; no limp mode in this configuration. I have subsequently tried the following:
-map 2 + 2 gives limp mode if the engine is rpm goes above 4,000 (close to redline). Awesome torque from approx. 1,500 - 4,000rpm
-map 2 + 1 gives limp mode if engine rpm goes above 4,200 (on the red line). Almost same amount of torque as map 2 + 2
-map 2 + 0 no limp mode yet and the torque is still good. Currently been on map 2+0 but I am thinking of changing because when I set the gearbox in Sport mode, it will not shift into 7th gear no matter what.

I wonder if the maps provided for the E250 CDI are the same as the ones provided for my SLK (I'm talking about the four graphs with the red and yellow lines that DTUK would have sent you with the box). The reason I settled on map2 is that on my map2 there is a increase in boost provided at low rpm (yellow line on the graph is boost). I will try to scan the piece of paper with my maps and attach it here.

 

[elbarry]

Would you believe it, map 1-0 just went into limp mode.
Now no confidence if the dtuk system in the 250 diesel. Spoken to others on other forums, even messaged guys selling on eBay, all with similar issues and fed up with limp mode.
Dtuk advised that I disconnected the turbo boost and just run it on fuel boost.......still limp mode.
Then advised to start tapping boost down -1, then -2 if needed. Can't see the point. Surely I'd end up tapping in a lower map than standard.
Isn't the attraction to such common rail and boost tuning is extra torque/bhp an economy as advertised. Why tap it all down and remove the turbo boost benefit if the crdt-2 device

As quoted above some of the maps just don't hold without limp mode even at low or zero power settings.
I've had the dtuk on a vectra and insignia previously with no real issues, just seems v common problems on the merc 250 diesels

Remap seems the way to go in afraid.
Waiting for the 'told you so brigade'

 

[bmv900]

Hello elbarry, on all the occasions when limp mode was triggerred, how long had you been driving using that particular map? In my instance limp mode was being triggered pretty much within 20-25 minutes of driving. Today I tried map 1+2 and within 20 minutes the engine entered limp mode. The most stable configuration has so far been map 2+0 for me. This evening I will go for a run on map 1+1 and see what happens.
I wouldn't worry too much about having to go to -1 or -2; according to DTUK, these adjustments are very fine settings and it is simply the case of maximising engine performance whilst being just shy off triggering limp mode. You may end up sacrificing 4-5hp by going to -1.
Next week its rolling road time and i will test the difference that +1 makes on a given map.

 

[elbarry]

It varies. When on map 4 pretty much straight away as with plus 2 on most maps.
When on plus 1 or zero it generally trips when u wouldn't expect it like at a constant motorway speed, no hard acceleration. Map 4plus 1 was v good just wouldn't stay out of limp mode.

 

[bmv900]

Ok I have had about 1.5 hours driving on map 1+1; a combination of motorway cruising (70-80mph) as well as back roads. Performance was really good and no limp mode. I cannot say I was particularly impressed with map 4 which makes me wonder whether we have the same maps or not

 

[elbarry]

My mistake I think it was 2 + 2 which felt the better
Which is the best so far

 

[elbarry]

Sorry meant to ask which map do you feel is the better which does not force limp mode. I'd be interested to give them a go to see if there are similarities

 

[bmv900]

Just so there is no confusion, please see attached link with the maps i was given. Map 1 (aka Program 1) is the top graph, Map 4 (aka Program 4) is at the bottom.

 

[bmv900]

If you click on the symbol it will give you the option to download the image. So far, I have driven for about 2 days using map2+0 and another 2 days using map 1+1; no problems on either. I have not tried map 3 at all. I have tried map 4+1 and was not too impressed. I have tried map 2+2, map2+1 and map 1+2 and all of those setting caused the engine to enter limp mode after 15-20 minutes of driving. So assuming that you managed to download my maps, I would suggest you try "my" map 2+0

 

[RichardM]

This all seems to be a lot of hassle just to get a few more bhp.

I had the same issue when I tried a DTUK box in my CLS350 CDI.

 

[elbarry]

Thanks I will try map 2-0. Let's know what your rolling road details map 2-0 to be putting out. Will prove a lot will that.

Richard agreed, it is a lot if hassle for a few bhp.
However you would think/expect quite the opposite as these are are advertised as simple plug and play items. Dtuk are also a well established company. Further advertised as proven to give up to near 250bhp -improved economy and 700nm torque. Now those figures are tempting but proving difficult to achieve, especially in mercedes diesels due to constant need for tweeting and limp mode.
At the end of the day limp mode is your engine management saying something ain't right against parameters set by the factory. It's that which worries me.

Remaps advertised by quality, recommended companies have rolling roaded 260bhp 720nn and an improvement in economy too.
Ok warranty and traceability aside, if such increases floats your boat then a remap must be the way to go. No limp modes neither.
I think Matt at rebellion remapped an e250 cdi estate at a meeting once with the above results.
Apparently the driveability was also excellent.

Andy

 

[bmv900]

Hi Richard you are probably right about the hassle factor but i guess its the thrill of finding the limit. I take it you no longer use the box on your CLS350?

I am not too concerned about limp mode when trying certain settings; when you are tweaking the box with the aim of finding the optimum power&torque you could well exceed the safety critical engine parametres that trigger limp mode. If that happens you revert to the next setting down. By the way, did you manage to see the photo with my maps? Are your maps the same?

 

[stevehg]

I assume the main issue is that the 250 is a tuned version of the 220. Given that you keep getting limp mode from over boost, I suspect that Mercedes achieved most of the gain from the 220 to 250 by simply turning up the turbo boost. This would be the logical reason why when you add the CRDT with increased boost settings it is going over boost sensor limit and tripping limp mode.

It's seems to be the sensible approach you are taking of picking a medium fuel boost setting and a dialled down turbo boost setting. As your testing so far shows having a zero setting doesn't trip limp mode, so this would fit the logic above.

Cheers

Steve

 

[bmv900]

Hi Steve, if you simply increase the turbo boost but you dont increase the fuel then i doubt you would see any performance gain...or do you?
I thought that for diesels simply increasing the turbo boost will put more air in the cylinder and if you dont add more fuel then no real gain..or am i wrong?

 

[stevehg]

Firstly, I'm no expert, but diesel engines are different though, so if you put more air in and compress in the same volume and with the same stroke you have more fuel to react and a higher temp creating a better burn for combustion. So there is not the fine correlation between fuel mixes as there are in petrol engines. There is a greater gain in turbocharging on Diesel engines than for petrols.

So often it's possible to get more performance out of a diesel from increasing boost pressure without increasing fuel by the same ratio. It's why turbochargers are so popular on diesel engines. So no doubt Mercedes have increased amount of fuel too, but not I suspect by the same ratio as the boost pressure. It's not plain sailing though, as you get different characteristics when you start to mess around too much. However, with the twin turbos, I suspect there is more room for adjustments on the 250 engine.

So for the CRDT increasing fuel settings will bring an improvement without having to adjust boost. Obviously there is a limit and under certain loads you may see more black smoke and combustion is less efficient.

This is my limited understanding though.

Cheers

Steve

 

[MattWW]

Hi guys are you using the CRDT stage 2 system (boost and Fuel) ?

The Plug and play CRDT units will extract X percent over stock so tuning a 220cdi will not get it to the power of a 250cdi with with tune.

We have a plug and play iTuning system that accounts for timing in the engine too allowing 250cdi's to get 250bhp +

Give me a shout if you need any more info.

Cheers,

 

[bmv900]

Hi Matt

Is the plug and play iTuning similar to CRDT box? Have you got a product description?

 

[elbarry]

Tried a few more settings, Map 2 power0 (limp mode) Map 2 power -1 (limp mode), Map 1 power -1 (limp mode)
Will update once/if i find a setting that works.