C250 cdi remap issues

GRIGGY001

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Hi all,

New to this forum but wanted to put something out there for people’s opinions and experiences

I recently had a remap on a 2013 C250 cdi by a local company I have been following on Facebook for about two years, they have done a fair number of Mercs/AMGs, some the same model as mine along with a lot of high performance stuff (RS3 & 4s, Golf Rs, BMWs, Bentleys etc). They have 322 5 star reviews on Facebook and no negative reviews, so figured they must be doing something right! They did the remap (sending the original map away for modification) and reinstalled it. On first drive I didn’t feel the gains I was expecting, in-fact I was sure there was less torque. That said, I wasn’t exactly sure what to expect so wanted to have some time driving the car before making an opinion. I also noticed average MPG dropped from mid 40s to 30s indicating something different must going on.

I took it to a rolling road yesterday and it turns out the car is doing 205bhp (4 more than std!) and 325Ftlb of torque, which is less than the standard 369 or so and certainly not the 20% increase promised. I contacted the mapper telling them the news, sending the print out to them and explaining I would like the original map returning to the vehicle and a refund. So far they seem open to this and have agreed to do it later next week, but they did suggest:

a) The car could have been down on original power, so 20% has actually been achieved
b) The rolling road folks might have given a dodgy reading (as they do maps too)
c) They have done loads of these with no issues!

I can tell they are very reluctant to refund, but are mindful a bad review could do them some damage so want to make sure I am happy.

Of course my worry now is that they upload a crappy map to the car and not the original as they are adamant the map should be fine and might want to prove a point. They did offer to upload the standard map, pay for another rolling road to see what the before and after difference is – but seeing as they suggested the car might have only been at 170bhp to start with, and the map has done as it should adding 20%…. I am reluctant to do this! The car was definitely running fine before the map, plenty of power, good economy etc. It’s on 30k with full service history, no obvious issues. I even waited to have a B5 service done before applying the map, just to make sure everything was in good order.

I have read a few posts where people have had remap issues, seems more like they have limp mode problems than odd power readings, I wondered if anyone has had a similar issue to me?

I do wish I had taken it to a re-mapper who does the map themselves onsite and uses a rolling road to show before & afters! I guess every day is a school day!... or just not bothered at all!
 

daveenty

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I do wish I had taken it to a re-mapper who does the map themselves onsite and uses a rolling road to show before & afters! I guess every day is a school day!... or just not bothered at all!

This is the critical bit, everything else is just guesswork unfortunately.

I'm not going to ask who the mapper is though if they can't test their own work then you instantly have problems. A lot of specialist tuners send maps away to be tweaked by professionals as, let's face it, there's a lot of skill involved so this is not necessarily an issue.

I'd give the guy the opportunity to put it back to standard for you, then run it on the dyno again. Not all dynos are equal by the way, lots of them over or under estimate and the 18% power loss for the drivetrain which they suggest is not an exact figure either, so worth sticking with WHP figures only for accuracy.

Oh, and welcome to the forum. :)
 
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GRIGGY001

GRIGGY001

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Thanks :)

Yes, agree 100%. Once I have the refund and the standard map back on I will take it to a mapper with a rolling road, at least that way I can have some peace of mind re what's actually happening and not be second guessing what map was re-uploaded.

I am also a little concerned about what damage a 'bad map' could do, the reduction in MPG is an odd one... more diesel must be going somewhere!
 

Rotorhead500

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Welcome and sorry you're having issues.

Dave knows his ref car modifications, so his line of thought is a good lead.

Have also heard more than a few issues on here with remapping 250s... they really don't seem to like it, and many have reverted to standard.

A lot of generic maps will just over fuel and hike boost pressure, hence mpg drops.
 
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GRIGGY001

GRIGGY001

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Yes, have read on here and other places that some experience issues with mapping these. I am puzzled by the dyno figures, in that the bhp is a couple over stock values and the torque number (325lb/ft) is below standard. Increasing bhp without a corresponding torque value? odd.... suppose without a before figure it's hard to surmise.
 

Capra

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Is this the point of using companies luke GAD? You at least get a before and after.
 

Rotorhead500

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Is this the point of using companies luke GAD? You at least get a before and after.

Yeah, basically.

The tuner can see how that specific car is performing, and where they can maximise gains, eliminate flat-spots, etc. They can also overlay any technical limits (torque, temperatures, etc) to aid longevity by not exceeding certain parameters.
 

bembo449

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id expect to see another 30bhp and at least 80lb of extra torque pal , even from a generic map , id get your money back and go talk to GAD or MSL about it
 

V6Matty

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Is this the point of using companies luke GAD? You at least get a before and after.
GAD does have a dump so no way they can do a before and after apart from in a digital form
 

Capra

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GAD does have a dump so no way they can do a before and after apart from in a digital form
Sorry what do you mean? Do they not do a rolling road before they update the car?
 

EXMERCTECH

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How did they remap your Merc.
Thru the Diagnosic port or remove the ECU.

Where was the rolling road.
 

JBell

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How did they remap your Merc.
Thru the Diagnosic port or remove the ECU.

Where was the rolling road.

Depends which engine 250CDi is through the OBD plug. OM642 has to have the ECU removed
 

C350Carl

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GAD don’t do a before and after readout. Although they do good work I’m inclined not to believe their figures. Never seen them produce any rolling road proof.

But figures are for pub talk. As long as you can feel a real difference then the headline figures don’t matter.

I have a 250CDI engine that cannot be tuned in my S212.

I’ve tried 3 different tuning boxes (both dual and Tri-Channel) and also had it remapped by GAD.

They all give the same fault of the rail pressure being too low.

No idea why and I’m not going to spend anymore £’s chasing why when there is no issues in standard form. I have already spent a fair bit having Mercedes run diagnostics at my request. Everything fell well within factory parameters. So there is nothing I can do and I could replace the injectors, fuel rail, pressure sensors, fuel filter (again) and still have the same problem.
 

Capra

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GAD don’t do a before and after readout. Although they do good work I’m inclined not to believe their figures. Never seen them produce any rolling road proof.

But figures are for pub talk. As long as you can feel a real difference then the headline figures don’t matter.

I have a 250CDI engine that cannot be tuned in my S212.

I’ve tried 3 different tuning boxes (both dual and Tri-Channel) and also had it remapped by GAD.

They all give the same fault of the rail pressure being too low.

No idea why and I’m not going to spend anymore £’s chasing why when there is no issues in standard form. I have already spent a fair bit having Mercedes run diagnostics at my request. Everything fell well within factory parameters. So there is nothing I can do and I could replace the injectors, fuel rail, pressure sensors, fuel filter (again) and still have the same problem.
Would you look at a 350 instead? I looked at the 250 but everyone on here said get the 350 so I did :D. I've been looking at tuners for a while and even before I picked this car up. But since driving I am less inclined to now, reason is I cannot really put my foot down with the wife in the car, and when I do there is enough power for me.
 

Capra

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He had one and sold it - Silly Carl

Mine was mapped by GAD and it made a massive difference
ha ha, that explains the name. Did it make improvements everywhere? Also, does it do much for off the line starts to 60mph? With the added power are there any areas of the engine that are over stressed?
 

JBell

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Did it make improvements everywhere? Also, does it do much for off the line starts to 60mph? With the added power are there any areas of the engine that are over stressed?

It is just faster and pulls like a train, all parameters are well within the safe levels of the engine
 

C350Carl

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He had one and sold it - Silly Carl

Mine was mapped by GAD and it made a massive difference

Needs must at the time. The C350 wasn’t big enough for 2 adults, 2 kids and 2 dogs when the second baby came along. At the time I couldn’t find a E350 to the spec of my E250.

I do miss the C350 as it was a great car.
 

C350Carl

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Would you look at a 350 instead? I looked at the 250 but everyone on here said get the 350 so I did . I've been looking at tuners for a while and even before I picked this car up. But since driving I am less inclined to now, reason is I cannot really put my foot down with the wife in the car, and when I do there is enough power for me.

No such thing as enough power! Ask @daveenty.

I used to own Skoda Octavia vRS. I tuned the two I had and the last one started at 200ps and 207lbft from the factory.

When sold it had over 380bhp and nearly 400lbft.
 

Capra

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Needs must at the time. The C350 wasn’t big enough for 2 adults, 2 kids and 2 dogs when the second baby came along. At the time I couldn’t find a E350 to the spec of my E250.

I do miss the C350 as it was a great car.
Fair enough. The E250 Estate is a nice car, I've only seen a few and they are a very nice looking estate car, and with loads of power. I carry bikes around and I had almost decided on getting one.
 

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