2.5 DSE Auto Gearbox unresponsiveness problem ?

Hi - I recently bought a 2000 2.5 DSE auto. The engine has had an ECU upgrade and modified intercooler from JE Engineering. There is a lot of power to be had when you put your foot down (JE reckon this conversion gives around 190 BHP to the 2.5 which is nice)

However when you are just taking off, or driving at low throttle you have to put your foot down quite a way before the gearbox appears to "bite". You increase throttle pressure slightly and the revs climb noticeably but Its almost like the gearbox is letting out the clutch as there is no change in speed. You have to give it some throttle to get any kind of response.

The affect makes the car very on/off with the power. I'm confident the engine is working well, but its being let down by the power delivery on the gearbox.

I've read postings about torque converters, throttle sensors and mass air flow sensors and can't quite understand what could be happening. Does anyone have any similar experience with this gearbox and any suggestions as to what the problem may be ?

All help appreciated

Bash.

I notice this with mine (01 DHSE) only when cold as if there is no power delivery but have been told by my trusty indie it is a characteristic of the model . I had enquired with a very reputable gearbox specialist who had also corroborated this and added there was a fueling related design issue with the model & unknown to have gearbox problems.So I'm happy enough as only initially when cold. Also have a Superchip power device which I am in the process of having re-checked & will report back if there is any significant news

On my 2001
I had a larger full-size Fern Intercooler & chip upgrade done on a recent trip over in june

and yep the change is like driving another vehicle! the economy with mine is a lot better too
with regard to the transmission, i was warned by the main local LR dealership if the vehicle was chiped not to gun the transmission when cold - let it warm up.
This i do, but also i notice the lower gear changes are a little "notchy! when the vehicle is cold. gear change is at about 2300rpm
Recently on a main service i had them do all the transmission oils & main box filter - didnt really make much of a diffrence.
I was thinking of putting some of the transmission addative ashcrofts sell with their re-con boxs to assist smooter changes

keep you posted on any inprovements

Hi GGG, yes I have been told that this is quite characteristic too. The reason why I am trying to pursue this is because there is a definite revs climb, but no speed climb when I accelerate slightly almost as if the gearbox is not interested in delivering the power until I get my foot down

On the temperature thing, I read somewhere that the engine is restricted by the ECU in that it does not deliver as much power until the engine is warm. But my problem occurs when the engine is warm as well.

The JE upgrade upgrade sounds as good as yours Abe. Bit of a shame its let down by the gearbox delivery

I'll try and do some more reasearch on the torque converter idea as this sounds like the most plausible at the moment

Bash

Had a chat with the Superchip guy who basically said they don't fail as such as the ecu is reprogrammed by what is in simple terms a data file & if there was a failure(unknown) the car wouldn't start etcetc & anyway would be covered by a lifetime guarantee (can't comment on the plug & play type)
Further discussion then settled on the old favourite Air Flow Meter /Air Mass Sensor & the symptoms are very much in line with this unit starting to fail.I didn't mention earlier the economy is down as well as a flat spot and not as sharp as it has been. Having had MAF issues with my Mercs I know what a tw*t they can be so I think I'll clean mine up & see if it helps if only in the short term. Try a search on here Bash for Maf/mas cleaning or I can post one up later from the Merc. forum but on reflection I think this could be the root cause

HI BASH THIS IS WHAT I WAS REFERRING TO

http://www.landyzone.co.uk/lz/f10/mass-air-flow-maf-sensor-32310.html?highlight=AIR+FLOW+SENSOR

How to clean your MAF - Mercedes-Benz Owners' Forums

Cheers Mate - thanks for this I'll have a look see. I've seen in some other places that there is a better replacement MAF sensor than the bosch one for about a 1/3 of the price.

This could explain the lack of initial power at low revs - I imagine that when I gun the throttle then the ECU does not care how much air is going past the MAF as it is probably more concerned about the throttle position and therefore letting rip

The only thing I still need to get my head round is the apparent feathering of the clutch where the revs rise maybe 600-750 rpm and no change in speed (this feels spongy and is a slightly different feeling to the box changing down where there is a little nudge)

I used to own a 308D (pre-sprinter) which had a turbo conversion (giving about 120 bhp) and it pulled better than this baby at low revs - the 308D is heavier than a P38. I know this engine is good as it really has a kick when I floor it so it would be really cool to get the power delivered properly.

bash, just unplug the maf & see how it runs this should prove whether or not the maf is the culprit

Cheers - although I must fess up that I am unsure where it is. Looking at your Merc photo, I think there are two places where it could be, one of which was where the tunit box used to be connected to (just over the strut) and the other is nearer the front of the air tube. (Its been a while since I did anything with engines)

My guess is its the one nearest the front of the tube.

Bash.

Maf Is The Flat Rectangular Unit In The Corrugated Hoses Between The Air Filter Box & The Big Plastic Flat Tube Which Runs Across The Top Of The Engine From R/h To L/h Side. With A Simple Push Fit Connection, Unplug There

Hi GGG thanks for that.

I just disconnected my MAF and it was actually worse !! Guess I'll book it in for a session on the test machine and get the gearbox filter and oil replaced.

Cheers for your help
Bash.

with the maf eliminated that's the road i'd go down, hope it helps as often an item that's overlooked & gearbox failures can be terminal & cripplingly expensive. btw mercedes technical support dropped the "sealed for life " crap after countless failures & now recommend oil & filter at 70k.
i actually changed my maf for new one & still feel it's off colour performance & economy so may revisit the Superchip guy again & see if they will check their work!! let you know the outcome.

Interestingly, my DSE had a superchip fitted when I bought it. You would not know when you put your foot down.

I fitted a tunit and this was much better, but then opted for the JE Engineering Intercooler and ECU upgrade. Now we are talking. I just need to sort out the responsiveness problem at low speeds.

I too have noticed this lack of response below 2000rpm, it's especially noticeable after driving a 3.9 V8 auto previously. I was hoping that an upgraded ECU and intercooler may solve this - giving more low-down torque - but looking at the posts it seems this isn't the case.

I can't help thinking that this was an issue that came up during development of the P38, and equally that it wasn't solveable by the development engineers at Lode Lane. Maybe its a bit of a gutless engine low-down - it definitely has plenty of go if you floor it - and that the shift points programmed into the gearbox ECU only allow changes when the engine is producing enough torque, otherwise it would bog down.

It's nowhere near as perky as a Disco TD5 I drove recently, that has an extra 40Nm of torque, so does that allow earlier shift changes and more driveability?

It's a good car otherwise, does 25-30mpg and can cruise at 85mph. Just a shame it lingers between 35-50mph...

Wow You Lot Sound Like Rocket Enginers ,i Have A Litte Blue Box On My 1999 Dse And When I Put My Foot Down From Stand Still All I Get Is Two Clouds Of Black Smoke And Fast Forward Movement.

I have no idea what im talking about here but don't the later DSE's have EGR?? i know you can get EGR blanking kits, i assume this gives more power back to the engine?? Could this be the cause of your problems or am i actually talking rubbish?? As you may guess, I dont have a DSE with EGR.

Im more with Beechy, if I put my foot down, fast forward movement and a nice black cloud behind Although to be honest, I think my DSE has turned me into an old fart, I dont really drive that fast, I stick to 30mph pretty much all the time in town and then 65-70mph on the motorway.

-Wills

UPDATE
I made a contribution to this thread earlier & here's my views.
I replaced the MAF (as cleaning it had not helped) & had the Superchip people replace the chip (all v. helpful & under the guarantee terms) -If any one wants details just PM .
The performance is as good & adequately fast as I expected ; smooth no flat spots no black smoke sharp enough from standstill & no real increase in consumption if sports mode selected as I do for mainly urban driving & lots of short trips.
My driving style is to put the pedal into the carpet most of the time & currently getting 22-24 mpg . Haven't been on a long distance run since work done but expecting too see 30mpg.
The qualities of these cars are self evident for the luxury & versatility safety & style but they are not hi performance cars & to try & make them so is unrealistic. If you want G force then this isn't the car for it unless £65k is no object. For all round feel good factor they are hard to beat at current values so my advice is tweak them but don't expect to transform.

Hi Everyone - thanks for lots of interesting posts. I just thought I would update you on this one.

I took my car to Ashcroft Transmissions. Dave Ashcroft took it out for a test drive and confirmed the gearbox was mechanically working fine. His mate who normally does their gearbox swaps said that there was nothing wrong with my car.

I then had "Gearbox Fault" for about 10 mins which went away after I restarted it. Dave's mate (sorry, I can't remember your name) said this may have been caused by an irregular shifting pattern and I should get the gearbox telemetry checked out.

So I took it to Greaves 4x4 in Wargrave (RG9). Peter greaves has a cool place with lots of racing LRs in his workshop.

His diagnosis was as follows.. Since I had my DSE upgraded, the power comes in much earlier. There is a lot of it too. The ECU on the gearbox has pre-programmed shifting patterns based on the power of the 2.5. My modded engine is more like a 4.0 and the power comes in much sooner.

The GBox on the 2.5 has a tendency at low speeds for the torque convertor to let out the revs up to about 2200 rpm. This looks like "thinking time" for the box which then catches up and does something about it.

Having got a more powerful engine it seems I need to somehow reprogram the shifting pattern to match this, something which Dave Ashcroft says is not easy.

Peter Greaves says there is something called compushift, but this is a lot of work and only of use on a racing mud plugger.

My guess would have been to swap the Gearbox ECU from a 4.0 petrol with mine, but Dave Ascroft reckoned this would probably have been risky.

It was a bit of a gamble, but unless anyone knows how you can reprogram the Gearbox ECU, I will probably have to learn how to drive it differently.

Maybe one day I will give it a bash and then let you know how I get one.

Cheers everyone

Bash.

Cracking reply bash (very interesting)

On the info you got back from Ashcrofts & Greaves

thanks & have a nice one

Interesting...I have similar characteristics with my diesel too, feels like there is a lack of power low down in the rev range thats why it finds it hard to change gear ( auto), I asked before but got no reply, but did anyone actually test the MAF? apart from removing the connector while running the car is there a better way to test it?
BTW does anyone know if the maf gradually dies? or is more like a fuse?