Rory1980
Active Member
- Joined
- Oct 13, 2012
- Messages
- 36
- Reaction score
- 0
- Location
- Sauze Vaussais France
- Your Mercedes
- 2001 e220 cdi
Firstly My thanks to all involved on the EGR shunt which really seems to have made a difference on my W210 CDi.
Carried out the shunt today and initial road tests are promising, before i had boost dropping away or not coming when needed, all thats gone now,
The next long trip will give it the proper test.
THE SHUNT - Apologies if this has been discussed before but if it has i have not seen it.
I can see no reason this would not work on all the Mercedes CDI range indeed anything with variable turbo.
Like many of you who did the EGR disable Mod i have now a bag of 99x 470 Ohm resistors and a bag of 99 x 1k ohm resistors as is the minimal purchase on Flea bay..
While i was reving my car today by moving the Throttle position sensor under the bonnet by hand - i noticed the little Variable turbo actuator snapping open and closed as the revs build and drop off ... all the boost pipes swelling up with the force and then dropping off.
When the engine reaches max boost the ECU tends to back off the boost by de - advancing the turbo vanes so to speak because there is 'no load'
In an old school turbo system a Wastegate opened via a Diaphram forced against a spring under mechanically set boost levels and the boost was as they say - wasted- no longer spun an Impeller
Variable turbos do not have this system so basically they drop boost levels by dumping the diaphram pressure resulting in gasses blowing closer to the inside of the turbine where the gases can only push to a certain rpm due to the radius etc. the further outside the center radius the hot gasses are directed the faster it spins and vice verse.
This variable turbo actuator is controlled by a vacuum which is in turn controlled by an electronic diaphragm controlled by the ECU and its parameters.
Manufacturers tend to leave a lot of room for error in engine management to cater for worst case scenario environment or servicing.
It would not surprise me if Mercedes had backed off the boost the engine is capable of supporting to leave it more reliable.
Of course too much boost is a fault - and too little also a fault.
With this in mind i thought about what controls this variable turbo diaphram and i came upon the electronic boost sensor.
The boost sensor is located before the intake manifold and after the intercooler, do not confuse it with the air inlet temp on the opposite side of the pipe which has only 2 wires. ( W210 2001 E220 cdi )
This sensor is in very close proximity to the radiator fan - after hard driving this may come on at any moment ignition on or off so watch your fingers if any of you attempt this mod !!
My E220cdi has 380,000 km on it so i don't really mind using it as a guinea pig. It already has a Tuning box fitted to the Fuel rail pressure sensor so is supposed to be 170 /180 hp over the 143 of origin, how true that is i don't know but it certainly snaps through the gears quickly.
However it does not matter how much fuel you give a car- when the ECU decides boost is enough it cuts it and without air you have only smoke and the engine starts missing one of the three factors needed in combustion triangle of Fuel ,ignition ,air.
With this boost sensor unplugged the car will refuse to rev past 3000- limp home presumably.
on the boost sensor connections are three wires, a ground a +5v feed and a return.
What if we tricked the ECU to thinking the boost was 'not adequate' ' max boost not yet reached' i was thinking, surely it would hold boost not only longer but always be giving slightly more where it used to back it off for safety reasons- Albeit delay the action of the vacuum actuator electronically yet it will still of course back off boost - just at a higher level of psi
So while the solder iron was hot i snipped into the return reference sensor of the boost sensor and inserted my smallest resistor the 470 k ohms...
and proceeded take the car for a test drive to see if a fault showed,
the car stormed along on the main road trip where i have the benefit of a 10km straight it showed not faults up to 160kmh full throttle .
At the end of this straight i pulled in - let the turbo cool and swapped the 470 ohm for a 1000ohm to see if i could trip a fault.
Back the road full bore again and still no fault.
on returning up the damp lanes to the house i floored it with the traction triangle still off and it swung the rear end right out like i have never experienced before except on snow !
I think the engine has more snap - and pulls longer up the rev range in gear before running out of puff. towards 4k revs before i feel the ECU was already starting to retard the diaphram to 'cull' boost levels - not now.
Yes its maybe half way to a remap, but i would deem it not really that 'crude' because it is a fixed resistor and progressive in that fact all way through the rev range torque load.
One could probably install a resistor on air mass meter - boost level - throttle position and basically slightly modify every input by a fixed rate and arrive with a very potent and responsive engine still inside its 'throw fault' factory limits and this will be my next trial once the cats are cut out.
Its just a bit of fun within factory limits and if the power is there why not take it as torque only ads to the driving pleasure.
When i re opened the bonnet at home i heard crackling from the exhaust system like i have not heard before, as in in like a tuned petrol after a hard run car it had generated a whole lot of heat, maybe more than ever before.
It is etc work for the turbo no doubt so a cool down period best respected as a decent quality of oil,
This is where my tests ended as i have chimneys to install today.
In reality a boost gauge would need to be put into the system and tucked under the wiper while the road test was carried out to see what the benefits are in gained Boost psi at acceleration and on the flat but to cut the story short my car feels more responsive and quicker and i imagine it can only help the MPG in what is already a legend of a car for efficiency.
Photos of my mod are not really necessary but i can if requested
Its as simple as a wire with a resistor soldered in it.
Any inputs etc welcome - if anyone has more time please do a boost gauge test. i also will and report back findings. I don't know where the inlet can be Tee'd into to check pressure but all is possible.
Happy modding
Carried out the shunt today and initial road tests are promising, before i had boost dropping away or not coming when needed, all thats gone now,
The next long trip will give it the proper test.
THE SHUNT - Apologies if this has been discussed before but if it has i have not seen it.
I can see no reason this would not work on all the Mercedes CDI range indeed anything with variable turbo.
Like many of you who did the EGR disable Mod i have now a bag of 99x 470 Ohm resistors and a bag of 99 x 1k ohm resistors as is the minimal purchase on Flea bay..
While i was reving my car today by moving the Throttle position sensor under the bonnet by hand - i noticed the little Variable turbo actuator snapping open and closed as the revs build and drop off ... all the boost pipes swelling up with the force and then dropping off.
When the engine reaches max boost the ECU tends to back off the boost by de - advancing the turbo vanes so to speak because there is 'no load'
In an old school turbo system a Wastegate opened via a Diaphram forced against a spring under mechanically set boost levels and the boost was as they say - wasted- no longer spun an Impeller
Variable turbos do not have this system so basically they drop boost levels by dumping the diaphram pressure resulting in gasses blowing closer to the inside of the turbine where the gases can only push to a certain rpm due to the radius etc. the further outside the center radius the hot gasses are directed the faster it spins and vice verse.
This variable turbo actuator is controlled by a vacuum which is in turn controlled by an electronic diaphragm controlled by the ECU and its parameters.
Manufacturers tend to leave a lot of room for error in engine management to cater for worst case scenario environment or servicing.
It would not surprise me if Mercedes had backed off the boost the engine is capable of supporting to leave it more reliable.
Of course too much boost is a fault - and too little also a fault.
With this in mind i thought about what controls this variable turbo diaphram and i came upon the electronic boost sensor.
The boost sensor is located before the intake manifold and after the intercooler, do not confuse it with the air inlet temp on the opposite side of the pipe which has only 2 wires. ( W210 2001 E220 cdi )
This sensor is in very close proximity to the radiator fan - after hard driving this may come on at any moment ignition on or off so watch your fingers if any of you attempt this mod !!
My E220cdi has 380,000 km on it so i don't really mind using it as a guinea pig. It already has a Tuning box fitted to the Fuel rail pressure sensor so is supposed to be 170 /180 hp over the 143 of origin, how true that is i don't know but it certainly snaps through the gears quickly.
However it does not matter how much fuel you give a car- when the ECU decides boost is enough it cuts it and without air you have only smoke and the engine starts missing one of the three factors needed in combustion triangle of Fuel ,ignition ,air.
With this boost sensor unplugged the car will refuse to rev past 3000- limp home presumably.
on the boost sensor connections are three wires, a ground a +5v feed and a return.
What if we tricked the ECU to thinking the boost was 'not adequate' ' max boost not yet reached' i was thinking, surely it would hold boost not only longer but always be giving slightly more where it used to back it off for safety reasons- Albeit delay the action of the vacuum actuator electronically yet it will still of course back off boost - just at a higher level of psi
So while the solder iron was hot i snipped into the return reference sensor of the boost sensor and inserted my smallest resistor the 470 k ohms...
and proceeded take the car for a test drive to see if a fault showed,
the car stormed along on the main road trip where i have the benefit of a 10km straight it showed not faults up to 160kmh full throttle .
At the end of this straight i pulled in - let the turbo cool and swapped the 470 ohm for a 1000ohm to see if i could trip a fault.
Back the road full bore again and still no fault.
on returning up the damp lanes to the house i floored it with the traction triangle still off and it swung the rear end right out like i have never experienced before except on snow !
I think the engine has more snap - and pulls longer up the rev range in gear before running out of puff. towards 4k revs before i feel the ECU was already starting to retard the diaphram to 'cull' boost levels - not now.
Yes its maybe half way to a remap, but i would deem it not really that 'crude' because it is a fixed resistor and progressive in that fact all way through the rev range torque load.
One could probably install a resistor on air mass meter - boost level - throttle position and basically slightly modify every input by a fixed rate and arrive with a very potent and responsive engine still inside its 'throw fault' factory limits and this will be my next trial once the cats are cut out.
Its just a bit of fun within factory limits and if the power is there why not take it as torque only ads to the driving pleasure.
When i re opened the bonnet at home i heard crackling from the exhaust system like i have not heard before, as in in like a tuned petrol after a hard run car it had generated a whole lot of heat, maybe more than ever before.
It is etc work for the turbo no doubt so a cool down period best respected as a decent quality of oil,
This is where my tests ended as i have chimneys to install today.
In reality a boost gauge would need to be put into the system and tucked under the wiper while the road test was carried out to see what the benefits are in gained Boost psi at acceleration and on the flat but to cut the story short my car feels more responsive and quicker and i imagine it can only help the MPG in what is already a legend of a car for efficiency.
Photos of my mod are not really necessary but i can if requested
Its as simple as a wire with a resistor soldered in it.
Any inputs etc welcome - if anyone has more time please do a boost gauge test. i also will and report back findings. I don't know where the inlet can be Tee'd into to check pressure but all is possible.
Happy modding
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