Choked inlet manifold on ML270

[w124tony]

The shunt didnt work for me, i get a code as soon as i start the engine if the vacuam to the egr is not connected. The vacuam transducer on my car is normally open, when the the electrical connector is disconnected there is vacuam applied to the egr. the ecu closes the egr by completing the vacuam transducer circuit to ground. Seems to work the opposite way around from what has been described here.

 

[dieselman]

Seems to work the opposite way around from what has been described here.

That's definitely wrong as the fail safe is meant to be closed.

 

[alexanderfoti]

The shunt didnt work for me, i get a code as soon as i start the engine if the vacuam to the egr is not connected. The vacuam transducer on my car is normally open, when the the electrical connector is disconnected there is vacuam applied to the egr. the ecu closes the egr by completing the vacuam transducer circuit to ground. Seems to work the opposite way around from what has been described here.

Mine does this as well if I remove the Vaccum pipe....(and plug)

My transducer is disconnected though so the valve is defo closed. ...

 

[dieselman]

Mine does this as well if I remove the Vaccum pipe....(and plug)

My transducer is disconnected though so the valve is defo closed. ...

Now I'm confused..

With yours, once the transducer is disconnected the valve closes, W124Tony says his opens..

 

[alexanderfoti]

basically on mine.

If the transducer is connected and I remove the vaccum pipe from the valve with the mod in place, the car goes into limp home mode.

If the transducer is electrically disconnected and I leave the vaccum pipe connected then all is seet. no EGR and no limp home.

 

[stumo]

if you guys want it all to look stock, and yet keep the shunt wortking, you can just do it the old fashioned way...

Shove a small ball bearing up the vacuum hose at the transducer.

That way you still get to keep everything connected, and you still stop the egr valve from operating. (you still need the shunt though to fool the ECU obviously)

 

[alexanderfoti]

if you guys want it all to look stock, and yet keep the shunt wortking, you can just do it the old fashioned way...

Shove a small ball bearing up the vacuum hose at the transducer.

That way you still get to keep everything connected, and you still stop the egr valve from operating. (you still need the shunt though to fool the ECU obviously)

Why not just unplug the transducer? surely that is hard to spot as well?

 

[dieselman]

Why not just unplug the transducer? surely that is hard to spot as well?

In some Countries MOT tests there is a check made on all emission control connections.

 

[dieselman]

if you guys want it all to look stock, and yet keep the shunt wortking, you can just do it the old fashioned way...

Shove a small ball bearing up the vacuum hose at the transducer.

That way you still get to keep everything connected, and you still stop the egr valve from operating. (you still need the shunt though to fool the ECU obviously)

If you don't disconnect the transducer the ECU will see a lower resistance and may log a fault or have a problem with the current draw.

 

[alexanderfoti]

In some Countries MOT tests there is a check made on all emission control connections.

Ahh yes. I forgot about that.

 

[HaydnM]

If you don't disconnect the transducer the ECU will see a lower resistance and may log a fault or have a problem with the current draw.

If you don't disconnect the transducer you will have to place a Resistor across the plug to fool the ECU that the valve is still contected

 

[alexanderfoti]

If you don't disconnect the transducer you will have to place a Resistor across the plug to fool the ECU that the valve is still contected

I didnt have to , but my shunt is drawn from the transducer 12v supply which could be why....

 

[dieselman]

If you don't disconnect the transducer you will have to place a Resistor across the plug to fool the ECU that the valve is still contected

Sorry, I don't follow you.
Adding another resistance of any sort will alter the output from the shunt mod.

 

[w124tony]

this is confusing, alexander fonti's car is behaving just like mine, if he dissconnects the vacuam pipe from the valve even with the mod he gets a fault straight away, that means that the egr must be at least slightly open at idle to get the required air flow drop to stop the ecu logging a code?
meaning if the egr is 100% closed at idle the ecu log's a code.
Alexander fonti, can you feel any vacuam present on the vacuam tube after the transducer at idle?

 

[oigle]

this is confusing, alexander fonti's car is behaving just like mine, if he dissconnects the vacuam pipe from the valve even with the mod he gets a fault straight away, that means that the egr must be at least slightly open at idle to get the required air flow drop to stop the ecu logging a code?
meaning if the egr is 100% closed at idle the ecu log's a code.
Alexander fonti, can you feel any vacuam present on the vacuam tube after the transducer at idle?

Why are you stuffing around? Just disconnect the electrical connection at the transducer and reconnect the vacuum and all should be well.
Why try to change something that works?

 

[alexanderfoti]

Why are you stuffing around? Just disconnect the electrical connection at the transducer and reconnect the vacuum and all should be well.
Why try to change something that works?

Yeah, im not sure if the transducer is leaking some vacuum when unplugged but if the connecter is disconected, there is no way that the ECU can actuate the EGR.

 

[w124tony]

the shunt isnt working for me, thats why im mucking around. Im just trying to understand whats going on so i can diagnose the problem. Yes It does look like i have some other problem. thanks to those who answered my questions i may even be able to fix this thing yet.will let you know the problem was when i get to the bottom of it.

 

[Alex Crow]

tony, how are the vacuum pipes connected to your transducer, and what fault codes do you get? there should be NO vacuum to the egr valve with the electrical connector disconnected from the transducer, so perhaps you have a couple of pipes the wrong way round.

 

[w124tony]

the vacuam pipes are definatly the right way around, the ports are marked on the transducer, input and output. i get an error instantly when i disconnect the vacuam tube from the egr valve. (there is vacuam present from the tube)and Transducer electricly disconnected. If i Leave vacuam pipe connected and transducer electricly disconnected, all is well for a while. Basiclly if me egr isnt open to some degree i get an error. the errors i get are; "EGR recirculation rate to Low", "Mass air flow implausability". I do get a fair amount of smoke when i accelerate. Im going to cheack my cat converter at the weekend, i suspect its clogged as i get a puff of smoke at the joint before it when i blip the throttle.

 

[alexanderfoti]

the vacuam pipes are definatly the right way around, the ports are marked on the transducer, input and output. i get an error instantly when i disconnect the vacuam tube from the egr valve. (there is vacuam present from the tube)and Transducer electricly disconnected. If i Leave vacuam pipe connected and transducer electricly disconnected, all is well for a while. Basiclly if me egr isnt open to some degree i get an error. the errors i get are; "EGR recirculation rate to Low", "Mass air flow implausability". I do get a fair amount of smoke when i accelerate. Im going to cheack my cat converter at the weekend, i suspect its clogged as i get a puff of smoke at the joint before it when i blip the throttle.

I suspect that your wiring is incorrect somewhere, especially becuase of "Mass air flow implausability".

.

I wouldnt worry about the cat, mine did the puff of smoke from the joint when my EGR was non functional also.