Loss of boost.

[renault12ts]

With 128,000 miles my car has been running exceptionally well recently. But, for the past 5 days it has been losing boost. What I mean is, it starts normally and accelerates like the proverbial scalded cat, but about 3 minutes in...no boost.

It isn't going into limp home mode, it does kick down...just no turbo.

Stop and restart the car it's back to normal.

No smoke or anything.

First thoughts?

 

[E270 Owner]

First thoughts?

MB Star

 

[renault12ts]

MB Star

Good...but it's not quite Carling.

 

[developer]

It's f*cked - ever the technical expert me C.

 

[merc85]

see if there's any codes, Could be poss Map sensor or Air flow meter

 

[renault12ts]

Guys, it's Saturday, the garages are closed, I don't have a code reader...as John says though...he knows nothing.

 

[gl boy]

Had this with my old 350 ml petrol , was the fly wheel sensor , was not diagnosed on the MB reader , took almost a week for MB dealer to find the fault !!!

 

[tjamesbo]

will it rev over 3000? if not could be MAF

 

[renault12ts]

It revs over 3000.

 

[E270 Owner]

Without MB Star everything will be pure speculation in this thread and a waste of forum bandwidth.

just saying...............................

 

[m2287]

Without MB Star everything will be pure speculation in this thread and a waste of forum bandwidth.

just saying...............................

Not really, it's quite a specific problem... Someone else has experienced the same problem, it's likely they had/have the same problem....

 

[Auto-mobile]

Not really, it's quite a specific problem... Someone else has experienced the same problem, it's likely they had/have the same problem....

It's more a case of it could be several things and forum diagnosis is not always going to be correct, 9 times out of 10 the first thing that should be done is a fault code read, so many threads start with "what do you think is the problem"

 

[m2287]

It's more a case of it could be several things and forum diagnosis is not always going to be correct, 9 times out of 10 the first thing that should be done is a fault code read, so many threads start with "what do you think is the problem"

Yep but having an idea is better than no idea!

 

[stef ptycia]

Could be egr valve.

 

[renault12ts]

Thanks for all the answers...I'll report back when I know what is wrong.

 

[Olivier]

Is there a little MAP sensor? Sometime the pipe connecting it to the manifold perish and leak, cutting off the boost.
Might worth a look?

 

[renault12ts]

When it happened today I stopped the car, but not the engine. I opened the bonnet and operated the throttle...and did not observe the actuator on the turbo move.

When I turned the engine off and then on again...the actuator moved as I revved the engine.

So, am I right in thinking this is operated by the vacuum system...and the pipe may be blocked or the actuator intermittently not working?

 

[BlackC55]

The car is in limp mode. This limp mode turns the turbo vac transducer off so the rod won't move.

 

[renault12ts]

The car is in limp mode. This limp mode turns the turbo vac transducer off so the rod won't move.

Thanks.

 

[renault12ts]

The codes said a problem with the EGR, so I performed the shunt suggested by Dieselman (using kit supplied by him 4 years ago!) and it is a complete success.