Vaneo A414 Topping out at 4000 RPM

[Tony Russell]

Hello,
The Vaneo again.
1.7CDI, Manual, Diesel, 2002, A-Class, 150K+ miles.

I had this problem last summer, then it went away and just returned during the nice weather.

Car starts fine generally and no issue. Plenty revs and pull etc.

When I get about 5 miles up the road, presumably when it's heated up, almost at the same spot every day, the speed drops to 70mph tops, and it can't rev beyond 4000 RPM.
It has no pull and dropping gears doesn't help.
I think there's maybe a slight judder, like if it was a petrol engine and was missing, but that might not be the case.

If I stop the engine and restart, it's fine, sometimes for a mile, sometimes for the rest of the 30 mile journey.

So, I'm thinking MAF, crank position sensor, flux capacitor, generic periconbobulator ?

Thing is, I can't find the MAF to disconnect it - I presume it's in the air filter housing somewhere.
And I presume the crank position sensor in these things needs an engine drop - as almost everything else seems to.

Any ideas ?

Thanks,
Tony

 

[Tony Russell]

Is it bad form to bump this in the hope of a reply ?

 

[Tinkerer]

Yes probably, but it does sound like a form of limp mode, the MAF can induce it as well as the EGR. If it is going away and then coming back I might be inclined to go for the EGR, but then when mine went (saloon) it was not any different between summer & winter. If I was you I would get the codes read which might give you a better idea of where the problem actually is.

 

[Dieselman]

Don't worry Tony,...mika, jonnyboy and simon_M will be along shortly to answer your query.