Rob_DOHC

iTrader: (4)

My car has lost LOADS of performance at low RPM, (m52 1998 328i). But still pulls above 3-4000rpm normally.

Its an auto and just boggs at full throttle, it still kicks down alright etc. But my average mpg has gone from 20 to 17mpg too....

It all seems to point to vanos woes.... but its still smooth and silent.

Any thoughts on other causes?

Rob,

Markb_s1

someone had a very similar sounding problem on bimmerforums the other day.. migth eb worth a search there...

Rob_DOHC

iTrader: (4)

Cheers mate, im a member on there so i will have a look... I just never seem to get sensible answers over there!

LHD220Turbo

iTrader: (4)

single vanos isnt it on the 328i?

does it sound noisy from stone cold, tapping noise?

Rob_DOHC

iTrader: (4)

Yea single vanos, not noisy at all. But apparently different parts can fail, one of them essentially locks the inlet in the retarded position so its got no low end power but goes like normal up the top (like mine) and the other failure makes the vanos area sound like its full of stones.

Just wondered if any one had ever had the same happen

Mike1

Have you had the fault codes read to rule out the cheap stuff like cam/crank sensors, MAF, air leaks etc?

I take it you've read the rebuild procedure on the Beisansytems site? You need to know what you're doing and have access to the Vanos tools IME

Rob_DOHC

iTrader: (4)

Hi mate,

A friend just came over and read the fault codes, the only code was as cam position sensor! So you may well be on the right track! But i have heard that the vanos failing doesn't always show a code, but it was operational (snap on scanner can make the vanos advance and retard at tick over).

Codes have been cleared, so i'll take it for a run and see whats what.

I have read a few rebuild procedures ect, and have looked at the BMW TIS disk. It certainly looks very doable, as long as i can get the viton seals etc, done far harder in the past.

Thanks for the replies, i'll let you know how it gets on.

Rob,

Mike1

If you re-query the codes after you've cleared the fault logged and then run it and it comes up as cam sensor again, then I'd do that first. It can feel very 'flat' with a dud sensor.
Easy to do

rsturbolee

compression test also