Quote:
Originally Posted by quasio
For the record, I also experienced this flat spot, it was more 3.5k-4k rpm. I changed the cam shaft angle sensor, and the intake VANOS solenoid valve (although both had logged codes at that point. but previously they didn't log any codes but i still felt the issue)
and now it revs much more freely. I also have the BMS powerbox "tune", and that made it worse when it was having VANOS issues. but now its better.
Talked to my mechanic and he said vanos solenoids are common issues, because over time the oil gunks them up (also the space between oil changes).
I'd suggest giving that a go, there's some guides of people taking it out and cleaning it themselves, but just get new ones.
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Yep, these engines are quite sensitive to oil condition and ultimately oil pressure going to the Vanos from the solenoids. Even a deformed or twisted oil filter can cause issues apparently. So cleaning the solenoids from time to time is not a bad plan especially if the oil is subjected to the normal lengthy service intervals, recipe for sludge build up as far as I am concerned!
Now, I changed the oil some weeks back and while the problems are still present, the engine feels a bit better to a degree. I did clean the Vanos solenoids last year but it made no difference at the time. But, another posted on the DIY thread mentioned that to proper clean them you actually need to feed 5V DC (or so) to open the solenoid so that proper cleaning can be done - must still do this at some point, and also just not sure about the polarity when doing this.
Something I am thinking of having tested now is the fuel pressure and possibly the operation of the injectors to make sure that there is not an issue there.
Then there is the timing issue which could very well be the cause of my pinging problems.