Diagnostics Doctor
BMW 3-SERIES
Low power
Q My 2003 BMW 325Ti Compact is, I suspect, not giving full performance. It’s got 103K miles on the clock but starts instantly and idles with zero speed variation. So I think cylinder compressions are not suspect. From idle the engine revs without hesitation as it does under load. There is no fault lights on instrument/binnacle panel. I compare its acceleration from standstill to my 17,000-mile Mazda3 165. And its slower with less pull – or should I say grunt!
New road test figures for the BMW are: 0-60mph. 7.1 secs. New road test figures for the Mazda 0-60mph 8.2 secs. Hence this is understandably difficult to accept. I cannot avoid suspecting that there could be a fault with the engine Vanos variable system.
To determine any such fault my enquiry is what engine scanner could show/read a fault with the engine Vanos valve system?
I notice in your December 2020 issue there is a Foxwell NT301 advertised but do l need a much more powerful/comprehensive scanner to detect any possible Vanos fault? Perhaps the Foxwell NT510 scanner would.
Most importantly can you tell me where in the front of the cabin is the diagnostic socket assuming it is inside the cabin!
Lastly what is the most effective fuel additive for the removal of carbon from engine valves and pistons? I have been using Redex.
Peter Geering
A The diagnostic socket is located up under the driver’s footwell to the offside and is covered by a plastic door which needs to be unclipped and swung down.
Any camshaft position problem should be detected on an EOBD scanner and will indicate a code which will be in the EOBD range of P0010 to P0029 or P002A-P002F. A code of P0021 for instance would indicate that the camshaft position (CMP), intake/left/front, bank 2 – timing was over-advanced/system performance problem. The Foxwell NT301 would be capable of this but if you can stretch to the NT510 this will give you more options.
The most likely part to fail in the VANOS system is the solenoid and these can be easily removed and cleaned, but a failed solenoid should leave a code in the system and this would put the engine management light on. There are also reports of the VANOS seals failing
