Posted to Technical Discussion Forum on 12/16/2012
Turbo lag after cleaning valves
[2007 BMW 335i, Emissions Photo] [2007 BMW 335i,
Emissions Photo] Hello, I have my neighbor's 07 BMW 335i
in my shop for a noticeable or perceived turbocharger lag
while accelerating. I notice the problem when accelerating
on to the Highway from an on ramp and while at cruise speed
and trying to accelerate for passing. When accelerating from
cruise speed of 50-60 mph the vehicle is hardly moving
faster, then 3 seconds later I can feel and hear the twin
turbos spool up and I have power.
My neighbor caused this problem, so it's not my problem:) He
found on the web how he can clean his intake valves himself.
He removed the air box, throttle body and plume. With the
intake valves now exposed, he would turn the crank by hand
to close the valves and while closed, he filled the head
chamber with a cleaner and scrubbed around the valve with a
tooth brush (his or his wife's, I didn't ask). When
finished, he cleaned out the camber with a shop vac. He also
cleaned the throttle body and plume. He reassembled and
installed new spark plugs. Manifold gasket and spark plugs
were OEM. He states the vehicle idles better and feels
smoother, but now has this lag.
I normally do not work on these platforms, but I would takes
a cursory look at it. Test drove and confirmed condition.
Scanned vehicle with Modis and DS708 and found no codes and
long/short term fuel trims close to 0. My underhood
inspection found this vacuum line disconnected. This is part
of the engine driven vac system . Ok, found the problem,
nope, still have this lag. So far I only removed the airbox
and everything appears fine, everything connected. Smoked
checked engine driven and engine vac systems and found no
Monday I'm going to take a test drive with another tech to
watch the PIDS.
Any key pids I should be looking for? Any ideas how my
neighbor caused this problem when the vehicle drove fine
before this worked on it?
BTW, I have not had a chance to figure out where or what
systems the vac line I did repair affected. The rubber line
on top of the airbox was disconnected from the hard plastic
line. This is on the driver's side and the rubber line goes
into the wiring harness running along the left fender. Any
Thanks for reading my post
Oceanside, California, USA
3 Replies Received
3 Replies Received