Hello all
We have VW Polo 1.2 3clynder with suspected stretched timing chain
Vehicle has a fault code P0171 system too lean bank 1
Enclosed is a saved cam shaft and crank shaft attachment file
Channel 3 is just a trigger from No.1 cylinder ignition coil
When the vertical cursers are lined up, as in frame 32.
When I scroll back through the frames the edge's should be in line every time?
We see left hand vertical is not inline in each frame on the crank shaft vertical, this is suggesting a stretched timing chain?
The vehicle came to us from a dealer who sold it and customer brought it back with engine lamp on.
They read the codes, P0171 and replace the upstream O2 sensor with an aftermarket NGK
A week or so later vehicle was referred to us, lamp on dash and no driveability issues.
Reading codes and looking at live data LTFT was high (using snap on in OBD), we smoke tested it to find inlet manifold gasket leaking along with vacuum pipe to servo leaking and rubber perished.
All other checks appeared ok.
The dealer took car away, replaced gasket and pipe and returned vehicle to customer.
Vehicle then came back again with same code P0171 beginning of last week.
I had a look at live data and all looked ok (forgot to save data again)
Yesterday I thought I would check a few basics and cam/crank synchronization, ( we have replaced a couple of noisy chains on these)
I noticed the manifold pressure reading on acceleration, would drop and then recover, removing and cleaning the oil covered sensor gave a better consistant live data reading.
The P0171 comes on as soon as test drive but dose not bring lamp on dash
That's when I saved and posted file yesterday, with the same thought of how can cam/crank cause P0171?
I will re do the tests again and post over the week end
I had another look today, and with vehicle stone cold from over night, I found a very small leak when I smoked the exhaust again.
Previous tested this when warm and no leak from joint
This leak was at the cat to down pipe flange just before the down stream O2 sensor. resealed the joint, reset all learned values, after a extended test drive the P0171 was back
STFT was +9% switching to 0% at idle.
I will do a fuel pressure test and injector voltage and amp measure in the morning.
I seem to be unable to upload files
When I click add file, my post a reply screen then goes blank.
Am I doing something wrong?
Typed this all out about 4 times now