knock sensors/lambda/ maf issue/ misfire and idle problems..

[deanpompey 0]

ok so i picked up my VR6 on thurs eve, 94 L reg 2.9 obd1 VR6.

she drove sweet from cold, but then once it warmed up a bit it would cut out when clutching coming to stop.

Then sat in traffic jam on the m25 it would hold its idle at around 650rpm, but when you pressed throttle revs would drop and car would stutter, then as soon as stopped again it would die. (nearly killed the battery i had to start it so many times :( )

 

Yesterday it developed a missfire under load, initailly just at 3k and above, but now it does it at any load at all. with the car in neutral there is no misfire at all.

 

I vagcommed her, and got the following:

 

00537 - Lambda (Oxygen Sensor) Regulation: Upper Limit

00525 - Oxygen (Lambda) Sensor (G39): Signal too Low / Implausible Signal / No Signal

00540 knock sensor 2

00553 Mass Air Flow Sensor -G70 Short to B+ intermittent

00518 Throttle position sensor (G69) Signal Outside Specifications - Intermittent

 

from this i assumed the lambda was screwed, so unplugged it.

then went for a drive and got the following:

 

00525 - Oxygen (Lambda) Sensor (G39): Signal too Low / Implausible Signal / No Signal

00540 knock sensor 2

 

none of the other codes came back, after many clears, and lots of drives.

 

00525 is obviously because the lambda was disconnected, so that will need replacing,

00540 knock sensor 2, is this the sensor on front or rear of engine? i ask because i disconnected what i think was the knock sensor on rear of block (grey plug), and when i did this vag com brought up the fault code for knock sensor 1, and didnt bring up knock sensor 2.

 

 

i think there is a slight blow at front of exhaust somewhere, possibly the downpipe/cat flange, so could this be causing the Lambda to be all over place? i dont know where the lambda is positioned, it has a 6 branch stainless manifold, but i would assume it would be in same position? if it is in front of cat then perhaps this could be causing the lambda to go mad, resulting in engine running too lean, and knock sensor detecting pinking??? that make sense to anyone???

 

apologies for long post, but have been reading a million and one VR6 misfire threads and with no joy, so wanted to get all the facts in so you lovely people might be able to help me out!

 

cheers!

[C488ADO 0]

hmmmm interesting....

 

 

by coincidence yesterday i have the same problems......

oilbreather went brittle and collapsed.... replaced with make shift bit of kit for temp fix.... all good.....then noticed the throttle body elbow had split so massive air leak ....replaced fixed......now the car has a weird splutter and loss of power it coughs out black smoke which is unburnt fuel ....it stinks really stinks.... checked isv all good maff seems to be working.....

 

faut shown on vag com

 

 

lambda

engine speed sensor

 

cleared codes and engine speed sensor remains... i guess this is the cam sensor? knock sensor?

 

front of engine...

 

 

what does this sensor actually do ? i mean what does it control on the rest of the engine?

 

 

do i replace my lambda at the same time??

 

 

 

the revs are hunting and it pisses me off 650 -1500 drops then settles then drive then shoots up then settles and so on

[deanpompey 0]

I also had split breather, but that was removed when i fitted the power rohr intake, now just has a straight piece of tube there with sensor in, and the smaller tube furthest forward is blocked off. i dont see that that would cause my issues now :shrug:

 

i have got my hands on a spare MAF, ISV, TB and coil, so some testing to come today!