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[Jay w]

Got home this evening, car has been running ok, you would never know there is an issue as she pulls like a train, stripped the soldered connection out and tried again, all the wires are clean, good connections, all heat shielded and finally taped off for protection.
Fire her up and no light......wayhey, result   until i start to rev it, and it then reappears and will not go back out  
strip it all out, recheck, all ok, rebuild, and again light is out so long at the revs remain below 2k, as soon as you have a fast idle of more that 2k the light is then on for good.

disconnect the battery for a few seconds and all of the above will be apparent, trouble code 17 (knock sensor LH bank)

the car drives like there is no issue, but heres the wierd thing, i have driven her down the road with it unplugged and it feels like normal....

any suggestions on how we can check to see if the unit is faulty?

[Marks DTM Calib]

Knock sensor does very little at low revs anyway hence why its only detected at 2K rpms......

When you say LH bank you are I assume refering to the 2-4-6 cylidner bank (coz it depends where you are as to which is the LH bank ).

[Jay w]

Knock sensor does very little at low revs anyway hence why its only detected at 2K rpms......

When you say LH bank you are I assume refering to the 2-4-6 cylidner bank (coz it depends where you are as to which is the LH bank ).

aha this would deal with that mystery

N/S bank, and we still cant find the sensor head, in addition i have noticed that the connector is more of an oval shape rather than the usual square ones that have been on Vauxhalls in the past

[Jay w]

after dicking around it with it for 2 days i still have an issue  

i have fitted another knock sensor, however the connector is different so i have had to solder the old end on to the newer connector.

fired it up and still the light is on so stripped it all out....again, cleaned the ends, checked the solder, cleaned the block, and went over the whole thing with a fine tooth combe.

fitted it back together, started it and the bloody light is still on, took it out to get some gas, on the dual carridgeway about 3000rpm the light went out!!!!

for about the next 10 miles the EML was on and off all the time.

below 2k the light is on, above 3k for any period of time and it goes off.

any suggestions

[Dazzler]

Have you had it Tech2'ed Jay, it might shed a bit of light over this mystery :-/

[Marks DTM Calib]

Heres the diag info.


Engine speed is greater than 2000 rpm
Control sensor reference voltage for knock sensor is less than 10 mV
(Value varies depending on the engine speed)
Knock sensor voltage is evaluated and produces an implausible resulting value for 20 consecutive checks (at 100 ms intervals)

Replacement Value:

Engine load signal is greater than 2.6 ms and coolant temperature is greater than 45 °C (113 °F):
The control unit retards the spark timing by up to 12 °CA for reasons of safety. (Value varies depending on the engine speed)
 
Concerned Terminals:
11, 29, 30

These things are hugely sensitive to noise, was the fault there before the LPG was fitted?

Is the cable right back to the ECU ok including the screen?

[Jay w]

The paperclip test gives me code 17, in addition i have used a code reader called Launch but not able to get hold of it currently

This problem only occurred when i did an oil and filter change last weekend, the wiring has been a little fragile since it was damaged sometime ago, it has been repaired a few times now.
i tried to repair it but this time it would not communicate with the ECU

[Marks DTM Calib]

What oil did you use.....?

I wonder if there is a bit of phantom knock?

[Jay w]

What oil did you use.....?

I wonder if there is a bit of phantom knock?

10/40 semi, although not Vaux stuff, quantum..

stealers were closed

just driven to london this morn, for the first 100 miles the EML was on, from there it was on and off dependant on load and engine speed.
partial load, or normal load above 3k light out
wriging the nuts out of it or pulling a hill the light would come on.
stationary, or less than 2k light on

[Marks DTM Calib]

What oil did you use.....?

I wonder if there is a bit of phantom knock?

10/40 semi, although not Vaux stuff, quantum..

stealers were closed

just driven to london this morn, for the first 100 miles the EML was on, from there it was on and off dependant on load and engine speed.
partial load, or normal load above 3k light out
wriging the nuts out of it or pulling a hill the light would come on.
stationary, or less than 2k light on

I would be tempeted to put some Vx semi in (wouldn't worry about the filter) to get it back to a known position.

[Jay w]

right.....

oil and filter change today along with a brand new genuine sensor, no joy, still the same symptoms.

So we starting doing some digging.

first - clear codes, disconnect n/s sensor, run engine, exactly the same as usual, as soon as it gets to 3200 rpm EML is on

Second - clear codes, disconnect both knock sensors, again 3200 rpm light is on and this time it picks up that both sensors are not there

Knock sensor is within values as given by autodata on both sides.

So i decide to start recovering my track, i was told the wiring was ok, hmmmmmmm, this is that i found...

This is the loom coming out of the ECU, after having the issue with the LPG install i left it in the hands of a auto sparky to sort out the lambdas


What you are looking at there are the knock sensor wires for both sides......

now that is shoddy repair work, BUT!! could this be the root cause?

[Jay w]

well we have a result!!!!

the red wire in the pic above was not soldered on properly and the shielding had been cut  

so i cut a section out of an old knock sensor, within 15 mins had it looking pukker and all connected properly.

cleared the codes and fired her up, no light    took her on a quick run and she is back to her old self, pulls like a train.

slightly pissed that i had to spend £90 on a new sensor only to find that wasn't the issue but her we live and learn.

[albitz]

go back to the sparky and tell him he owes you 90quid

[Cav9_4]

Glad you got it sorted Jay

[Jay w]

go back to the sparky and tell him he owes you 90quid

been trying to get hold of him in order to find out if it was him or the bloody guide dog that did the work, he is busy and 'not taking calls currently'

he did a rush job, cocked it up and now won't take responsibility for the job he did, it's ok, i can live with that, what i have done is pass on the details of the job, he does a lot of freelance work so having heard about my issues there is now at least one garage who wont use him in a hurry