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Vauxhall Astra G Z16XE 2001 - Knock control, code P0325 - Fixed #

Posted by Alan Kane on November 16, 2011, 4:06 pm

Year of Manufacture *: 2001
Engine Size and Code *: Z16XE
( Optional ) ECU Type: Multec

Anyone familiar with the operating strategy for Vauxhall Multec knock control, Z 16 XE engine?

I have one which logs P0325. When it does this it looses power and will not rev. I caught it doing it once and it had narrowed the inj pulse. Now I am wondering if the code (ie knock control limit) is a symptom or the cause.

The Vauxhall fault description is – Knock sensor circuit fault. The knock sensor voltage is evaluated and produces an implausible value.

The question is, does the ECU pull the inj PW back as part of the knock control strategy?

I still have some work to do on this but knowing this may help me with the direction of my diagnosis.

TIA

Re: Vauxhall Astra G / P0325

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on November 16, 2011, 5:01 pm, in reply to "Vauxhall Astra G / P0325 "
Peter Mutlow

Hi Alan,

http://www.obd-codes.com/po325 gives some info on this. I had the same problem and code with an Astra a couple of years back and went in with a new knock sensor which cured the fault.

Regards

Pete M

Re: Vauxhall Astra G / P0325

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on November 16, 2011, 5:20 pm, in reply to "Re: Vauxhall Astra G / P0325 "

Hi Alan, have you had time to look at TIS 2000 / Global Tis and if so was it any help?

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Astra G / P0325

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=alankane' width='330' height='300' border=0 style='border:none;'> on November 16, 2011, 11:30 pm, in reply to "Re: Vauxhall Astra G / P0325 "
Alan Kane - Administrator

Pete and Mark, thanks for the replies,

Pete, I tend to put more store in the code definitions and setting criteria from manufacturer sources than generic EOBD info. The info on the code I posted is from TIS2000. The problem being that manufactures data is far from fool proof. As I said I haven’t done much with this one so far, but what I have seen with the Inj PW does not make a lot of sense to me, hence my question.

Mark, I have looked on TIS and it appears to fault the integrity of the signal but I have yet to test the sensor. I just have a hunch that the knock code has a poor definition and could be the result of another fault. Sometimes hunches are great and sometimes they can be a waste of time. I haven’t touched it wit a scope yet, that’s due to happen in the morning. I haven’t worked through the TIS2000 test schedule yet either but I did read it and it focuses on testing the integrity of the sensor.

To get back to my question and rephrase it slightly, does it make sense that the ecu would lean the engine under knock?

To put this in perspective, I am not the first to work on this. Previous attempts have included, as far as I know, 2 new knock sensors, an ECU, a cam sensor, a check of the wiring, a set of plugs, a coil pack and God only knows what else. When someone else suggested engine mounts the customer bailed out.

From the little I looked at today, which was just a bit of live data, I wasn’t happy with the pulse width, the rear O2 sensor or the MAP figures. More testing to be done.

Thanks

Alan

Re: Vauxhall Astra G / P0325

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on November 17, 2011, 12:49 am, in reply to "Re: Vauxhall Astra G / P0325 "

Hi Alan,

>>> To get back to my question and rephrase it slightly, does it make sense that the ecu would lean the engine under knock?

To put this in perspective, I am not the first to work on this. Previous attempts have included, as far as I know, 2 new knock sensors, an ECU, a cam sensor, a check of the wiring, a set of plugs, a coil pack and God only knows what else. When someone else suggested engine mounts the customer bailed out <<<

That certainly puts it in perspective, without teaching someones granny to suck something we both know that the main function is to retard the timing and then creep it back to the optimum CA.

It may well make sense for the ECU to reduce the fueling at the same time, however it would make just as much sense for it to do the reverse and increase fueling.

I have a similar vehicle at work and I will monitor the Injector time whilst activating the Knock sensor in the morning and see what the results tell me.

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Astra G / P0325

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=alankane' width='330' height='300' border=0 style='border:none;'> on November 17, 2011, 7:34 am, in reply to "Re: Vauxhall Astra G / P0325 "
Alan Kane - Administrator

Thanks Mark, that’s a very kind offer. I would also be interested to know how it runs under load with the sensor disconnected. Apparently this one runs the same with the sensor unplugged, plugged in but not mounted to the engine (understandable) or mounted normally.

Cheers

Alan

Re: Vauxhall Astra G / P0325

Posted by Mark carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on November 17, 2011, 4:34 pm, in reply to "Re: Vauxhall Astra G / P0325 "
Mark Carter

Right just got to this one,

Vehicle warm and idling with Knock sensor connected;

Injector duration 2.8 ms and timing point between 9 & 15 degrees CA

Vehicle warm and idling with Knock sensor disconnected;

Injector duration 2.1 ms and timing point set at 12 degrees.

Vehicle runs "flat" with sensor disconnected as I would expect.

Fault code with sensor disconnected (using Tech 2) is P0325 knock sensor 1 circuit low input.

Hope that helps.

Regards Mark

Modern cars, Its all wizardry and witchcraft

Re: Vauxhall Astra G / P0325

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=alankane' width='330' height='300' border=0 style='border:none;'> on November 18, 2011, 7:55 am, in reply to "Re: Vauxhall Astra G / P0325 "
Alan Kane - Administrator

Thanks Mark, appreciate that.

This job is put off until next week. I will update then.

Alan

Re: Vauxhall Astra G / P0325

Posted by Matt Booth <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3028' width='330' height='300' border=0 style='border:none;'> on November 18, 2011, 8:17 pm, in reply to "Re: Vauxhall Astra G / P0325 "
Matthew Booth

You may have checked this but these log a knock fault code when the oil level is low. Worth a check before getting too involved.

Matt

Re: Vauxhall Astra G / P0325

Posted by alankane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=alankane' width='330' height='300' border=0 style='border:none;'> on November 29, 2011, 11:30 am, in reply to "Re: Vauxhall Astra G / P0325 "
Alan Kane - Administrator

Got back to this today. After reading Marks input I decided to start from scratch. I scoped the knock sensor and am not sure of the results.
I removed the sensor and scoped it while knocking it against the block.

In an effort to see if it had a valid signal I knocked it first gently, then hard and then very hard.

While I think the trace looks about right I am wondering if it is a bit low?

http://img600.imageshack.us/img600/9929/gentletap.gif
http://img197.imageshack.us/img197/6479/hardtap.gif
http://img842.imageshack.us/img842/9653/veryhardtap.gif

Re: Vauxhall Astra G / P0325

Posted by ray ferreday <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5108' width='330' height='300' border=0 style='border:none;'> on November 29, 2011, 2:14 pm, in reply to "Re: Vauxhall Astra G / P0325 "
Raymond Ferreday

ps check your oil level thats what causes the code ray

Re: Vauxhall Astra G / P0325

Posted by Alan Kane <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=alankane' width='330' height='300' border=0 style='border:none;'> on November 30, 2011, 6:52 am, in reply to "Re: Vauxhall Astra G / P0325 "
Alan Kane - Administrator

Sorry, forgot to mention oil level. that was the first thing I checked.

Fixed #

Posted by Alan Kane on June 15, 2012, 7:21 am, in reply to "Vauxhall Astra G Z16XE 2001 - Knock control, code P0325 #"
Message modified by board administrator June 16, 2012, 2:08 pm

I completely forgot about this one. I could not fault how the knock signal was working so had to be an ecu. Thanks for the replies.

Alan

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