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Mazda MX5 1.8 2011 - Code P2097 post cat rich #

Posted by david evason on April 4, 2013, 9:54 pm

Year of Manufacture *: 2011
Engine Size and Code *: 1800 L8
( Optional ) ECU Type: JMZNCA88200256333
( Optional ) Scanner Used: Solus Pro
( Optional) Fault Codes: P2097

Good evening people, just after a little help and direction with this.
Set a code P2097 Post Catalyst Fuel Trim System Too Rich.
First image Probing the downstream (red trace) shows 889mv obviously rich.
Blue trace is Pre cat sensor. Not switching.But way too high at 2.74v ??
Second image shows where i have introduced an air leak so this proves (or doesnt it) that this sensor is working. Which turns my attention back to the pre cat.
Not being too familiar with the system, and quite new to scoping im questioning my technique and wondering if for some reason the pre cat sensor is possibly a wideband one althought it only has four wires. Can you get 4 wire wideband sensors ? i didnt think you could.
Is the pre cat fractured or shorted inside ? Just after a bit of info before i go ordering a £200 sensor.
Short term fuel trim is 0.00
Long term fuel trim is 12.50 and neither of them change.
Thanks for any help and input

Re: Mazda MX5 P2097 Post Cat Rich

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on April 4, 2013, 10:09 pm, in reply to "Mazda MX5 P2097 Post Cat Rich"
Mark Carter

Hi,

You are right to query the upstream sensor, at present I feel the post cat sensor is just reporting the facts.

You may well have a AFR sensor up-stream with a default voltage of 3.3 volts, switching either side for a rich / lean reading.

Check all the basics including air leaks up stream of the cat.

Mark

Modern cars, Its all wizardry and witchcraft

Re: Mazda MX5 P2097 Post Cat Rich

Posted by david evason <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3433' width='330' height='300' border=0 style='border:none;'> on April 4, 2013, 10:29 pm, in reply to "Re: Mazda MX5 P2097 Post Cat Rich"
David Evason

Hi Mark,
Thanks for the quick reply.
I too felt that the downstream was reporting true
Scan data doesnt show a PID for Bank 1 Sensor 1 either but it does show a few PID's for AFR.
Arent AFR and wideband sensors the same thing just different names ?
Smoke testing in the morning then !
Thanks
Dave

Re: Mazda MX5 P2097 Post Cat Rich

Posted by aidan birley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on April 4, 2013, 10:43 pm, in reply to "Re: Mazda MX5 P2097 Post Cat Rich"
Aidan Birley

Hi

may be worth a look at EOBD live data & fault codes

Cheers Aidan

Re: Mazda MX5 P2097 Post Cat Rich

Posted by James Eardley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3143' width='330' height='300' border=0 style='border:none;'> on April 5, 2013, 12:44 am, in reply to "Re: Mazda MX5 P2097 Post Cat Rich"

Only thing I can add too the above replies is to check heater circuit of the upstream sensor.

Good post and nice captures too mate

James

Re: Mazda MX5 P2097 Post Cat Rich

Posted by James Eardley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3143' width='330' height='300' border=0 style='border:none;'> on April 5, 2013, 1:16 am, in reply to "Re: Mazda MX5 P2097 Post Cat Rich"

Just because you mentioned 'questioning your technique' (if you meant scope technique)and not because I'm picky

Nothing wrong with yours (technique)..... Nice to see alot of time on the screen

If you wanted to and had another channel

You could shove a probe in the MAP/ MAF sensor as it Is generally an easy connection to make, to see the air leak you made. No real reason to do so in your case though.

Just abit more of a scientific/accurate test and is easier to become familiar with your capture when you come to review your bad and hopefully when you fix it, good capture in months/years to come

Like I say mate, just saying

James

Re: Mazda MX5 P2097 Post Cat Rich

Posted by Andy Evans <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5518' width='330' height='300' border=0 style='border:none;'> on April 5, 2013, 3:34 pm, in reply to "Re: Mazda MX5 P2097 Post Cat Rich"
Andrew Evans

Is this vehicle not under VM warranty?

Andy Evans

Ongoing#

Posted by David Evason on April 8, 2013, 10:53 pm, in reply to "Re: Mazda MX5 P2097 Post Cat Rich"
Edited by board administrator April 13, 2013, 11:39 am

Thanks for the replies.
Checked for fault codes and that is the only code showing . Checked the heater circuit on the upstream and the current was correct. Re probed it and it was showing 330mv but no switching. I thought perhaps I had probed the wrong wires at the first check but I was sure I had double, triple checked it.
Now when I probed the downstream sensor this now jumped up to 2.74v ?
Due to the no switching on the upstream I changed it but alas it was the same. Luckily my parts man said there would be no problem returning it although I don't like doing that !!!
I did advise to take it back for the VM's warranty but because he had missed his service schedule they were being awkward about it.
I have returned the vehicle to the owner till I can get more info and understand the system better.
Cheers for the adviice James

and yes your quite right with what you said about probing MAF/MAP for a bit more of an accurate test. I shall do that in the future.
Once again thanks for everyone's input.
Dave

Re: Mazda MX5 P2097 Post Cat Rich

Posted by Glen Strachan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat1463' width='330' height='300' border=0 style='border:none;'> on April 11, 2013, 1:43 pm, in reply to "Re: Mazda MX5 P2097 Post Cat Rich"

what is your manifold pressure ? Have you had it on a gas analyser ?

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