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        General >> OBD Advice >> MAF zero o/p - Code P0102
        
(Message started by: KeithCEng on Feb 26^th, 2005, 7:45pm)

Title: MAF zero o/p - Code P0102
Post by KeithCEng on Feb 26^th, 2005, 7:45pm

:)Evening All!

My Motor (24V Cossie) failed MOT emission test on IDLE (High CO). OBD-2 shows 'P0102' Code together with 'permanently rich' (high) readings from upstream HO2S Sensors. Have checked that 12V Supply is present at 'MAF' and have cleaned same using appropriate Carb Cleaner aerosol - No difference! System is running 'Open Loop' (I think) because I don't see transitions from the HO2S's. Is my 'MAF' broken?

Any help would be appreciated!

Cheers

Keith :)

Title: Re: MAF zero o/p - Code P0102
Post by scorpio_man on Feb 26^th, 2005, 8:11pm

hi there

i take it you cleared the code after cleaning the MAF? have you monitored the MAF output? it should be about .450 lb/min.

are you using VE? you can check if it's open or closed loop. that way you know for sure.

you say high readings from lambda sensors. what do you mean? up at 1 volt? or your Short Term Fuel Trims are at high %.

if you are using VE, post your scan (3 bits) to anyboard (http://www.anyboard.net/autos/cars/scorpio/index.html) so we can have a look.

hth
ps. mind and post the link

Title: Re: MAF zero o/p - Code P0102
Post by KeithCEng on Feb 27^th, 2005, 11:53am

:)Hi Scorpio_Man

Many thanks for your prompt reply - I have a confession to make! My motor is a 1996 Ultima Cossie but my partner has a 1996 Escort 1.6i. It is her car that has the emissions problem.

I had bought VE for the Cossie (which is running very well) and didn't even realise that the Escort had an OBD port until a few days ago! In posting the MAF problem, I was hoping for some general pointers from fellow Scorpio owners (I have looked at the Escort Owners Site and it is not a patch on the Scorpio Site!)

Further investigation of the Scan results shows that "O2S11" Sensor o/p is switching between 0.05V and 0.9 dependent on Engine RPM, but at Tickover (Hot Engine), the O2 sensor output stays at approx 0.9V. I measured the o/p voltage of the MAF with a DVM - it is approx 9mV regardless of Engine RPM and the VE Data shows unchanging ZERO Airflow. I did not reset the P0102 Error Code because it came up each time I refreshed the "Codes".

I have not attached the Scan files because I feel that would be too much of an imposition.

Cheers

KeithCEng :)

Title: Re: MAF zero o/p - Code P0102
Post by Eric_R on Mar 1^st, 2005, 7:52pm

Keith,
Escort ????? What absolute front ;D ;D ;D

No worries m8 - we're here to help - and the Escort is sort of like a cousin to our Scorpios ;)

Incredibly, the Escort engine OBD is exactly the same as your 24V - only it has only one bank instead of two, and 2 HO2S sensors instead of 4. The diagnostics are the same, so apart from little foibles of that particular engine what goes for the Scorpio 4 cylinder also applies to the Escort. ;)

P0102 is the Comprehensive Component Monitor (CCM)http://www.fordscorpio.co.uk/ccmonitor.htm recording a problem with the MAF sensor. The sensor voltage is checked routinely while the engine is running (KOER) and if the MAF sensor voltage falls too low, typically <0.23v then the DTC is stored.

Without a rational signal from the MAF the Fuel monitor will stay on open loop (ie not controlled by the HO2S) and this will often lead to an over-rich condition, similar to running on choke.

Causes can be the following:
Faulty wiring or connector to the MAF sensor. Check the multipin for corrosion inside the connector and make sure the pins are nice and clean.
Break in the loom - check the wires carefully for chafing or corrosion damage.
Make sure the air trunking is tight and that there is no leak anywhere such that air is bypassing the MAF into the air intake system.
A damaged/failing MAF is still a possibility. Try to arrange a substitution with one known to be working.

If you do a scan selecting the MAF and then blip the throttle - check the MAFV. It should rise smoothly and not drop too low.
Then select the following sensors,
MAFV, HO2S11 and 12, RPM, LTFT1 and drive round the block so we can check the fuelling system as a whole. Put the three scan files into a zip file and post it on the Anyboard site Scorpio Man mentioned.

HTH

Title: Re: MAF zero o/p - Code P0102
Post by KeithCEng on Mar 4^th, 2005, 9:27am

Hi Eric

Appreciate your detailed reply. Because I'd measured virtually zero output from the MAF itself, I concluded that it was u/s. Mr.Ford sold my partner a new MAF for £71; I fitted this and carried out another VE Scan - BINGO ;D - MAF showing 0.3lb/min airflow at tickover, rising to 0.78lb/min at 2k RPM. System now running 'Closed Loop'.

My partner took the Escort for MOT re-test the following day and it passed, so she is now a very happy bunny and I've gained a few brownie points! ;D

Again, many thanks for your suggestions.

Cheers :)

Keith

Title: Re: MAF zero o/p - Code P0102
Post by Eric_R on Mar 4^th, 2005, 7:59pm

Excellent, Keith.

Glad you're sorted. ;D