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        General >> Problems >> O2 sensors, emissions, mpg
        
(Message started by: Octavian_P on Dec 14^th, 2006, 8:49am)

Title: O2 sensors, emissions, mpg
Post by Octavian_P on Dec 14^th, 2006, 8:49am

Hello to all

I don't know if you all remember that I bought a second Scorpio, a cossie that wouldn't pass the MOT because the emissions where about 4 times bigger then normal. Well last evening I managed to put the cossie on OBD and found out the following:

1120 = Throttle Position Sensor out of range.
0122 = Throttle Position Sensor circuit Low Input.
1406 = Differential Pressure Feedback Electronic Sensor circuit Downstream Hose.
1131 = Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1.
0171 = System Too Lean - Bank No. 1.

Now I know I should have written this to the OBD page but it makes me think "I have a problem" because the car has had fitted new oxygen sensors about 6000 miles ago.

The TPS: could have errors because of the battery pack which went flat and I know that the TPS re-syncs with the ecu.

The EGR: I took the decision to block its vacuum pipe such that the engine will run cleaner.

The real problem is with the oxygen sensors which are brand new and the do not switch. I have plotted a graph. With the engine off, the graph is a straight line. With the engine on, the variations are almost imperceptible....only slight variations, way further than normal switching. Is there a power supply or a fuse for the O2 sensors? The mpg is pretty worse also. The fuel trims after closed loop, went into fault and not open loop....

Title: Re: O2 sensors, emissions, mpg
Post by scorpio_man on Dec 14^th, 2006, 9:05am

hi there

first thing i'd check is all the wiring in the engine bay. :(

when completely sound, clear all the error codes, disconnect battery for 10mins and try again.

btw, are you sure bank1 sensor(s) were changed? maybe it was bank2 that was changed. :-/ or maybe they changed the rears by mistake?

hth

oh, are you using VE? is so, email the 3 files and i'll have a look. you need to scan the following...

RPM
MAF
LTFT
BOTH LAMBDA SENSORS
run these for 5 mins at idle (a/c OFF). every minute, blip the throttle to 2k rpm. end this scan.
then do another scan, switching on and off various temp sensors. also check the tps with the engine off (ignition on). should be from 16% to 92% ish.

try not to drive it on the scan.

Title: Re: O2 sensors, emissions, mpg
Post by Octavian_P on Dec 14^th, 2006, 10:45am

Hi Scorpio Man ;)

Thanks for the quick reply.

Both pre-catalyst sensors where renewed. As for the requested data i can't obtain it because i don't own an OBD cable yet, so I have asked the ex-owner to scan it for me ;D. The TPS is ok. With the engine off it reads between 15.9 -16 to 87-89, but the accelerator pedal was hitting the floor mat a bit ...this I have found out later.

Cheers