Emissions Test help

[johndaily693]

got an engine management light which says oxygen sensor from the reader
I got the below results from an emissions test:










the car is an LPG car rover 25 1.6 engine with 52000 miles. The first two tests were done using LPG while the last one was done using petrol. does these results suggest that the oxygen sensor has a problem as I am running out of ideas regarding what is causing the light to come up. I read the OBD reader results which look ok I think see below:



OBD Reader results at idle and engine warm:

Feul sys1 - CL
Calcload - 2.74 %
Coolant - 66, this increases and stays between 90-102 eventually as car warms.
Stft b1 - hops around between -5%and 5%
Ltft b1 stays more or less constant at -3.91%
Map - 34 kpa approx
Engine rpm- 870
Spark adv - jumps around between 8-12 btdc
Iat- 23 celcius
Tps- 3.92%
O2sl - 1112
O2s11- varies between 0.1v to 0.8v for upstream 02 sensor
Shrtft11 - varies between -5%and 5%, I am guessing this is reading is from upstream 02 sensor
O2s12- voltage stays constant at approx 0.85v for downstream 02 sensor
Shrtft12- 99.2% does not change stays constant. This for downstream 02 sensor


OBD Reader results at 2000 rpm:

Feul sys1 - CL changes between ol drive and CL
Calcload - 5.09%
Coolant -this increases and stays between 90-102 eventually as car warms further, does not go past 102
Stft b1 - fixed at 0%
Ltft b1 stays more or less constant at -2.35%
Map - 27 kpa approx
Engine rpm- 2000rpm
Spark adv- 28
Iat- 29 celcius
Tps- changes upwards
O2sl - 1112
O2s11- varies between 0.1v to 0.8v for upstream 02 sensor
Shrtft11 - varies between -5%and 5%, I am guessing this is reading is from upstream 02 sensor
O2s12- voltage stays constant at approx 0.85v for downstream 02 sensor, moves around a bit
Shrtft12- 99.2% does not change stays constant. This for downstream 02 sensor



does the IAT look right compared to coolant temperature at both idle and 200 rpm?

also does the voltage for the downstream sensor staying constant at around 0.85v sound right as it is it high? also the does the Shrtft12 look right at 99.2%?

car has new spark plugs, new air filter, new engine oil, new oil filter. Feul filter still original but should not need changing as car is LPG and car only done 52000 miles and car was converted to LPG in 2003 a few months after first owner bought it new so fuel filter should be ok.

Hence I cannot understand why the engine management light comes on. I reset it many times , it seems to come up randomly every 80-100 miles or so. I have been told if any sensors are faulty and you clear the management light , the light will come up within 30 mins of driving as sensor is faulty.The fact that my light comes up every 100 miles or so is confusing.

Please can anyone answer the above questions
Any ideas would be very much appreciated, also if you spot anything above which looks abnormal please let me know. No mechanic seems to be able to pinpoint the problem so I decided to do those emissions test above. the engine management light was on when I did the last emission test above in the last picture and it still gave good results.

Edited by johndaily693 on Tuesday 17th June 16:56

[Nighthawk]

What is the exact code ?

From what you've posted both the upstream and down stream sensors are switching correctly,and the short and long term fuel trims don't look bad. The same can be said the the Hc ppm and the lambda so the pulsation of the injectors and the reading of the O2 sensors looks ok. It's quite possible to have a fault in the heater circuitry of the O2 sensor though that won't show under this conditions as the engine is already hot enough to have reached the closed loop running phase.

Can your OBD reader display freeze frame or snap shot data , that should give the exact conditions the engine was under when the fault code was set.

[johndaily693]

I got the freeze frame data now

P0130 02 sensor circuit bank 1 sensor 1

Feul sys- ol drive
Feul sys- 0
Calcload- 2.35%
Coolant temp- 92 Celsius
Shft b1 - 0%
Ltft b1 - -4.69%
Map - 36kpa
Engine speed- 835 rpm
Vehicle speed 0km/h
Mil-dist 17975km

I/m readiness reads

CAT and 02s circled and
Mis, fue,ccm,hca,Eva in black bold
AIR,ACR,HTR and EGR has dotted lines through them.

I also have p0340 camshaft position sensor a circuit bank 1 or single sensor, but once I clear the above management light
The p0340 code comes up as pending and no light. Last time 100 miles ago when light last came on prior to current light, mil-dist was in the 10k area, not sure it has jump to 17k.

The above freeze data looks fine to me , light came on when I stopped at a traffic light. I did the third emission picture test above with the light on the dash.

The voltage on the sensors move every second or so from obd reader is this normal? Or should it move more often?

Any help would be much appreciated. I can replace the sensor but the light may come back on , hence was interested to as what is causing the light although it says O2 sensor. Does camshaft sensor affect 02 sensor?



Thanks

[Nighthawk]

The O2 sensor voltages will rise and fall, thats the switching action that the engine module reads, the upstream sensor switches at a higher frequency than the down stream sensor.

The upstream sensor is checking oxygen levels present in the exhaust gas and reporting back to adjust the fuel mix, the downstream sensor is checking levels to assess catalyst efficiency in order to comply with EU legislation.

Cam position sensor is important as the control unit uses the signal to work out sequential injection firing order by identifying the position of the cam on one cylinder, and when it's data is overlaid on the crankshaft position sensor signal the spark advance can be calculated. An issue here could cause a misfire and then a subsequent rich mixture.

what vehicle is it?

[johndaily693]

The vehicle is a rover 25 2003 model. Can the camshaft sensor be the culprit here? if so why does the management light come on after 80-100 miles? If this sensor was faulty then the light would come up within 10-20 min of clearing the light from the dash if it is faulty?

This car does have an additional problem that if it stalls it takes 3-4 secs of cranking to start, but I have been told LPG cars are known for this problem. Can the camshaft sensor be contributing to this problem?

[johndaily693]

could it be another sensor or something else in the car which is causing the oxygen sensor to go off? what other sensors affect the oxygen sensor directly and indirectly. i.e. what other sensors or items have an impact on the fuel/air mixture e.g. map sensor, spark plugs, coils etc?

[ch427]

My 52 plate 25 has a similar issue where it will flag the rear oxygen sensor after a few days of driving.
It runs great and has no issues at mot time so i decided to ignore it and remove the management lamp as it was bugging me.
It may just be a rover thing as all my live data looked fine.