Volvo Owners Club Forum - View Single Post - V50 General :

thecuist · May 6th, 2015, 12:35

Firstly thanks to everyone for their comments, heres an update on the situation. Took it to a diagnostics specialist and so far we have changed the plugs for new iridium tipped longlife £15 a pop. OUCH.
He did a smoke test for air leaks and found none.
We verified that the o2 sensors are reading correctly (very rich)
Changed oil and filter because he suggested that with that much unburnt fuel the oil could be contaminated and be throwing the readings out, HC readings have dropped from near 1200ppm to about 600ppm which is still 400ppm above minimum requirement for emissions.
He checked injectors for leaks and says they are all ok.
Only fault code coming up is o2 sensor reading out of range rich, and the sine wave on oscilloscope shows the same.
We are pretty sure its not a CAT issue because the upstream o2 sensor is showing rich and is trying to lean back the fuel to compensate but cant lean it enough so its switching to open loop operation, which as I understand it means that it goes to a default base ECU map and stops using the o2 sensor signals to control mixture.
So now I'm thinking possible worn injectors/high fuel pressure, or possible MAP sensor issues.
I know the injectors aren't leaking but is it possible to have worn injectors which dont leak? and if fuel pressure was too high could that cause too much fuel to be delivered.
Any thoughts? Is there a way to test for worn injectors without buying replacements and testing emissions afterwards, and what should the fuel pressure be at the rail?

May 6th, 2015, 12:35	#7
thecuist thecuist Last Online: Sep 2nd, 2022 12:19 Join Date: Feb 2007 Location: Castlebar, West of Ireland	Volvo V50 emissions still too high. Firstly thanks to everyone for their comments, heres an update on the situation. Took it to a diagnostics specialist and so far we have changed the plugs for new iridium tipped longlife £15 a pop. OUCH. He did a smoke test for air leaks and found none. We verified that the o2 sensors are reading correctly (very rich) Changed oil and filter because he suggested that with that much unburnt fuel the oil could be contaminated and be throwing the readings out, HC readings have dropped from near 1200ppm to about 600ppm which is still 400ppm above minimum requirement for emissions. He checked injectors for leaks and says they are all ok. Only fault code coming up is o2 sensor reading out of range rich, and the sine wave on oscilloscope shows the same. We are pretty sure its not a CAT issue because the upstream o2 sensor is showing rich and is trying to lean back the fuel to compensate but cant lean it enough so its switching to open loop operation, which as I understand it means that it goes to a default base ECU map and stops using the o2 sensor signals to control mixture. So now I'm thinking possible worn injectors/high fuel pressure, or possible MAP sensor issues. I know the injectors aren't leaking but is it possible to have worn injectors which dont leak? and if fuel pressure was too high could that cause too much fuel to be delivered. Any thoughts? Is there a way to test for worn injectors without buying replacements and testing emissions afterwards, and what should the fuel pressure be at the rail? Last edited by thecuist; May 6th, 2015 at 14:19.