NOT FOUND ANYTHING LIKE THIS ON THE FORUMS - SORRY IF IT IS THERE.
Hello All,
The problem is with a UK vehicle, 4.7l 2000 model WJ, build date September 1999. It has been converted to run with a multipoint injection LPG (propane) system as well as gas (petrol). 76000 miles, I have owned this for 14 years and it is lavished with attention but rarely sees a stealership other than for its annual test.
The fault code P0174 (lean condition, bank 2) originally showed up on changing from gas to LPG automatically and also manually if the changeover was left to reach a higher temperature, but not every time.
Thinking it was an LPG problem it was given an LPG service (filter changing etc) and all seemed well – for 20 miles or so!
Returned to LPG specialist whose scanner suggested an air leak – high long and short term fuel trims on bank 2.
Nearly identical fuel trims on gas . Smoke test carried out – no leaks detected. MIL cleared.
No time to investigate further and it seemed to run OK on both fuels with normal tickover. “Go away and try it”.
Not much mileage later, MIL came on again and my scanner detected P0174 and Pending 0302 (misfire detected, cylinder 2). Bank 2 fuel trims high.
“Experts” suggested curing the misfire first so I changed Cylinder 2 plug and coil. Plug VERY sooty. All seemed OK at tickover/fast idle – o2’s cycling though upstream two was not as regular as upstream 1, fuel trims on bank 2 still high but coming down. After 20 miles or so – slight hesitation and MIL on again. Fault codes P0174 and this time P0306. I think the “experts” are wrong and the over rich fuel is causing the misfires. Scanner showed upstream o2 sensor bank 1 cycling normally, but upstream bank 2 hovering around 0.2 and not cycling. However, whether this is cause or effect I do not know!
As this is happening on LPG and gas, I am assuming it is not fuel pump/strainer, PCM (the LPG system has a separate one), MAP sensor (only bank 2 affected), or anything else associated with both banks. I cannot find an air leak in the exhaust prior to the o2 sensor.
This is only a summary of work to date.
Conclusion at this time - intermittent fault on upstream o2 sensor, bank 2. I have it out and that too is very very sooty.
I have a new one coming today but because of time constraints could not get a Mopar one. It is a BLUE PRINT, a quality European brand made by Bilstein (hopefully not Bosch).
If this does not solve it, I need a Plan B.
Any thoughts please as I am just about “thought out”? My local professional resources for this are very limited.
Thank you
Hello All,
The problem is with a UK vehicle, 4.7l 2000 model WJ, build date September 1999. It has been converted to run with a multipoint injection LPG (propane) system as well as gas (petrol). 76000 miles, I have owned this for 14 years and it is lavished with attention but rarely sees a stealership other than for its annual test.
The fault code P0174 (lean condition, bank 2) originally showed up on changing from gas to LPG automatically and also manually if the changeover was left to reach a higher temperature, but not every time.
Thinking it was an LPG problem it was given an LPG service (filter changing etc) and all seemed well – for 20 miles or so!
Returned to LPG specialist whose scanner suggested an air leak – high long and short term fuel trims on bank 2.
Nearly identical fuel trims on gas . Smoke test carried out – no leaks detected. MIL cleared.
No time to investigate further and it seemed to run OK on both fuels with normal tickover. “Go away and try it”.
Not much mileage later, MIL came on again and my scanner detected P0174 and Pending 0302 (misfire detected, cylinder 2). Bank 2 fuel trims high.
“Experts” suggested curing the misfire first so I changed Cylinder 2 plug and coil. Plug VERY sooty. All seemed OK at tickover/fast idle – o2’s cycling though upstream two was not as regular as upstream 1, fuel trims on bank 2 still high but coming down. After 20 miles or so – slight hesitation and MIL on again. Fault codes P0174 and this time P0306. I think the “experts” are wrong and the over rich fuel is causing the misfires. Scanner showed upstream o2 sensor bank 1 cycling normally, but upstream bank 2 hovering around 0.2 and not cycling. However, whether this is cause or effect I do not know!
As this is happening on LPG and gas, I am assuming it is not fuel pump/strainer, PCM (the LPG system has a separate one), MAP sensor (only bank 2 affected), or anything else associated with both banks. I cannot find an air leak in the exhaust prior to the o2 sensor.
This is only a summary of work to date.
Conclusion at this time - intermittent fault on upstream o2 sensor, bank 2. I have it out and that too is very very sooty.
I have a new one coming today but because of time constraints could not get a Mopar one. It is a BLUE PRINT, a quality European brand made by Bilstein (hopefully not Bosch).
If this does not solve it, I need a Plan B.
Any thoughts please as I am just about “thought out”? My local professional resources for this are very limited.
Thank you
P0174 puzzle - help needed
0 commentaires:
Enregistrer un commentaire