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I am using a IID scan tool. There is enough stuff in this tool to get me into trouble. (I Cleared the trans adaptive values, took the better part of 2 months for the trany to relearn :-) )
Does resting the adaptive values reset the trims? I did that 2 weeks ago.
The lambda's are hovering around the 1.00 mark. I will pay more attention to them tomorrow?
I dont usually let it idle before driving unless trying to figure this out which is mostly after/during a drive cycle. The code takes usually takes 3-5 drive cycles to show up and there are no other codes to go with it.
I know its still not right since the plugs and fuel trims tell the story I havent seen it for a few weeks since adding injector cleaner.
It could be a coincidence, I added the injector cleaner then the weather warmed up both times. Last fall as it got cold the code retuned every few days until it was parked for winter. I used it twice on nicer days over winter and just cleared the codes until now, since now I am driving it daily again I can hopefully sort this.
Ha, now this is bizarre. Its a good thing i have lots of hair to pull out.
My scan tool gives me a fuel pressure reading of 40 to 60 psi depending on how much lead my right foot contains. The unit I borrowed reads 10 psi less. Im not sure this means anything yet until i get an actual gauge on it.
Apparently my o2 sensors do not flip between 0 and 1 volt. They provide a constant variable readout between 0 and 1 volt, usually around 0.6-0.7 volts. Regardless both sides have very similar readings for upstream and downstream sensors. However the long term fuel trims are quite different. At idle they are quite similar but few decimals apart. But at 60mph cruise bank 1 reads 13.3% at 60mph cruise and bank 2 reads 8.8%.
I did read on another forum that plugs/coils or a bad cat could cause this. For all the work it takes, I might just swap the white plugs and coils to the other side and see if the fuel trim moves with them.
I was able to graph these and compare both banks, they stayed quite similar other than the fuel trims separating as I accelerate to cruise speed. Comparing cyl 1 and cyl 8 this also shows up in the injector timing with bank 1 having a longer firing time than Bank 2 as the speed increases.
Can I upload pics or do they have to be in some sort of online cloud thing?
You guys know all the links! I havent found that one yet. I did look into the pcv valve. I removed it the diaphragm does move with suction. There is a small vent hole in the top that allows the diaphragm to move, tested that with wd 40 while running and nothing changed. Since it enters the manifold before the supercharger it should set off bank1 and bank2 codes. That's why I pulled the plugs to see if it was actually an issue or some stupid tiny vacuum leak somewhere affecting all 8 cyl. Since it seems to be only 3 cyl that would point to a local vacuum leak at the intake but it passed the wd40 sniff test.
I have borrowed a cheap obd2 reader that has the o2 readings, fuel trim readings, and lambda readings.
Thanks for the info on the o2 sensors. That was going to be one of my next questions. Can someone explain what the lambda is and what to look for. I have heard this term and it appears that i misunderstood it thinking it was another name for o2 sensors.
The plugs are iridium type. I had planned on changing them after i figure this out. I should have other ignition faults if they are the cause of the issue.
I need to get some new tools. My 1980s compression guage no longer holds pressure. And my IID scan tool does not give me all o2 sensors.
I will have to check the manual again, I thought bank1 was on the RH side from the drivers seat. It is also the furthest forward closest to the rad. Unfortunately the manual does not help with diagnostics only how to replace parts.
I dont think im going to get to far this weekend if my tools are no good.
Ok here goes
Leolito, No idea how old the plugs are, They dont look bad, no misfires or codes other than system lean bank1 (right side i think) which is where the white plugs are located. I can post a pic when i figure out how. I have o2 sensor reading for bank 1 only for some reason, not sure about voltage. It reads 96% for the first 20km or so then goes up to 98%. Interestingly though during accel or decell it does not read. Not sure if this helps will look into this more.
Gilbertd, 1 maf sensor right at the air filter, i think 4 o2 sensors (I think this is what you mean by lambda) before and after catalytic each side. More research to be done on this. Ditto on the fuel pressure. Im leaning toward poor/plugged injectors.
mad-as. Fuel pressure is controlled by ecu via a pwm signal, According to the manual it should fluctuate but be a relatively steady 45psi at idle.
Aragorn I need to get a pressure gauge and figure out where it gets hooked up. The injector rail is buried under the intercooler's. I am currently reading pressure from the scan tool, thats why i pulled the plugs. It is a returnless system.I believe the pressure regulator is vacuum referenced since there is a vacuum line running to the intake prior to the supercharger. The absolute pressure reading is approx 5-6psi at idle. I think this is a vacuum since with the engine off it reads 14.5(1bar) Fuel Pressure at hard acceleration is 50- 60psi (3.25-4bar?) Engine is a 4.2L supercharged Jaguar.
I did unload a whole can of WD40 all over the top of the engine looking for vacuum leaks and none were found. I will do a bit more this weekend with vacuum and hopefully a pressure gauge. For right now I have put 3 cans of fuel injector cleaner into the fuel, cleared the engine adaptive values and have not had the code return. Although I believe this is a temporary fix. I will pull the plugs again this weekend to see if there is a change. I expect the code will return at some point in the next few months. I am currently leaning towards poor/plugged injectors. Opinions and suggestions are welcome since I do not want to turn this into a parts cannon.
Sorry guys I have forgotten to check this forum after i realized I posted in the P38 section. Since I cant find an L322 section I assumed this forum was dedicated to P38. I will catch up tonight after work.
I currently am trying to find the cause of system too lean codes. PO0171 and PO0174
A little history
Purchased last year around April PO171 code showed up almost immediately. Cleaned Maf sensor, and put injector cleaner into fuel. That seamed to clear the code until September. Then the code started showing back up intermittently. Stored the truck until spring. Smoke tested intake over winter and found no leaks. When i started driving the truck a week ago both engine lean codes came back. Added injector cleaner to fuel that cleared the bank 2 (P0174) code but the bank 1 (P0171) comes back. There are no other engine codes shown. I started watching some live values while driving the fuel pressure fluctuates a bit at idle and while cruising at 2000 RPM. It falls to 41psi at times. and then quickly recovers. It does increase to about 55-60 psi under harder acceleration.
Today I removed the spark plugs and the front three spark plugs of bank1 (right side not sure what the cyl numbering is) are white compared to the rest which are a nice light brown.
Im trying to determine if the injectors are partly plugged or the fuel pump is possibly getting weak. It does not run rough or stumble when driving.
Scan tool is a IID tool
2008 Range Rover Supercharged Canadian vehicle