Good video!

Gus
www.jagrepair.com

 

When they did the smoke test did they look at the EVAP system when they tested or just the engine? Remember it goes back to the fuel tank.

Gus
www.jagrepair.com

 

Sorry but that's not usually true.

When it is true it's normally because the EVAP parts were NOT tested.

That does leave some of the tiny leaks but those don't normally flag P0174; instead they flag a small (or very small) leak (P0455 / P0456).

That said, a purge valve is fairly cheap as is all the piping but where do you stop when replacing things on guesswork? The fuel tank seals as well?

 

friends, I am sorry I have bothered you with this for so many posts now, but what else can I do? This forum is my only hope of finding a cure. I can't pay a mechanic to go thru all the process of elimination that we have been thru, and even the jaguar dealer service dept told me they would only be hunting and pecking at great expense. Local mechanics are all vague and seem to not be too interested in taking the job. I am a senior citizen on his own with a car that must pass a smog test.
Please remember here that the code that keeps insisting on appearing is 0174 which would indicate it is a problem more or less isolated to bank 2. It would not be fuel pressure, and would it even be evap purge valve if only effecting one side? Also, wouldn't a vacuum leak of any kind effect both banks? I don't know what to do obviously. I did stop and talk to a smog guy today who explained that with comp and evap monitors showing incomplete, it is still possible for the car to pass smog as long as no hard codes or cel on. He said pending codes do not effect emission tests. I'm leaning toward letting him run the smog on the car and see if I get lucky enough to get a sticker. That would take the pressure off of me for California registration, and leave me with a bit more casual approach to getting to the bottom of the lean code and incomplete monitors. I know there are some very experienced Jaguar mechanics in this thread and I appreciate your ongoing patience and assistance.

 

The purge valve is a known weak spot on our cars so that alone makes it a prime candidate. A complete smoke test on the EVAP did not find that it was indeed faulty.

Does the OP's car valve a vacuum leak though his valve leading to P0174? Dunno. Would have a leaking valve and a pending P0174 inhibit the EVAP system test? Dunno.

 

Mikey, where is the purge valve and what does it look like?

 

??? I gave you the thread link in post 59.

 

My car did not throw any codes but the fuel trim on one side was way out. I changed plugs, coil packs and a few other things. I took a hunch and replaced the purge valve and all was good.

Gus
www.jagrepair.com

 

You are no bother. At this point we are all trying to help.

 

+1
and we want not only that a fix is found but that you tell us what the fix was!

 

I am extremely grateful to you guys for so graciously putting up with this long thread. I have some new information.
After learning more about the elm scan tool, watching the very entertaining videos, and taking everything you have offered as advice, I now believe I have a mysterious leak somewhere that is actually effecting both banks, but bank 2 more so and bank 2 hits the limit for lean condition first and sets 0174 pending, then if it does not correct itself within a few cycles, sets the hard 0174 and cel.
I think I am going to bite the bullet and replace the maf with a factory oem, and the evap purge valve and canister (resonator?).
I tuned the DashCommand obd scanner to read air/fuel ratios and I am getting crazy and erratic readings. I know that 14.7 is ideal, but I see that it does not sit on 14.7 and frequently goes up to 18 when accelerating. When that happens, the stft's go up to +25 and sometimes the ltft's also go up a few points. It is weird though that contrary to the education the videos have provided, my air fuel ratio hovers close to 14.7, going up and down slightly, and goes up when rpms increase. Videos and other info suggest that a vacuum leak would do the opposite? O2 sensor voltages are oscillating between 0.1-0.8 almost all the time.
NEW VARIABLE..... Months ago, I noticed that when I top off the fuel tank, there is a strong fuel odor in and around the car. There was a recall for faulty tank seals for my vehicle in 2007, and the Jag dealer replaced my fuel tank way back then. Now I wonder if the seals at the tank have failed again, causing the odor. I have avoided filling the tank for a long time to see if the problem was present at 3/4 full and it is not.
So I know I'm throwing too much on the table probably, but my questions of the day are......what would cause my air/fuel ratio to be so wildly erratic. If the fuel tank seals were faulty, how would that effect metered air, or would it be effecting fuel delivery enough to cause this? My fuel pressure reads 57.87 psi.

 

What sorts of values do you get for the LTFTs with a hot engine, parked, first at idle and then if you rev to about 2500?

You're NOT wanting 14.7! You're wanting roughly zero (which in a sense implies 14.7) because these are adjustments from the expected values (being those that get roughly 14.7 i.e. ideal AFR).

(You're unlikely to get zero - mine are about 3.)

 

I have noticed that when first started cold, the fuel trims are positive all around. Everything seems to get better when the engine is hot.
The last readings took this morning after driving the car a few miles to hot were
idle rpm 731
fuel pressure 55.26
ltft bank 1 .....0%
stft bank 1......+0.78%
ltft bank 2......+2.34%
stft bank 2.....+1.56%
mafs rate....3.84 g/s
air/fuel ratio....14.75:1............no codes set

but at 2500 rpm (parked)
ltft bank 1......-1.6%
stft bank 1.....-11%
ltft bank 2....+0.8%
stft bank 2....-12.5%

DRIVING approx 2000 rpms and especially when accelerating
air/fuel ratio climbs as high as 18:1
both stft banks climb to +25% and seem to hold there for a long time
both ltft banks linger behind but eventually seem to go up to about +7%
mafs rate.....11.6 g/s
fuel pressure.....62.22psi...........PENDING 0174 SET

 

The idle trims look OK. The 2500 trims have me wondering a bit.

Have you disconnected the battery recently (such that it's still relearning)?

That fuel pressure is higher than I expected (especially the high one)! Anyone with a 3.0 can confirm?

 

I started wondering after pondering this a bit, if the evidence points o fuel injectors? My reasoning being that if the air/fuel ratio goes up beyond acceptable under load, its either too much air or not enough fuel. An air leak would result in fuel trims going down with throttle if I am learning correctly. But if injectors are not delivering enough fuel due to clogging, would that tell the computer to add fuel (+25_) and could it cause an increase in "backed up" fuel pressure due to injectors not allowing enough to get through? But what do I know??.....I am only learning on the fly from all of you.
I talked to my local mechanic who I like a lot and he tells me he can perform an injector/airflow service for $150 where he basically pumps some sort of high performance injector cleaner thru the fuel line with engine running. But he suggests that I pay a smog guy $20 to run a "pre-test" on the dyno first to get true readings out of the tailpipe to find out what the car's exhaust really looks like. He implies the computer readings could themselves be faulty, and throwing us all off.

 

I doubt it's injectors. It's happy at idle & 2500 parked (is even reducing fuel).

Hard accel (WOT) means it goes rich to protect the engine so you have to avoid readings then (and it can report garbage if it likes because it's not closed loop).

Could do with another 3.0 owner to say what their MAF & fuel pressures look like. (The idle looks OK to me.)

$20 is cheap, though...

 

Sunday update......well guys........I took the gamble and ran the car over to an emissions test station today with no codes except pending 1000 and 2 monitors incomplete, the evap and comprehensive. After handing the key to the technician, I literally prayed.
He returned smiling and said.... "she passed!". I don't know how it passed but it is great news for me today. I can get the valid registration sticker tomorrow and breathe a little easier.

I have not remedied the unknown cause of the lean codes, but I can at least take a breath. The car has not thrown a hard code in 2 days, but the fuel trims remain very erratic. I can't make sense of them. They seem to be fine at idle, then not fine at idle, fine under load, then not fine under load. I will go into wait and see mode for this week and see if it kicks out another 0174. I won't be surprised if it does and I will keep looking for the answer. I'm leaning toward the mafs or injectors at this point.

I cant thank you all for the many contributions on the thread to try to help this older guy out. One of you even gave me a private phone number to call directly to chat about the problem. So many thanks to those who didnt come back with smartass responses to my request for help. There are some really good people on the forum.

 

Good news!

I'd still like it fixed, though...

Save me re-reading - have the IMT O-rings been changed?

 

At this point, enjoy driving the car since it has passed the Smog Check and you have another two years to correct any of the issues, if indeed there are any.

Do post the DTCs that present themselves along with the fuel trims or other relevant data regarding drivability or fuel economy changes.

 

Yes, my friend. I did the imt orings. Have to say that was about the easiest thing I've been thru