ok, so I'm using the ELM 327, talking to ANY of my mobile devices with the Torque Pro app. This is the combo rhat is only showing 0171 and 0174 as PENDING. I also have an Actron pocket reader that does not do any real time, just codes and monitors, and that one is showing hard faults 0171 and 0174.

 

If the MIL is on, the DTCs are no longer pending but are set.

 

The software talking to the elm327 must be faulty. As the MIL is on, the codes are either not pending or there other codes.

As the other tool shows the codes are not pending you can be sure it's the software used with the elm327 that is itself faulty. You can get other software to talk to the elm327

 

I know, I can't help myself.....

Question for you. You stated you have been battling this P0171/0174 for years. Did you change your air filter years ago? If you have, did you purchase from a BIG box store? The reason why I ask is, BIG box store air filters do not fit correctly even though "they" state Jaguar S Types. If it is an incorrect filter, Bob's yer Uncle.

 

thanks for that input...You're right, I have experienced the bad fit issue with an AutoZone filter, and was able to finally get one that fits properly . I keep going back to fact that each bank on this motor behave somewhat independently regarding fuel trims. Having replaced all the injectors, coils and plugs, and gaskets, the only thing I can think of that might allow different fuel trim behavior would be the O2 sensors????

 

You may want to go online and order a big can of confidence. As others have suggested, inaccurate fuel pressure can really throw the computer for a loop.

Remember how I've said computers are really, really smart AND really, really stupid at the same time? If the fuel pressure sensor is wrong, the poor computer has no way to know. The computer calculates fuel delivery assuming a certain pressure at the injectors. If the actual pressure is low, despite what the electronic sensor says, you get less total fuel delivered. This gets wrongly interpreted as a vacuum leak, because it matches those symptoms.

I'd suggest looking into how the factory intended for fuel pressure to be physically checked. There may be some special adapter that tees in place of the pressure sensor, or something like that.

Or if that is not practical, perhaps you can check the calibration of the sensor. Disconnect it from the fuel rail and cap that line so pressurized fuel won't spray out. Then rig up a test fitting to the sensor and apply compressed air at a certain pressure. Whatever pressure is applied, turn on the ignition (don't think you'd have to start the engine) and see what your scanner shows. It should match the pressure of the compressed air. If not, the sensor is bad.

 

Below are the X200 fuel system specifications and test procedure showing the gauge adapter fitted to the fuel line.

 

Here's one source for the adapter:

https://jaguar.service-solutions.com..._Valve_Adapter


They're not giving them away, but maybe you could fabricate something similar or find another source online. Remember, per my previous message, I think you can test the sensor independently with compressed air.


Not sure if you've seen this, but look at page 1407 in the Service Manual, courtesy of Gus:


http://www.jagrepair.com/images/Auto...M-Workshop.pdf



Note the big shopping list of possible causes that can flag P0171 and/or P0174. I believe the ones listed at the top are more likely. This falls under my theory of computers being really, really smart AND really, really dumb, all at the same time:

• Air intake leak between mass air flow (MAF) sensor and cylinder head
• Fuel filter/system restriction
• Fuel injector restriction
• Fuel rail pressure (FRP) sensor fault (low fuel pressure)
• Low fuel pump output
• HO2S/catalyst monitor sensor harness wiring condition fault
• EFT sensor fault (low fuel temperature)
• Mass air flow (MAF) sensor fault (low intake air flow)
• Exhaust leak (before catalyst)
• ECM receiving incorrect signal from one or more of the following sensors: ECT, MAF*, IAT, fuel rail temperature

Note how after a possible air leak in the intake duct (between MAF sensor and intake manifold), the next several likely culprits are all related to low fuel pressure. So if those possible faults are listed in order of likelihood, I think confirmation of actual fuel pressure is warranted.

 

The vacuum line to the fuel pressure sensor may also develop a small crack that could possibly allow air to intermittently enter thus changing the fuel pressure and causing the DTCs to set.

 

Jakesdad, have you had any luck with resolving your issue of P0171, P0174 on your Jaguar S Type? I believe I may have a solution.

 

Joycesjag.....no, I have not had any luck with it. To the point that I garaged it and bought wife a different commuter. However, I had to take the newer car in for a repair and on that date I told wife to drive the 05 s type with incomplete registration due to inability to smog it...guess what, she got pulled over for expired tag and now I have a citation to deal with on a car that is not smogged, not current, parked in the garage. and now I am forced to deal with it again. Still getting 0171 and 0174 with evap refusing to complete before the cel comes on again after clearing it.
A while back you posted a pic of the evap canister thingy with the whole bracket and assembly and i believe it is about $99. If you could share that pic again or what it is called and where to buy, I am tempted to try that.
or...youmay have another solution???

 

A friend of mine recently purchased an 05, 3.0 S Type. He and I chased the P0171 and P0174 for a month. We replaced plugs, plenum/lower intake gaskets, new Denso MAF, fuel filter. We "sealed all" the canister. Just by accident, I ran my hand under the resonator on the intake tube. I found that it had disintgrated in several spots underneath allowing more unmetered air into engine. Also the round tube that the resonator attachs to the intake was cracked, again allowing more unmetered air into engine.

I would pull intakw tube with resonator off and have a good looksie at it!

 

Rick,

Haven't heard from you in several weeks now so I assume the new plastic resonator and associated tubing indeed fixed Todd's car. No more P0171/P0174 issues since?

I hate the Jaguar engine bay plastic. I have had to replace several plastic components in Jan's 2006 XK8 engine bay during the past year or so and I am dealing with more of it right now (awaiting the new part from rockauto.com which should show up on Thursday). Long-time owners eventually learn to inspect all plastics under the hood on a regular basis. Sooner or later you will have to replace most of those components....

 

Yes Jon a new resonator/intake took care of the lean codes. Maggie and Karen just returned from a 1000 mile round trip, zero problems!

Used resonator/intake tube $20.00 local auto recycler

Oddly enough even with those holes the codes popped up randomly. Sometimes they would clear themselves and other times I had to use my OBDII.
​​​​​​

 

 

Eureka!!!!!!!!!!!!!!!!!!! Mine has a whopper of a hole in it. I will replace that and cross fingers. If this is the cure, with everything I've done to it, which is pretty much everything you did to your friend's car plus a little more, I should be good for another 10 years. And I am very grateful to you !!!! Crossing fingers.

 

Holy cow! All this ongoing anguish and that got overlooked? Over two years ago your alleged mechanic did a smoke test and found nothing:


https://www.jaguarforums.com/forum/s...7/#post1438155


I would suggest putting several bars of soap in a tube sock and beating the daylights out of him. At least that's how we dealt with problems like that when I was in prison. Or maybe it was in a movie, I can't remember...

Also, is that resonator thingie rubbing against something? It's curious how yours failed exactly like the one for Joycesjag.
​​​​​

 

No rubbing, like Jon stated, inferior plastics that has disintgrated over the years.

Jakesdad cut the resonator off. Cover the 2 holes with duct tape or something else(?) until you find a replacement intake tube. The resonator is there only for sound depression from my understanding. Only the V6 engines use it. The 4.0 and 4.2 do not.

BOOM! This thread is worth a million bucks!

 

I guess you could also duct tape the resonator as well until you find a replacement. Todd spent $20.00 at our local salvage yard.

Karl, from my understanding. A smoke test is hooked into the emissions purge control cannister. I don't believe the smoke would make it's way to the resonator, at least in my little world.

 

To be honest guys, I've had that resonator on and off probably 30 times in the past years trying to solve the lean codes. It never occurred to me to inspect it or turn it over. The smoke tests would not have pointed at this because it is removed for smoke test and the throttle body intake is plugged with a big rubber bung. At least that is the way I observed it done.
So I am hoping beyond hope that this huge hole is the cause of my problem. I would think it is a huge possibility since all of you have been advising me that any miniscule air leak can cause lean codes and this thing is a gaping hole downstream of the MAF.
I will duct tape the resonator today and report back to you results. (I may buy a large enough roll of duct tape to enclose the entire engine)