Okay, for reasons unknown, I'll still try to help. Trust me, I ready to walk away and just let you keep replacing parts. But I also see nobody else is exactly rushing in to take a stab at it. Unfortunately for you, that leaves me as your last and only hope unless you can find a better option. Before proceeding, you will need to take the following vow. Raise your right hand and repeat after me:

"I, (insert name) [actually say your given name, not just "insert name"] do solemnly swear to actually follow the advice of some stranger on the Internet. He is doing this for free, out of the kindness of his generous heart, and I repeatedly am doing my utmost to frustrate him by repeatedly blowing off the very clear troubleshooting instructions and methods."

The preceding was industrial strength humor, intended to grab your attention. At this late stage in the troubleshooting game, I can't stress strongly enough the importance to only make ONE change at a time. Then disconnect the power to reset fuel trims to zero and test this change with the same driving pattern as before. To get his important point across, I've told charming stories. I've made cheap jokes. Please, oh please, oh please, do not make two changes at once. Not now. You're WAY past the shotgun stage. Myself, I've shotgunned plenty of problems, but this is no longer the time for this. There is a fix to this problem. You are so stinking close. I'm burned out on this one step forward, two steps back business from making multiple changes at once. Yes, I'm busting your butt. I'm ready to drop out.

If any of the preceding sounds amenable to you, swap your two upstream oxygen sensors. Leave the downstream ones alone for now. Only swap the upstream ones. Please, please, please, do not go one step further and try a new one in there. I don't care if an angel descends from the clouds and hands you some part, an O2 sensor or whatever. Tell him he'll have to wait, and you're only swapping the two upstream sensors. Reset the fuel trims to zero with a battery disconnect, and then go for the same test drive as before. See if the high LTFT shifts to the other side or stays put. See if the code stays as P0174 (bank 2 lean) or shifts to P0171 for bank 1.

Remember, resetting the fuel trims is not a fix. It's only a troubleshooting technique, starting from a known baseline and observing any change. Swapping the sensors is also not a fix. This is also just a troubleshooting method to help decide the next step. You should get a fault code. The only question is which code.

 

I am not exactly to sure about that Karl. I have been following this thread since it was posted. I see many veteran members posting their 2 cents, including one of our last Jag tech's motorcarman offering his free sound advise as well.

The OP is throwing Chinese parts at his vehicle in the hopes that something sticks. You and I both know 2 things. One throwing and using cheap parts will never work on our beloved Jaguars.

The OP has been offered VERY sound advise from strangers on the board. Each of us have read thousands of posts over the years. If he chooses not to follow our very detailed advise then c'est la vie.

I do know you like a challenge. I wish you both well but, I will not beat my head against the wall trying to convince someone to follow VERY sound direction. In the end I hope that the OP will post a detailed follow up to his problem.

 

Tag! You’re it! Going camping for a few days, out of cell range. Can’t wait to hear how it goes for you...

 

I do NOT mean to come across thick or stubborn ! although we all can be that !! ( right wing wackos and backwards thinking people ... ) … just kidding

actually I have appreciated you guys's verbal orientation and advise .. believe me I DO....

in reality I have thrown many parts to the issues -- however of all them old coils and injectors rebuild kits are the only ones from Ebay rest of them were from autozone , rockauto or online vendors / after all this vehicle was an auction deal with blown head gasket .. I t has taken lots of work to get it where its at ..

I get It ..its been a learning process for me and have a lot to learn still . I JUST HAVE NEVER HAD A CHALLENGE LIKE THIS JAG …

I have NOT worked on the car today - just too much going on at work ! I will follow exactly your instructions once I get to work on it ..

again greatly appreciate your help !

 

No worries....do what Karl suggested and swap front o2 sensors side to side and see what readings you get....you are real close to success...post the trims and we go from there..the lean code can also be an air leak, but we need to address the sensors first and proceed in order and it will take care of itself

 

SO I have done the ECM resetting , swapped the upstream 02 sensors - still getting the P0174 code system too lean bank 2 … and actually feels idling worst even
the "restricted performance " came on and off now ..

drove back and forth ,, went to gym then drove to get some food got home . Car parked idling and this is the data I Got :

STFT BANK 1 - 2.3 %
LTFT BANK 1 - 8.6 %
STFT BANK 2 0.0 %
LTFT BANK 2 7.8 %

AIR FLOW RATE FROM MASS FLOW SENSOR 6.46 g/s

Like i said the car feels worst NOW.. I m thinking ( i know a dangerous thing right ... ) ...

a while back .. I did a smoke test - found NO leaks , However maybe I should another test , I have the smoke tester from Ebay..

 

Ok....switch the o2s back....do a smoke test and see what happens.....look real close at the imt o rings area

 

Thank you, thank you, thank you for swapping the O2 sensors and nothing else. Had hoped to see the values and codes cleanly swap, conclusive proof of at least one bad sensor. But alas, not quite so clear cut.

However, look at post #60. The sensors showed -2.3 and +15.6 in positions 1 and 2. That is a wide split, 17.9 percentage points. When swapped, the same sensors showed -8.6 and +7.8 in their new positions. That's still quite a wide split of 16.4 points. With nothing else changed (very important, I'm sure you're sick of me stressing that...), this makes me think you've got two issues active at the same time.

First is a suspect O2 sensor, possibly both. I hate to say just replace them, but they are normal wear and tear items. If both sensors were accurate, the values would have swapped too. One or both bad? Hard to say. At this point in the game, I'd say pull the trigger on both. Definitely get a quality name brand. If you want to try just one and save a few bucks, be my guest. It's all guesswork which one is worse, so try one and see. I'd still lean towards replacing both, just to reduce the aggravation factor.

Second issue is probably mechanical, such as a vacuum leak on bank 2 (consistently higher fuel trim). So please do the smoke test like you were thinking.

Please check the intake tube between the air cleaner and throttle body, as detailed here:

https://www.jaguarforums.com/forum/s...2/#post1934812

I don't think that's your problem, but is quick and easy to rule out. Theoretically a leak there should affect both banks, but if you've also got another leak only affecting bank 2, that may get flagged first.

If all of that checks normal, it's probably time to revisit those compression test results. Repeat the test, but make sure condition are as equal as possible between the two banks. For example, If you have to pull the big intake plenum like on the early V6, do that first and then test all cylinders at roughly the same time. Keep a battery charger connected during a cranking compression test, too. This helps limit starter speed dropping as you move from cylinder to cylinder and the battery runs down. The cranking compression test is imprecise at best, subject to many variables such as temperature, starter speed, etc. You want to keep the playing field level for best results.

Leaving for a few days of camping now. Fingers crossed to hear some good news when I get back.

 

appreciate getting back to me Karl.

yea ! I have looked at the intake tubes ..looked OK last check about a month ago and placed teflon tape around the "o
" ring for the MAF sensor so to sealed any possible leaks and have order a new electrical plus for the MAF senor only 25 bucks . I also thought both 02 sensors might be causing issues so I have been looking at rockauto for pricing and options ! . don't want to spend more than 120 for both of them - will order them today ..

- I feel so close to the finish line .. might as well give it hopefully one more push ..
its been raining today so i m not gonna be able to do the smoke test ,, probably tomorrow or tuesday

enjoy your time with nature ! if you run into big foot ! take pictures please..

 

I don't think there is any reason to over complicate this step. It is a highly reliable test, when used as a comparison between cylinders. You are not striving for an absolute value, where environmental conditions could play a (small) part, you only want to compare 6 cylinders.
To that end - outside pressures, temperatures etc don't even come into play.
So remove all spark plugs, fit the compression tester and crank the engine with an open throttle. Do that until the pressure stop increasing, a few revolutions is sufficient per plug, stop when it reaches a plateau ito pressure.
Then compare the results. Normally they should be fairly even end pressures like about 11 to 13 bars, depending on engine, compression ratio and wear.
If there is one outlier, it points to an anomaly pertaining to one cylinder, valves, rings, carbon build up, holed piston or what have you.
If there are several, and if they are specific to one side (bank) it can be assumed that you have a systematic error, although in error searching, I have been stung plenty a time by "assume", which is what it says! -- *** U ME -- .

You would however be hard pressed to find anything but cam timing that would provide that!
I *** U ME!

 

yesterday I did the smoke test - found no leaks , also replaced the MAF (plug in bad shape ) to new plug and reset ECM again,,,,,it idled pretty good / did NOT drive it NO codes at all . Fuel trim numbers were lower .

this morning started the car check engine flashing , restricted performance on ! for a bit then they were gone ... I got to work around around 15 miles away - check engine light misfire code cylinder 1,3,5

guess my best hope would be the 02 sensors now ??? then move on to VCT opereration and cylinder compression test - which last time they were something like ... 175,178,175 BANK 1 , 200,200,205 Bank2 I will have to do them again..

 

Flashing MIL = misfires so terrible they're causing cat damage - DO NOT DRIVE IT LIKE THAT

 

My experience is that when you replace automotive electronica sensors you always get the OEM part because you are guaranteed that they will work. When you get BlueStreak or allied or United or American parts conglomerated you’re taking a risk that something is going to be slightly different which gives weird results and confused
s everything.

Same for the Chinese crap you get on eBay. Throw that crap in the trash. Oem for O2 sensors, Spark plugs, modules, computers, anything that’s critical. I believe you probably have a vacuum leak because it is very easy to end up with a vacuum leak putting these engines back together. I know I did it to my own

 

i forgot you went thru the same thing...where ya been....long time no post...hope all is well

 

still kicking. Lost my job in March. First time unemployed in over 21 yrs. But im doing well hope u are too!

 

I m thinking about naming my Jag the " twilight zone Jag" ...

Its getting really confusing ! So i thought i would improve the connection to the MAF sensor just in case and also the plug was looking kind of shady.. replaced the connector from the unfamous Ebay source .. I had also DONE A smoke test found NO leaks at all , did NOT check torque on bolts maybe I should DO that since that INDY shop JAGMAC in dallas mentioned they found a bad bolt there and replaced it .. I m still have my reservations about those guys all I got out of paying 600 bucks was a " diagnosis of BAD engine/timing " and a emission test certificate .. I feel I got ripped off there WILL NEVER GOBACK THERE AGAIN..

ANYWAYS .. replaced plug on MAF sensor then ECM reset too - car started pretty nice afterwards , ran data numbers Bank 2 which was the one LTFT that was prevoiusly high NOW around 10.0% all other FT's negative lower numbers so I guess i thought that was an improvement , MAF sensor around 6.0 g/s

- morning after check engine flashing for a bit then gone.. got the codes misfire on cylinder 1,3,5 and rate above limit ... so I erased them .. then fuel tank was running very low so I filled up 3/4 full ..

- yesterday car felt decent notice :
when I ran the A/C in the car LTFT BANK2 RUNNING ABOVE 10% A/C OFF BELLOW 10% ALSO MAF SENSOR ABOVE 6.0 g/s A/C OFF AROUND 5.5 g/s ?????

today car is idling pretty rough misfires codes are back cylinder 1,3,5 so on ..

 

I agree, wholeheartedlyish...

Years ago, I was taught a marginal or failed cranking compression test is not conclusive. if the test passes, you're good to go. But if the test results aren't good? Basically, never condemn an engine on a cranking compression test alone. There are just too many external variables. Make sure the battery is fully charged and the starter system is in good order. Make sure the intake is wide open, meaning the throttle body on an injected engine, or the choke and throttle plate on a carb. If those factors were all good and consistent, before tearing apart an engine, you'd still want to follow up with a leakdown test. Even then, a leakdown test isn't always conclusive, as it can't detect things like cam timing.

I had previously mentioned all those prerequisites for a cranking compression test to avoid a scenario like this:

You test the three easily accessible cylinders on the V6. The engine is warm, so the rings expand and seal better, which helps the compression values. But it's a lot of work to access the other bank and the Matlock marathon is about to start, so that gets put off until morning. By now, the engine is colder than Nancy Pelosi's heart (if she even has one), so that bank may read lower.

Could such a difference in test conditions account for a 30 PSI difference? Probably not the whole thing, but maybe part of it, enough to push a goodish engine out of limits. So really all I'm saying is make the test conditions as even as possible. Don't induce any possible errors with one's test methods.

Back to the subject of cam timing:

Is there any way to verify without tearing apart the front of the engine?

 

Karl, from reading bob gauffs training seminar book on engine rebuild, i do not see any shortcut to verify timing other than removing the cover....i do not even know if you can do it just by engine rotation...give it a read and see what you think...maybe i am overlooking something simple and over thinking it
It has a link in post 7, this thread

 

Well, I don't know what to suggest next. I think we're all just making expensive guesses at this point. Educated guesses, mind you, not just wild stabs, but none of us have come up with anything conclusive that your car needs a new (insert name of expensive part).

Cylinders 1, 3, and 5 keep faulting as low power (misfires). Soapbox time: Misfire is bad nomenclature. It just means low power from a particular cylinder relative to the others. It is not always an ignition problem, as the "misfire" name would lead you to believe. It could be low compression, improper cam timing, a bad fuel injector, a miscalculation in fuel flow due to a bad O2 sensor, etc. And of course, it could also be a bad coil or spark plug, a true "misfire". {/soapbox mode off}

How to make sense of it? Heck if I know. I'm still willing to gamble your money on a new pair of upstream O2 sensors, but that's just an expensive hunch. Others may have better (but equally expensive) ideas.

The only other thing that comes to mind is a problem with the fuel injectors. It would be VERY rare for 3 individual injectors to be bad, especially on one side, so the odds are virtually nil. But at the same time, you did have them apart and it won't cost anything (but your time) to swap injectors between the two banks. See if the fault follows.

I'd also look into repeating the compression test, and seeing if the one bank still reads lower. If so, the most likely culprit is cam timing, which appears to be a booger (sorry if I'm using overly technical terms) to check. Maybe arrange a second set of eyes to review your work, just in case you made some error originally. It would really stink to repeat the same error...

 

What the battery voltage in different locations around fhe car? Corroded connections will lower the voltage to sensor and then the pcm starts making adjustments that arent needed. See if the voltage is steady or does it change a lot over time?