Ok enlightened ones... Anyone have any idea why I’m having MAF failures every twelve to fourteen months. I have just installed my fourth one in nearly five years. It doesn’t matter if they are cheap Chinese ones or expensive OEM parts, they still fail...

Apart from carrying a spare, I’m at a lost as to cause. Wiring loom all looks ok, no shorts or possible troublesome connections. The vehicle only spits out the P0174 and P0171 codes and the ubiquitous restricted performance. The engine will cough and splutter, shudder and shake and eventually stall (even when kept well under the 3000 RPM restricted performance limit). Most surprisingly, I can stall the engine just by applying a gentle pressure to the top of the MAF. The replacement, once installed has no reaction to even quite robust pressure.

The connector is ok, it’s been cleaned, checked and there’s nothing obvious there either. I’ve taken a failed MAF unit apart with no obviously faults. Even I can not be unlucky enough to have bought so many dodgy ones...

Donna :-)

 

Hi Donna,

This is certainly an odd one.

Do all the replacements look the same? I'm wondering if they all come from the same potentially defective source, whether in a very expensive Jaguar box or a cheap Chinese one.

The reaction when you push on the top? Now that's REALLY strange. Any chance you're also flexing the inlet duct or air cleaner housing, which opens a crack and lets in excess unmetered air? That doesn't make sense either, as you say it doesn't happen with the new sensor. But does it happen consistently to the new sensor once it ages a few months and starts to act up? Cue the Twilight Zone music...

 

Mine does similar. I just take apart the air intake and clean it and it is good to go for another year. Have never replaced the unit.

 

I’ll give that a try.... thanks ;-)

 

Donna, I am having lean code issues also. Can you please tell me which specific maf sensor is the factory unit on the 3.0?

 

Wait! Start by doing the more common things to check WHY you have the codes.

 

The generic part number is 22680AA310, but, as JagV8 says don't assume and throw parts at your car. Lean codes can have any number of causes. I'm still looking into what is causing my problems, the MAF failure I believe is only symptomatic of a greater concern.


There are lots of threads here on the more common causes of P0171 and P0174 codes such as vaccuum / air leaks, fuel pressure / fuel feed faults, failing lambda sensors... Get yourself a good realtime monitor and enjoy the challange of finding what's really the problem.


Donna

 

Donna, thanks for the part number....fyi...I have been member of this forum for a few years and I have a good real time monitor and I have been chasing these codes for years. I have been the recipient of a wealth of knowledge from others here about the lean codes and the MULTITUDES of possible reasons..and I have engaged in throwing parts at it for at least 3 years. This is not my first Jag. I have owned an older XJS 6 cylinder, a gorgeous early '90's red convertible v 12, a debut year 2002 x type, and this s type purchased new in 2005. The 2 older cars were awesome, despite the notoriously bad Jaguar reputation back then and the only complaint I had about the V12 convertible was an oil leak. The x type never gave me one day of trouble. I traded it in to buy the s type, and for the past 3 or 4 years, this car has driven fine, but the lean codes have been a maddening experience. If it werent for need for smog, I would just drive it as is, but since I can't I am forced into battle with this freaking computer. Venting.

 

I see your many posts about MAF and about fuel pressure - which seem guesses.

I probably missed the ones that led you to those as definite (bearing in mind lean codes are usually neither of those), rather than guesses but remind me...

 

Jagv8...you have been among the many helpful responders to my lean code battle (and other items) for quite some time, and i appreciate your help. To refresh...originally i knew (suspected) a primary cause of the lean codes were leaky IMT rings, since I had oil leaking back there. I did the IMT rings, and while under there I replaced the upper manifold gaskets. I examined the vacuum lines and decided they were in tact and left them alone. Things were a little bit better, in that I was able to keep the codes off for a longer period of time and I got the car smogged. But they kept coming back. In researching the forum, I see countless posts that any of numerous conditions can throw 0171 and 0174, Principally an air leak, but can also be insufficient fuel. So....I replaced maf, gas cap, cleaned throttle body, did the accessible plugs and coils, changed the fuel filter, changed the air filter. Codes were somewhat less frequent for a period of time, but started to reappear more frequently after a while. I then started to think that maybe the problem was clogged injectors, so I gave the car several heavy doses of BGK 44 into the tank. The fuel trims and lean codes improved dramatically, and I determined that maybe I had cured the disease with fuel injector cleaner. But then, the 0171 and 0174 started coming back so I dosed it again with injector cleaner and once again it improved. But alas, they come back in a short while. So....I convince myself that it must be fuel supply related and I replace all the injectors, and this time while under there, I do the plugs and coils under the plenum. As a result, the car is markedly running smoother and with better acceleration, but 0171 and 0174 will not surrender. All readiness monitors are completing except evap. The cel is coming on, even though 0171 and 0174 are showing up as "pending". The ltft's are maxed out at low rpm and improve with throttle. Everything I have learned here tells me this is an air leak condition, or the computer "thinking" there is an air leak. Joycesjag has posted in response to my posts, that Jaguars "do not like" certain replacement parts (mafs particularly) that are not factory oem. I have ordered and await a factory replacement fuel cap, and my next move will be the oem maf, since the one that I put in the car was a Duralast part from Auto Zone, and maybe it's not good enough for this car.
Things I have not done.....all the 02 sensors, the lower intake gaskets, the fuel tank seals, the fuel pump itself.

 

If you let the LTFTs learn - i.e. do NOT clear codes and do NOT disconnect the battery - after a number of drives, what are they? There really are a lot of posts about this! If they drop significantly when revved you know you have a leak.

If you can't find the leak it sounds cheaper to find a tech who can than go on swapping parts at big cost.

 

after a number of drives, the ltfts sit at 19.5 at idle and drop to 0 at highway speed. I already took the car to a "Jaguar" tech who smoked the car and determined he could not see a leak and it could be any of a number of things (as I already know), and he has no clue but to start process of elimination at my expense. No thanks. I am going to go back and try a couple cheap fix attempts and if still not resolved, I THINK i can perform a hard reset, and immediately put the car thru the drive cycles to complete readiness monitors before the ltfts go back up and immediately smog it. If the cel stays off and all monitors complete except evap, I can at least pass smog.

 

I really wish you'd read existing posts. They do not ask about highway speed but to rev when parked with a hot engine.

If the LTFTs drop a lot then you have a leak. If one tech could not find it then about all you can do is find another or DIY but swapping parts looks costly and unlikely to fix it. I suppose if you can "game" the system and pass smog that may be what you want.

You could try looking at sensor readings but unless you understand what they do and how they should behave this needs a (competent) tech.

 

Jagv8.....I can't tell you how many times I have read the posts. I am not ignoring them. I agree that the fuel trim behavior points to a vacuum leak. But I firmly believe the accessible lines and fittings are in tact after countless re-examinations. I could be missing it but they sure look ok to me. As I have reported, I have not done the lower intake gaskets and I am leaning toward taking it down again to get to those. I am also curious about a mysterious hidden vacuum line that I have seen mentioned a couple of times. Where is that? I didn't notice anything like that when I had everything apart for the injectors. This is the 05 S type 3.0 v6.
Donna, if you are still following, can you please tell me what specific codes or readings you were getting that led to your conclusion of faulty mafs?

 

This thread should stay on the MAF discussion.

It has been pointed out several times in your thread there is no mysterious vacuum tube under the lower intake manifold on face lift MY's (2003 up US). Again refer to my post #23 in your thread Jakesdad!

 

Joycesjag....I was merely replying to inquiries about my symptoms after I asked Donna a question about her maf diagnosis. And I still have question about that diagnosis on her mafs, nor have I seen much other in the way of responses to her original question. You're getting a little uppity. I thought the forum was about helping each other out. If not the case, I'll stay off the site and figure it out myself.

 

Now, now, don't make me break out the tranquilizer gun.

Unlike yours truly, JoycesJag is a man of few words. When he says something, I listen. He has a wealth of knowledge about these cars. Through the medium of this forum, it's easy to miss the cues as he gently tries to persuade you back to your other thread, so as not to steer this one (about Donna and her MAF sensor punch card) into the weeds. I've got to admit it gets frustrating sometimes to offer some in-depth technical advice and it never really gets any follow through. I'm not picking on you, as this applies to many folks seeking advice in this forum.

I'm sure no offense was intended in this latest dust up. Now I've always suspected JoycesJag could best me in a barroom brawl, so I've always been careful to stay on this good side. However, I do know he's presently recovering from knee surgery, so I'm sure if we followed prison rules and I went all Tonya Harding on him, I could best him. And if nothing else, I'm sure I could outrun him and his gimpy knee.

Now I just posted some stuff in the other thread, so take a look and reply there as we try to help you.

 

KR..I appreciate your feedback. I also saw your latest post on my fuel pressure thread. You have provided some really good stuff for me to check out and i appreciate it a lot. I might start a fresh thread on my issue because the other one is getting lengthy.
My frustration here is that while I agree that my diagnostics point to a vacuum leak, I have determined that from what I see on this car, the codes are not coming fro a vacuum leak under the hood. And the forum is rife with threads about 0171 and 0174 being attributed to a plethora of possible causes, including maf...and since Donna started this thread about maf, I picked up on it and asked in essence..."what led her to determine her codes were coming from maf" .
You have made a good effort at intervention here , and I know it is to continue to help me. You should try your hand at negotiation between CNN and Fox news.
I will reply to your post on my other thread...then start a fresh one with further questions. thankyou.

 

Hiya,


It wasn't codes that lead me to the MAF as the problem but rather a far more unusual occurence. As I said earlier in this thread, I merely opened the hood and leaned in, supporting myself on the airfilter box and on the hose in the vicinity of the MAF and the car stalled.


I restarted the engine and began trying to repeat the stall by placing pressure on the individual air intake parts. A gentle pressure on the MAF top plate stalled the car. This was repeatable. MAF was inspected, cleaned, mounting point checked, connector cleaned and inspected and then reinstalled a few times. Problem persisted. MAF was swapped out for a new unit and the problem disappeared.


The only codes in the system were the P0171 and P0174 which, as you are aware are not particularly insightful as to cause or diagnosis.


Now I'm unconvinced that I have just been unlucky with MAF units. I am currently trying to see what could be causing the MAF failures, thinking that it's probably electrical but I cannot discount something physical within the air intake system.


If I find a cause, I'll certainly post the solution.


I do hope this helps...

 

Hmmm strange to see MAF's to behave in this manor. Cant say I've seen this before.


So to make a long story short - you get check engine light, P0171 & P0174 codes logged. Since you were applying pressure of some sort to the top of the MAF, led you to believe it was at fault, being that you replaced, and fault went away.


Now it's returned..... As for electrical issues, I have seen issues with the engine harness in the past on V6 and V8, early and late model. These 2 codes being logged could be a multitude of things causing it.


May need to take it to a dealer or someone who has SDD and see if any flight data has been logged along with those 2 codes. If you can get this info it will definitely help.


As for jakesdad - the slightest vacuum leak can wreak havoc. Even if you've had the intake off for injectors, did you replace the gaskets or reuse old ones? There are several vacuum hoses on the V6, some are covered in wire conduit, so you may need to disassemble to fully inspect to eliminate as cause. The upper and lower intake gaskets, these can be cut while refitting intake, doesn't take much. IMT valve O-rings fail just like the X-Type ones did, another place to look.
As I mentioned to Donna, you may need to take to dealer or someone with SDD, or has a proper scanner than can monitor sensor data, or even read flight data, this will give insight as to what the car was doing when the fault occurred. I would suggest this before throwing parts at the issue, it can..... no it " will " be expensive, and time consuming.


Keep in mind, if you've been looking at one problem for so long, you start to get frustrated. May need to go back to square 1 and start over, you " may " have missed something. I've done this when I've been stumped, just a suggestion.