Sorry to hear about your problems, but your way of thinking is not really working in your favor.


You said "I trust this guy more than I do a main dealer and lets face it they are only as good as their mechanics!".


This is simply not true at all. The dealer not only has their own mechanics but they also have other mechanics from other dealership they can call upon. In addition, they can call Jaguar Corporate for further assistance if needed. They also have diagnostic software that is up to date that can go deeper than a regular inexpensive scanner. This is not about a matter of trust, rather it's about getting results.

You said "I can also say with certainty that ANY work that may have been done at a main dealer would not be cheaper! They charge £80 just to hook up to their diagnostic machine"


Again your way of thinking is not working out for you. Wouldn't it make more sense to pay £80 and get an accurate diagnostic report than £50 for an inaccurate one? Of course it would.


Think about it.

 

Without knowing the DTCs his mechanic is getting from the car I don't see how anyone can reasonably find fault with the mechanic. I normally don't think too much of the mechanics but will hold off criticism on this one until more information is provided.

 

He DID provide more information, it's in the 1st and 13th posts. Didn't you read them before you posted? His mechanic is guessing and is suggesting very expensive trial and error fixes.

 

This is the part that concerns me and honestly makes it a moot point to take it to the dealer. Repair at your shop vs. replace at the dealer. Big question is what caused the fault to come back, faulty repair or something downstream killing the processor? The dealer is going to want to play the parts swapping game too and their prices will hurt a lot more than an indy's will.

In for a penny, in for a pound. I think this one is going to get expensive. I would make damn sure the last repair is still working correctly before moving to another place. I've also read here that pulling the downstream O2's and leaving them plugged in will keep some cat efficiency faults at bay. I'm still having that trouble as my downstream ones are original and failing to cycle.

 

I read the posts. Again. I also used the search function on his posts and the search function doesn't find it either.

Since you feel I have trouble reading, would you please enlighten me with the DTC code numbers his mechanic is getting? They will start with P and be followed by four digits. Or don't you read before you post something?

thanks

 

Read post 14, 16 (your own post) and 18. The mechanic is NOT providing him the codes and is guessing and wasting his time and money. Time to move on to another mechanic.

 

just to point out --- air can only leak from the supercharger during boost conditions .
and not otherwise .
and the rest of the time would be called a vacume leak ! un metered air being drawn into the supercharger via the same leak .
this can easily be confirmed or ruled out by watching the fuel trims on your elm 327
. and im very surprised this technique has not already been implemented on this car .

 

+1
an elm327 costs a few $$$ and you can easily watch fuel trims yourself.

If you don't want to do that, at least change to a mechanic who has a clue about engine control since the year about 1996.

 

Can't you read?? That was my EXACT point. Unless you are psychic no one here has the codes. Without the codes how do you know the mechanic is guessing? I think YOU are the one that is guessing.

The OP doesn't want to ask for them either. See post #3. Without more information all anyone can do is guess, about the cause of his problem and whether the mechanic is any good or not.

I suggest a truce here, at least until we get some more real information with which we might be able to actually help the OP.

 

He is guessing because what he is doing is clearly not working and the OP is frustrated by all of this.

Truce accepted!

 

Just been on the phone to my mechanic who has had the car since last Monday (10 days) and "hopefully" appears to have resolved the issue. Here's my interpretation of the problem.

The reason for the engine malfunction indicator was due to too much air being sent to the engine, but it wasn't obvious what was causing this. He cleared the warning and has struggled to get the warning indicator to fault again and so has been using the car for collections in order to drive it in normal conditions. Then it happened, while sitting in a queue of traffic, it finally came on again and he was able to determine the cause was due to the difference in air volume between the left and right sides. 5 on the left and 17 on the right. Sorry, I forget the measurements he used.

He determined it was the air flow meters and so has fitted a 2nd hand part and after extensive testing, this appears to have resolved the issue.

I collect the car later, so fingers crossed the engine malfunction indicator stays off!

 

Hope that does fix the problem. Intermittent issues can be REALLY hard to find. See if he will tell you what error codes he was getting from your car.

 

+1 on Dave's request. This forum doesn't benefit from one way information. The codes will help any future members if they encounter the same symptoms.

DTC CODES please and thank you.

 

Yes, if he had numbers, he was looking at the data stream. I watched it when I had a borrowed Snap On scanner plugged into mine. I'm also curious what failed on the MAF since they are just a heater element and temp sensor along with a controlling circuit.

 

When I picked my car up, the mechanic explained that NO error codes were being displayed for the MAF failure and he only saw this while using the car and analysed the air flow when the engine warning light came on while he was sat in traffic. Surely an error code would have to be raised for the engine warning light to be triggered?

He replaced both MAF's with 2nd hand ones from a low mileage XKR and said he could see the difference as the new ones both reported the similar values, whereas one of the old ones was reporting a higher value and wasn't fluctuating.

Had the car back for a week now and no warning light, so he appears to have resolved the issue. Haven't received the invoice yet

 

Yes, an error code would have to be set and saved if the check engine light came on.

 

Intermittent MAF issues are notoriously hard to diagnose and the most common code car throws when it happens would be bad O2 sensor. I guess implementing cold resistance check on no-flow before startup would make MAF too expensive, but it would save so much grief for troubleshooting these.

 

Do you know why the car would show a bad O2 sensor when the MAF is bad? I would think it would flag a bad O2 sensor for zero volts, 12V, or no change on an O2 sensor as a bad O2 sensor.

It does look like that the OP was originally getting a code for a bad O2 sensor so I believe you. I just don't understand why.

thanks

 

It seems an odd claim. I'd expect this kind of Jaguar would not throw an O2 code for a bad MAF.

Maybe it's what older cars sometimes did (though I've not seen it - didn't happen on unplugging the MAF from a Ford I used to own).

 

O2 sensors are often misdiagnosed when they are simply reporting what they are sensing. They read the mixture, period. If the mixture is very lean it will show a constant low, even zero reading. If too rich, a constant high reading. Ideally a constantly fluctuating reading is desired which is usually the case under steady state cruising. When a fixed reading is detected for a period of time it will set a code. It is up to the mechanic to find out why the sensor is reading this, not simply condemn the sensor and replace it. In this case the MAF on the side the mechanic replaced the O2 sensors on was likely causing constant 'lean' readings and setting codes. This may have led to the original leaking SC diagnosis. By the way, the voltage range for O2's is generally between 0.2 - 0.8V.