Mass Air Flow Sensor Failure

Edited on 2012-02-20 8:59:56

Thank you, Dave, for reporting back and the kind words.
You are very right about the 'computers' we use for diagnosis. The idea of 'plugging in' and being told the answer is the unfortunate and popular misconception. What they DO, however, is give many more and more accurate FACTS. You still have to interpret the FACTS, along with whatever HISTORY you can come up with and substantiate. Obviously some of that history came from you, some came from our history with the car, and some came from Jaguar Cars; and some of those facts substantiated each other.
Most of the time when I nail down a problem, I come away with that confident feeling that I'm done, it's over and I have the 'smoking gun'. I will confess that in this case here I'm in a different spot. I sort of have the gun..........but without the smoke! That's uncomfortable for me. So all I can say is, I'll sit here and sweat until say Memorial Day, when hopefully you HAVEN'T called me to say, "Jill said the car burped, we're two weeks away..........."
See, I know the drill.

Cheers,

Dave, I am sure that your problem is solved.I had a similar problem with my 95 XJR years ago. Luckily, my mechanic traced it to a intermittent connector wire. He sent me home to solder/splice the wire.( I think it was the black wire.) Thankfully I did not have to go through 7 MAFS as you have. There is no way that 7 could all be faulty. No doubt the diagnostic tools tell the technician to replace the sensor, when in fact the wire/connector is faulty. Depending on which wire was intermittent will no doubt give different readings/symptoms. After you get to look at the connector in question, you will understand why it is so vulnerable to failure.

Only time will tell whether the problem has been corrected as it does this every 5,000-8,000 miles. Steve kept the car for a week or so and decided it wasn't the Mass Air Flow Sensor and reinstalled the one the other technician said was the problem. Appears that this car has had 7 that it may not have needed. He finally replaced all 5 leads going into the mass air flow sensor as he felt they were the culprit. He also felt the thermostat was a bit irratic so replaced it also as temperature is apparently critical on the XKR's and the supercharger (This car is now on its third thermostat at 50,000 miles). Hope this helps others out there who might experience a similar problem. You just can't trust those plug in computers. It still takes a lot of knowledge, the right tools and an experienced person who asks why and not just what. Thanks Steve.

what was the outcome?????? others would like to know.

Steve-I hope you get to the bottom of it so we comfortable driving it out of town/out of state. Unfortunately the history you point out was provided to your service technicians at the first replacement at the dealership as I had the service records. The testing results of the initial MAF replacement by the dealership were offered but refused. It still seems to me you need to know why the MAF sensor failed-was it a contaminate or mechanical (drop in voltage). At one time the dealership had the car for nearly two weeks. Hope this does it but I think my best bet is to have a spare in the trunk if I want to drive it out of town very far. Will wait to hear from Dan as to when it is ready. Hopefully if there is another poor soul out there who has had the same problem they will speak up. Thanks all. Ask around. Multiple heads are better than mine at this point.

You will get it Steve! I am sure Dave will be happy. Sure does sound like that harness may have been the culprit all along.

Hi Fellas,

George -- Thanks for the shout out! I appreciate your confidence. I'm already on the caper......was handed to me after Dave raised the repeat nature of this issue with our Service Adviser, Dan.

Dave -- Let's start with I appreciate your giving us the extra time so I could dig into this thing and research the entire history of the vehicle. Got out the detective hat and found this business has plagued this car virtually it's entire life; well, starting at 13,000 miles in early 2005. Counting the original, it had 5 MAF sensors BEFORE you bought the car! That's just nuts. That's why I had Dan ask all the silly questions, I had to be sure I could see all the pieces to the puzzle.
I spent quite a bit of time running the car with some of my own gear to try an grasp what was happening. Finally began to see some erratic behavior, but it took a long time. One instant it looked like a vacuum leak, sometime later it looked like it was about to almost flood. A little bit later yet, it was perfect. To cut to the chase, turned out temperature was a big factor, and also engine movement was a factor. For some reason, what appeared, and tested to be perfectly good wire harness terminals to the MAF sensor, were causing erratic MAF signals to the ECM, especially when hot. All five terminals have now been replaced, and it appears we're over the hurdle. I still have a lean condition, only at idle that I'm not happy with, which is why I asked to keep her 'til Monday; plus I want to prove out the harness repair more thoroughly.

Thanks for your patience!

Cheers,

Dick--the one supplied by the local Jaguar Dealership who installed it. I refuse to let anybody touch it otherwise. I don't know the brand but can check with the dealership if you think it might make a difference.

Just out of curiosity, what kind of air filter are you using?

Yes George it gets expensive. Use to be around $400 after the $90 charge to hook to the computer. This time it will be over $500. The warranty runs out before it happens again as we only drive the car 4-5,000 miles per year since we rarely take it out of town due to the problem. Indianapolis Jaguar has never been able to determine the cause. The computer only tells them the affected part. They have it right now but I won't know if it has been repaired until it doesn't do it again. I need a spare to keep in the trunk but cost is an issue. I myself think it is some electrical surge that affects it . They wanted to know if I run it through a car wash--I won't even let them wash it Then whether its gets rained on-it is a daily driver and it rains in Indianapolis 12 months out of the year. I have to think maybe someone else has had the problem and can share a solution.

Dave that has got to be getting expensive. At this point I think I would be tempted to take the old one and open it up and look for something obivious--burned circuit etc. Making an assumption that there are not a batch of bad MAFS out there I would look at the signals it receives and those connections/ circuits. Perhaps Steve P. will see this post and shed some light on it.

George--my wife always tells me about 2 weeks before it goes bad-might run a little rough for a second or two or fail to stay running when first started-both actually happened two weeks ago. Later the engine symbol comes on and the message performance restricted shows. The first time it would hardly make it home and I had it towed in. The second and this time I immediately headed for the dealership. I had one tested and it showed no contamination but slightly low on the voltage. The second I did not have tested. I have had an independent mechanic check to make sure the right part was installed in case the XK8 has a different one than what was installed in her XKR. Jaguar never sure they have found what is causing. We bought the car with 29,000 and I just had it in two weeks earlier for its 50,000 service. This happens every 6-8,000 miles or so.

Dave is there any more information? What happens just prior to failure? Is it fine and then just stops working?