MAF Sensors
 

Today in traffic my car started pulsing at idle and I was experiencing a loss of power at low RPMs. Seems like a MAF sensor to me, but reaching the MAFs on these cars seems to be a nightmare. Can they be accessed from the wheel wells and do I actually have to pull the front apron?

Perhaps you should invest in the Workshop Manual. It can be purchased from vendors on the Internet for less than 30$US.

Or downloaded in PDF format from here, for $0 - JagRepair.com - Jaguar Repair Information Resource

The MAFs are located in the air filter housings (one for an XK, two for an XKR) which are located behind the front bumper (fender?) and in front of the wheel arch. You'll need to lift the front end, get the undertray off, undo at least the lower half of the wheel arch liner and tie it back out of the way. Then you can access the air filter housings - the MAF is on the top/rear side in the short tube between the housing and the pipe that runs upwards toward the top of the engine bay.

Check for fault codes before you do anything, if the MAF is dodgy you'll likely see a code related to it. If you do have to replace the MAF then you can save about 50% of the Jaguar dealer price by buying the corresponding Denso part - at least on the 4.2 XK/XKR, the MAFs are manufactured by Denso.

Or download from this forums "How-To" sticky link with other useful technical documents see post #3 https://www.jaguarforums.com/forum/x...k-links-20091/

And here's your classic check the battery voltage at rest before spending a dime on anything.

Done. Got a brand new battery the other day.

Did installation of the new battery fix your driveability problem?

When? Did it change the symptoms?


Mini-rant time.. Is it just from texting, or does the younger generation not realize that the more interesting info they put out there regarding their problem, the better and quicker resolution they'll benefit from?

:icon_doh:

No, new battery was installed about a month ago. Charge seems normal at the battery posts. Tried doing a hard reset today while I wait for new filters to arrive, but one of the cable tightening bolts broke on me, so tomorrow I'll have a verdict on that one.

More or less assumed it could be gathered that I am still having problems if I didn't acknowledge their resolution. I'm aware that I'm new to this side of the forum and you may not be familiar with me, but I'm no stranger to the XJS forum and I have had no trouble communicating with the folks on there. Please don't be so hasty with the judgement.

OK, a few more questions:

1. Have you measured battery voltage after the car has rested overnight and remains IG-OFF?
2. Is the check engine light or any other warning lights or messages on?
3. Do you have the Jaguar SDD software to retrieve any logged fault codes?
4. Since you posted on May 29, has the driveability problem been intermittent or constant?

Sorry for the late reply. Got super busy with my cross country move, didn't have time to mess with the car yet. Hoping to tackle it this week. I haven't measured battery voltage after sitting overnight, probably should give that a shot. The check engine light is on. Just had the codes scanned today. Getting P0193, P0088, and P0087. Drivability has been intermittent for sure. If I restart the car it clears up.

P0087: fuel rail pressure too low
P0088: fuel rail pressure too high
P0193: fuel rail pressure sensor circuit high input

Fuel Pressure Sensor and wiring harness both look okay. Ordered a new sensor anyway because the compatible Mustang part was so cheap. If that doesn't fix it I'm inclined to check out the MAF sensors next, because I've already got new filters to put in and otherwise what could it be? Pump and fuel filter?

If you can replicate the problem "upon demand" and while the car is parked, then I would suggest putting a fuel pressure gauge on the fuel line so that you can see what is the fuel pressure when the loss of power issue occurs. You are looking for 55 psi minimum.

If the fuel pressure can be seen to drop when the issue happens then I would conclude the sensor is accurately reporting a problem with the fuel pump.

Since the problem is intermittent I would not think the fuel filter is the problem.

The fix might be as simple as replacing your engine air filter, particularly if it's dirty or not genuine OEM Jaguar. You have only one, since you have a 2007 XK. See these threads:
https://www.jaguarforums.com/forum/x...sensor-161155/
https://www.jaguarforums.com/forum/x...ptions-122210/

Y.Y.You're joking. I was under the impression I needed 2. Shoot, already bought them. That would mean I only have one MAF sensor then, is it on the driver's sideY

I can't replicate it on demand. I always replace pump and filter at the same time. You think that's the culprit then?Y

On the left side of the car. LHD and RHD within the same model, makes "driver's side" a poor identifier.

I'm an idiot, thanks.