I posted this same question on J-L already.
Okay here goes, I believe the MAF on my 91 XJ40 is the wrong one. But I would like some feedback as to the readings from the connector.
My connector pins out from front of car to rear as B/Y B/Y G/K blank W/N G/R. which seems to differ from diagrams I've seen. However I get Battery voltage at W/N and 5v at the G/R wire the manual states less than 4v for the G/R? What does this mean to you guys? The grounds test good, but when I check the resistance on the MAF pins I get nothing, that's why I think it's NG. But could the 5v at the G/R be causing me problems.
The reason I think the MAF is wrong is that there is no adjustment screw available for idle trim and the pins are gold, indicative of a later model MAF.
I ordered a new one which should arrive on Thurs, all I've got left to clear is a FF 11 so this should do it unless that 5v is a problem.Sorry for the long post but I wanted to give as much info as possible.
Charlie

 

No problem , detailed posts are cool and informative . Keep us updated on your progress

 

I sent you TSB 18-38 to the email from your Jag Lovers address.
I'll post it here also

bob gauff

 

Thanks Bob, I'll be getting a new MAF tomorrow so I'll update after the install. I hope this is an end to my CEL/ limp mode at least for a while, lol.
I'd love to drive this car trouble free for a change, haven't since I bought her.

Charlie

 

Okay, got my remanufactured MAF, installed it and no more CEL.
Great right? Still have limp mode but it may be related to the
relay under the passenger knee bolster in the purple socket it
clicks alot then the trans goes into limp mode. I'll check my
grounds and contacts replace the relay and see what happens, ugh.
Need to reset the base idle as it is now a little low since the ECU
is back in control of things.

Thanks for the input, maybe some of you have an idea on my limp
mode trouble (no cel codes).Could it be just a faulty relay ?

Charlie

 

If the TPS isn't in the right position on the throttle body it will send you to limp mode without a VCM code. This can take a bit to work out because each time you adjust you need to take the oil filter off.

 

The BLUE Hella relays are pretty useless and I replace them when strange things start to happen.

here is some info

bob gauff

 

Thanks Bob I don't think it's the relay I have put three different ones with the same result. After changing I now get FF 69 so it appears to be something in the rotary switch. My PRNDL works okay as it starts in park and neutral and not in other gears and the parking engages when in park so that the car won't roll. Maybe just a cleaning is necessary, just a little lazy to crawl under the car. I set the TPS dead on and changed the EGR valve and it's solenoid, replaced the MAF with the proper one. All of those CELs are gone, now just this one.
I thought Jaguars were cats, mine is more of a dog lately, lol, a bad dog too.

 

One thing I did notice is the relay in the purple base, (for the trans) starts to click rapidly then it goes into limp mode, while in limp mode the relay clicks madly while accelerating, and when making a right turn it goes nuts like it's tapping out morse code. Ever hear of anything like that? Fluid is good and clean, no leaks to speak of.
Charlie