Got a CEL today on the way home, P0101. The PCM is getting MAF readings that are out of range from what it expects.

Freeze frame shows it set the code at:
73 mph
26% throttle
4.9 lbs/min MAF
88 kPa MAP
100kPa baro
360 kPa Fuel Pressure
197 F ECT
98 F IAT
91 F ambient
20.5 degree BTDC
86% EGR
100% purge
7.8% STFT1
16.4% LTFT1
1.6% STFT2
18.8% LTFT2

I just took a 500 mile highway trip this weekend and the car ran great, 32 mpg round trip. But seeing those LTFT values so high concerns me, I haven't seen them like that in the past. If the PCM is enriching the mixture, seems to point to a vac leak common to both banks.

I checked over the intake this evening, nothing is out of place that I can see. All vac hoses are secure, no loose ducting. No other codes set.

I have been dealing with a stupid pinging issue since last spring, I'm starting to wonder if this may all be related to a vac leak (even with a bottle of Techron added it didn't change the pinging at all--usually that's at least good as an octane boost).

Do the intake bolts on these cars loosen up like some other cars? I don't want to start guessing at problems, going to get some TB spray on it this weekend when I have a free moment and check for leaks.

Thanks,
-Michael

 

32mpg nice !
.

 

I had the same code pop up a few weeks ago. I removed the MAF sensor and cleaned it with a spray MAF cleaner. That solved the problem. You might also want to check the condition of the intake air filter.

 

Thanks! I was thinking to myself that I will do that next. This P0101 comes and goes on its own.... I cleared the code after the 1st incident, the CEL stayed off for a few days, then back on, and later that afternoon it cleared itself.

Air filter is new from a few months ago, but I never looked at the condition of the MAF.

 

Try replacing the full load breather

Cheers
34by151

 

Thank,s I'll take a look at that. Does the little hose have o-rings that leak on those quick-connect fittings?

 

Yes, you should be looking to verify no induction leaks, but most likely you are dealing with a failed MAF sensor. It's probably under reporting the incoming air and fueling for that incorrect air. That would account for the LTFT in the high teens. It probably accounts for the spark knock you've noted as well. I would also make sure the terminal connections are good a the MAF. I anyone's been probing those terminals, they could be sprung and loose on the sensor pins.

Good luck!

 

My car did the same thing when I drove it home from Sydney a 3000k trip about 700 k,s from home the engine warning light came up luckily I had my laptop with me so plugged in my reader same code for maf came up
I just reset it and went on my way it came on again about 200 K,s up the road so I reset it again hasn't come back again
I was wondering could it be something to do with the long trip as my car had only been used for very short around town trips till I bought it a month ago

I am going to replace all the O2 sensors, cats and maf anyway car has 165,000 k,s on the clock still gets exceptional economy but I have been told that's normal for the car
I am just used to the poor fuel economy of my old XJR6

 

Thank you Steve and Doc, appreciate the advice.

I was thinking about that myself last night... if my MAF is dirty/failing it would be reading less air than actually was flowing through the intake, and the PCM would not give enough fuel until the O2 sensors detected the lean condition. Certainly fits the symptoms... and when the CEL was on the PCM defaults to mass-air metering, the pinging is nearly gone.

Surprisingly the CEL has not come back since it cleared itself the other day. I tend to do short trips during the week, and longer ones on the weekend.

I'm going to try some MAF cleaning spray first. I'm hoping with only 62k miles that it's not failing but just dirty (the old air filter was very neglected). Also will look up the Denso part no and source a replacement MAF.

 

I just ordered a new Map sensor from Rockauto $142.65 it wasn't a denso it was a standard motor parts one but have used there parts before seem to work allright searched for the denso couldn't find one the denso also said made in Spain so another reason why I didn't push for a denso the standard motor parts one is made in the USA I like that better

 

Finally got the MAF cleaner and pulled it out to look at the sensor... I was shocked to see the sensing wire and IAT thermistor coated in gray dust. I've never seen a MAF get dirty like this, that's crazy. I know the PO neglected the air filter, but I doubt air was bypassing it.

Anyway, a few sprays of that and my sensor was shiny inside. Have to wait and see how it does under stop-and-go conditions that usually make it ping like crazy, but so far it's almost not pinging at all! So minor that unless I was listening for it, I would never notice.

We'll see how it does...

 

Hi Doc,

Could you tell me how well was the rock auto MAP sensor? I have the Code P0101 too. I replaced the air filter and cleaned the sensor with the CRC cleaner, but code didn't go away. I plan on ordering the same part too. Thanks

 

Just be careful as the XJ8 and XJR have different MAF's, they are not interchangeable.

 

thanks Cambo!
i ordered the part from Rockauto. It is listed under the XJR; if not, how can you tell?

 

They have different part numbers...

Supercharged #C2C7635
Non-supercharged #C2S2670

As far as I know the measuring range for the S/C is much higher (a S/C engine consumes more air) so if you put the non-S/C MAF on an S/C engine it will be a problem...

The same MAF's are used on the S-Type 4.2's too...

 

Mine is going absolutely fantastic after replacing all the items I did use genuine denso 02 sensors map sensor was rock auto generic big job to get to it though

I also had a custom flash tune done because I was getting catalytic converter mil lights all fixed but hell it cost a bit!

The price is forgotten now its goes so well and its so economical just did another 850K to a tank lots of of highway and small trips round town looking forward to a big trip soon

bummer is sold my XJR6 to a guy in Tassie and will be dropping it in Melbourne so the big trip for the XJ8 will have to wait not that I don't mind driving the XJR6 on big trips just realised its the last trip in it

 

I got confused with MAP sensor and MAF sensor. After hours of reading and reading the threads in here, finally figured it out. When Doc said he ordered MAP sensor, thats what i did, ordered a MAP sensor, but when CAMBO mention that XJR have different MAF sensors, I should of know that they are different thing but they look both look similar in a sense that they both sense air. Anyhow, when I got the MAP sensor today, it all came clear for me that I ordered the wrong part. So I now ordered a MAF sensor. Will let you know on Monday when I go pick up the part to see if the CIL will go away for P0101 code. Its very nice to learn something new everyday!

 

I was getting the P0101 code recently and it's been a pain to get rid of. I looked for the Denso MAF but nobody carries that anymore. Instead I bought a remanufactured MAF from Auto Zone and I was told it works fine with my car (04' XJ8). I replaced the MAF and the car ran great but then after 50 miles the P0101 code popped up again! I cleaned it and reset it and the same thing happened again and sometimes the code clears itself but returns. I replaced the MAF again for another one and the same issue returned! I don't know what else to do or to check for. No hoses are leaking and now the car is running very rough and the Restricted Performance pops up now.


Is there a certain MAF I need to purchase? What other components can cause this code? Any information on this would really help me.

 

Any other codes coming up?
Its hard to diagnose not knowing the vehicles history that's why when I bought mine I went crazy and changed so many sensors plugs serviced transmission diff oil and so forth even though it had a full dealer service history plugs where still original transmison never serviced diff oil never chnged

 

I had the same issue with my 2005 XJ8L. I could not resolve the issue until I used a Jaguar MAF sensor ($168 from "Cheap" Jaguar parts - Genuine Jaguar Parts Online at Discount - Jaguar Replacement Auto Parts), changed the intake filter, and the full load breather.