OK, my gf bought this car last year (8mos ago). It went into restricted mode one day and I got a P0103 code. I bought some MAF cleaner, pulled the airbox out, cleaned the maf, put it all back together and it ran fine.

Then it went into failsafe mode. I did some research, found the plug by the throttle cable, pulled it, cleaned it and plugged it back in. During this, the snap on the plug broke. THe car started and ran fine.

Intermittently, both codes would return, I would repeat the procedures above and was just living with the quirks.

In January, the fuel pump went out, it took us a bit to get the $ together and start working on the car. I eventually gave up on the tank removal and paid a shop $300 to do it for me.

Once the fuel pump was replaced, the shop started the car, but it went into failsafe and restricted mode right away... I told them not to worry, picked the car up, unplugged and replugged the connected by the throttle cable and the car started up in restricted mode only. I brought it home, cleaned up the maf, put it back together, but it stayed in restricted mode. It is throwing a code P0103.

I picked up a reman Cardone MAF at Advance. Installed it, still got the code and restricted performance. (I had a similar issue with a Cardone Reman on a Jetta) I went and did a warranty replace. Still P0103. Still thinking it was the actual MAF, I returned that one and picked up a brand new Pierburg OEM replacement through CarQuest. Guess what, still getting a P0103 and restricted performance. I have checked the whole intake system, no apparent leaks, the code gets issued as soon as the car does the system check, prior to even starting.

I am thinking electrical, but I don't have much information to check.

I read the MAF Value today, as soon as the key is turned on to connect to the ECU, I get 399.8 g/s. The value never changes no matter the speed, engine on or off. The intake temperature reads correctly.

The instances of going into failsafe mode are also increasing. So far, if I pull the connector, clean it with electrical cleaner and plug it back in, it will run for longer than if I just unplug and reseat the connector.

Any help on this one would be greatly appreciated.

 

One of the most important courses I ever took in high school or college was chemistry: I learned that if you put green stuff into yellow stuff it turns brown. Every time.

I am guessing it is not the MAF. maybe cleaning the throttle bore and plate and checking for air leaks. Also check the pins in the connector. Betting on a break in the plastic tube from the filter box to the throttle body.

Did you also change the air filter?

 

It may have a bad reading and be substituting a default.

Maybe wiring.

 

I do not have my computer with my Jag manuals with me, but I assume JTIS gives the test resistances for the MAF circuit. They are done with the battery disconnected and can find shorted or open wiring, which you might have.

My next try would be to disconnect the MAF and crank. Not, crank, then disconnect. Then read the codes.

Your code apparently means a bad circuit, not high air flow, so cleaning anything except the connectors is wasted effort.

If you have carefully examined the MAF connectors and wiring and see no bent pins, no corrosion, no broken wires and so on, then the ECU would have to be considered. Having another XJ8nto swap parts would help, so an indie garage might be your best bet. If you were near Atlanta, I would let you try any of my known working parts.

 

I agree that it sounds like a wire fault or the ECM has internal fault.
You might remove PI1 (Petrol Injection 1) harness plug behind the engine and look at the connector pins. It is the link between the body harness and the engine harness.

A 'pinout' continuity test from the MAFS connector to the ECM should tell all you need to know about harness integrity.

Also check Fuse #12 (10 amp) in the Engine Management fusebox. It powers the MAFS.

bob gauff

 

Not sure about the relevancy of you chemistry info, my most important course would have to have been HS Trig, or College Physics.

Some more info. No breaks in the hose leading frI have m the airbox to the throttle body. As noted the code comes immediately, before the car is even started.

When I unplug the maf, I get the appropriate codes. So I don't think it is the wiring to the ecu, but I don't have a service manual to get the appropriate values to test the maf.

I have looked at the pins, but as my gf points out my eyesight aint what it used to be, will check them closer today, but the obviously are not shorting while unplugged.

 

I uploaded the 2000MY Sedan Electrical Guide and that is what you need to do all your investigation.

bob gauff

 

Bob, I saw that earlier. Thanks so much, I have not had a chance yet to dig into it. Rich

 

taijirich after i bought my XJR i found some electrical problems to. What i do?
I clean all the connectors on ECU, gear bpx computer, fuse box from the engine also from the trunk everything is on engine bay and has electrical contacts.. This solved all my problems.
I use contact cleaner spray R22 with some grease inside.
Hope it will help you my advice.

 

Taijirich: Don't like the chem metaphor? Try Einstein (physics) expect different results from same . . .

 

I think I follow what you are trying to say, and it still makes no sense applied here. Thanks for your input even though it really hasn't been helpful.

 

After trying three separate MAFs, the problem didn't get fixed. So the problem is likely up circuit or down stream from the MAF sensor. The pros (Bob and Ross) have corrected my faulty logic and noted it is in the circuitry taking sensor data from the MAF to the ECU and not in the air stream measured by the MAF. Working back from the MAF, the first logical choice would be to check the alignment of the pins, then each wire from the connector .. . . Or, as Bob has noted, start from the ECU and work towards the MAF sensor.

Good luck. There is always a dealer or really good Indy as an alternate.

Why do I care: because someday I might have the same ^^^^ing problem, and this is how I learn.

 

pay attention to pin connections too, they use gold plating for a reason. But at that reading you have a default not poor connection. @idle you should see about 5-7g/s not 399. past wiring and connectors I would say you have a bad circuit in the ecu of which you can send to several rebuilders.
Rebuilt ECM, TCM, & ECU | Cummins, Dodge, Ford ... | Go ECM
ModuleMaster

 

And please, Mr. Jhartz, do not put me in the category with bob or Brutal or someone might give undue credibility to what I say!

 

But Ross, you sound like you know . . . .

The message: You get what you pay for on this forum! Still, multi-comments is very acceptable method for problem solving . . . The forum 'self' qualifies inputs, assuming participants provide their best knowledge and the pros toss the BS flag at the right time.

 

Bob,

I got into the diagrams today, and am a little confused.

I started at the MAF... tested the pins at the plug active, unplugged from the maf...

Pin 1 should be battery/alternator volage.
Pin 2 is ground
Pin 3 goes to the ECU.

Pin 1 reads correct Battery Voltage
Pin 2 reads correct 0V
Pin 3 reads correct 0V

When the plug is connected and the circuit is active the readings change

Pin 1 should read battery voltage
Pin 2 is ground
Pin 3 should read 1.2v at idle

actual
Pin 1 reads battery voltage
Pin 2 reads 0
Pin3 reads 9.97v

It stays the same at idle.

This looks to me like it is in fact, a problem with the MAF... please let me know if I am missing something.

Rich

 

While I was messing with the plug, the wire from pin 2 came out of the connector. seems it broke free from the pin... I have rigged the connection to the maf outside of the connector and the code has gone away, now to find a used connector with pigtail that does not cost me a fortune... any help would be appreciated. I could also use the one that connects to the throttle body on the drivers side.

Rich

 

I think they are both Denso plugs: take some sharp photo and see if Advanced Auto or your Ford dealer has a look alike. Also junk yards. I Am glad you solved this.

 

A wrecker will have both MAF + connector.

 

This is a pretty good site for obd II codes and ideas. You are already on the right path.
P0103 - OBD-II Trouble Code


Some cleaners will destroy the MAF. This is the one I use. I am sure there are others.
MAF is pretty sensitive.
CRC Mass Air Flow Sensor Cleaner, 11 oz. 05110: Advance Auto Parts


If you have tried various MAF's and that didn't fix it, then wiring is the logical
place to look. If you have an obd II reader that can display an MAF gauge, then
set it up and carefully wiggle connections until you see which one isn't quite right.
(Momentarily looses output).


Intermittent issues are hard to find until they happen 1/3 of the time or more.