I have been troubleshooting my 1996 XJ6 for what I thought was a bad TPS sensor. I have an Actron 9575 scan tool and my TPS seems to be working correctly.

However the MAF reading on the tool shows 0.2 lbs/min at idle and only goes up to 0.2 lbs/min at any RPM above idle, no matter how high I go. Car idles and revs fine, but major issues going down the road such as wont upshift, RPM hang (RPM's stay elevated after removing foot off accelerator)

Anyone know what a totally broken MAF sensor would do?

Backstory is I cleaned the MAF and throttle body then put back together and now this problem. Anyone know if I could have totally wrecked the MAF sensor if I sprayed the MAF cleaner too close (too much pressure)??

Thanks for any input!

 

The MAf readings read low on both the Autoenginuity and proscan elm software, leading me and others to conclude there is a scaling discrepency. I do not know what the true pictiure is and I have not looke dyet on WDS to see the value shown there. It might be worth measuring the MAF output voltage and finding the calibration curve in JTIS. I am pretty sure I have seen it there or in othe rliterature. Maybe motorcarman or Jim Lombardi can help- they have the documents organized. I will look to see if I can find it.

What were the original symptoms and what has happened now?- And no, if you did not actually contact the sense wire, I would not believe you could damage it with spray alone. There is a TPS adaption procedure which requires dealer level software. It has been reported that you can set the TPS to .5 volts by enlarging the holes, but I would think that you would have to know what voltage was present when the original or subsequent adaptions took place, so I discount that somewhat, although it ewas reported by a highly respected poster.

 

All started when I took apart throttle body to clean it. Car ran fine, just a little throttle delay. I cleaned TB MAF sensor and installed K&N filter. Car had 117k and TB was very dirty when I put it back together the next day it was basically undrivable. It starts and idles and revs fine. But whe I get it on the road it doesnt want to shift into high gear, the RPMs hang after I take foot off accelerator. Eventually the car will just rev with no power or trany engagement but will kick in at higher RPM. Tranny fluid is full and bright red. I thought I ruined the TPS by getting carb cleaner in it but my code PID reader showed it working OK however MAF is not working per my PID read. It shows very low lbs/min airflow. I have no idea what is wrong and it has thrown NO codes! I have not replaced the TPS nor the MAF because I want to make sure before ordering $300 parts on a guess. i

 

First, let me state I am far grom being a Jaguar purist like some folks on here- They will not put a screw on their car that does not have a Jag logo! BUT, there have been a number of reports both here on the X-300 and on the X-308 forums of drivability problems after KN filter installations. I would attempt to go back to the factory setup and go from there.
I would sure have a look at the TPS. Make sure the connector is clean and tight. If you replace it, there is a good chance you will have to have an adaption done with dealer type software. Obviously your scanner reads paramanter values. If it charts values, check for smooth TPS operation over the renga. The symptoms sound verymuch like a TPS failure to me.

 

Sparkenzap has a point about the K&N filter, I too, think it would be smart to go stock until this is ironed out.

First, you need to go back to the throttle body and make sure the base air gap is set to .002 inch. Second, and this will require a trip to a dealer most likely, you need to have the throttle potentiometer adaption reset. Any time the throttle bore, air gap or base setting is disturbed, you generally have a poor driving car until that is done. I don't know of any tool that will do that other than a Jaguar PDU or IDS. There may be something out there, but I'm not aware of it.

Good luck!

 

Well I went ahead and changed out the K&N filter and changed it back to a paper element. Cleaned the MAF again.

I have an Actron reader and when I do a live data reading my MAF values are very low, only 0.2 lbs/min to 0.3 lbs/min regardless of RPM. I also checked the 3 wires going to it with a voltmeter and this is what I got....

Black wire = 13.71 volts (nearest front of car)
Green wire = 1.24 to 3.24 depending on RPM (middle wire)
Orange wire = 0.03 to 0.04 (I would believe this is the ground)

Does anyone know if these readings are in spec? I have the jaguar service manuals on CD, but I cannot find the damn things anywhere!!!

I have an appt to take the car into my mechanic who has some experience working on Jaguars, to see if he can re-set the TPS sensor.

I am at a total loss here.

 

If you can find a shop in the area with a Autologic diagnostic tool - you might save some money instead of paying dealer prices.

 

Well, sh**, I forgot to mention that the X300 MAF PID is always translated weird. It always seems to have the decimal point off by two columns. I have never been able to get an explanation for why that is. I have considered 0.06 to be 6.0 g/sec during diagnosis. For instance, see the attached image. This is an X300 SC under a pretty good load. The MAF is reported as 1.14 g/sec under a good acceleration from 30 MPH at a 65% calculated load value. If I adjust that by two places and make it 114 g/sec, it is a more plausible value for the conditions. Then there is the same car at idle. See what I mean?

Sorry I spaced that.

Cheers,

 

XJR guy,
Thanks for the insight. So considering my PID reading from my MAF (which shows as lbs/min) does not fluctuate really at all regardless of RPM mean my MAF is probably fried? Car has 117k and the MAF is original to the car. I mean regardless of the scale the PID is read the numbers should fluctuate based in RPM and they are not.

 

With the information I have, I would agree with that assessment. What I don't know, is the condition of the circuits themselves, to and from the MAF sensor. There could be a problem there preventing the ECM from properly receiving the MAF input.

Cheers,

 

Well I went ahead and ordered a MAF sensor from a salvage yard for $100 delivered!. At that price cant go wrong, and they have a 30 day return policy.

I will post if this fixes it. If not then the car goes to a mechanic to see if they can diagnose it. I hate bringing my cars to the mechanic cause it means I have been defeated

I am going to go with the facts that my Actron PID shows no change or activity of MAF when RPM's change. If its not the MAF and its another circuit then its probably out of my abilities anyways.

 

I have tested the MAF readout via the ECU using an OBDKey (OBDII) compatible reader. If the MAF reading is taken as-is then the value is right, but if you divide by 100 (as the OBDII spec dictates) then you will get errors.

If your software keeps the 2 decimal places after converting the ECU reading using the divide by 100 calculation, then you can easily convert back to the Jaguar readings.

 

my maf sensor readings do fluctuate with rpm speed but my long term fuel trims are stuck at 35.1 at all times. my short term fuel trims are always -1 thru -25 under normal driving conditions and when i hit it hard it goes to 0.00, it rarely goes to the positive end of the scale while driving. I am concerned because I noticed my car is not as fast as it once was and it seems to be running rich during normal driving. what do you think ?

 

You would do well to create your signature and add your car's year and model, so we have an idea what vehicle you are inquiring about.

If you have a 1995 model, the readings you cite are probably normal. The OBDII system was not fully implemented in '95 as the mandate was for it to begin in 1996. Consequently some functions of the system don't seem plausible; they usually aren't.

Serious diagnosis of those models really needs the Jaguar equipment that can read other parameters like AMFR and FMFR; which are Air Mass Flow Rate and Fuel Mass Flow Rate, respectively.

Cheers,

 

35.1 does sound quite far off....

Have you checked the fuel systems statuses?

There are two (if you have the AJ6 engine) which should go to closed loop once the engine has warmed up (above 60 degrees C IIRC). If not closed loop then the fueling will be rich.

Mine did this (X300 Daimler Six) and it turned out to be a faulty heater element in one the pre-CAT O2 sensors. Worth checking your engine's air filter too. If clogged this can cause rich fueling. Of course, check hose(s) from MAF to engine for leaks too.

A scan tool could be used to reset the ECU which will casue the engine ECU to "relearn" the fuel trim values. Engine may sound a bit off while it does this though.

 

after replacing the stock filter in my 06 vette with K&N filter had MAF reading issues, same on the 06 Hummer h2.
looked on line and found bunch of guys having the same problem. the oil from the filter would screw up the reading of the MAF.

put old filters back on and cleaned Maf with electronic parts cleaner and problem disappeared.

thinking about it then, it became apparent to me that if GM or ford could claim a few more hp by simply going to a cloth filter, they would certainly do it , so i decided that K&N filters are like Italian shoes, they look really good but they do not work very well

 

this is my maf question, has anyone used theGranatelli Big Air Series Mass Air Meters? and where you happy with it?

 

Be careful with oiled type air filters I killed a brand new maf like this
I now have a non oiled type pod on it