I have had a problem with my XJR since picking her up, she was cheap and I knew she had problems, so no come back on the seller, I have had a problem with the Mass Air Flow Sensor, which i have now replaced and there is no change to the symptoms of the car, but the error codes have gone.

Not sure if this is a coincidence or not but I have replaced all the doors, including all the electrics which came with them and now I am getting a P1637 Manufacturer Control, which I believe is communications, could this be to do with the door change

P1637 CAN Link ECM/ABS Control Module Circuit/Network

Also would this effect the error codes from displaying for the MAF sensor problem?

Where else can I start to look for a MAF sensor error now that it has been replace, the connections to it look good and I have cleaned them with electrical cleaner?

 

If you clear the codes does it come back?

I can't see it relating to the MAF unless you've disturbed wiring that happens to be near it and is causing the new code.

 

At the risk of sounding like a one record DJ, did you do a hard reboot after installing the new doors?


How good is the battery?


These Jags are VERY sensitive to battery voltage, and can do some truly odd things electrically if the battery is not 100%.

 

The battery was on charge whilst I was doing the work, so it should be good, I have put it on charge again, to see if that helps

No I haven't done a hard reset, I didn't know about that one, are the instructions for that on the forum?

Edit: Oh yes then it has had a hard reset the battery was off the whole time the doors were being replaced

Thanks for you replies

 

Just disconnect one battery lead for a minute or so. The self proclaimed experts will say you need to short the disconnected lead to the other one to "discharge the caps" but if you know electronics and you know what measuring the residual voltage as zero means, you know that is BS. So, short the leads if it makes you fell good, or just disconnect and reconnect.

And, yes, I believe the door modules are CAN bus, so they are either not connected right, or they may need to be married to the BPM with dealer software.

 

The battery has been disconnected for 9 hours, so I don't think there will be any residual voltage left to worry about, so it has basically had a hard rest already.

I am going to pick up a new battery today and if that doesn't fix the problem then I'll look at refitting my old door modules, to see if that has any effect.

I assume that the CAN bus comms runs in and out of each device so the fault could be a brake in the system between devices but only show a fault for the first device it doesn't see, are there any wiring diagrams for these cars, ideally I am looking for a full set as the electrics has been cannibalized by the previous owner/s

 

You can get the wiring diagrams from JagRepair.com, or download the JTIS from the forum.

 

Okay, just a quick update of work done so far and what I have found.

1. Fitted a new battery
2. Refitted the old door modules
3. Cleaned and checked all the spark plugs
4. Cleaned all connectors that I can find (electrical cleaner and air)
5. Replaced the MAF sensor (this was the original message)
6. All seats are out of teh car (not sure if that makes any difference)

The engine fires up almost first time and throws up a number of errors, some trivial but this is what I see when I connect the OBD II

1. P1637 CAN Link ECM/ABS Control Module Circuit/Network
2. P1720 Vehicle Speed (Meter) Circuit (this error has now cleared, so I am only left with the above code)

This is what I see on the cars display

1. Drivers Door Open
2. Bonnet Open
3. Traction Control Fail
4. Stability Control Fail

When I rev the car it will not go above 3000 and if I hold the throttle in this position it constantly hunts between 2800 and 3000 revs, it also smells very rich in petrol

 

The XJR, will not rev beyond 3000rpm in neutral, there is a rev limiter fitted, it is also the same (3000)rpm that the second fuel pump kicks in.


It is the ABS system that controls the traction/stability systems, by grabbing/ releasing the brakes and limiting power.


If the bonnet open light is still on with the bonnet closed, it is the plunger type switch on the right hand side of the radiator support panel.


If the door open stays on with the door closed it is the micro switch in the door latch, normally.

 

Although it is limited to 3000 which makes sense, the problem is that it is constantly hunting 3000 - 2800 with no movement on the throttle pedal

So it looks like all the faults seem to point to the communications side of the ABS unit or the ABS unit itself?

 

I simply cannot see a good reason to keep revving like that unless it behaves badly on the road (and probably not then either).

You can check the fuel trims for better info.

For the code, look at JTIS known causes and work through them.

 

Yes it behaved badly on the road, that is why I am looking at this problem, the only way to see if the "Hunting" problem is fixed is to rev it to to see if the problem is still there, the car is currently off the road with no interior in it, so it is not possible to road test.

From what I have read, Hunting is not normal on Jaguars, so i am trying to determine what the problem is before I put her back on the road again.

 

The only way to check the revving above 3000rpm, without it being driven, is to have the rear of the car SECURELY up on stands, with BIG chocks under the front wheels, and try it with the car in drive.


I STRONGLY advise against doing this, as the risk of it all going seriously Pete Tong, is too great, IMHO.

 

I have driven quite a few cars on a rolling road and had them rock on the rollers, not something I enjoyed doing, so not something I would even consider at home.

I have hooked up my laptop to the car and have taken some readings with the car at idol and at 2800 rpm (ish)





Flow pressure data at 2800 rpm





Flow pressure data at idol





General Data at idol





Oxygen Sensor Data 1





Temperature data, this was taken before it got to temperature





Fuel Trim Data at 2800 rpm





Fuel Trim Data at idol

 

You have a definite air leak on bank 1, so that will need addressing first, then take some more readings.


Have found that with these computer controlled cars, (all, not just Jags) that people go straight for a computer/wiring/sensor fault, totally bypassing even the most rudimentary of mechanical checks.

 

That was my thoughts, I will need to take the Supercharges off so that I can do a proper job I assume, which TBH will be a good thing as the boy racer who had it before me has painted them in silver (Doesn't look good) so I will be taking them off and cleaning them, replacing all the gaskets as I go.




All the silicone hoses and silicone tape has been removed, I also have to replace the nearly new radiator as some idiot has fitted it with 55mm long bolts and punched then straight through one of the plastic side walls, not happy when I found that little gem

 

Before you do that, check the breather hoes from the cam covers for splits.

 

I can't see how you can have exactly 19.53% at high & idle revs. Suspect the tool / repeat the test.

Puzzled why you want the SC off. You seem to be looking for an air leak or the like.

BTW it's very hard to read text with big pics scattered all over. Others just put the readings in as text.

 

Is 19.53% the max that the ECU can enrichen the mixture ?

 

I have just run the test again and Bank 1, climbs to 19.53 and tops out at that, if I rev the car up and let off the accelerator it drops to 0.00 and then gradually climbs back up to 19.53 again in about 5 seconds.

Is bank 1 the side closest to the air intake?