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Can you check your fuel trims? I'd like to know what your LTFT is pegged at.
Your mileage isn't too good. I had the same problem which was cured only after I replaced the TPS, which tested well, but apparently had something in it causing the ECU to overfuel the engine.
I have also experienced 35 imperial mpg.
But I was cruising at 70km/h in all flat terrain.
Reset the cars computer after having reached the cruising speed and after 80 kilometers it averaged 35 imperial mpg .
But as soon as I reached the highway I set the cruise control to 115 km/h and with some more hills etc I averaged 28 imperial mpg
You sure that was not downhill or a stiff wind behind you? I mean not to be a skeptic but that is crazy good. What else did you do to your car to achieve that?
It was actually from Golden to Kamloops, BC through the Canadian Rockies. I think a big factor is most of that is through the national parks where the speed limit is 90 km/h, and in the mountains outside the park it is also mostly 90 km/h. The diff would have hurt my economy, not helped, as I replaced a 3.58. The only reason was I wanted limited slip and I found a 3.77 limited slip as a NOS diff for cheaper than rebuilding the one I had.
Can you check your fuel trims? I'd like to know what your LTFT is pegged at.
Your mileage isn't too good. I had the same problem which was cured only after I replaced the TPS, which tested well, but apparently had something in it causing the ECU to overfuel the engine.
Hi Vee,
I checked my LTFT Trim this morning while on the way into work. I used the Torque ,the application for android. It came in at -1.56 I don't know how bad or good that value is.
What I will say is a few weeks ago I got stuck at work one day when I got bad gas. It wouldn't start at all. I put fresh gas in it along with Marvel Mystery oil and gas line antifreeze heavily mixed in. It start right up after that but I wonder if that whole episode screwed something up. Also previous owner said he had a exhaust manifold leak that he previously had repaired. I don't hear any exhaust leaks but maybe i do have one enough to screw things up.
-1.56 for LTFT is fine. You’re a hair off, but nothing worth chasing. If anything your car is slightly underfuelling! Again, at this age of your car, a slight deviation is absolutely normal.
Thanks for checking. I think you perhaps just drive with a heavier foot?
That is good news Vee,
Thank you. I don't think I really have a heavy foot. But I will say that my terrain driving to and from work is rolling hills. I know the previous owner did some work with the ignition coils as a few extra ones came in the trunk. It is on my to do list to check what plugs are in there just so i know. Also I do think I should check my idle control solenoid, sometimes it idles high for a little every now and then.
There should be two values for long term fuel trim (LTFT); one for the front 3 cylinder and another for the rear. Having one value close to zero is good, but the other one should be similar. If part of the closed loop fuelling control system fails, then the corrections can reach +25% or -25% which is very bad and can lead to very poor fuel consumption.
So i quickly found the second LTFT trim yesterday and pulled it up along side the first one to monitor on the way home. When I was leaving work it was still at -1.56 for both of them. I checked when I got home before turning it off and said 0 for both. Did a double take there. But I confirmed it this morning. They both stayed at 0 the whole way to work.
Last night I needed to change a headlight bulb on the left side of the engine, I found it was easier to access the bulb by removing the air filter and it's cover. Upon doing so it looked like the crankcase ventilation that connects to the bottom of the air filter box pulled out of it, the one from the right side of the engine.. Not sure how long it has been that way, but it is fixed now. Wonder if that would effect fuel economy to some degree.
There should be two values for long term fuel trim (LTFT); one for the front 3 cylinder and another for the rear. Having one value close to zero is good, but the other one should be similar. If part of the closed loop fuelling control system fails, then the corrections can reach +25% or -25% which is very bad and can lead to very poor fuel consumption.
Hi Andy,
Out of curiosity what outside of exhaust system/air leaks can cause the closed loop system to fail?
On an unrelated point are your rear anti-roll bar items now available to buy?
At the risk of getting "off topic" on this thread, I have created a separate post on this subject. I offer front and rear drop links assembled with spherical bearings, to remove all of the compliance associated with the metallastic bushes of the standard parts. The rear drop links are intended to be used with a much stiffer anti-roll bar taken from the XK8. Please read my other posts or send me a PM , if you want more details.
I installed the bracket from your latest new batch received in early July. My car couldn’t start after installation. I revert back to my old bracket and the car could start normally.
Anyone who got the recent new batch facing same problem?
The AJ16 engine starts with the Cam position sensor at first then reverts over to the crankshaft position sensor for the rest of your drive
If the connector of your Cam sensor is removed ( simulating it failing , CEL code P0340 ) the engine will still start but takes a few more revolutions
It takes a few more revaluation because for every turn on the cam there is 2 on the crank in a 4 cycle engine
There are 6 targets on the cam sensor so in the starting sequence the ECU can determain The TDC of each cylinder ( or the best it can with the targets accuracy )
With the Crankshaft only as the single target come around is it the TDC of the # 1 or the TDC of the X cylinder of the compression stroke
The ECU must try the first revolution as the # 1 TDC and if unsuccessful will electronically shift to the second time around as the # 1 TDC for the rest of your drive
With the Andy bracket the 5 degree shift in position may be too much for the ECU to cope with as it relearns this crankshaft sensor only starting sequence
Another thing is the bad environment of the crankshaft sensor location
You may have disturbed it enough now to where it is bad to the point of failing
Look for CEL of P0335 for crankshaft and P0340 for the cam
The AJ16 engine starts with the Cam position sensor at first then reverts over to the crankshaft position sensor for the rest of your drive
If the connector of your Cam sensor is removed ( simulating it failing , CEL code P0340 ) the engine will still start but takes a few more revolutions
It takes a few more revaluation because for every turn on the cam there is 2 on the crank in a 4 cycle engine
There are 6 targets on the cam sensor so in the starting sequence the ECU can determain The TDC of each cylinder ( or the best it can with the targets accuracy )
With the Crankshaft only as the single target come around is it the TDC of the # 1 or the TDC of the X cylinder of the compression stroke
The ECU must try the first revolution as the # 1 TDC and if unsuccessful will electronically shift to the second time around as the # 1 TDC for the rest of your drive
With the Andy bracket the 5 degree shift in position may be too much for the ECU to cope with as it relearns this crankshaft sensor only starting sequence
Another thing is the bad environment of the crankshaft sensor location
You may have disturbed it enough now to where it is bad to the point of failing
Look for CEL of P0335 for crankshaft and P0340 for the cam
Thank you so much for the long writeup and sharing the pdf, it adds up to my knowledge from googling for information, understanding how a Crank position sensor works and gave me the confidence to give it a shot again to install the bracket as I believe the first failure was maybe bad luck. And know what! Car fires up at first crank woohoo! Now fingercrossed, going to go for a test drive
Dear All,
It has be a long time since I posted on this thread because I have had problems finding a machine shop that can manufacture these brackets for me long term. I have now found a very good machinist who has made several batches which have enabled me to satisfy all the back orders that have built up. I now finally have a stock of parts (see photo), so I wanted to let everyone know that these brackets (replacement for EBC5017) are available again for 1993MY and onwards AJ6 engines and all AJ16 engines. We will soon be making a batch of brackets to replace the bracket (EBC1253) used on late 3.6 L and earlier 4.0L / 3.2L AJ6 engines.
I'm not familiar with the different vehicle applications of the GM4L80E transmission. If the gearox came from a different vehicle it could have any number of different features including torque converter stiffness and internal gear ratios. These could affect the suitability of the XJR6 calibration. The transmission control modue (TCM) is mounted somewhere under the dashboard/ footwell on the LH side (viewed from inside the car). Provided this was not changed when you changed the transmission hardware then you should still have the correct XJR6 TCM in your car. However, whether that is compatible with the actual transmission hardware that you now have is another matter. I suggest that you try to find some part numbers on the transmission and see if they are the correct Jaguar part by going on the www.jaguarclassicparts.com website.
Hi XJRengineer, do you know if the internal (not the external harness) wiring harness on the XRJ6 GM4L80E transmission is the same in all of these GM4L80E transmissions or is it also different in the Jaguar. I have a 1995 X300 XJR6. I also purchased one of your brackets back in 2012 and she returns 30+mpg at freeway speeds (110kph) from Gold Coast QLD to Sydney, the bracket is a brilliant modification, thank you.
Improved drop links?
