Hello guys,

I was previously registered here, but I forgot my password.

For about a month I have been having an intermittent problem with my XJS:

The car would suddenly, after about 10 minutes of driving from cold, start violently shaking at stops as if it was fuel starved. THat could continue for 20-30-40 minutes of driving, and then after turning it of for about 6-10 minutes it would act completely normal again.

That went away for some days and then last friday I was in stop and go traffic for a while and the car started shifting very poorly. It then attempted to act fuel starved again but would not do so as severely as before. It then died at a U-turn..it then tried to die at the steep ramp to come into my garage, but I gave it gas and got it to leveled ground where it promptly died. I tried to turn it on and it would fire right up but died as soon as given gas. The next day I tried to replace some parts, let it warm up, and it threw code P1179 "Adaptive fuel metering too rich"-

These are the new parts that the car has

Coolant temp sensor X4-(correct part purchased overpriced from dealer)
Crank sensor
TPS
MAF
EGR valve
Idle Speed Control Valve
6 new original coils (not the cheap aftermarket kind)
O2 sensors
ECU itself is new
Champion 12ry spark plugs
Every single relay in the vehicle with original Hella and Bosch relays.
Cleaned every single connector including ECU connector

I have a crappy OBD2 reader that does not record real-life, but I do not have any MAF codes or O2 codes and since both are new I doubt they have gone bad (although possible), however the car was running very rich yesterday . I can smell fuel from the exhaust; in contrast to appearantly running very lean when this all started and it would try to die at stops

Logic (which never works with these babies) is telling me that the car is going from running lean to righ because outside air is making the O2 sensors to go insane or I have a bad fuel pressure regulator.

I apologize for the long litany of complaints, but please share your thoughts on this...

Thanks a lot!!!!

 

Could it be vapor lock? Does it happen at steady speeds over say, 40mph or just during stop and go driving?

 

After all that has been done to that car, the fueling adaptions are probably pretty messed up. I have many times fixed an AJ16 by simply clearing them to start fresh. I have to clear them once or twice a year on my '95 XJR because they stray too far off. I know when the fuel mileage goes to pot, that it's time to clear the adaptions. That was Jaguar's first foray into fully adaptive fueling, and I don't think they had the limits quite right.
I think you need to find a dealer that still has a working Jaguar PDU, [that might be tough] and have them reset the "Adaptive Terms". The attached bulletin describes the procedure pretty well. I don't know of any other device that can clear the ECM like the bulletin describes.

Good luck!

 

thanks a lot for the replies!

I absolutely agree that it is necessary to reset the parameters, but as sporadic as this is , I am thinking it's a flaky part.

I am not shy about throwing parts at the car, since I intent to keep her, but this is really beyond my scope. I took her to the garage with all the pertinent TSB s in hand and a list of things to check for (cracks in manifold, cracks in exhaust near fuel line causing fuel to boil, grounds, wiring, fuel pressure reg etc) for them to sort out. I will post the results

Thanks!!!!!

 

Yesterday the mechanic called to let me know he thinks my 2 year old ecu is fried. He says even though he has replaced the ground connectors associated with the ecu and checked their continuity, the ecu does not recieve full ground and won't map the fuel trim regardless of how many times he resets it. I do not know how th can possibly happen to a new Ecu.

 

If he doesn't have a Jaguar PDU, he is NOT resetting the adaptions. How about running the oxygen sensor orientation? Has that been done? He may not be equipped to do you justice.

Cheers,

 

Thanks for your reply. He explained a little more. He said my ecu is not recieving ground properly. He tried another and he said that one does. He does not have the pdu equipment for my car, but I would hate to pay the dealer 100.00 to try to reset mine, when it could have been 100.00 towards a new ecu. Does that even sound plausible ? I have been looking at my electrical diagram all day trying to find another cause but I can't . Do you think it's worth trying to get it reflashed?

 

Well, here's where you stand. The AJ16 ECU cannot be flashed. The only way to change anything is to replace the PROM's, the pre-programmed chips on the board. The different part numbers are because of external hardware or option differences, like EGR or no EGR. The procedures I mentioned would need to be run on any replacement ECU to really make the installation right and prevent your possibly chasing your tail.

1. Throttle Adaption Reset
2. Oxygen Sensor Orientation
3. Reset Adaptive Terms [Zero out fueling adaptions]

Once all that is done, the AJ16 is a gem of an engine.

Hope that helps!

 

Thanks for your replies. Mechanic is having second thoughts about the ecu. He says multiple components are receiving a stutering ground from the ecu, but the ecu is recieving stuttering ground itself, so hopefully it is just a grounding issue. The problem is when the car is of ground is clean, but once it's on it starts failing.

 

Hi There, today I started having the same problem as you mention. 1996 xjs. Exactly the same, as long as I can pull off from the light or stop sign the car go's. Problem again if I have to stop. NO problem what so ever when in park and just standing at idle. Did you go deeper into the problem, was it fixed??

Thanks

 

Hi Noe;

The problem when I posted this last year turned out to be two-fold:

First, water had entered the engine,and gone into the black ECU connector, and corroded one of the pins.

Second, the alternator was leaking current, and the car basically had a stuttering ground all over....if you would put an osciliiscope on any ground terminal it would go on and of like crazy...that caused the MAF to go out.

Are you running rich?

Your problem could be a number of things from a bad TPS or CTS, dirty throttle....

I would check the ECU connectors and see what shape they are in. Under the passangers foot well, will take you like 10 minutes to get out. Look at the black connector as that is where water tends to drip. If you see a bluish substance there, you have a problem.

If you have never relpaced the CTS, you should as well as it is super cheap.

 

Thanks. This morning, got in the car and was working fine so took to mechanic. easy quick fix was just to have have it at a higher idle 1200 rpm in P 900 in D at a stop. Did not like the solution. Bought a new gas filter, this thing still had the original, it was super clogged, sprayed mass flow cylinder, looked at throttle body but was clean, added some sea fome to gas. Car has worked perfectly today. brought idle back down too 750 in P, 600 in D at a stop. No check engine lights so far all day. It was giving a fuel something code. Thanks for the help.

 

Hello,

There is no way to "raise the idle speed" on a AJ16. On the aj6 there is an adjustment screw, on the aj16 it is controlled by the ecu.

I hope your problem was just the fuel filter.

Good luck

 

Just so we're accurate, that's not exactly right either.
Both the 3.6L and 4.0L AJ6 had an idle control valve very similar to the AJ16. The idle bypass adjustment screw on those engines was there to be like a 'base air' adjustment. It was used to keep the idle air valve the correct distance off it's seat at the correct idle speed. That way it was in control of the speed via the ECU.

Cheers,

 

I am trying to remember if the early versions of WDS had the 'reset adaptive terms'.

I have not looked in a while but I don't think it is in the last version (43) of WDS.

There were things in WDS that were deleted as the software was updated. I remember calling Tech Line and having to do some procedure with WDS and the guy tells me to load version 38 because that was the last version to have a particular function AND was reliable (some versions were unreliable and we were instructed to NOT use them).

I wish I could find an old PDU and some software.

Here are some OLD TSBs for the 1055 and later software releases.

bob gauff

 

I can tell you WDS sadly, never had the 'Reset Adaptive Terms' application. That is precisely why I have rat-holed everything I can to keep our PDU operating. I am currently using a CD drive for it that is on loan from a friend. Ours died and I have been on the hunt for one to replace it for going on two years.

If you ever get your hands on a PDU, you holler; I have just about all that software archived, too.

Cheers,

 

The dealer I worked at no longer has an operational PDU. The CD drive died and the computer repair shop down the road could not find a replacement or fix that one.

It seems to be a strange 2X CDROM that is NOT a standard IDE connection.

I don't know if they scrapped it or it just sits there collecting dust.
I should call and see if it is still there!!!!!!!!!!!

bob gauff

 

I am not the most mechanic saavy person. My car is a 96 XJS well I am almost sure the motor is the aj16. With a very small allen wrench on the side of the throttle body I saw my dad move it and go from 1200 rpm tp 800 rpm. Unless it was just a coincidence that we did what we did to the car and that the ecu adjusted it at the same time my dad did his thing with the allen wrench ok. That could be the case, but the little screw is there.

 

Ohh also. The mechanic although did not see him since I was in the drivers seat. did something similar opened up got a tool don't know which one, and voila from 700 to 1200 rpm in a second.

 

Personally I think you should call and try to get your hands on anything that is still there. Maybe that drive would be repairable by us tinkerers, the one we have is not.

The drive is a 2X caddy type drive that has a 40 pin connector that EVENTUALLY became the standard for first generation IDE. This interface is a proprietary Sony interface that was used when CD drive/sound card kits were new for home computers. These kits many times had three CD drive interface connectors on the sound card; one Panasonic, one Mitsumi and one Sony. Just so happens GenRad chose that Sony interface drive for the PDU.

Here's a picture with the model number....... I thought I had one located about a year ago, it was on a UK company website. When I inquired, it was gone. Haven't found one since. I tried to contact Sony and ask for model numbers of any other drives that might have also used that interface. They slammed the door in my face, didn't want to help at all, didn't care.

Someone out there knows these answers, I'll find that person someday.

Cheers,