Dear forum members,
Please help!
I first noticed this problem when coming to an almost complete or full stop at a traffic light. With the transmission in drive, the car would attempt lunge forward. then the problem disappeared and only came back when car was cold.
Brief history on recent changes on this car: a year ago replaced all spark plugs, all coils and one of the knock sensors because of a leaking valley hose killed the knock sensor. (misfire and knock sensor codes went away). Had to replace the upstream O2 sensor on the right because it threw a code. Again the trouble code disappeared as a result..
The car was running great for 900 miles after that. This problem started in the winter. I then stopped driving the car and maintained the battery regularly.
A few days ago decided to do an oil change with oil pan gasket replacement because it was leaking.
Also did a transmission fluid and pan replacement. Filled with Mercon SP.

There is also an ABS fault that comes and goes but it clears itself after one drive cycle.
I don't have a reader for ABS codes, just a basic one.
No engine or transmission warning lights are on now.
There is a variability in the sound of idle. It's a periodic higher frequency pulsating component.
When I press the sport button on the shifter, the LED also blinks at the same periodicity! (in P or N)
Very odd.
When I put the car in reverse or drive it jerks. (attempts to lunge)
Any ideas?
Really appreciate it folks, if someone would point me in the right direction.

 

Read about "the lurch"

 

I am afraid this is more serious than the lurch itself. I had experienced the lurch before, years ago and it never affected going in reverse gear. Again, this "jolt" occurs in both D and R. Even in a completely stopped situation with my foot firmly on the brake pedal. I will try to post videos soon.
Thanks.

 

I am attaching two videos to this message.
In the first one the car is idling in Park.
The second one is the jolting forward in drive, with my foot firmly on the brake pedal.

I was unable to attach my videos. Is there a size limit?

 

I'd fix known faults first (so, ABS). A reader isn't costly; you may even be able to use OBD Facile

 

Need to get the abs code for sure. The tcm reacts to wheel speed sensors which are a part of the abs. Start there first

 

The ABS fault warning disappeared. Do you think there is a stored code? Would that affect idle in park or neutral?

 

It should be stored, but if the CEL went away then it is testing fine. You could as Scott indicated have trouble with the speed sensors which could be something as simple as being dirty. However all those are integrated to the TCM and a misread in speed internally would cause strange behavior.

Tom in Dallas/Plano
05 S-Type 3.0 119k

 

Ok. Thanks.
I have checked/cleaned the rear wheel speed sensors.
Not the front yet.

Would these be reporting even when the wheels are stationary?
There is a slight fluctuation in idle, not enough to see it clearly on the needle but there is a periodic whine (?) .
Like at a one second interval.
Tried to listen very carefully and could not be sure if this was coming from the throttle body area or resonating everywhere.

I will be inspecting the throttle body and will look at the MAF today although I'm not getting any codes.
Thanks,
Gabor

 

I am not sure as to any time delay on the speed sensors, but it still looks like the TCM is not getting correct info. The MAF and I have seen people in Jags have problems with the MAF, no codes and then all the other codes cleared when replaced. Although I bet you will find the MAF with quite a bit of black carbon on it if you have not cleaned at all.

T

 

MAF was super clean.
Ended up cleaning around the throttle body flaps with rags/solvent.

Just to try it in another way, disconnected the MAF connector and started up.
Restricted performance came up but the fluctuation and transmission banging were still there.
Reconnected MAF; no warning lights, but transmission banging did not change.

I think you are right, something is seriously messed up.
TCM?
After 17 years in my possession, I would hate to see this car go into the junkyard if in fact that's what's going to happen.

Put it in reverse and it barely moved, plus the banging, (surge?) at the frequency of this fluctuation.
So I stopped it in my driveway after backing up two feet.

Consider having it towed to my local indie for diagnosis, but have serious doubts overall.
I just don't know what kind of tests should be done and if he needs Jaguar specific equipment.

 

If someone you knew had the SDD you could read the TCM and know for sure. I have no idea what the dealership would charge for a computer diagnostic. When was he last time the transmission had a service? Did you get the lurch programmed out with software? There could be numerous problems with the transmission, but from the sound of it, you are having more trouble with the TCM. Attached is Jag's ZF troubleshooting matrix.

TBB

 

I keep records of major repair and maintenance events.
Got the car in March of 2014 with 19,000 miles on it.

Reprogramming of TCM was done in 2006. First fluid change was also in 2006 by dealer, under warranty.


Listing of some relevant events:
06/08/2006 dealer:
Transmission flush to repair squawk on acceleration 35,214 mi 11/29/2006 dealer replaced heater valve and thermostat under warranty 39,842 mi
reprogrammed existing TCM using WDS 1109 WJ 1.10


After the warranty expired, indie mechanic worked on it.
05/12/2014 engine work: gaskets (oil pan, timing cover, valve cover) and mass air flow sensor, fuel rail sensor 108,014 mi
09/14/2014 dual coolant flow valve replaced 110,225 mi

I did this myself:
08/14/2017 transmission fluid drain and fill Mercon SP 122,141 mi
09/26/2017 transmission fluid drain and fill Mercon SP 122,382 mi

05/10/2021 Engine oil change. Oil pan gasket replaced. 5W30 synthetic 127,453 mi

05/21/2021 Transmission pan replacement and fluid change
Total amount drained 4.4 qt
fill: 2.75 initial fill. Fill with engine running 2.1 qt.
Total fill volume: 4.85 qt. 127,480 mi
Fluid: Mercon SP
127,480 mi


At my current location, the dealer is about 100 miles away.

 

Looks like you need to see what the TCM has to say. I am hoping it has nothing to do with the torque converter. I have the SDD and then got this for quick diagnosis. You may find it cheaper on Ebay or some place else.


TBB

TBB

 

Thanks!
I am perfectly fine with getting the Carsoft Auto Diagnostic Scanner LR V1.0 from Amazon if that's what you recommend.
Can I check the TCM with it?

Gabor

 

Yes. You should see all the systems/modules and be able to clear codes as well in the ones you would not normally see with a generic. Also many more points of live data to look at as well.

TBB

T

 

Hello,

Unfortunately, I had the same issue with my 2000 S-type. After several months, we tracked it down as a transmission issue. If you can call it luck the lunge became worse and the transmission started slipping at acceleration. Ended with a transmission rebuild. The transmission in my 2000 is a ford product known for this issue.

 

i am going to order this scanner and will report back on the findings.

 

I understand. Thanks for the info. I will let you know where this thing progresses in my case.

 

I might have missed this, but do you have a zf tranny or a 5r55n. I ask because i think they take different fluids