We did check/verify fluid level a second time after the valve body was out. I also replaced solenoids.

 

A couple of thoughts:
There is one major change when you hit the gas quickly. The System reads and uses the MAP sensor instead of the MAF. At other times the car will run well, using the MAF, however if the MAP is intermittent or erroneous in some way the TCM will be misguided when asking for high power.
Another item is that the ABS supplies the cars speed to all other modules by way of the ECM. If CAN bus is bad the reading may be incorrect or missing when additional vibration is transmitted to a bad connection during heavy acceleration.

 

OldKarz,

I’ve been thinking about that and think you’re on to something. I have been trying to understand the MAP sensors. If I read correctly, there are two. One referred to as TMAP. One is before and after the compressor. If I hook up my scanner I see 5 pounds of boost at idle, which I think is the one before the throttle body.. I pulled the vac line of the relief valve in the intake and felt vacuum there. That valve seems to be functioning.

Is there a way to test the MAP sensors?

 

OldKarz,

Can you point us to the documentation that describes the different engine control behavior for SC engines under light vs heavy throttle? My car has very similar behavior and error codes to Brad K above. It runs and shifts flawlesly under light to moderate throttle, but blows shifts and throws CAN codes when asked to accelerate hard. I'm very interested in any factory description of what changes under hard acceleration.

Thanks
Jeff

 

I have not looked but would think you can watch the readings in SDD as you have for others. It should output reading changes even when not in acceleration mode. I also do not know what the end is shaped like, however if you can apply vacuum and pressure to it there should be a linear change in resistance.

 

I will see if I can find it in our 8000+ pages of documentation for these cars! May take a while since I cannot remember where I read it.

 

Thanks OldKarz!

I have the same problem, I’ve been researching and reading until I’m blue in the face. Will you confirm the car has one MAP sensor? If I am reading 5 pounds at idle I would think (Pray) that’s it and I can return the ignition coils.

Brad

 

I have the NA V8 so am not very familiar with the SC version. I can only find one MAP sensor for the SC in parts or engine management. However in the Pinpoint tests there is a reference to a MAPT which does not seem to show up anywhere else. Unfortunately the Jag documentation is not very consistent in naming conventions. The MAPT is supposed to be a MAP with temperature readout. In actual fact the MAF has the temperature readout as part of it. It may be just a miss naming of the part. Just guessing.

 

Well I confirmed that the SC car has one map sensor and replaced it. No change to transmission behavior. I believe I misunderstood how my scanner reads vacuum/boost.


My next theory is the TPS sensor. Based on other threads I’ve been reading both tracks should be the same. Mine are not as seen below, video shows idle position key on engine off, up to full throttle.



Any thoughts on on this and where I can source a TPS? It looks like it may be a challenge.

Brad

 

The throttle tracks are close to being the same, TPS 2 runs in parallel a little higher evidently Peddle position sensors are different. The second one starts higher and ends sooner if memory serves.
Have you checked for bus faults yet?

 

I haven’t looked for bus faults yet, I’m not sure I know how to do that yet. I’m gonna throw a throttle body/new tps sensor at it and see what happens. The transmission issues definitely happen at a certain throttle pedal position.