Hi all,

I have a 2003 XKR Convertible and it seems a bit down on power. Now, it could be that I have not driven any other to compare (and my other cars are pretty beefy).

My main concern is torque/acceleration from say 30-50 and from a stop. Other wise the car seems ok. It just doesn't have snap you back acceleration.

Granted, the car has 107k. I just don't know if this is normal for the car or if I have an issue (no codes, btw).

Thoughts and suggestions?

Thanks in advance!
dsd

 

my XK8 at 106k has god pull when I get on it. SNAP BACK on it when I pull away, well I have had two of these cars and can't say that it is that type of car.

 

The throttle cable has probably stretched and your not getting the response out of it. Do a forum search for throttle cable adjustment and you will probably be amazed at the difference.
A couple of the threads on the forum have pictures to do the adjustment.
If once you have adjusted the throttle cable and don't see an improvement it is time to search for fuel pump testing. Your vehicle has 2, the main one is for all around running. The second one is for accelerating. You willl need to make sure they are both working.

 

Avern,
I believe MY 2003 4.2L XKR's and up only have one fuel pump. This excerpt is 'cut and paste' from the Technicians Training Shop Manual.

ENGINE MANAGEMENT

There are substantial changes to the engine management system to support the installation
of the 4.2 liter engine which include the following:

• A new Engine Control Module (ECM) approximately 25% smaller and uses new fixing
within the cool box.
• A new throttle cable and linkage along with a new throttle body (similar to 2003 MY
S-TYPE AJ33 engine) with modifications to the intake elbow to suit the 4.2L
application.
• New injectors (similar to 2003 MY S-TYPE AJ33 engine).
• New variable inlet valve camshaft (similar to 2003 MY S-TYPE AJ33 engine).
• The air conditioning control module (ACCM) remains the same however, is now
linked to the CAN bus using the instrument cluster as the gateway between the
engine management system and the air conditioning control module.
• New pedal position sensor.

*• New fuel pump (only one used on S/C models).*

• New air cleaner housing assembly with auxiliary air control flap (S/C models only).
• Introduction of EGR valve.

 

No cable on a 03 TB, it is drive by wire.

 

As far as acceleration it stuffs me and anyone I am showing off to, firmly into the seats at any speed if I drop the pedal. It has scared the crap out of me and my passengers since I bought it, and still has more to give, but I am only at about half the miles at 58,300.

I cannot touch the pedal without the car kicking down and taking off. Seriously, I run out of road and opportunity before I run out of pedal, and I have only gotten it up to around 130 mph once, but very quickly. This was a 'one off' pedal to the floor, let's see what this thing has got type of things, (turns out allot), before I shut it down; I decided I wanted to keep my license.

I am a bit of an 'outcast' to my family as far as my choice of auto's is concerned. My brothers are wrenching on 68 Firebirds, and installing performance parts on brand new Challengers. Not to say I have not had my fair share of old Mopars, my first car being a 68 Plymouth Satellite II. However, after taking my brother for a little 'ride' in my XKR, the only thing he said was 'Wow, I would have never expected it, your car is faster than the Challenger', all without looking me in the eye the rest of the ride home. The only other thing he said was when I dropped him off, he called me a dick and then punched me in the arm.

 

So I adjusted a ton of slack out of the cable and it is much better.

However, I was test running the car with an OBD2 scanner and it reported:
PID "O2 Voltage (Bank 1 , Sensor 1)" was steady at 0.0
PIDs for: (Bank 2, Sensor 1), (Bank 1, Sensor 2), (Bank 2, Sensor 2) all reported voltages.
No codes thous (except P1111)


Thoughts?

Thanks!
dsd

 

I had a similar issue. It turned out to be the auxiliary water pump for the super charger located under your airlifted. It worked 50% at the time. replaced it now i got lots of power. Also a 03 XKR.

 

My thoughts are that I do not know about the PID's, but I have read onsite that not all OBD2 Scanners will work correctly with this vehicle and display the proper data. One scanner may correctly identify an O2 Sensor that is actually the fault, while another scanner hooked up to diagnose the same fault will incorrectly list a completely different component at fault for the same problem.

I am fairly certain that the 'P1111' code is good and what you want to see, as it identifies that all the diagnostic processes have been completed and no faults were detected, a process that takes several drive cycles after the power has been interrupted to complete, but I need to do a quick search to confirm that this is the accurate definition of what 'P1111' means.

Found this excerpt:

OBD II MONITORING CONDITIONS:
When testing for OBD II DTC reoccurrence, it can be determined if the Service Drive Cycle was of sufficient length by performing a
PDU “Systems Readiness Test”.
The Systems Readiness Test is accessed via the PDU menu structure.
Further confirmation of the System Readiness Test status is available by retrieving the logged DTCs.
– If DTC P1000 is logged in memory, the on-board diagnostic tests have not been completed.
– If DTC P1111 is logged in memory, all on-board diagnostic tests have been completed.
NON OBD II MONITORING CONDITIONS:
When testing for reoccurrence of non OBD II DTCs, ensure that the vehicle is operated as described in MONITORING CONDITIONS
for the particular DTC. Retrieve non OBD II DTCs from the TCM via PDU through the Data Link Connector (DLC).

 

I would also take out your MAF sensor and clean it out with some type of spray cleaner like MAF cleaner or brake cleaner. Blow compressed air thru it when you are done spraying it down. Check the underside of your air intake tube for any cracks. You'd be amazed how many of these cars run with no codes and cracked tubes.

 

Thanks all. I think I am chasing a ghost. I believe the car is as it should be with the throttle adjustment.

Again, thanks!

 

We'll my03 has a cable that goes to the potentiometer under the left side of the hood and the cable adjustment procedure detailed on the forum works just fine.