Hello again guys
I'm having a problem with my 2004 STR with 122500 on the clock.
Every time I start the car with the engine cold at about 1400 to 1500 RPM the rev needle flutters about 20 - 50 RPM causing the car to slightly surge up and down in speed, coincidently this is at about 40 mph which is the speed limit around where I live. However when the temp gauge reaches operating temp and about 5 minutes of driving after that it all goes away with no issues whatsoever.
I get no fault codes from this which is leading to a hard diagnostic.
The last fault code I had was P0121 Throttle body sensor position error this caused the car to loose all power until I turned the ignition off and restarted the engine and it was gone and has not returned in 2 weeks but my issue still exists. I did find some corrosion on the electrical connector to the TPS and I've cleaned it up and sealed it from any more water that drips on it from the wind shield.
I have replaced all spark plugs and air filter with still no joy. I purchased one ignition coil and have tried it in each one still no joy and I can not afford to replace them all. At first I was confident my issue was a coil but why would the symptoms go at high temperature?. Finally I did have several air leaks that I paid £500 to have repaired with new gaskets, could it still be possible I have a very small air leak that is causing my fluctuation and when the engine is hot and all components expand with heat the leak is sealed which is why it goes away?
I drove a 200 mile journey twice over the last 2 day and my issue only occur'd in the first few miles each time. The car is great other than that. Does anyone have any ideas what is causing my problem?

Cheers Will

 

Could be early signs of a problem with the transmission. I think when the torque convertor of the tranny gets to a certain mileage, it is prone to some malfunction. Signs are exactly the same- in D, the rpm may fluctuate.

 

I'm having a problem with my 2004 STR with 122500 on the clock.
Every time I start the car with the engine cold at about 1400 to 1500 RPM the rev needle flutters about 20 - 50 RPM causing the car to slightly surge up and down in speed, coincidently this is at about 40 mph which is the speed limit around where I live. However when the temp gauge reaches operating temp and about 5 minutes of driving after that it all goes away with no issues whatsoever.
I get no fault codes from this which is leading to a hard diagnostic.
The last fault code I had was P0121 Throttle body sensor position error this caused the car to loose all power until I turned the ignition off and restarted the engine and it was gone and has not returned in 2 weeks but my issue still exists. I did find some corrosion on the electrical connector to the TPS and I've cleaned it up and sealed it from any more water that drips on it from the wind shield.

Do you know if the throttle body was cleaned? Crud under the valve plate so not making required position.
Do you happen to remember if you ,backed off on the throttle, just before you lost all power. 2 weeks back.

A clean of the throttle body so the valve plate does not stick etc may help.
Cheap option.

When was the transmission oil and filter last changed?
Worrying option. see post 2

 

I agree, if you're not in a rush, just let the car warm up before you begin driving to see if the issue is only when cold or when you first begin driving...

 

This is a very common and well known problem. It's a software, not mechanical issue. A reflash has cured it in all cases I'm aware of.

TSB S37-14

Summary
S307-14: This Technical Bulletin has been issued to address a customer concern of a surge in
excess of 150rpm during engine warm up, at a temperature of 30°C to 50°C and at a vehicle speed
in the region of 40mph (64.3kph) to 60mph (96.5kph).

 

Also, does your car change gears smoothly, or is there a kick and delay between shifts. As others suggested- if the oil and the filter hasnt been changed now is a good time to do it. I think that early problems with the torque convertor will not show any codes on diagnostics.

 

Do the TSB Mikey posted first. Let us know if that fixed it or not. There is a somewhat related problem of a failing TC lock up clutch.

But you describe the TSB perfectly.
.
.
.

 

I believe the TC issue continues even after the car has fully warmed up whereas the software issue doesn't.

 

Hey guys thanks for replying
gearbox is silky smooth and i have not any reason to suspect it may be going faulty.
oil and oil filter were replaced 500 miles ago.
where can i have a reflash done? And how much could i expect to pay for this?
so no one thinks small air leak or possible ignition coil issue.
does anyone know why all of a sudden issues arise with software, requiring a remap?

 

I lost power under heavy acceleration, it literally had nothing even though the engine was still running but only at 1000rpm even with my foot down. I think that issue was down to the TPS as the fault code displayed as it was corroded and it has not returned even when driving aggresivly.
i had cleaned throttle body myself prior to sending it to the garage and it was pretty clean anyway so i would count that out.

 

On moday i will try this i will start the car and let it heat up for 20 minutes before driving to check for the fluctuations.
one thing that i may have noticed is that when the car is hot and the fault is no longer present whilst travelling, if i put the car in neutral with no revs, after about 2-3 minutes did start to idle roughly like the car was lean on air, the second i began to drive again it was good and did not return. This has happened twice now.
Im so confused.
still leads to possible air leak again :/

 

It's a transmission issue, not engine so sitting at idle in park will just waste gas.

You may have a second unrelated problem with the rough idle.

 

I think it cannot be an air leak, or at least it must be quite a bad one in order to fluctuate rpms. A month ago both of my IMT O- rings were leaking and there wasnt any change in the rpms. Still, the wisest thing to do would be to visit a garage to run a diagnostics.

 

How do I Reprogram Engine Control Module (ECM) ??

 

You will need the Jaguar SDD/IDS software.

V130 is the best for your car. This runs on a Windows XP computer that must have no internet connection at all and be set up to re-set the date each time it turns on.
This connects to the car using a jaguar dedicated interface, JLR Mongoose for example.
When programming you must also use a substantial power supply connected to your battery, enough to run all the car electronics because if the battery voltage drops while you are programming the car it will interrupt the update and destroy the control modules! (I have a 30A stabilised power supply with a voltage control that I use.)

Mellow

 

exactly