Gearbox light, idle problems
 

Hello all,

I have learned a lot of things about Jaguar XJ6 problems here, but now, I have to post something that I cannot confirm what it is.

I had changed the pump-to-engine water hose. I removed the supercharger to do that... I had to unplug the TPS and now I think that it needs to be updated because it’s generating my gearbox problem. The idle is not stable it sometimes at 1500 rpms to 2000 rpms, but never under the 1000 rpms.

Could be the TPS the problem of this mess?

Symptoms that are present on the car:
Fluctuating revs.
Light gearbox warning light on the dashboard.
Not smooth shift.
180.000kms showed on the dashboard.
No OBDii code.

CAR information details:
XJR X300 automatic transmission
MY1994 November
180.000kms


thanks in advance
kind regards to all readers

Welcome to the forums Alejandro,

I've copied your question from New Member Area - Intro a MUST forum for advice from members with the same model.

Graham

Certainly sounds like it. A TPS reset should reolve that for you. A WDS, PDU, dealer, or mechanic with Jaguar software uploaded to his machine can do it for you in minutes. (Dealer should charge you an hour of labor.)

thanks for your response Vee

Do you known how can I do that? could you please subject a software to connect the car to the computer?

kind regards Vee

With the supercharged engine you have the different GM transmission then the rest of the non - supercharged ZF transmission

There are a couple of Jaguar TSB's with the GM transmission you may want to review

JagRepair.com - Jaguar Repair Information Resource :icon_dance-disco:

One that comes to mind is if you have the orange dot or not

In removing the supercharger you may have left off the inlet air temp sensor connector and your TPS could be just fine

The engine ECU and the transmission ECU must talk to each other to coordinate their activities around the areas of throttle kick down and idle position expecting a 1st gear selection

The later X308 with the V8 has 2 separate TPS's one dedicated to each ECU where the X300 must share the one TPS

You would have to own a WDS, PDU or an expensive dealer level device, or a VCM-2, or a Mongoose. The clone devices may work, but not for long, so try to stay away from those.

Unfortunately, it is not possible to simply hook up a laptop to the car, you will need some special hardware/cables to connect to the cars OBD2 port. No way to make one at home.

Since you have a supercharger, there won’t be any way for you to even attempt to adjust the TPS manually, as you’d have to do this, in the blind, by feel, with the engine running. You would have to loosen the two bolts holding the TPS in place, adjust the position while engine is running, and then be able to tighten in place.

That is the problem. On supercharger engine, the throttle body is not properly designed :$ to do this job. Any way I will have to pay the Jaguar shop to do this.
Tanks you so much.

I will post when I finally have the solution and the price for this kind of job in Spain
kind regards Vee

You don't want them to remove or even adjust the TPS unless they can adjust it properly

There is a throttle body return spring TSB X that they may not be accounting for

See page 11 , note that it mentions only non - supercharged engines
http://www.jagrepair.com/images/TSB/...all%20R493.pdf :icon_dance-disco:


The previous owner may have addressed the return spring by preloading it with a different attach point as you wind it ( This instead of a stonger revised return spring )

That could explain the butterfly not returning to the idle closed position and proper idle speed

Your throttle body butterfly may need to be cleaned as well. Having gunk collect on the butterfly on, at least, the non-supercharged version of this engine is common, and does cause these issues.

On the non-supercharged engine, cleaning the butterfly is an easy task.

Your work seems to have shifted something there. A vacuum leak could also create this problem. Please make sure you have no gaps where unmetered air can enter the throttle. People report success using propane around the intake to see if the engine idle changes….if it does, you have a leak.

Before taking it to the dealer, you may want to go back and double check your work.

Thanks for your response Parker,

I tried to close the butterfly manually and it was not possible it was on its position. I do that because I rode here the problem with the spring that you mention but the butterfly doesn’t moved. Other think that I tried was to lose tension on the throttle cable in order to give more freedom to move but it wasn’t worked. That is the reason to make me think in a sensor problem. I also tried to release and check the IAC sensor and the measure of resistances was fine too…

Other question, the TPS failure is represent on the dash? It is, what is the light or warning code of this?

Thanks for your response
This is possible to happen. A little hole on the intake could false the MAF sensor value but I don’t think used propone on the engine bay help me to find the problem. I have a tool to read the vacuum force but on supercharger engine it is difficult to find a properly place to take a measure.

See page 111 for a 94 / 95

Beginning with PO122

http://www.jagrepair.com/images/Trai...20-%202000.pdf :icon_dance-disco:

But I have no code for the problem… I only have the gearbox light on the dash, but I cannot read the code with my OBD reader. Maybe someone of you known the way to read the code using the dash display. Could be it possible on XJ6 x300?

We need to get to the bottom of your transmission light. I don't think that you can get that read very easily. I just reread your post and you have a 1994MY, so no OBD2. Other than a PDU, I'm not sure what you need to get your code read!

I would heavily recommend taking another look at how you reassembled the car after your repair, and pay very close attention to the TPS. Make sure it is installed correctly, without any loose connections. Also check for possible vacuum leaks. Something happened when you unplugged, then replugged the TPS. I am not confident your Jaguar Dealer can address this for you, unless they have the old equipment. I would definitely call them first.

In the meantime, if you're up for it, get back in there and re-inspect that TPS.

I will pay attention to the TPS connection sensor and I will spry conector cleaner as I did on the MAF sensor. I sure that it is the TPS the cause of this problem. I will do the job on the following weeks and inform you if changes happen.

Other information that I would like to share it that the car is 1994 November, I could say that it was one of the first which arrived to Spain. So maybe it has a software and hardware from model year 1995. I rode the MAF and oxygen sensors measure with the OBD so I am not sure to confirm which OBD the car has.

If you read the MAF and Oxygen Sensors with an OBD port, there is a very good chance that you should be able to read the TPS too! What did you use to read the oxygen and MAF sensors?

I use a wireless ELM27 dongle that can be bought very cheaply on eBay or Amazon. Just make sure you buy the WiFi one if you use iPhone. If you use an Android phone, you can buy the Bluetooth one. Then you just buy an app for the phone!! The app should be able to tell you what percentage open the TPS is. At idle it should read at about 12.9%.

Look under the intake manifold for loose vacuum lines as one of mine was missing

I also found the TPS connector was missing the metal bar locking clip , you can find a replacement from one of the trunk dome lights

You will see 2 coolant fluid lines to heat the throttle body butterfly throat

See page 60 of the OBD 2 PDF as there are 2 versions of fuel and vacuum line hookups , 1 or 2 vapor canisters versions . A 2 canister system will have a square canister on each side of the car just fwd of the rear wheels . A 1 canister will only have one on the left side

The mobile App torque and the cheap OBD II reader… I now I cannot do it because I am not with the car, it is in other town. When I’ll connect the car to my mobile I’ll pay attention to the idle opening percentage.
Thank for you advice.

I will follow all your advices, I will keep in mind what you subjects. Thanks