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I unplugged the TPS to see if the computer might reset. 96 XJS HAS A FIXED POSITION TPS (no adjustment). I-read somewhere on some vehicles the computer might reset a stuck TPS.
one (1) of the issues was the fuel systems has been loading with lots of soot coming out of the tail pipe All over the drive out of both pipes.
one (1) of the faults of the TPS was potentially (stuck in position) calling for more fuel when not needed.
Yesterday let the car sit in the garage. Today I UNPLUGGED THE CONNECTER TO THE TPS AND LET IT SET FOR 15 minutes.
I did this to see if I could reset the computer. Fired it up and spent the next 15 minutes driving ( on and off the gas) around the neighborhood to see if I could recreate the failure symptom. The car ran great!!!
I have an OBDII, it does not give values but rather ….OK’S OR FAILURE. WHEN PLUGGED IN WHILE RUNNING IT IS REGISTERING OK FOR FUEL SYSTEM.
SO, not sure whether this may have solved the issue but will keep monitoring the situation.
As far as the fuel system, I have new injectors, both the original and new fuel pressure regulators, relatively new Denso fuel pump (tank was really clean when I installed new Denso fuel pump), fuel filter has maybe 5K miles or less.
- Buy a cheap OBDII bluetooth / wifi sensor - no need to spend more than $10
- Buy the TorquePro App for your phone (works on Android, not sure about iPhone, but plenty of similar apps around) about $5
- Scan car for fault codes - TorquePro is limited but should show any XJS AJ16 engine fault codes
- Every time you start the car, even if it's running bad, try and get it up to temp before turning it off. AJ16s hate short start and turn-off cycles. It can make them almost impossible to restart.
- Next time you try a startup, bridge out the CTS (Coolant temp sensor) These are a known wear item. They send signals to the ecu to determine fuelling based on temperature. It could easily be causing the over-fuelling. If you just take it out of the equation, you may see a difference in symptoms.
If you had an OBD2 reader, you would know whether the car was in closed or open loop. That would help shorten the possibilities.
If the coolant temp sensor is bad, then you would not enter closed loop, rendering most of your fuel related sensors useless. In order to get to closed loop, the car needs to get good readings from the TPS, MAF, oxygen sensors and lastly, the coolant temperature sensors. If any one of those sensors doesn't satisfy the ECU, you will be running off of a fuel map. That tends to mean you are ovefuelling. Again, an OBD2 reader would reveal what your Long Term Fuel Trim is. Anything over 5% is out of the ordinary.
I would get another coolant temp sensor and try again. It's a cheap enough part. (LHE1600AA) It's also super easy to access and replace.
If you remember I had tried to replace the water temp sensor 3-4 wks. Ago. When I did,
Upon ignition I immediately had an overheated pegged water temp gauge. , so I thought the new temp sensor was no good…….put the original back in. Went back to the way it had been for the last eight yrs. VERY……VERY SLOW COMING UP TO NORMAL…….WHICH IT NEVER DID……ALWAYS BELOW NORMAL.
Well I ordered another temp sensor and picked it up this morning at the auto parts and installed.
NOW, THE CAR FIRED UP NORMALLY…..USUALLY BY THE SECOND REV…..PRETTY NORMAL
Prior to INSTALLATION OF THE NEW TEMP SENSOR
this current start/drive condition…WHERE IT FIRES UP IMMEDIATELY BEFORE ONE (1) FULL REV AND IS USUALLY VERY RICH WITH SOOT OUT THE PIPE………..AND.KEEPS DYING OUT WHILE DRIVING.
I drove the car for about 15 minutes after installing the new temp sensor and it drove normal. I was up and down with the gas pedal trying to get it to die out……..IT DIDN’T……DROVE GREAT, ALTHOUGH THE GAUGE SAID IT WAS OVERHEATED upon startup……JUST LIKE THE OTHER TEMP SENSOR DID……..SO DO I HAVE A GAUGE THAT IS FAULTY???
I know the car was not overheated otherwise I would have blown coolant out…..just guessing!!!
drove back home pulled in the drive shut it off and immediately fired it back up……AND IT STARTED UP NORMAL…. 1 to 2 revs.
1. WOULD A BAD OR GOING BAD TEMP SENSOR CAUSE BOTH OF THE CONDITIONS PRIOR TO THE INSTALLATION OF A NEW TEMP SENSOR. A. OVERFUEL CONDITION AT STARTUP AND B. FLOODING OUT OR DYING OUT WHILE DRIVING?
IS THIS POSSIBLE AND IF SO ………HOW DIFFICULT IS IT TO PULL THE TEMP GAUGE AND CHECK WHETHER SOMETHING IS LOOSE OR THE GAUGE NEEDS REBUILD?
- the coolant temperature sensor (CTS) that sends a signal to the ecu to influence fuelling
- the temperature transmitter that sends signals to the temperature gauge
The CTS is LHE1600AA as advised by Vee. This is the key factor in temperature signals for fuelling
The temperature transmitter is DAC11079. Even if failed, this shouldn't affect fuelling.
Slightly confusingly, they sit side by side on the thermostat housing on an AJ16 and look similar.
You've talked about changing (one of them). I infer from your post that it's the temperature transmitter. You've definitely changed with the right part numbers and also connected wires appropriately, have you?
.I changed the unit with the single blade wire. SO ARE YOU SAYING THAT I SHOULD HAVE REPLACED THE OTHER WATER CONNECTOR
the other is the unit with the spring clip to keep in place. I only removed the connector so that I had better access to the single blade unit that I replaced.
NOT SURE WHAT MY NEXT MOVE IS?
I do have another used TPS spare part ON THE WAY TO INSTALL and see if it has any
effect on my original issue.
I ALSO ORDERED A TEMP SENSOR GUN FOR THE WATER TEMP GAUGE AND A BLUETOOTH COMPATIBLE REAL-TIME OBDII UNIT.
GIVE ME A COUPLE OF DAYS TO SEE IF THE ISSUE REALLY CLEARED UP OR WAS COINCIDENTAL.
I’m still thinking TPS…….MAYBE FOR THE MOMENT IT IS UNSTUCK.
If you read my last reply I now have to get to the temp gauge and figure out why the gauge goes to the red immediately upon startup.
HOW DIFFICULT TO GET TO THE GAUGE…..JUST REMOVE THE BOLSTER AND LOOK UP? And go from there?
A picture would be worth a thousand words here. Can you post a picture of what it is you replaced on the car? One SENDER should have a single male spade connector. The SENSOR should have a two spades protected by a plastic shroud.
I sense you may be mixing up the SENSOR and the SENDER which would be easy to do, since they are both next to each other. I would hope they are not threaded the same, but I'm not surprised if they are.
Please unplug the sensor/sender and send a pic in situ?
OK, that's a bit clearer. As you've indicated, the item you've changed is the temperature transmitter. This merely sends a signal to the gauge. The signal is a measure of resistance driven by the temperature in the thermostat housing. If the gauge pegs straight to hot, but previously sat ok, I would SUGGEST that the transmitter is not exactly the correct one. Did you purchase it from Jaguar or is it a pattern part?
Are you in a position to measure the resistance that it is showing when the engine is completely cold but the transmitter is pegging the gauge to Hot? I will try and look up the resistance readings and where they should move the gauge to. I have heard of a number of these pattern transmitters that do not transmit the correct resistance reading. Some people have still used those transmitters and then by working out the actual resistance readings compared to what they should be, then added an inline resistor of the correct value to force the gauge to where it needs to be at normal temp.
Anyway, don't worry about the transmitter at this point. If the engine is stone cold and the gauge pegs to Hot, there is a either a problem with the transmitter, the wiring or the gauge, not the thermostat or engine.
The Temperature Transmitter does not affect the fuelling at all, so in theory, changing it, or even disconnecting it can't affect how the car runs.
However, the Temperature Sensor ( the one with the plug clip) absolutely does affect how the car fuels. If it's sending a signal to the ecu implying that the car is cold, it will run richer, irrespective of what the temperature transmitter (and the gauge) think is the temperature. I'm not sure if I've got any docs that give the sensor readings at different temps that you could check, but I'll have a look.
My suggestion of bridging it was to take off the plug, use a bit of wire to bridge across the terminals on the plug and see what that does to the fuelling. It's just a crude way of seeing if the sensor is causing a fundamental problem.
If you're going to change the CTS anyway now, then forget my suggestion!
Let's get the car running properly, then you can come back to the Temperature Transmitter and the gauge problem.
Just installed the new temp sensor and took the car on a 15 mile round trip to the dentist……….OUCH!!!! And returned home without any car issues.
Put the old temp transmitter back in and the gauge started woking again…….albeit very slow based on the registration of the gauge before the “N” the temp with the infrared gun was ~156 F
So I will continue to drive and see what happens. It still starts immediately upon turning the ignition key but no blowing out soot!!
Would it be possible to hop on a phone call for a few minutes to chat about this stalling issue?
I'm out in California, she was having a misfire on #6 before she quit two days ago.
I welcome anyone that is available to give me a ring if they see this. I'm comfortable fixing my old merc with youtube videos, but I'm out of my element here and could use some advice.
Stalling also, would like to chat about it.
