Hi there,

Lately I've experienced a weird problem with my 1993 XJ6. Initially the engine runs fine. After driving for ±10 / 15 minutes, a 'hickup' occurs in the gaspedal and the car accelerates less. This lasts for about 3 seconds and then the acceleration continues as before - although with a 'Check Eng.' light lit on the dashboard. While driving, there is not much difference but when I stop at the lights the engine runs at about 600 / 700rpm, while usually the engine runs at 1000rpm stationary. This results in a shocking engine, as if the engine doesn't get enough fuel.

Any suggestions as to what the problem might be?

 

Hi 93 XJ6 = XJ40.

Hope the guys can help you out.

 

For the "Check Engine"...what code do you get on the display?

 

@Translater: Sorry for the rookie mistake.

@fritterfran: The "Check Eng." light is lit on the dashboard, on the bottom left side of the display. Hitting the VCM button to show possible error codes only shows 'PAD', which indicates a problem with the braking pads. VCM has shown that error code for a couple of weeks now and I haven't come around to looking in to it, however in my opinion that's not related to this particular problem. Or am I assuming incorrectly?

 

VCM doesn't give you any clue about error codes ,whenever I press the button with engine light on , nothing is coming onto the screen regarding codes just odometer .
Your problem should be ignition , I would also say fuel pressure but as far as I know fuel pressure problems are not temporary or intermittent

 

micktenbosch,

According to Haynes manual, to test for the codes:

1) Check to make sure you have more than 11 volts on the battery

2) Turn the ignition switch on (Position II) and don't start the engine.

3) Press the VCM button and observe the LED Display for the designated codes. An asterisk next to the code indicates there are multiple codes stored.

4) The numerical values will be displayed on the trip computer display on dashboard

5) If there are any malfunctions in the system, the corresponding trouble codes are displayed in numerical order, lowest to highest.


On my 88 for testing the codes, it is somewhat similar to above with the exception that I don't have to press the VCM button. Basically, I turn off the engine -> wait 10 seconds-> turn the key to Position II-> then watch the VCM give the trouble code with the # (like Check Engine #6 - an issue that I am presently tackling). Your car has more sensors and thus more codes than I do.


Your PAD warning is for the break pad sensor, either front or the rear. I had mine disconnected because they were a PIA. They are there for a reason so I check and change my pads when necessary. To disconnect them permanently, pull the sensor plug and insert a jumper between the two wires, on the harness side.

 

I had a problem with my 1990 XJ6 Sovereign that was very similar. In my case, it was related to the O2 sensor. A rodent had chewed part way through the wire that is visible on the right side of the engine compartment in front of the battery. I repaired the wire and she's been running fine.

As for the fault code, my local Jaguar repair shop told me - and it seems to have been true in my case - the VCM will only show one code at a time. In order to see other codes, you need to first clear the code that is showing. Can anyone else confirm this?

I had the PAD fault showing and found that the sensor in the left front brake was missing. I installed a sensor, connected the wire, and the PAD code went away, only to show the next fault.

 

Rob,

My Check Engine Code #6 is for "High potentiometer signal with low air flow sensor signal" You think that the oxygen sensor may be the culprit? I personally think its a problem I am having with the electrical signal going to the stepper motor. For some reason, I have two voltage signals reversed from the harness connector. The electrical signal originates from the microprocessor (ECM). I have a post about it at Jag-Lovers:

http://forums.jag-lovers.org/tv.php3...GxMLYCAIF9CCg=


I've posted about this issue there in the past however, no one seems to either care about helping me troubleshoot the problem or it's something that has the forum scratching their heads. I know that some whom frequent that forum are here as well. I don't think my question is foolish.

Whatever.....it's good to hear that the PAD problem has been resolved.

 

Who said your question is foolish...?

I should imagine that there are many folk who can't answer it off the cuff, me included.

We are all here to learn IMHO.

 

@fritterfan: Thanks for the suggestion about a different read on VCM. I went through the steps, and to my amazement it didn't show the unrelated 'PAD'; instead it showed a 'fuel fail 44'.

@Robert: Spot on. The fuel fail 44 corresponds to the O2 sensor.

Thanks both for the useful tips! Finally something I can work with From a different forum I found the following text:

So what's the best next step? Replace the O2 sensor and check the air intake parts?

 

If you don't mind getting your hands dirty, the first thing I would do is check all the rubber hoses associated with the air induction system. Also pay attention to the bellows that attaches to the throttle body. Make sure there are no waves in the rubber around its perimeter. Needless to say, check that the air filter is clean as well. When you've exhaused those options, then do the O2 sensor.

Good luck

 

fritterfran,

You said "My Check Engine Code #6 is for "High potentiometer signal with low air flow sensor signal" You think that the oxygen sensor may be the culprit?" I wish I could help, but I've only been a Jaguar owner for a couple of months and am still learning about these cars.

Robert

 

Hi Rob,

Yes, I am on a learning curve with mine as well. I think I've had mine for about 3 years? I try to do most of the under the hood work myself. I haven't removed the head, which will hopefully hold intact for a while longer.

I believe my problem is related to the ECM (Electronic Control Microprocessor), basically the computer brain of the vehicle. I believe that I mentioned earlier (maybe not) that I am getting reversed currents on two pins from the connector, harness side, for the stepper motor on the idle control valve. What does that mean to anyone simply...something is making my engine idle not respond the way it should. All of the engine parts were cleaned and operational. Connectors cleaned and WD40'ed. Last stop...the ECM. The only thing throwing me on all of this is that if the ECM was on the way out, wouldn't I get glitches elsewhere in the car? With all my review and analysis of electrical schematics and Pin readout information, it's just two pin connectors right next to each other. How about some other places??

Sorry to have strayed a bit. BTW, for the oxygen sensor failure on my car, its Check Engine #4, which I have not seen.