Thanks to this forum, I've nabbed some replacement cuts from Everyday XJ for very reasonable prices (along with a host of other bits and pieces). Pauls has supplied some seats (need redyed, but I'm very cool with that). It sits at the body-guy right now to get her paint and panel job done.

Again: My thanks to all.

I need, now, to run through a new 'bug' in the system for everyone's perusal.

Keep in mind: it's now about 20 F here in the Midwestern US where I'm at.
The car is only running on the LH tank, with new fuel in it.
New lines are run and a new cold-start injector is in.

Issue: During the summer, the car exhibited no driving issues -- it would happily start, accept being put into gear, and drive around.
Now: it will start, and happily putter away in the garage (engine is fine, no miss, idles at about 1k, though). However, if I don't get the RPM up to 1500 or so, it will die when shifting into any gear that requires power (R, D, 2,1). If I do keep the brake on and shift into gear, all is well and it will drive (though I have to keep the RPM's up when slowing down to a stop).

So: owing to the temperature difference, and since this is fuel injected -- is the likely culprit the air flow meter + temperature? A few searches across the Interwebz seem to point in that direction, but one or two suggested the ignition switch too.

Thoughts would be appreciated!

 

hi,
generic thoughts here: make sure the transmission fluid level is where it should be. I do not believe ambient temperature has anything to do with it, it might cause cold starting to be slower, but once engine is started, it should not, the system does not care what the outside temp is assuming everything is working. i.e., the Cold Start Injector is doing its job; Instead of the AFM flap, (which most everybody inmediately blame), check the plug at the AFM, wiggle it up down, side to side to improve contact, maybe remove it and clean it with a wire brush. Also check the Coolant Temp Sensor, known to cause weird symptoms. And last, but not least:

is your Oxygen Sensor the one wire only type? if yes, take a thick copper wire, wrap it around the O2 sensor metal body with one side of the wire, (with a cold engine of course, the O2 sensor gets extremely hot), and attach the other side to a good clean chassis bolt, to see if idling or anything else changes. It is an old tip from the early 1990's when I bought my XJ-6, that adding a ground strap to the 1-wire O2 sensors improved idling stability and overall computer response because as these cars age, the exhaust manifold-to-engine-block Ground is reduced by grease and carbon, so adding a ground strap to the O2 sensor itself improves overall system response.

I manufactured a ground strap for mine and it caused the idling to become more stable, even improving starting to the point where my car starts from a single turn of the ignition switch. Please note I really do not care to argue the point one way or another because for some this is "snake oil", (they've never done it to their cars either but they inmediately conclude in the negative); I still remember this tip that was used back in 1990 when I bought my XJ. Here's pictures of the ground strap I manufactured for the O2 sensor, The ring connector is placed between the sensor's body and its crush washer, similar to a spark plug's crush washer, so the ring connector flattens neatly when you tighten the sensor to the exhaust manifold, no leaks.

 

Okay- when the car is back from the body guy, I'll check the ground.

Interesting you should mention cooling sensor: This car runs about 1/8th of an inch below 'green' when idling -- I cannot recall what temp that would be, but it never enters the 'green' range. It is stable, however, when it reaches it. I've been blaming the gauge and planned to check connections.

 

And, speaking as an EE -- your ground strip makes sense to me if corrosion is an issue (though I suppose 'breaking the sensor loose and re-seating it after a good clean' should also work -- the strap would provide an additional grounding source and perhaps make this maintenance less required).

 

exactly, if you look at 1986 O2 sensors, they started to include an additional wire, a ground wire!! curious, ehh? in my car, adding the ground strap did the job, and it has been there for around 15 years now.

as to the Gauge not entering the green zone, I think the thermostat might be opening too soon and staying open, it should reach the green zone or go a little after it, these 4.2 liter (and 3.8 liter) XK engines run hot. Unless your auxiliary fan (below the bumper) is coming on too soon, keeping the temp down...

the Coolant Temp SENSOR is not what you read in the GAUGE, that would be the Coolant Temp SENDER, two different parts; The C T SENSOR tells the computer ECU info about fuel and air mix required depending on the temperature of the coolant,

the C T SENDER is what you read in the gauge.

Note that sometimes we add teflon (plumber's tape) to the thread of these sensors and senders (to avoid leaks), and that should not be done because these sensors and senders need to GROUND to the engine block or intake manifold, so the teflon reduces the ground contact areas ! (I'm guilty of that). Check that your C T sender or C T sensor does not have teflon in the threads!

 

CT sender, okay -- IMHO more likely a corrosion/sensor issue than anything else. I should recheck the ATF, I suppose, as well.

 

also look carefully at the top of the intake manifold vacuum/air hoses, to the left of the Auxiliary Air Valve, and before the air intake, there is one little 90 degree vacuum hose/elbow which attaches to a vertical nipple/port. the elbow is partly hidden from view by the water rail and the torque bars. this elbow/hose has a tendency to come off the nipple/port and because of its orientation, it is hard to see when it is coming off by itself, (it is not clamped, as the elbow dries out with the years, it becomes lose and if it comes off), it will cause the engine to shut down or start coughing untill it stalls.

another way to view this vacuum elbow is from the driver's side, by pulling yourself partly over the top of the engine to see it.

 

As to the O2 sensors, I suspect the exhaust system is not a good ground, therefore the strap made by Jose would insure a good ground if sttached to a well grounded location. The chassis ground and/or the engine block would do just fine. The exhause has a donut or olive and is hung in fiber or rubberm leaving only rusty bolts as a ground path!!

I fail to connect why the engine pulls better with the brake on??

And, off idle poor running means a lack of power for whatever reason. At idle, even a weak engione can pull it's own weight so to speak. but, add a load and it becomes shaky.

Time to isolate as to an ignition issue or a fueling issue.

Oh, on the tempo guage, anything left of center is a warning of impending disaester. Don't ask!!!! Why it is green befuddles me. REd would be far better.

I sure have learhned a lot about these critters. I haven't driven mine in weeks. Just firted it, a bit ago. All eight purring away.

Carl.

 

Lots of "could be" items on the list.

Personallly, the first the first place I'd start looking is the ducting between the throttle body and the air flow meter. Make sure it is properly positioned, secure, not torn, etc.

Cheers
DD

 

Carl,
I connected the opposite end of the ground strap to one of the lower bolts at the Cruise control bracket, out of the way to avoid any tangling or accident.

as to the Temp Gauge: there should be a SKY BLUE (Normal) zone and a RED (DANGER) zone. I never understood why it's green. Too late now.

as to Freddy Fender, I would have selected "Raindrops Keep Falling on my Head" as a substitute song. (BJ Thomas). I would change the words a bit: "Raindrops Keep Falling on my Screen, and just like I thought my Xj wipers can't keep up, nothing seems to work, those, raindrops keep falling on my screen, they keep fallin'..."


there is a guy who sells on eBay, he's in Delaware, who rebuilds starters, wiper motors, generators, etc., for old Jaguars. I told him about the XJ-6 wiper motor being as lazy as Freddy Fender; Could he "hot rod" one of these wiper motors for mucho more speed and torque and sell it to me? He promised he'd work on it, I never heard back. Going to write to him again (if I can find his e-mail). Nice fellow, very knowledgeable about Jaguar components.

 

To clear up the question on why it pulls better with the brake on: I engage the brake so I can get the rpms higher before going into gear. Otherwise: stall out. Runs fine out of gear, though.

 

then it is definitely a transmission issue, maybe something as simple as the Safety Neutral Switch mounted in front of the shifter, gone out of adjustment, or gone bad.

 

Near as I can tell it's not so much a matter of "pulling better" but, rather, "stay running". In other words, the engine won't idle when in gear.

Cheers
DD

 

If the starter operates when the key is turned, the neutral safety switch is OK. It has no bearing whatsoever on how the engine runs.

However, a transmission problem....such as some sort of torque converter fault....is a possibility.

Cheers
DD

 

The 4.2 fuel injected engine often has idle difficulties....sometimes they can barely sustain life when loaded.

I've experienced some that can barely tolerate torque converter drag or an engaged a/c compressor....both of which tend to be on the high side on the Ser III 4.2s.

However, what you are experiencing is rather extreme.

I strongly suspect a vacuum leak....a rather big one.

If no vacuum leak is found and the ducting to the throttle body is ok, you should check that your throttle body is clean and the blade is set to the proper .002" gap.

If none of that pans out I'd say that you have a fueling problem.

In your original posting you mentioned ambient temperature but not coolant temperature. Do the symptoms change if the engine is cold versus warm (or hot)? If the problem happens only when the engine is cold it might be a problem with the coolant temp sensor.....perhaps not signaling for enough cold running mixture enrichment.

Cheers
DD

 

I'll have to investigate more when the car is back from the body guy, in a week or two. Thanks for the ideas!

 

Doug, the coolant temp gauge in the car doesn't quite hit the green. About 1/8 of an inch too cool for that.

 

OK, but does the problem change or go away as the engine warms up? Or is the problem the same regardless of engine temp?

Cheers
DD

 

Ah, good question. I think the answer is 'once it warms up in this ambient temp', as it didn't exhibit this in Oct.

 

Heh heh. I must not be communicating very well.

Let me try again....

"Once it warms up in this ambient temp" does the problem go away? get worse? get better? no change?

Cheers
DD