Jagtech,
Yeah, the thing goes dead like I turned the key to off. And yes the folks at Jaguar/LandRover Treasure Coast in Ft Pierce, FL told me there were no codes showing what happened, although the tech there did say he found that the transmission harness (temp sensor) was failing and the lower control arm bushings were also failing. The service rep told me the trans sensor could possibly cause my problem. But I'm not buying that, particularly after what you have said.

 

Yeah, we've already been there.

 

Jagtechs on the right page, trans temp only gives gear box fault and limp home. Do some of the basics while everyone here works on scenarios. Like water in the battery. tight cables. including the ground strap under the car by the starter, engine to frame. Also the power cable in the ecu fuse box, swap the relays around, check and make sure you dont see rodent droppings. they love English made wiring for some reason, and wouldnt be the first time ive seen wires chewed up. But I still wouldnt rule out a throttle body either as Ive seen them loose power(internally and externally) and shut the throttle, which at speed will kill the engine..Its just time to think of past causes, possible reasons, and eliminate the usuall suspects

 

I'll check all the above.

 

OK, the prologue is that I had a '97 XJ6 once that played tricks like this, it would shut itself down, immediately restart, and logged no codes. The customer never came back with the same problem after I replaced the EMS relay. Nothing too profound there, I'm sure people have been through similar situations, this was just a verifiable example because I was driving the car when it died and I know that's what fixed it.

Brutal stole a little bit of my thunder, but what I wanted to do was a little testing before I opened my yap. I drove one of my XJ8's in the shop, hooked up WDS and made sure it had no stored fault codes. Then I grabbed an old brown relay, LJA6703AA, and took the case off. I plugged it into my EMS fusebox and started the car. Then I took a tywrap and opened the relay contact, simulating an intermittant open circuit from a failing or corroded relay. The engine died straight away, only "Engine Stalled" warning appeared, no MIL. Without even turning off the key, I scanned the car for DTC's and found none. The engine restarted immediately, I ran it for a few minutes and scanned it again, all clear.

So that's ONE example of an intermittant fault that can occur and leave no diagnostic trail, even if you have a code reader with you when it occurs. I didn't try the same test with the throttle motor power relay, or ignition coil or fuel injector relays...I'd guess they would flag a code, but I'm not sure.

The ECM isn't smart enough to know everything: one good example is all the fuel pump failures, there is no fuel pressure monitoring and it isn't reading pump amperage draw either. If you design that stuff in, you have people bitching about having to have a check engine light reset because they ran out of gas. The ECM has no idea the pump doesn't work.

Your car doesn't sound like it has a fuel pressure problem , since it cuts off immediately and restarts just as fast. But the ECM isn't monitoring it's own power relay, it didn't know whether I opened the relay contacts or turned the key off.

I'd go buy some LJA6703AA relays, and plug them in to replace the four I mentioned, and a fifth for the pump relay just for fun. If you don't have the electrical guide map of locations, I can write it out for you (or somebody could maybe send you the pic). The relays are $5.70 each Jag list, so it's no great loss to eliminate a few possibilities. Of course Lew George could probably tell you where to buy aftermarket ones for like 30 cents apiece, and recommend a Wendy's in Georgia where you can go to the drive-thru and they'll lean out the window and swap them out for free.

That's all I got for you. Unless, of course, you want fries with that?

 

can i get a strawberry shake?

 

I always pegged Real_Tech as the milkshake drinker, not you.

 

JagtechOhio,
Thanks. That's certainly worth a shot. Oh, and about the fries...can I get that supersized?

 

If you drive to Georgia, land of the golden deals. I live in the real world.

 

I'll follow up after I change out the LJA6703AA relays

 

Sorry Jagtech, I can get them for $4.62, OEM no less. Less the fries and shake of course!

 

jagtechohio or brutal

I've got a question. I bought an OBD-2 tester and when I did my first (and only) test I saw messages pop up in the message window telling you things like you don't have traction control and you have limited preformance and transmission fault. The heater control system started to beep and Er popped up in the window (where the temp usuall is). The tranny locked up and I could not get it out of Park. The check engine light came on and stayed on. I took the car out for a test ride and it ran fine although the CEL was still on. After I pulled into my garage and let the car sit for a couple of hours, I turned the key to the I position without starting it and the CEL light was no longer lite. I received a P1642 message and also a P1000 message.

Is all of this "normal" when you do a diagnostic test? What should I see and/or hear while a test is in progress?

 

The only thing I would consider as normal is for the scanner to read either P1111 or P1000, which are system readiness codes. Anything else is a fault code stored in the vehicle's ECM's, or a fault code induced or imagined by a scanner that is incompatable with the vehicle's software. I hope that doesn't read too much like I'm a high techie, 'cause I'm not. If you read enough posts by people who are plugging God knows what into their OBD sockets, you start to get the impression that alot of the equipment they are using, from cheap Actron scanners to AutoEnginuity software, is not telling the truth.

When I first started working on XJ8's, I bought one of the more expensive Actron generic code readers. I drove the car with the scanner plugged in, and after about ten minutes the car went into limp home mode. Much gnashing of teeth ensued, I got to change my first throttle body (for no good reason), and the symptoms were repeatable every test drive: until I cleared the codes and disconnected the scanner, and found out there was nothing wrong with the car.

This is the sort of thing that makes my crazy, since you can never diagnose anything until you verify that the "givens" are, in fact, givens. So everything has to start with the basics confirmed, and you follow a path from there to the fault. The worst things happen when you assume something is OK, like a battery, or a replacement part you installed, or a reading from a piece of diagnostic equipment, that is not verifiable. That's when the path turns the wrong way.

 

Jag thanks.

 

I would hesitate to say all your symptoms matched mine. However, I would put my dime on the TB plugs! Your Vin is in line with the TSB. You also need to keep in mind that you are getting help from others who have a better understanding of the problem than I do. Please let us know what you find.

 

I had my first couple of engine cut outs just in the last few days. Two today within 2 or 3 minutes of each other. Low speeds and engine just dies. The first as I was coming up on a red light. Tonight I cleaned the TB and Part Load Breather; although they had both been cleaned within the last six months.

I am reading about Service Advisory 514. Where they either reflash the ECU or give you a new throttle body. Is that SA still in effect?

Gordo

 

It is my understanding that this will expire June 30, 2009! It covers xk8 97 – 99 vin 001036 – 031312 and xj vin 812256 – 878717. Hope that helps!

 

What does reflash the ECU mean?

 

thats meens loads the latest software updates into the ecu to change parameters. And if youre in Vin range, replacement of the throttle body too. At least your much more consistent on the failure which makes it easier to fix since you can duplicate much faster. Im still leaning on JTO's ecu and power along with a throttle body fence tho. But let me ask 1 other question, have you verifies fuel pump operation? I dont remembeif we've discussed. But Ide hate to think youre not chaseing a pump and circuit thats not getting hot from amp draw and or poor connection causeing a loss of fuel pressure which will cause dying immediatly.
Ive just have never seen 1 do so much without total failure....so might be just thinking out loud

 

Hey Brute,

That's a sound theory, the first time I saw the burned link lead deal I thought for sure it could cause intermittant (and even momentary) open circuit to the pump. I haven't seen one that wasn't on a tow truck either, however. My guess is that you would feel a stumble, maybe even get a lean pop in the intake, before the engine stalled..and it wouldn't always immediately restart when the failure occurred. But I'd bet is has happened to somebody driving an XJ or XK, maybe this is one example.