Dangerous problem--please help
 

Hi All,

If you don't mind, I'll tell the story first, and then ask for your guidance.

We finally got our first Jag. Settled on a 1997 XJ6 VDP. She has 81K, and is in overall very good shape.

We knew owning a Jag would be exciting, but not in this way.

Purchased from a private party, some 90 miles from home. Picked her up on Saturday, in a miserable rain/snow storm. After about 30 minutes on the Interstate, at 50-70mph, I attempted to accelerate and the car just bucked like it was going to come apart. Backed off throttle to about 50mph, and it smoothed out for a while. The next time it happened, it bucked slightly, and seemd to be losing power. Pulled over to the shoulder, and it was idling smoothly.

Got off at the next exit, and pulled into a parking lot to assess. Seemed to be running fine, so headed back to Interstate. As soon as I pulled out, I got a Check Engine Light. Still seemed fine.

Back on the highway, ran great for another 20 minutes..... Now for the Dangerous part.

Still pouring rain, tons of traffic, I'm cruising along at 65mph, in the middle lane, and the engine just quits. No warning, no lights, except battery. Somehow, I managed to get to the breakdown lane. On the second try, she started right up, and the CEL was off.

Drove to a nearby rest area to change my shorts. While at idle the CEL came back on, but the car seemed to be running fine. After a short break, got back on the highway, and drove the remaining 50 miles at 60-70mph, with no problems at all.

At home, I have a cheap scan tool, which showed a P1193. Erased the code, had a few glasses of wine, and admired the beautiful car now safely in my driveway.

That night it snowed, so the roads were still wet the next day. Took a short ride to a store with my wife. She waited in the car with the engine idling. I returned, 10-15 minutes later to find her (Jag) still idling fine, but the CEL was back on.

On the drive back home, at about 30mph, she quit again. This time I was able to shift to neutral and start it back up without stopping. Back home, I read the codes again. This time I had P1193, P0138, and P0158.

All of these codes seem to point to HO2S circuit, high voltage.

The only other thing I've noticed that seems odd to me is the Alternator/Voltage guage reads between 14 + 15 the whole time it is running.

I bought this car mainlyfor my wife to drive around town, and occasional trips to visit her mom, about 100 miles each way. Obviously, that cannot happen until I solve this little mystery.

I am looking for any suggestions as to how I should proceed, in order to pinpoint what the problem may be.

Look forward to hearing from you.

Thanks,
Leo

Hey Leo. I'm not well versed in the electrical systems of Jags yet (as I'm having my own issues as of late), but it seems to me that the alternator is reading correctly. A 12 volt battery PLUS the car itself, needs MORE than 12 volts to charge the battery AND keep everything running at the same time, so that shouldn't be your problem.

HOWEVER (not paying attention to the codes), you could have a short or be grounding out somewhere. Now, THAT'S the trick (the problem I've run into, also) is WHERE is it.

First thing I would do is call the previous owner and ask them if they had this problem as well, and if anything electrical was changed recently. That's about the only input I have for you.

Thanks for the quick response. I will try to contact the previous owner.
Please stay tuned

Be tactful with the previous owner, they will most likely be instantly on the defensive, thinking that you want your money back.

No expert by any means, but those codes are pointing to O2 sensor issues.

For further reading look here: http://www.engine-light-help.com/jag...ine-light.html

Cheers

I would try cleaning the throttle body.

I was thinking part of the problem may be fuel related.

Forgot to mention in original post.... the car has been sitting for at least several months.

I put fresh fuel in before the trip home. Is it OK to add some dry gas??

Since the O2 sensor codes come up for both sides I would vote for a throttle body or MAFS issue. Clean both with some spray cleaner labeled for that purpose. Also might try disconnecting and reconnecting electrical connectors on both the TB and MAFS. A little spray WD40 on the connectors would not hurt.

Corrosion and wet drive might be the problem.

Thanks.... I'm sure I can handle cleaning both. However, I have never worked on a Jag before.

Is there someplace on this forum where instructions are posted?

I have not had much luck searching so far.

Also, Is it normal for the Voltage Guage to be reading 15?

It seems high compared to most other vehicels I've seen.

Look under 'Articles' here

http://tiny.cc/TBCleaning

That is for a V8 but the V6 is close enough.

Reading 15v is a little high, 14.5v is about right.

Thanks

This is indicates a very high charging load on the battery. If the battery has been partially discharged, this is normal. Otherwise not so good.

Thanks for the response Mikey.

Not sure about the history of the battery, but I can test it.

If the battery is OK, what do you mean by "not so good"? Does that indicate a short somewhere? Bad alternator? Could it be the cause of the CEL or the stalling?

You apparently have some kind of problem with your O2s. I suspect someone changed them to generic sensors, which are a different type. If you know what the lamda sensors look like, check to see if they seem to have the factory plugs on them, or if there is a splice in the wire from the sensor to the wiring harness back of the engine.

I wouldn't jump to saying the dreaded 'short' word just yet, but it does infer that you'll need further investigation done. Normal voltage should settle in the lowers 14s, high 13s.

I doubt it has anything to do with your other problems.

A weak battery in these cars can cause all kinds of strange events. Be sure you have a strong battery in the car!