Hello, my name is Kurt Doelle and I have a sincere question about my painfully maintained 1997 Xj6 Vanden Plas


The 1997 XJ6 will often stall at stop lights, red lights due to a voltage drop. By gradually giving it gas or frequent re-starts it will fire back up to 13 volts. On the highway there are no issues and it glides effortlessly. This is based on the premise that I make it to the highway.

I often times will take the limp mode Jag for a fill up and it usually fires back up to full voltage.

I would be beyond thankful for any advice. i am a newbie and suffer from ignorance and a fear of pricy mechanics. I have already spent thousands on this car and hope to resolve the issue

Cheers and thanks for the opportunity.

Kurt Doelle

 

To clarify, you observe the voltage dropping ....and *then* the engine dies?

When you go to re-start the engine what happens? Does it behave as though the battery is dead?

Cheers
DD

 

Welcome to the forum, Kurt.
+1 to Doug's clarifying question. I'm dubious that your car is stalling due to low voltage. As it stalls and dies, voltage will naturally fall to +B. Even if your charging system is kaput, if your battery has enough reserve to accomplish a restart, it would've had sufficient voltage to keep the car running.


You may want to research the Idle Air Control Valve (IACV) many have posted on, here.

 

Thank you Doug & aholbro1,
Yes, I do observe the voltage meter drop and the car comes close to stalling or is in limp mode. Upon re-starting the car is usually in limp mode with the trans icon on the dash lit. After repeated start attempts and a refill of gas? it will come back to life. After leaving the car set for a day it needs a jump. I have replaced the batter twice, serpentine belts x 2 and an alternator. If I run the car daily for long periods (highway) it behaves much better. I hope this is clearer and thanks for your patience. I have spent thousands (around 3 +) and I am hesitant to take it in again unless I am sure I know what the issue is.

Cheers,

Kurt

 

I had similar problems until I found this: the heavy positive (+) cable from the battery to the starter is not a continuous piece of wire, there's a connection where it passes through the firewall (just to the right of the transmission hump). Check for loose/bad connections there. Also be sure to check the inside-the car part of the connector. You'll have to pull up the passenger-side floor carpeting to do this. Mine was loose and the nylon insulator was melted and scorched.


If I'm right, you're seeing good voltage when the engine is running fast enough to get full voltage out of the alternator, but when the engine slows down and you need to draw from the battery to supplement the alternator you're getting a big voltage drop across this bad connection, hence the low voltmeter readings.

 

the above mentioned or simply bad alternator diodes.