I have a P430 code that indicates the catylatic converters are bad. I’ve had them inspected and they are fine. The issue I have is the car chokes out on Wide open throttle or going up a hill and when it’s at half tank of fuel it runs like it’s running out of fuel . I have to keep the tank topped off. . I’m Open to suggestions as to where to start.

Car has 108,000 miles
new coils packs
new iridium spark plugs
new fuel pump
new fuel filter
New fuel pressure regulator

 

Can you please describe how the cats were inspected? A visual inspection of the interior with a snake camera? A back pressure test? Comparing the inlet and outlet temperatures?

Usually a P0420 or P0430 code indicates a failing cat. This is determined by comparing the O2 sensor reading upstream of the cat (relatively dirty exhaust) with the downstream O2 sensor, where things should be cleaner. As long as you have a healthy margin between the two, with the downstream substantially cleaner, you don't get the code.

The '99-'02 models base this difference on the O2 sensor switching rate. A slow switching rate means cleaner exhaust. Also, as O2 sensors age, the switching rate slows down. We can use this to our advantage. If you want to gamble $40, try a new O2 sensor on the upstream position for that cat. Leave the old one downstream. This is very important. The new sensor upstream should have a faster switching rate than the old one downstream. The computer will see this difference and be happy.

No guarantees, but I'm willing to gamble your time and money on it. This only works for a cat that's only slightly over the line. It won't work for one with a severe problem.

Not quite sure what to suggest for the other stuff. I read your intro, sounds like you've got your hands full resurrecting a car that sat for five years:


https://www.jaguarforums.com/forum/n...9/#post2036811

 

Probably not the cause but I thought the 3.0 used platinum plugs.

(The 4.x use iridium.)