My s type r misfires on one bank when under sharp acceleration. Would a faulty cat cause this?

 

short answer is yes . normally a clogged cat will cause a pinking sound also .

are you getting any misfire codes ? if so start with new plugs , and swap your coils around to try and shift the problem , not silly to swap in a new fuel filter as well.
and get your self an ELM327 scan tool to watch your fuel trims in real time .
and wile your at it check your MAF sensor is with in speck . as any one of these things will cause a bad cat to start with .

 

Thanks,
I have had the coils and injectors tested .New plugs. Engine still misfires, pinks and goes to restricted performance when pushed. Was showing lean running but found vacuum hose off.

 

Check fuel trims at idle (parked, hot engine) then rev to about 2500 to see if you've an air leak.

 

Sounds like what I just dealt with. In my case, I had a combination of:

- a couple of bad coils
- both cats melted
- failing O2 sensors (both up- and downstream)
- vacuum leaks

Magnaflow makes drop-in replacement cats now for the S-Type. Find them on Amazon, they work for 03-05 MY.


My vacuum leaks were:
- supercharger outlet to elbow seal (big square one)
- elbow to charge cooler (funny oblong donuts visible from the top of the engine)
- brake booster to TB connector failed (replaced with OEM, but there is a better fix which requires tapping the push-connector bung and using a screw-in brass compression fitting)

I suspect I still have an out-of-spec MAF, and need to replace my upstream O2 sensors.

Of course, your mileage may vary - the ELM scanner is essential, as is the Jag workshop manual for your car. There are specific troubleshooting and spot diagnostic steps for each code you'll find.

Cheers,

Ken

 

Listen to Ken.
These are the known problem area's
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