My car has a random misfire (new plugs and ignition coils) and a cat code on bank 2. If I clear the codes and drive like a granny, no issues!!!!! But when I put my foot in it....yellow restricted performance pops up on the screen.... BUT PLEASE HEEEEEEELP MEEEEEEE

 

Have no idea of what you are driving. Like what make model year engine. PLEASE HELP US HELP YOU!!!

 

I have a 2011 XJL 5.0 none sc

 

So you have a 2011 5L NA engine. What oil do you use? How many miles on the XJ? Do you use "Top Tier" rated fuel?

 

I have a 2001 jaguar xj8 it needs a load part breather hose in the engine i could use some help.

 

First off, big disclaimer, I’m not a mechanic. So take my thoughts with the appropriate grain of salt.

My best understanding of the issue is that the cat code you have occurs when the car checks the upstream (of the cat) o2 sensor and compares it to the downstream (of the cat) o2 levels. If a fault threshold is exceeded it results in a fault. As there are only 3 parts (upstream sensor, downstream sensor, and cat), I would narrow the search to these three items. If you can live monitor your sensor voltages on this bank you might be able to determine whether they look normal or not. I’m not sure how the misfire plays into this. My understanding is that this fault is supposed to tell you your cat isn’t functioning properly.

Is the misfire registering a code, or is it something you feel?

Hope that helps.

 

My codes are misfire on cylinder 2,4,6,8 all on bank 2 and the cat code low efficiency on bank 2

 

sounds like the fuel rail/ injectors needs replacing. Several members have had this issue causing misfires on all cylinders. I’m sure they will be able to tell you all you need to know.

 

You may want to try using fuel injector cleaner first. BG44K gets good reviews (buy online), but you can also try Techron concentrate (Costco/ Walmart).

your cat is probably overwhelmed by the fuel and air due to the misfires. So it is likely secondary to the misfires

 

I purchased bg44k today haven’t used it yet. I know Audi newer models have issues with DI fuel systems due to build up on the tip of the injectors and bg44k fixes it. I hope it works for mine

 

Good luck; let us know how it goes.

BTW, it’s generally advised to use BG44K or similar injector cleaner every 3-6months to prevent injector problems. It is well worth it.

 

Fix the misfires and yes probobly injectors. The misfires are killing your cat and why its going rest perf. Because its severe enough to cause damage. After misfires are fixed you may or may not need to replace cat but youll need to see if the code even comes back after repair. Misfires are the #1 cat killer. I can get you a 4 pack of oem injectors for $320 pm if interested