I've been experiencing a missfire in 3 cylinders when raining heavy and as most here have dealt with, turn the ignition off to reset. However the other day when merging the hwy at almost full throttle, cylinders 1,4 and 5 missfired on a day with no rain. Took the vehicle to the dealer and the tech ran compression and leak tests. Checked the wires and coils then all normal and said he wanted to check the catylitic converters because of the aftermarket magnaflow exhaust and "back pressure" as he called it. I'm aware of backpressure from our exhaust but to cause a random missfire??
No oxygen sensor codes thrown just the missfireing cylinders.
Fuel pump maybe. CPS? Vacume leak possible. The valve covers were leaking and repaired 6 mnths previous at the dealer.
Anyone have or had the issue? At a loss. Charged $200 to diagnose with no real solution as yet.

 

Checking fuel pressure today....

 

THere on one side, so that bank is in question, check for leaks and swap parts to the other side. Missfire is from low f/a OR high f/a mix. Get some info on the O2 sensors and compare sides to see whats amiss- pun. Woody

 

The're on different sides according to my knowledge.
#1 is passenger side nearest the radiator, #2 and #3 are behind it.
#4 is nearest to the radiator on the driver side, with #5 and #6 behind it.
I am going to check this out though as I have seen two patterns.

 

Hi Waldig. Thxs for ur time. Could you elaborate a little more about weather an O2 sensor can cause a missfire and not throw a code. The dealer just called and said the fuel pressure shows normal and they
say the cats(not sure what bank) are restrictive to the point that they need replaceing. How could a cat cause a missfire? Vandalism?? or is the dealer soaking me? Leak and compression and fuel pressure all normal.
Plug wire and coils normal. Intake and TB seal unchecked.

 

It used to be odd number cylinders on one bank and even number cylinders on the other. Has this changed ? How are our cylinders numbered?

 

Can a catalytic converter cause a missfire if malfunctioning? Need help!!

 

I was wrong, miss read it as 1,3,5...........my bad.

A clogged cat should kill performance a lot, did it? The o2 sensors could change the fuel signal and cause a miss, I had it big time on a hemi durango. It took 2 styles of sensors, three of one???? and one of another that took me a week to find that detail, thanks parts guyz.

Can you get the o2 sensor signals ?? They should give you a bit of information about the F/A ratio and how it THINKS it is doing.

Woody

 

Thxs for the amazing help!!! I guess I'm a little scared at having to replace 2 cats not covered on my warranty. The left bank is clogged and causing a pinging as per my conversation with the shop manager so bingo!! I guess the next logical step is to source a much cheaper replacement cats that work like the oem ones. Can anyone recomend a make and model of cat at a good price? Could I run Hi-flow cats as I have an emission test soon?
I'm already seaching the forum

 

For some reason I think your located in Ontario....right??

 

Checked some posts ....you are local. What about buying the cats from that guy in Vaughan that was parting out his car...(Max). You were asking him for speaker trims. The car is/was sitting near Keele and 7 and I think I pm'ed you his phone number a while back?

 

Great idea! Thxs Sparkie. Your a genius!! Do you have his number?

 

What year is this XF? Isn't the cats covered by an extended warranty?? Sorry but thats the only ideas I have if the cats are nfg...

 

Mine is a 2005 and an american vehicle here in Ontario wich voids warranty
I do have an aftermarket warranty but no coverage for emmissions. Thxs for the
idea.
The dealer next step is to remove the left bank cats and o2 sensors and drive the vehicle. The miss is showing up at 4200rpms. Hopefully it just an o2 sensor.

 

Well, I looks like the catalytic gone as the test showed no missfire right up to redline.
You can see my prob. Does any members know or have installed a high flow or aftewrmarket cat with no o2 sensor or tuning issues. There no way
I can't pay what chrysler asking. Trying to reach Max as Sparkie suggested
with no luck. Will keep trying. A local recker might have the part but $$.
Wondering if anything south of the border?

 

Just pm'd you his phone number again !!
Good luck.

 

So, the update: replaced all 4 cats and she runs like a peach but a new dtc code missfire in cylinder1,2 and 3 on the right bank. Shes not missfireing like before though? Power's good and exhaust note returned however, the engine light returned after deleting the code?? the old o2 sensors were not switched. So the cars back at the dealer.
Thxs to Sparkie for suggesting Max. He was a great help and I recomend his services.
The tech suggested deleting the back cats but not sure about emmissions testing. Can our crossfires
run emissions legal with only 2 cats? I know some srt's have cats deleted but not sure about our N/A's
on the street. I'm liking the exhaust note at present with the magnaflow but with 2 cats??