Hows everyone doing?

First post here on the forum, and was hoping to gain some insight on what's going on my rev up coupe (2005 6MT) From a glance the car definitely has an exhaust leak at the manifold or near it. It starts with no hesitation and idles fine between 650-750 rpms, however when going under load any gear, throttle position, and RPM range the car falls flat on its face (extremely sluggish to get up to speed). And also has misfire p0300 running nearly immediately under load. Things I've addressed to try and correct this issue: ran a compression test ( kind of on the lower side averaging between 150s and 160s, none below minimum though and none with a 15psi difference), changed spark plugs to OEM NGK plugs ( verified gap at .044) and changed valve covers ( heard hissing from the pcv valve and oil leaking from covers so two birds with one stone on that one) also the coil packs are definitely getting replaced ( mismatched between OEM and Amazon brand SMH) have a new OEM set on the way. In addition I've had some strange data readings from the B1 S1 and B2 S1 when driving and at idle their readings are drastically different, ( at WOT at around 3k rpms I'm seeing short term fuel trim on bank 1 at 25% and bank 2 is at -19.5%) of course it's misfiring with this happening. I feel like this is a huge reason my car is acting up, would you guys have any suggestions? Thanks for any input of course.

 

Update**

Ran the STFT data at idle and am coming up with 25% added on Bank 1 (Passenger Side) and varying between 5 and 9% on Bank 2 ( Driver Side). Long term fuel trim on both banks are at 99.2%. Of course it gets much worse under driving conditions for Short Term Trims, I'm thinking maybe clogged cat? Again any input or opinions would definitely be helpful. I'm a bit stumped.

 

Father's truck had the same symptoms and it turned out to be a faulty O2 sensor. No codes for the sensor were thrown, but swapping them out fixed the issue.

 

Thanks for the input man, I thankfully have fixed the problem and it turned out to to be the driver side catalytic converter, the upper core was missing a chunk and presumably clogged the lower core. I swapped out both cats for non damaged ones and she runs great with good power like I'd expect.

 

How did you discover that the catalytic converter is the issue?

 

Sorry if this is a bit long winded in advance lol, but when it first started to misfire I initially did a lot of research on these "Rev Up" engines for the possibilities of their misfiring and found that they like to consume oil due to a design flaw with the piston rings (which would have been worse case scenario) and started off with that compression test, (which thankfully passed), with that out of the way I moved onto fixing any vacuum leaks (changed valve covers and pcv valve) due to them hissing/ leaking oil. This also didn't fix the misfire so I moved onto spark plugs and ignition coils which also did not fix the issue. I then used my handy OBD2 scanner to see exactly what was going on with my fuel since I was able to rule out compression and spark from being the problem, (I initially thought I was possibly dealing with leaking injectors) but then saw that the ECU was adding 25 percent more fuel to one side and subtracting nearly the same amount on the other, I scoured the internet until I found this video talking about a similar occurrence on a Ford V8:


The video is long winded as well but helped me understand a possibility on why fuel was being added a large amount on one bank more and completely opposite on the other bank. In sumed up terms the MAF sensor was seeing a certain amount of air go in and was trying to evenly distribute fuel between both banks but couldn't due to exhaust gasses not being able to flow correctly on one side so made a rich condition on the clogged bank ( tried to subtract fuel on that side to correct hence the -25% in fuel pulled) and created a lean condition on the other bank since air was not being trapped by a bad converter( tried to add fuel to correct the lean condition by adding 25% fuel). After learning all of this I pulled my catalytic converters being suspicious of them and found the driver side converter had a core broken out and clogging the secondary core. Swapped for some brand new test pipes with added rear 02 sensor extensions and instantly got the car running right again with much better power and no more misfiring.