[SOLVED] No power, enters limp mode on acceleration

ENGINE/DRIVABILITY

Year/Make/Model: 2013 mazdaspeed 3
Mileage: 141000km
Location: montreal, QC
Concern: No power, enters limp mode(flashing CEL) when trying to accelerate into boost
DTC's: p0401(egr is deleted), p0300, p0442

Modifications
stock sized intake(sure and cobb), autotech hpfp, turbosmart bov 50/50, OCC pcv-> sealed->Manifold+VC->vented occ->intake, cobb RMM, Magnaflow CBE
ECU/Tuning Software: AP V3
Tuner: freektune, ots+ tune (21psi) from couple months ago
Is the concern intermittent? no
Can you duplicate the concern? Yes
Recent Repairs: step colder plugs gapped to .028, valves cleaned, injectors serviced and overspeed seals, coolant thermostat replaced, engine and transmission fluid change.
Correction:

So sunday night i was driving already up to temp, off a stop light i accelerate once it would normally hit boost car feels like its choking and goes even slower. I pull over check things out everything is visually okay. issue persists, i can drive it as long as im in vacuum but i get gapped by semis lol, it is able to make boost if i force it too, made 1psi today. Im thinking its the cats are clogged and tomorrow im going to remove first o2 sensor and start the car to see if it runs better.

cleared the codes and after repeating the issue only codes that come back are p0300 and egr delete, car runs way worse with MAF unplugged so i ruled that out. the car feels like its choking for air, and rough startups as well. LTFT aren't out of the ordinary ranging from +2,-7, and fuel pressure and AFR are normal. Revs also are very slow compared to usual

ill attach a log of limp mode being activated and idling and a video showing it happening, please let me know what you guys think

@Enki @Awafrican @L337TurboZ @StreetSpeed6

 

You've got a vacuum leak somewhere, your STFT is pegged and you're running lean as a result. Check all hoses that connect to intake mani and intake itself, remove the air filter and make sure the straightener hasn't come loose, clean/replace filter, etc.

 

Ill disassemble my intake system tmr and recheck all hoses, everything visually looks proper. I don't understand how a vacuum leak would cause limp mode tho it feels more serious.
do you think the cat could be a problem as well?

 

Unlikely. Engine is wanting more fuel for the air it's getting, so either you've got an injector down (doesn't sound like it in the video) or a massive tear/hole/crack in something.

Not sure how your cat could instantly clog after doing the stuff you did to it, but did it start immediately after that? Did you do anything behind the engine at all (to the turbo/downpipe/etc)?

 

I haven't done anything to the exhaust system or turbo, it came with the CBE, ill look for leaks. Limp mode is always followed by a p0300, what ive been reading is the cat doesn't let air flow through so it throws off the fuel system could be the cause for p0300, also read that only the o2 sensors affect airflow, still trying to figure all this out. I just wanted to ask for a help to get a better understanding of what I should be doing tmr when diagnosing

 

O2 sensors have absolutely nothing at all to do with airflow, so not sure where you got that. How long before you started having issues did you make any repairs or adjustments to anything under the hood/to the engine?

 

o2 adjust AFR not airflow*, the last thing i did personally wan install the catch can on my VC probably more then a month ago now. But i had it at a mechanics on friday to get the thermostat replaced, but i drove almost 400km after that before this issue came up.

so I checked things out today, no vacuum leaks from what I can tell, exhaust smells awful and there wasn't much pressure coming out the exhaust. I checked the heat pre cat at the top of the manifold and it was 270c ash and after the first cat it was 170c. I didn't disconnect any of the exhaust because the bolts are all rusted to shit and need to see how I'm going to get them off.
Is it possible airs not flowing out of the exhaust and causing it to go back into the cylinders which then causes the STFT to be pegged? @Enki

 

Unlikely if it's lean. Even then, it should be registering a reduction in airflow at the MAF if flow is terrible so should auto-compensate for that. Did you pull the intake filter and make sure the straightener wasn't in there sideways or something?

 

My MAF screws into a solid map housing from sure motorsports, its a solid metal piece that has no play in it.

 

Never underestimate the ability of sure to make garbage

 

Beautifully packaged garbage.

 

It same with the car lol ive heard that sure is garbage, probably why they don't exist anymore
ill check it out tmr

Flaps are not bent i just went out and looked, nothing is blocking the air into the engine

 

Did you check and/or clean the filter too?

 

filter is basically brand new it probably has 2000km on it, its good

 

So have you performed an actual boost leak test? This might not be your only problem but I'm pretty certain that boost issues can cause limp mode at times. Like Enki said, your stft is going way out but I would check for a bad vacuum line off the turbo and then check your bov for leaks. My bov used to leak, which drove me crazy, so I am now rocking no bov (not recommended really lol).

I'm not a tuner but looks like your AFRs get leaner instead of richer as you near zero vacuum which seems odd. Usually they start to richen up I thought until boost which then should stay around 11.5-7 around wot. The primary (first) o2 sensor is the one reading your afrs. The secondary is for the cat to make sure it is working.

 

If this were me, I'd disassemble all couplers between intake mani and air filter, inspect each one, check the intake mani for potential gasket issues, etc.

 

I removed my first o2 sensor today and it instantly started to run better and rev more freely, the hole where the sensor would be let the exhaust gasses out and it relieved the access back pressure

 

Well cut that cat out and be done with it lol

https://eccppautoparts.com/ss-racin...NbqGTSujwyq7hFbvqMSkyxtjH_A6h1DRoCZE0QAvD_BwE
This will give you a good start and if you need cats again then just buy them and add them onto it. It's your more cost effective option.

 

I took out the o2 sensor and the car ran better and there was a lot of exhaust gasses pushing out of the o2 sensor so pretty clear to me something is clogged in there.

Cpe catted downpipe incoming

 

In extreme cases exhaust back pressure can cause bad enough reversion to be an actual problem. Hopefully this fixes it!