Hey all. Just wondering where we should start with this thing. I'm kind of puzzled. We did a bunch of work on my buddy's car in the last few months and he claims there is a loss of power on it. I think it's just a damn autotragic but he's convinced it's lost power since we've done the work. Only code that comes up every now and then is P0420 but that's because we're running a gutted cat.

Transmission blew and previous owner was a filthy liar, so we opted to pull the whole engine and do the timing belt just in case, and trans at the same time.

List of parts done:
Gates timing belt, water pump, tensioner
Full A/C rebuild: Evap, Condenser, R/D, expansion block, 5oz fresh oil and charged with a scale to 19oz
Cam, crank, rear main seals
Valve cover gasket
Spark plugs (Some stock NGK forgot part #)
Camshaft sensor (ADV auto brand. fixed recurring p0341)
ECT Sensor (Broke it while removing engine somehow. Also ADV auto)
Rebuilt Auto trans at a professional shop (USDM trans, not that stupid JDM garbage that spits out 3 codes)
Oil and filter
ATF DW-1 6-7 ish quarts
Front rotors/pads
Front right wheel bearing (was growling and sticking)
VTEC gaskets (also cleaned the solenoid)
Camshaft end plug
Alternator
Battery
Drive belts
Condenser fan motor

All wheels now roll freely after the brake and bearing work. I followed the timing procedure per the shop manual, rotated it through two rotations before pulling the pin etc. The marks lined up perfectly and I even used a sharpie to do additional marks since these can be a pain to time correctly. Starts instantly, runs and shifts super smooth, goes all the way to redline without issue. I'm just not sure if it's in his head since he drove a b20 swapped Integra while his car was down, or maybe cheaping out on the sensors robbed us for performance. Also, if it was a tooth off of timing, would it run so damn smooth? I'm not convinced there's anything wrong with it but I do wanna double check for him. I rock a SOHC ZC EF so his car feels slow regardless. I wanted to get him the upgraded cam but he didn't have enough money after getting raped by a surprise trans failure.

 

Exhaust restriction? You said you gutted the cat though...
OEM O2 sensors?
Previous engine VTEC? PCM incompatibility?

 

Just wanted to say I probably figured it out yesterday. I think it blew the headgasket. It has phantom coolant loss with no leaks anywhere, and it threw p0118. Replaced the coolant temperature sensor with OEM, then refilling and burping coolant got rid of the code. I'm pretty sure the low coolant tripped the code but we wanted to rule it out and get it back to OEM. Tired of working on this car so we might trade it in.

And yeah the oxygen sensors are OEM. It's got the factory engine and PCM.