To start with I have a 2003 ap1 with about 61k miles, and about 23k on the motor, as far as i can tell the shop that did the swap was not very good, or the customer was in a pinch, as they swapped almost all the hardware and sensors from the old motor into the new one. Had the water pump fail within 2 weeks of having the car.

I got it about 6 months ago, up until about 3 months ago the car was working perfectly fine. I started to notice that i was redlining at around 86-8700, which i didn’t think much of as i’ve heard of people having similar issues. But over the course of about a week vtec got weaker and weaker, it dropped from redling just below 9k to less than 7k. It wasn’t much longer after that vtec stopped engaging almost entirely, if i put my foot to the floor the car would either rev all the way out without vtec, or occasionally engage vtec and redline at around 6700rpm. For clarification, when i say redline, im saying that the car was “bouncing off limiter” but instead of right at 9k where it should be, its doing it at less than 7k.
It could be misfiring but i honestly don’t know, I will try to take a video when i get the chance. On top of that it is definitely misfiring on downshifts sometimes. I bought a brand new vtec solenoid almost immediately and it only solved the issue of vtec not engaging every time, the car engages vtec with WOT every time now but still redlines just below 7k. With that i also bought brand new ngl spark plugs, a denso fuel pump, a pair of oem cam position sensors, and a brand new one battery from my local dealership. I cleaned my IACV and did valve lash pretty recently too during all of this and noticed that i have 3 different brands of ignition coils, 2 denso, one delphi and one that was completely unmarked, no serial numbers or anything.

I have a set of oem ignition coils on the way but it’s honestly a hail mary, if that doesn’t solve the issue then the car is going to have to sit at my brothers for the next few months until i can work on it again, as im contracted to go to japan for most of fall and winter.

Any info helps!

 

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Did you get any CELs? Is the oil level fine? Is the wire mesh filter in the VTEC solenoid clear of debris?

 

Exhaust or failed/clogged cat?

 

would there be one on my current exhaust setup? I have a old magnaflow on the car right now, it’s probably as old as the car itself