So i have a problem and i searched and got no good answers

On my way to school today and was around 4500 rpm in 5th gear on the highway and it starts misfiring bad. Like it has on occasion misfired but not like this. After getting closer to school and off the highway it misfires like missing a cylinder through every gear.. it gets better at higher rpm and seems worst through 2-4k rpm. Idles fine

This is what I have
99 Civic SI
GSR motor ran fine until now
SI ecu but never had a problem with that
Blox intake manifold
APC fpr

Problems I know of
IAC is out
VSS is out
O2 1 is apparently out
and until today none of this really affected the way it was running

Check engine lights that were being thrown originally are
1- O2 1
9- CYP Cylinder Sensor
14- IAC
17- VSS
45 Fuel system too rich or lean
90- dunno

So here is what I have checked and adjusted.

Checked spark plugs- will change tomorrow seem fine
Lowered fuel pressure seemed to help slightly but can't lower much more
Checked wires seem fine
Reset battery and stopped throwing code 9 45 and 90 so only throwing 1, 14,17

I need help i use this car everyday to get to school and yeah gotta get it fixed.

Thanks guys and sorry if this is a redundant post just couldn't find answers

 

bump

 

update since no one is helping...

I changed the fuel pump tried using the stock FPR
changed the plugs


checked the timing... just dunno what to do

 

I would believe it to be related to O2 sensor, since it's your primary that blew up. My IAC has caused a little stutter issue, but would definitely not hurt at higher RPM (nor lower power of course). VSS just fine, but CYP sensor (assuming it's the crankshaft position sensor) could cause issues definitely. See about fixing the stuff, cheapest to most expensive.

Sup Dallas buddy?

 

I am having the same problem, except my car was not throwing any cels untill it happened. I scanned it and it came up with a misfire in cylinders 1 & 3. I was thinking it is a clogged fuel filter or an injector. But im not 100 % sure.

 

Try removing the iac valve as far as the code 14, clean it with brake parts cleaner and put it back on and see what that does, or just unplug it and see if it's running any smoother with it unplugged, could be a bad iacv.

 

did you do a compression test? I figured out that my problem was burnt valves.

 

The CKP code is most likely the problem. The O2 sensor is a fine tune sensor, and will not cause a major drivability issue. The CKP sensor tells the computer everytime the piston hits top dead center. The car will not run right without that sensor. It sounds like you have some kind of wiring issue since you have so many codes. What do all those codes have in common, look for the source of your problem there.