Rep Power: 0

Pretty much since I have had my 06 civic Si I have been chasing the infamous p0172 code (-15 to -30 fuel trim) accompanied by a slightly rough idle with small pops coming from my exhaust. Changed the O2 sensor, check. Replaced MAF sensor, check. Went through my entire intake, cleaned it out and replaced my throttle body did an idle relearn and no difference. Got a used stock intake and made no difference. Switched to eBay injectors for 6 months and recently switched back to OEM ones and there was no difference between the two. Pulled off my fuel rail with the injectors on them, primed my fuel a couple times and didn't see any external leaks on the injectors. Compression test is a strong 180-183 across all cylinders. Adjusted my valves, slapped on a ITM components timing kit (engine has 250k miles on it). My main concern is my buddy's got a sick 04 sti and he's calling me out. My excuse that my car aint running right for the last year is starting to make me sound little silly. 2 shops keeps throwing parts at her with no solution. Any good advice I could use to help diagnose my issue?

https://www.youtube.com/watch?v=FhN8...ature=youtu.be

 
Rep Power: 125

Did you replace with OEM sensors? Honda’s are notorious for not working the cheap aftermarkets.

 
Rep Power: 0

Ordered the MAF and O2 Sensor from my local parts store. The shop replaced my downstream O2 sensor. So to my understanding they are not Honda OEM. I did read somewhere that the MAF sensors are very delicate to CAI and even a pre oiled filter can ruin the sensor and give it false reading. Should I expect 2-4 g/s at idle?

 
Rep Power: 222

Clean the maf sensor, figure out what brand the primary o2 is, if it's not denso change it

 
Rep Power: 0

I bought the Primary O2 Sensor which I know is in fact a Denso sensor. The MAF I cleaned out good with some sensor clean a few days ago when I went through my entire intake. Oh I also forgot I just replaced the PCV valve with a Honda OEM part because it was making a screeching sound but when I changed that out there was no difference.

 
Rep Power: 0

Is the car 100% stock? Mods?

 
Rep Power: 0

All it has is an Ingen CAI which was installed on the car in 2008 from the original owner. I put a stock intake on it and it was still running rich (around -15 to -20 fuel trim). Perhaps a bad tune from the original owner? My rev limiter goes to 8600 which I thought was only 8300 on the Z3s. When I first got the car it has a code P0113 for IAT sensor faulty so I replaced the MAF and the cone air filter and got the code a week later for running rich. I did not take note for what my fuel trims were before unfortunately.

 
Rep Power: 222

If it's been tuned then all bets are off as to why it's acting up

 
Rep Power: 0

Bingo. Thats why I asked about mods. If its been tuned before you dont know what he/they did to it.
I dont believe the cai would make you run rich. In my experience a cai made my car run lean if anything. Was a differnt car ls1 camaro but still.
Look into how its been tuned man.

 
Rep Power: 0

To make it clear I am not sure if the original owner had it tuned or not. I am the 3rd owner and don't have much info other then the car came with a CAI and a HFP kit which I dont know came factory or put on after the fact. I think its going to come down to me getting a ktuner and leaning how to make a custom fuel map. Does the car revving to 8600 pretty much confirmed its been tuned before?

 
Rep Power: 0

I would like to add my VTEC engagement is at the stock 5800 and I have some nasty rev hang as if it wasn't tuned, just my rev limiter is at 8600. If it was tuned it would have been in 2006-2008. The second owner of the car just used it as a daily commuter and thought hitting vtec was breaking the motor.

 
Rep Power: 222

If 8600 isn't the stock redline then it points to something going on. The original owner might have even had a turbo on the car, and then put it back to stock when he sold it/traded it in

 
Rep Power: 0

Perhaps you are right although I have an update. I took a multi meter and probed the back of my MAP sensor with the ground and the sensor wire and didn't get a value over 1.1V. I revved up to 3000RPM, gave some quick shots of gas and did not get consistent readings at all. Its the only sensor I haven't replaced on this car yet perhaps that could have been an oversight?