I have read different threads on loss of power and after rebuild threads but i can't seem to find anything like my issue.

First of all, before i rebuilded the motor felt week, i was also getting the CEL for the valves stuck open (p2004) along with a misfire at start up (p0301) which was fixed (sparkplugs). The motor was bad, Coolant was leaking into the housings, i had to buy brand new housings, also new water pump housing. The rebuild was a mild port job, pinned, and rotors were machined to fit 13b REW seals. SuperSeals were put in.. Anyways the motor was rebuilded a month ago, after the rebuild i have never had any problems to start (even the first start was at the first crank). Note, I have not tuned it yet, but the problem i have is in mid range rpm.

First gear has power thru all the way, and it feels very good and smooth, but second and third anywere between 5500 to 7000 theres a sudden loss of power, then picks up again all the way to 9000. The motor already has 900 miles since the rebuild, I have not run it hard or raced it, just the couple of times that i was testing it, I been babying it since the rebuild, driving under 5k rpm. I'm not going to drive it hard until i can buy the Cobb and tune it, but this problem is worryng me, and am not sure that it has to do with the tunning, even tho it was mild ported.

What are your opinions on this?

 

You might still have a stuck intake valve (SSV, APV, VDI, etc.). Make sure they are all operating correctly. You could also have a weak fuel pump.

I was experiencing power loss similar to yours after I got my car. The previous owner put a new engine in, but forgot to hook up one of the secondary fuel injectors, so I would check those if I was you. They may have gotten mixed up or one of them might not even be connected like mine.

Who rebuilt/installed your engine?

If you have access to an OBDII reader that reads live data, it would be a good idea to look at your fuel trims when the power loss occurs.

 

if you didn't, you should always clean the intake and all the ports/switching valves while the engine is out, there's no reason not to.

 

what does your engine do when it looses power

 

Thanks guys! We did cleaned all the valves and ports, yesterday we checked the injectors and were fine. Saturday am gonna check the 6ports valves again to make sure they are working properly. I did made some data logs yesterday with the torque app but I'm still trying to figure out how to upload them to the computer. If the AFR measurement on the app is somewhat correct then the problem is too much fuel at that rpm and no air flow. The AFR is on the 14s thru the rpm, once is from 5500 it drops by 6000 is on 11s stays like that and after 7000rpm is back up to 13s-14 which is when the power kicks again.

Luckyboii69- The engine revs fine from low rpms till 5500rpm, when it gets there you feel like it buggs out(chokes) sudden loss of power, till 7000rpm, then the power kicks again, and you feel the pull. I will try to make a video today and post it. Also trying to figure out how to upload the logs.

 

Ok i just got the logs... Still dont know how to upload them here??

 

Ok here is the log i took...

 

The problem was the apv motor. We removed it but left it connected, drove it around and no problems at all. Car runs perfect without it, at the moment its still removed, and the car is fine, so it would stay like that till i get a new apv motor. Thanks for your help.