I currently have a 91 Civic hatch with a D16z6 swap. Recently I installed a Skunk chipped ECU with a redline of 8800. It worked fine for the first week but now it won't run above 100mph and it stops gaining rpm's at 7k. Could this be Limp mode? And if it is, would it be possible for the ECU to not throw a code? The pnly code I'm pulling now is 1. thanks

 

Code 1 is a bad O2 sensor. When an OBD-0 ECU switches to 'Limp' mode, the motor will not willingly rev past 3k.

Chances are you are hitting the cold revlimiter - the P28 (stock Z6 ECU) cold revlimit kicks in at 6800 RPM. It's possible your skunk2 ECU is doing the same. Solution: Buy a 'hotter' thermostat.

 

Not running the stock Z6 ECU though, just a rechipped PM6. Seems odd though, I've never had the problem before 2 days ago, and I've had the ECU for a few weeks.

 

I still think the cold revlimiter is what your feeling. Chances are, your thermostat is slowly beginning to lose it's edge - just replace it with a higher temp model and see what happens!