2006 Civic SI will not rev past 6000 rpm and loses power
 

As the title says, the engine will not rev past 6000 RPM
Seems like the VTEC system has malfunctioned somehow.

I took the VTEC solenoid off the car, put a 12v power on it and it clicks. The filter is clean and looks great.

Once you get to the 6000 RPM area, it feels like the ECU cuts off gasoline injection to the engine and it loses all power.
It wont red line and it will not rev limit nor will the shift limit indicator come on.

No CEL, no problems with the car other than the fact it wont rev past 6000.

I recently changed the oil and oil filter. Also reset the ECU.
Did not fix the problem,. The oil is the correct level. ( It was also doing this before the oil change so I figured changing the oil would fix it)

I thought the VTEC passage was blocked so I started there but now I am starting to think the ECU has gone bad.

Anything left for me to test?
There is no CEL on the car. OBD scan tool shows no errors recorded.
Whatever is happening to the car the ECU is not picking it up.

Re: 2006 Civic SI will not rev past 6000 rpm and loses power
 

Restricted air filter or intake?
Restricted exhaust or cat?

Re: 2006 Civic SI will not rev past 6000 rpm and loses power
 

I will check the air filter and intake tomorrow after I get off work and report back here!

Thank you for the reply . I really appreciate it.

Re: 2006 Civic SI will not rev past 6000 rpm and loses power
 

I ran the car today and the VTEC started working again. No clue what was causing it to not work.
I have a feeling its related to the air conditioner compressor tho.
I was running it without the AC on and its working now.

Might have something to do with AC compressor. I was reading another post from 2011 where another guy had his AC compressor changed and VTEC stopped working.
No clue how they're related but maybe the ECU checks the pressure sensor in the Air conditioner and if it has low pressure it stops the VTEC from working.
That is my theory anyway.

Re: 2006 Civic SI will not rev past 6000 rpm and loses power
 

No, it does not work that way.


If could have some AC related issue, but it cannot disable vtec nor change redline electronically because of AC issue.

Re: 2006 Civic SI will not rev past 6000 rpm and loses power
 

When you run the AC compressor does it cause oil pressure to drop in the engine? I don't have any way to check oil pressure in the engine.
But you'd think if the oil pressure for the engine was low, there would be a CEL error which OBD2 scan reports no errors and no CEL is on.

This is a really weird gremlin. it might be an electrical issue then. either a bad ECU or bad wiring harness going to the VTEC solenoid?

Re: 2006 Civic SI will not rev past 6000 rpm and loses power
 

No.
You can buy a pressure gauge or pressure test kit if you really wanted to.

But if it's all working correctly now, you won't find a problem there LOL
Yes if should set a vtec related code (probably one of the P264x codes) if oil pressure were too low to make the pressure switch change states when vtec was activated.

Doubt it was even vtec related because you don't have any fault codes for it.

Does the problem come back if you drive with the AC on?