Code help h55 and h64
 

So my car is throwing codes h55 and h64. It's riding rough around 3000 rpms and the power seems limited.

Anyone familiar with this problem?

Re: Code help h55 and h64
 

We're two! See my thread here:

http://www.zr1.net/forum/showthread.php?t=26445

Keep me updated if you find something! Are your codes intermittent? What year is your ZR-1?

EDIT: I searched and I noticed yours is a 1991, just like mine.

Take also a look at this thread there:

http://www.corvetteforum.com/forums/...-and-64-a.html

Changing my o2 sensors is my next step.

Re: Code help h55 and h64
 

Seems like it's either the O2 sensor or ecm, leaning towards ecm since it feels like power mode is not getting selected. Does that make sense?

Re: Code help h55 and h64
 

What do you mean by "power mode is not getting selected"? For your information, when you got a SES light, you can't enable "Full engine power".

Re: Code help h55 and h64
 

I think if there is an issue with the ecm it can result in the power mode being "unselectable"

Interestingly I drove it again this morning and it seemed to run fine, now I'm wondering how far to push it before diving in deeper.

Re: Code help h55 and h64
 

If the check engine light is on, the ECM won't let full power mode turn on, even if the code is not related to the secondary system.

Re: Code help h55 and h64
 

Swapped out the injectors and all is good now....!

Re: Code help h55 and h64
 

For future reference, the GM Service Technology Group Fuel and Emissions Course handbook, states that Code 55 is "Fuel Lean Monitor" It gives 3 possible causes
1. Secondary ignition insulation fault
2. Lean Injector
3. Inlet filter restriction to injector.

Code 64 is "right Oxygen Sensor signal-lean"
It gives several causes one of which is injector restriction - right bank

So it looks to me like you nailed it by changing out the offending injector. Good work.