I have been having this problem a while now and can't seem to figure it out.
I did several searches and can't find anything, here goes:

When i drive along the highway the car runs normal, vtec engages as it should and everything but once i release the gas and let the car decelerate in gear CEL comes on and stays on and vtec doesn't work.
Once i turn off the car and start back up CEL goes off..

I did not get the code because when i turn off and jump service connector, no CEL is found.
Can i jump the service connector while the car is running?
I think that is the only way that i would be able to get the code.

Background:

Engine is OBD1 B16a
I changed knock sensor and speed sensor thinking that might be the problem (had those parts lying around)
I have an A/F gauge that is hooked up to the O2 sensor and the gauge works fine, just sometimes takes a few second to read. (i'm hoping the sensor is going bad and causing this problem)
I swapped out the vtec solenoid as well and still same problem.

I run a chipped P30 with a stock B18C type r map but I have a spare virgin brain that i tried in the car and resulted in the same problem so i ruled out the brain..

Anyone ever came across this problem?

Any help would be greatly appreciated.

Thanks

 

yes you can check it while running

 

thanks. will get code and hopefully solve..

 

got codes 17 (VSS) and 36 (traction control)
i know the vss is working because it was changed and the speedo is working so i', gonna rewire from the sensor to the ecu.
concerning the traction control, i check my abs codes and got about 6 of them. gonna start from the basics and change the relay, clean the sensors and work my way up from there. will post as i go along just for anyone else who might run into the same problem in the future..