I have a 94 Civic Cx with a jdm b16a. I recently had a pr3 ecu and my knock sensor is shot so vtec wouldn't work. Long story short, I just picked up a p28 and vtec kicks in hard but my car seems to idle way lower. Close to 500rpm.

And randomly(about after 25-30 min of driving)code 21 and code 43 will pop up. It will also start to lag after this, like as if you we're in 5th at 20mph.

What all does code 43 deal with? and what could cause this?

 

CEL 43 is the fuel system.....I'm going through the same BS right now, lol check out my cel thread for help.

 

90% of the time that CEL is caused by a slightly faulty Primary O2 or the wiring for it.
7% of the time Fuel filter
2% fuel pump
1% serious WTF moment

NOTE: one of the WTF moments that I've seen personally... really poor tuning.

 

Thanks Relic. It hasn't been on today but still my idle is lower with the p28.

Any idea why its like this and why would the cel come on randomly if its a faulty 02? Wouldn't it come on at start up.

 

Bump for answers.

 

Wow, that's a seriously precise breakdown for code 43. What was the sample size?

Now the service manual isn't always right, but it suggests that if code 43 is accompanied by driveability issues, then you should check the fuel system. I would suggest that you measure the fuel pressure. Maybe fuel filter is clogged or a fuel injector isn't working.