I swapped an ls motor into my 93 cx hatch but the motor idles funny. I used the stock harness from the cx and I'm using a p28 ecu but I don't really think the ecu is the problem? I was wondering if I have to change the fuel line from an ls integra and replace it or the fuel pump also?

 

Funny idle? What's it do exactly.

 

IACV try that

 

Well, you don't have to replace the fuel line from the pump to the firewall. You could swap the line from the filter to the fuel rail if you really wanted to. If by funny idle you mean it bounces then it could be the fast idle valve or idle air contol valve. Both are easy to fix and if you search you will find a few topics on how to fix both.

 

The motor idles funny like its lacking fuel but when it drives it runs fine and I have seen other hondas with bad IACV but they don't shake as bad or idle as low as mine, and it also turns itself off after warming up a bit, but then it starts right back up.

 

So your idle is really low, low enough to the point that the car shakes. This is the IACV. Take it off and clean the screens. Put it back on and see what happens. If it's still low adjust the screw on the side of hte IACV.

 

iac motors can get gunked up freeze (no in or out movement) or the passage is clogged

 

Idle Air Control Valve, un bolt it and clean the 2 screens off with some brake cleaner. I did it and it helped me! there was a lot of gung built up on the screens. if this doesnt work maybe the FITV.

 

Yeah check both my FITV was copletely backed out of the threading and the plunger fell right out when mine was having an bouncing idle.

 

just a thought, but have you set base idle? if your timing (ignition) is too far advanced it will idle like shit but run great @ higher rpms