I have a loping idle problem on my 98 Civic with a LS swap ,obd1
I have searched and tried all of these : cleaned,tested and swapped IAC valve- cleaned and adjusted FIT valve- checked for vaccum leaks (with carb cleaner and a gauge)-cleaned throttle body-bleed coolant 4 times-checked throttle cable-adjusted idle screw on top of throttle body-checked timing(ignition and the belt)-changed plugs, wires, cap, button, fuel filter and pcv valve-checked connectors going to sensors to make sure they were correct-tested TPS-and swapped ECU's . After all this the idle still jumps between 800-1250 rpms. It has been doing this since the I did the swap in early January. It did not do this in the previous vehicle it was in. I am out of ideas , any help would be appreciated.

 

bump

 

Sounds like your in the same situation as me .................bump for some input .

 

Are you sure about the Idle screw, it sounds like the idle it is set too low.

 

the same outcome with the idle screw all the way in and all way out and everywhere between

 

first unplug your iac valve and set the idle to 1000 rpm with vehicle cold. if that does not solve the problem you may have to adjust the tps with the vehicle running until the surging stops.

 

What kind of cams you running? Back when I used to have a 00 Si with JUN cams it would idle funny, but not terrible. Changed out my ECU to a chipped one and the idle was really rough.

 

quick thought do a ohm check on the wires from connector to connector on the IAC circuit maybe make sure no bad/weak conn from computer to IAC?

 

I set the idle with iac disconnected but did not work, have not adjusted tps how would i do that?

 

I have stock cams , the 1st ecu was chipped and was the ecu that was with the motor when it was in the previous vehicle

 

I jumped the terminals at the ecu for the iac and heard it click when it was grounded

 

bump

 

In the same boat as you. Was told a valve adjustment would do the trick. Guess i'll find out friday.

 

you need to remove the throttle body and slot the two breakaway screws. once slotted loosen them enough so that you can rotate it with a little resistance. start the car, let it warm up, rev it up a couple of times. if it surges, rotate the tps until the idle settles. carefully remove throttle body and lock the tps screws.
alot of times the sensor gets tweaked during the motor swap.

 

thanks I will try that this weekend

 

adjusting the iac helped a little, but I noticed it was cracked , so replaced it with the one from my d16 and the problem went away with the stock ecu but not the chipped ecu? also where the iac is set with the stock ecu and no loping idle the voltage reads .17 closed and 4.79 wot? but it idles almost perfect now