ok, the motor is in, but the engine searches at idle from about 1000-1700rpms, up and down

any idea what this is?

 

Your throttle cable could be to tight, also your throttle body might have something in it not causing the butterfly valve to close properly.

Inspect the throttle body while running. Make sure nothing is causing it to stick.

 

I;'m quite sure its not!

 

Could also be one of the sensor not hooked up all the way or something.

 

yeah my gs-r is doing the same thing. i just swapped it in. 98 gs-r into 95 hatch runnin 95 ecu..........except thats not my biggest problem. its annoying though

 

adjust the TPS so that it is 0.5v at closed throttle...?

 

you might have a vacuum leak, my friends car was doing the same thing, then realizes he forgot to connect a hose

 

how do i do that?????

 

yeah i have had both happen it could be either the tps wich happen in my car it would fluctuate to crazy number. and a vacme leak from the fast idel valve. just look at the tb and intake manifold for a vacume leak if there is no leak get a multimeter and check for 0.5 volts at idel.

 

if you wanna find a vacuum leak try spraying some propane around the area and listen if hte engine revs increase...

 

Propane!? Dude just use some carb cleaner and spray around your tb gasket and intake manifold gasket.

 

yeah - you could use carbie cleaner - but have you read what it says on some labels!?!?

you dont wanna be spraying carbie cleaner on too many places...

you could use butane??? that's easier

 

Try reseting the ecu. Unplug the ecu let it sit for a minute or so, plug it back in again. Then start you car and let it sit for a good 5-10 min and warm up to operating temp. Dont touch the throttle or anything and have all accersories off. then turn off your car and then on again. My car used to do the same thing sometimes. I checked everything it could be, tps, iac valve, etc... Then i thought it may be becuase i switched my ecu out a few times, and i never give it a chance to read all the sensors. It has seemed to work for me and my freind well. My car hasnt done it since. You should still check everything else.

 

use carb cleaner
dosent hurt anything
i had a vacume leak on my intake manifold was causing a 1500-3000 rpm surge. also my tps sensor was bad but it was the leak that caused the surge.

 

Why are you using a 95 computer on a 98 motor? Did you just not use all of the 98 sensors?