Engine Idle Wrong After Swapping

[BrownDog]

hey guys,

i have a 1995 BA Astina, and i just replaced the dead motor with one from a 1991 BG. so far all works except for a small leak with the rocker cover gasket. Now my main problem is that when its cold it idles around 2,000 RPM and when its warm it idles at about 1,500 RPM.

If you tap the throttle it goes down to 800 RPM and then goes back up, how do i fix this

[TheMAN]

are you using the intake manifold from your BA or is it the BG one? The BG one won't work

check to see if the throttle sensor is adjusted correctly... also check the throttle cable tension.. too tight and it will pull the throttle open
also check for vacuum leaks!

[BrownDog]

no its the ba one, if i remove the plug from it, it idles right but stalls when you open the throttle, the cable is loose enough not to open it

[TheMAN]

sounds like the throttle sensor is out of adjustment then

[BrownDog]

how do i go about adjusting that

[TheMAN]

you'll need to check the specs and instructions in the shop manual unfortunately

[Clean_Cookie]

Ive got the specs for the ba here, I found I needed a new iac valve, but you put it in diagnostic mode to set base idle with the screw, it'll self adjust without putting it in unfortunately...

[BrownDog]

righto, just gotta find a manual on how to do that

[BrownDog]

actually if you got time tomorow i need someone to help bleed the brakes

[Clean_Cookie]

Working all.day. if you come down to brissy I can help on Saturday though. There's an explanation posted today! Short 10 and ground, then adjust then turn off and remove jumper.

[BrownDog]

nah its not road worthy yet, where is the screw located

[Clean_Cookie]

On the throttle body, near the throttle cable.

[Kevaclone]

Originally Posted by Clean_Cookie

On the throttle body, near the throttle cable.

This problem doesn't seem to be that straight forward
The engine sits on about 1300rpm once at operating temp, IF you don't do anything from first start up
if you load the engine up(like ride the clutch a bit etc) the engine drops to a normal 900rpm
if you touch the throttle at all it climbs again and won't drop below 1300 again

leaking vacuum hose maybe or maybe the aftermarket cruise control unit has a vacuum leak?

[Clean_Cookie]

Iac valve. Happened to me. After it was cleaned with maf cleaner I had to adjust the screw higher...

[BrownDog]

Where would all the vacuum outlets be

[Clean_Cookie]

Intake manifold.

[Cosmo Dude]

Originally Posted by BrownDog

Where would all the vacuum outlets be

All of the black hoses that connect to your engine either have vacuum or water. None of them should leak.

[BrownDog]

Okay, so i replaced a vacuum hose that was cracked a bit, and made no difference except now Im able to adjust the idle in diagnostic mode, so now it tries to idle at ~900, and by tries it fluctuates up and down, however if you push the clutch right in and not load the motor it idles fine

[Clean_Cookie]

Adjust clutch?

[Rupewrecht]

IAC valve.