strange idle conditions...
 

88 T2 engine.

TPS is adjusted properly. no obvious vacuum leaks.

RTEK 1.8 all emissions and idle controls removed. atmospheric bov.


when revving down to idle...sometimes the engine will idle at 1,500rpm and pull 350mmhg. other times when revving down it will idle all the way down at 800rpm and only pull 200mmhg.

with initial set coupler jumped it wants to idle more often at 800rpm, however timing changes between the two idle conditions. at 1,500rpm timing is dead on yellow mark. at 800rpm the timing is severely retarded, a few degrees past red mark.

with the initial set coupler unjumped its a 50/50 chance of which rpm it will choose to idle at.

any ideas ?

Shouldn't the timing be dead on the mark when the idle is at 800? Sounds like you need to reset your timing. Once you're sure that's OK, go back and adjust the TPS and then idle speed.

adjusting the timing to align with the yellow mark while the car idled at 800rpm caused the idle to raise until it began to hunt back and forth.

going to spend more time on it in a little while.

ok timing and TPS are now set properly 100%

was running into an issue where the BOV was causing some of the strange idle until i hooked up an additional vacuum line to the rear of it.

it still has a bit of a surging idle...especialy right after it comes off of throttle. it eventually settles down and evens out...but the surging isn't right.