teknics

Ok so i have an 89 T2, just got it last week.



It idles rather high 99% of the time, I'm talking 1500-1700RPMs.



I was trying to narrow down what could be causing the idle problem by seeing what would affect it. the only thing I've found however is something that makes absolutely NO sense to me.



If i'm idling (at 1500ishRPMs) and put on the A/C, the idle drops down to about 1000-1100 rpms. but not everytime, if i leave the a/c on after a while the trick stops working and it goes back up to 1500-1700rpms.



does anyone have any clue as to what would cause this?



any possibilty it could be linked to injectors because the car does run really rich, and im trying to figure out if leaky inj = high idle, perhaps.



kevin.

pengaru

vac leaks, tps, dirty/broken bacv



It's not surprising that turning the ac on will drop the idle, the hatch defroster will probably do something similar. It's putting a load on the engine.

MazdaEnthused

lights.. steering... a/c, hatch defroster all bog down mine too... but it seems to idle real nice warmed up ... you gotta stop back by peng.

teknics

havent tried the hatch defroster, but nothing so far but the a/c brings it down.



there's no rats nest left on my car so there's not many vac lines to check, i'll check them, and evilt2 (former owner) checked and fiddled with the tps but said it did no good.



how would i check the bacv, im sorta in a rush or id look the website lol.



kevin.

evilT2

oh yea, just to let you know, the acv or bac, i forget which one you adjust, has been adjusted to the lowest idle setting possible.

Pazuzu

The TPS???



Step 1: check the BAC. When the engines warmed up, pull the electrical connection to the BAC. Does the idle drop/change? Put all electrical loadsef on (brights, AC, refrost, radio), does idle drop severely or does it pretty much stay constant?

Step 2: timing

Step 3: idle level. Jumper the check connector, and adjust the idle screw till you can get in the 700-800 range, if that's possible. Disconnect jumper, check idle speed

Step 4: TPS. Adjust TPS

Step 5: Vacuum lines, check all and all intake manifold interfaces



This should solve things, unless you have actual broken components.

evilT2

nothing ever happened when i disconnected the bac it just sat there doing the same thing it always did.



tps made little difference, as did timing. i just adjusted the timing with a light and lined up the marks on the front pulley



the only thing you could do to get it idling properly was to feather the clutch and get the rpms down low (7-800) and then they would stay there like it was idling normally.

pengaru

check if the throttle is binding up on anything when the car is running, maybe the dashpot is sticky, or the cable.

evilT2

checked all of that, took off the tb and reset all the screws to allow for minimum idle, even poked at the throttle best i could with a screwdriver (ic in the way) when it was running to see if it would calm down.

teknics

could it be the cruise control? i just noticed today it doesnt seem to work (i dont know how to set it up so it could be me being stupid) so possibly it's causing it to stay revved?



kevin.