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.

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.

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.

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.

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.

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.

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.

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

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.

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.

ok fixed it https://www.nopistons.com/forums/pub...IR#>/smile.png



i'm not sure of the proper name for what i adjusted but here goes:



There's a threaded bolt (no head, threaded with a slit in top) that has a nut put on top to hold it in place. The job of the bolt is to specify the throttle's closed position. i simply removed the nut, turned out the bolt a bit, tested it's idle, put the bolt back on and walah, a perfect 900 rpm idle https://www.nopistons.com/forums/pub...IR#>/smile.png. (800 seemed low)



kevin.

https://www.nopistons.com/forums/pub...1047683561.gif well, you're a better man than i

lol i was staring at the TB for a while, i felt stupified, i just kept opening and closing the throttle couldnt find anything that would do any good.



thn i saw this little crusty looking screw, and it all hit me in a flash lol.



now im designing a boost controller, it's only cost $4.74 so far and with the extra hose ya gave me i shouldnt have to pay for hose until the testing period is over.



kevin.

home depot racing boost controllers are great in the cold weather. you are gonna end up like freestyle if you are not careful

plz go to ebay and get a turboxs MBC.... less than 100 bux shipped.....

well i think im going to have to buy one off ebay or something.... im go9ing to make a topic about what happened with my mbc thing as im confused as hell and think it might be linked to my mods.



kevin.

The screw you found is called the idle stop speed screw. I think.

thermo wax ???



my is fucked so Ihave adjusted it to the minimum and now the car idle well.



my 2 cents



chicoutimi

what is the stock idle setting with a warm engine (in rpms)?

i believe its supposed to be 750rpms

sweet, good to hear u solved the problem

750rpm is factory idle setting with no load

if you need a boost controller i can send you one of those ebay special jobs i originally got for an audi i had. never used it but it looks fairly reliable. its the ball and spring setup.

that would be great https://www.nopistons.com/forums/pub...IR#>/smile.png



kevin.

750rpm? hmm gotta play with the screw.



oh and to whoever said it, yea i think it';s the idle stop screw, inmy head i was thinking throttle stop screw.



kevin.

same ****..