astrochild7

iTrader: (3)

full port and polish intake/ exhaust mani... upgraded compressor... all emmissions removed including bac.... ttwin scroll removed.... soleinoid rack removed... idle hanging around 1600 1700 will not drop. set tps 3 times on hot eng. throttle cable loose. tried to drop idle with low throttle on safc. can't find any vacuum leaks... all put together with new gaskets/adhesive. can't seem to get idle to drop one bit... holds steady. out of idea's please help...

AreExSeven

Lol.
Sounds like me.

New rebuild, started up the first time and the idle bounces like crazy in 500 rpm sweeps. I triple checked the vacuum lines, and everything I were it is supposed to be. I removed the ACV and replaced with a block off plate and it still did it. I replaced the intake manifolds with jspec ones with resurfaced at a machine shop to insure proper mating. New gaskets, new everything. Still has the same problem. I let it break in for 300 miles hoping it would die down a little. Its still as strong as ever. I adjusted the tps 10 times over, still did it. My next step is going to be replacing the vacuum lines with silicon ones, and removing everything that isn't necessary for the car to run.

I've about had it too.

kep0ne

check your bac...clean it up, lube it, check it with 12v voltage...my wandering idle cleared up after that.

also follow FSM procedures for setting idle.

HAILERS

astrochild7
Make sure the throttle stop screw is not holding the throttle plates open. Make a intercooler bypass so you can adjust and check the linkage without the intercooler on the engine. See J-RATs post on this site today.

That up and down is strange. Almost like vacuum is being pulled on a hose that should not get vacuum. Hard to say which if most have been pulled off and done away with.

You might try capping off all four of the nipples on the aft side of the throttle body and the three on the front of the throttle body to eliminate those and go from there if it stops cycling after that step. Just a thought.

astrochild7

iTrader: (3)

bac is gone...

only vacuum's used> 1 on the front for oil meter's..
1 on rear for fuel pressure reg..
1 on passenger side for boost sensor/factory recirculating valve. all the rest are capped....
the idle dosn't go down and up it's diff erent every time i start it.. but usually 1500 or 1600rpm....
as far as i can tell the butterflies are closed as far as i can go with out stalling. it's got to do somthing with fuel.??? but how do i lwer the fuel input????
tps was off but now is good no change in idle...

kep0ne

may be a TPS with bad values...warm up the engine and double check that.

pengarufoo

if you suspect fuel, and you are controlling the a/f ratio at idle via s-afc or other controller, perhaps you have it running too lean @ idle. Do you have an a/f ratio gauge that you can watch at idle?

A lean ratio will make the rpm high, until it gets so lean it can't run... rich will make it drop til it is so rich it bogs. On the NA's you can use the air/fuel mixture potentiometer to demonstrate this, it effects the idle rpm, significantly even. I doubt this is your problem but if you've exhausted everything else it might be worth verifying. I'm not sure if the turbo's have that a/f ratio pot also, I'm only experienced with my NA.

HAILERS

Yup. The 87turboii has the variable resistor also. The turboii likes to idle with a rich mixture. Using a wideband I don't run idle any leaner than 13afr. Anything leaner than that starts causing a bumpy idle that likes to die on you if you get too close to 14afr.

Henrik

Its not fuel related - too much fuel will not cause your idle to be high. You are getting air past the butterflies somehow. Have you set the clearances of the plates? I had to do this when I cleaned my throttlebody. Before adjusting, I could not get my idle below 1500 or so.

Henrik
87TII

AreExSeven

I think thats addressed at my fluctuating problem. Anyone know how I got about doing this? Do I just cap them all off? Do I have to plug the lines that went to them? Is it safe to run the car w/o vacuum to those things? (ie oil injector spider)

astrochild7

iTrader: (3)

tomarrow i'm going to check the clearances on the butterflies. the other thing i thought of was the bypass hose that came out of the back of the intercooler that went to the intake mani.. i capped it ... maybee i could add that back on to add more air and richen the air mixture....
with that variable resister.... i've been told by multiple people not to touch that, unless i had it hooked up to a wideband.. don't have yet.... i.ve seen people screw up cars that way.. i think if all else fails i'm going to finish with my new blitz sbc. and take it to ralph at excessive and let him fine tune it... not a rotary genius yet... just aspiring.... my only other concern is that every time i went to adjust my tps at normal opp.. temps i would get a diff reading every time... going to get a better meter.... still looking for ideas...

HAILERS

1. The hose on the back of a 87 turboii is a air feed hose for the Air Supply Valve. It's used only during pwr steering on a 87. That's when that valve opens and Takes air from the intercooler.

2. I'd suggest taking the intercooler off and setting it to the side. Then read the latest post by J-RAT where he is using a couple of pieces of pvc to replace the intercooler. You do that so you can work on the engine while it's running.

3. You need to check the throttle stop screw and make sure it's not holding the throttle open. I'd do that prior to pulling the throttle body and checking the throttle plates. Also get a mirrior and look at your fast idle cam and see if it's coming off the roll pin and holding the throttle open (I forgot what you've removed).

4. I'd buy me a can or two of starter fluid and spray the turbo inlet duct and try to find air leaks.

5. Just now re-reading your first post, and the remarks about the tps varying........I'll bet money the problem is indeed with the fast idle cam/thermowax on the rear of the throttle body. Mal adjusted. The cam is riding on the roll pin and that's why the tps value is changing on you. The thermowax is causing the throttle linkage to move, which in turn changes the tps plunger in/out stroke/movement.

5. VAriable resistor is not brain science. But also not your high idle problem. Just turn it back where you found it if you mess with it. Also you could put a wire tap on it and look at the voltage prior to messing with it, and then put it back to the same output voltage when thru.

6. That's why the engine should be HOT when adjusting the tps or going back later to look at it. Water temp effect the tps reading if the car is not HOT. In the morning with a cold car, my tps has a output of 1.90 volts. After the car warms up the value is 1 volt give or take .05. See what I mean???

7. Keep in mind......tps setting does not/should not effect the idle speed. Unless the screw is cranked in sooo damn far it does make the throttle linkage move. But that should Never be the case.