Why won't my IAC counts go down ?

[turbotaone]

I just got my engine back together after replacing the head
gaskets. The only thing that I changed was I had the heads
ported while I had it apart. Now the IAC counts won't go below
60 no matter what I do. I've checked all the grounds, I've set
the TPS up and down, I even replaced the IAC valve, nothing
seems to help. Right after I replaced the IAC valve I thought that
I had it fixed, the counts went down to around 25, but when I
took it for a drive the car ran very bad, it would bog if I tired to
exelerate quickly. The car was running very rough and would not build any boost. I brought it home and parked it because I was
tired of messing with it. So I go out and start it today and let it
warm up and the IAC is back up to 80. I checked my TPS and it is
at 40, so I start adjusting it up and down a little, but it did not
help. I get the car where it sounds like it is idling normal and
when I look at the IAC counts they are between 60-90. I did
notice that when I set the idle up high the car seems to rev real
smooth(no bog or hesitation)when I stab the throttle.

What else can I try

Thanks
James

 

[milesengineer2]

James,

I am fighting the same exact battle right now. I thought of replacing the IAC but if you did to no avail, then I think I am wasting my time as well. The only thing that I did was put in a RED armstrong chip. I am running 009's.
Anyway, I tried to adjust my IAC and when I get it close, 23 or so, my TPS is around 58-65. Then when I adjust the TPS where it should be the IAC goes up to 60-80.
Vacuum leak maybe? I cant figure it out either. It is really frustrating and when I take it for a drive, it bogs and dies. The only other thing that I can think of is plugs or wires.
Does fuel pressure have any bearing on IAC at all? I have my FP set at 43 with line off.
I know this didnt help but maybe two brains are actually better than one.



Lee

 

[turbotaone]

Hi Lee, sorry to here that you are having the same problem, I
know how frustating it can be. I also have a Reds 93 chip and
009's, but the car ran fine before I took it apart. I've sprayed the
engine with carb cleaner while it was running in hopes of finding
a vacuum leak, I've adjusted the fuel pressure up and down. I
have new plugs and wires on the car also. I don't know what else
to check. Hopefully someone that has had this very same problem
and solved it will chime in and help us both out.

James

 

[milesengineer2]

James,

I just had my TB apart, I am wondering something, what about the gasket on the IAC? Can it be reused? Another thing, what about proper torque on the IAC. Vacuum leak around either of these might cause a problem..


Points to ponder, back to the garage to check the Helms manual on torque.

 

[turbotaone]

Lee, you may be on to something , I took my plenum and T/B off
in one piece, and while I had it off I was looking through the
under side of the plenum at the T/B alignment and I noticed that
it was a little bit off, so I then broke the T/B loose and twisted
it a little to re-align the two. Maybe this is where I'm getting a
vacuum leak from ?

James

 

[milesengineer2]

I had the same scenario, I am wondering it the gasket between TB and Plenum can be reused. Screw it I am going to buy both gaskets and try that. Seems reasonable.


Lee

 

[turbotaone]

Hey Lee, I pulled my T/B and plenum off last night and put some
gasket sealer on both sides of the gaskets, If one of them was
leaking , I don't think it will now, this permatex gasket sealer is
really sticky stuff. I normally don't use it on my gaskets unless I'm
having a sealing problem, and right now I'm willing to try
anything. Well, we will see what happens tomorrow when I fire
it up again. I'll keep you posted.

James

 

[milesengineer2]

James

I played around with my car last night and pulled the Armstrong chip out and put another chip that I had into the car. All my problems went away.Idle is fine, I am able to set the IAC and TPS properly, dont know if that was the culprit or not, going to do a little more diagnosing today. Do you have another chip for the 009's? If so give it a try.
BTW someone correct me if I am wrong but I dont think that you are supposed to use permatex on the intake, something to do about the gases it emits while drying. But I could be wrong.

 

[turbotaone]

Hey Lee, I'm glad to here that you found your problem. I don't
have another chip to replace my Reds chip, I do have a 107 race
chip that came with the car, but it's a Reds also, maybe I could try
it, although I've never used it before. How old is your Reds chip ?
My Reds chip is only a couple of months old and it worked fine
before I had the engine apart, but it does seem like alot of people
have trouble with his chips, especially with the 009's. I use his
chips because he is only a few miles away and I can get a new
chip for $25 and it only takes a day. I have been thinking about
trying a Jim Testa chip, I hear alot of good things about his chips
and 009's. I started my car today and nothing has changed, I still
can't get the IAC to come down, so it must not have been a
leaking gasket. I think I'll take your advise and try a new chip.
And about the Permatex, it's not a Permatex silicone, it's what the
old timers used to call gasket shellac, and you just put a thin layer
on both sides of the gasket to help them seal better. I've never
heard anything about Permatex giving off gases as it dries, and
I've used Permatex products all over my cars for many years. Hey
wait a minute, that could explain why I'm so goofy ? .

James.

 

[milesengineer2]

James,

I lied!! I started the car today after lunch and it is acting up again. The only thing I have left to look at is the spark plugs. It is really strange. As the computer was learning the new chip it was running good, but as soon as it went into closed loop it goes right back to rough idle, smoking black and missing. I am thinking about going to 50 lb'ers and getting away from 009's. But I am not sure that is the problem either. Back to the drawing boards.



Lee

 

[turbotaone]

Hey Lee, I finally got my problem figured out. Basically I didn't
have the patience that I needed to make the adjustments and I
didn't realize that the TPS and IAC needed to be adjusted
together. What I mean is when you lower the IAC, that in turn
will raise your TPS, so then you have to lower your TPS back
down, now that will allow you to go back and lower your IAC
some more. You will need to go back and forth between the two
and make adjustments in small incruments until you bring the TPS
and IAC down to within their limits. Once you get the two dialed
in you won't believe the difference that it makes, my car idles
good and runs great now. I got some help from zam70 over on
the General Turbo Buick Tech. section, you might want to check
out my thread over there. Good Luck.

James

 

[Razor]

Idle air is the amount of air that bypasses the throttle body to keep your car idling. In other words if you crack the TB open, the IAC goes down. Some chips you must drive around for a while and have the computer relearn the setting. If the IAC is too high, turn the TB screw 1/4-1/2 turn thus opening the blade, reset the tps if needed and drive around a little. Then watch the number with car idling in park. If you turnon lights, AC, fans, anything that slows the motor down, the IAC will go up to maintain the commanded RPM settings of the chip. Typically any number above zero is ok. I usually set mine to 30 ish in park, engine hot. Put it in drive, they go to mid 40's..turn AC on..mid 60's.. make sense?

With a scanmaster, its a piece of cake.