Fixkick help! High idle and surge...

[Trailkick]

I've got an 89 US Sidekick 1.6 that I just acquired. I bought it with a engine surge and I found the fixkick site which has helped me do some troubleshooting. I started by vacuum testing all the lines and actuators. I can pinch off all the lines and it stays running. I pulled off the isc and put a sheet metal plate in between it and the throttle body. Surge and high idle is still there. I put a piece of duck tape over the hole on the inside of the throttle body for the iac and the engine idled at about 400-500 and the lope went away. Are these the right steps to take, and if so does this mean my iac is bad or not getting to temp?

Here is a video showing what the car was doing. Here

On another point, I ran the car for a couple minutes to see what the temp was at the iac, the tstat housing was getting over 120 using a temperature probe on my ohmeter but the iac housing wasn't even at 85 degrees. Shouldn't it be just as hot as the tstat housing, or does it follow a different coolant path?

[fixkick]

nice work all that.... very nice job
that is the way to fix ths, blocking all air sources
do not forget the TB on this car has an idle stop screw for hot idle duty cycle settings.
i can not help until i know true engine tempratures. this is KEY.
As the engine warms to 180F, as it passes 150F, near, the IAC in the base of the TB closed 100% if not , it will never idle right again.
the loop is the ECu failing to stop air flows with the ISC.


the TBI system is dirty when cold EPA dirty. the TBI uses a wet fuel induction, so to reduce smog they run fast idle for a long time
the TB based IAC does that.
then closes and the ISC takes over.

so what does do hot....??? cold is ok, 2000 rpm is normal but mine was 1500 in summer. dead cold. but varies. by actuals.
does engine reach 180F this is the first key factor.
the video is all cold. why ?

if idle is high hot, ? then block the ISC port like you did above, get about 500rpm even less. hot
if it races still hot, leave the above block in place
now block the iAC. in the base, doing this is tricky. the cover screws can be rusty. or find its port in the upper section
also make sure the TB center gasket is not bad, cracked and sucked in, as most are. this old.

if the ISC is open hot, its bad.

this slide photo is 1991 but the IAC in base is SAME.
http://www.fixkick.com/fresh-air/Slide_S...age_8.html


see those checks?

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the IAC input port on mine is square
seen at 1pm here. left photo, and the radiused port there. clay here will work i think too.

i liked booking at the 3 hole plate only to reduce likelyhood of dropping something in the main air valve bore, throttle valve.
but for sure there are 2 ports. to block, easiest im not sure. luck happens.

[Trailkick]

nice work all that.... very nice job
that is the way to fix ths, blocking all air sources
do not forget the TB on this car has an idle stop screw for hot idle duty cycle settings.
i can not help until i know true engine tempratures. this is KEY.
As the engine warms to 180F, as it passes 150F, near, the IAC in the base of the TB closed 100% if not , it will never idle right again.
the loop is the ECu failing to stop air flows with the ISC.


the TBI system is dirty when cold EPA dirty. the TBI uses a wet fuel induction, so to reduce smog they run fast idle for a long time
the TB based IAC does that.
then closes and the ISC takes over.

so what does do hot....??? cold is ok, 2000 rpm is normal but mine was 1500 in summer. dead cold. but varies. by actuals.
does engine reach 180F this is the first key factor.
the video is all cold. why ?

if idle is high hot, ? then block the ISC port like you did above, get about 500rpm even less. hot
if it races still hot, leave the above block in place
now block the iAC. in the base, doing this is tricky. the cover screws can be rusty. or find its port in the upper section
also make sure the TB center gasket is not bad, cracked and sucked in, as most are. this old.

if the ISC is open hot, its bad.

this slide photo is 1991 but the IAC in base is SAME.
http://www.fixkick.com/fresh-air/Slide_S...age_8.html


see those checks?

---

the IAC input port on mine is square
seen at 1pm here. left photo, and the radiused port there. clay here will work i think too.

i liked booking at the 3 hole plate only to reduce likelyhood of dropping something in the main air valve bore, throttle valve.
but for sure there are 2 ports. to block, easiest im not sure. luck happens.

---

ok, so thats where I got, blocked isc and that didn't change anything, so i covered up the hole on the intake for the iac, with some duck tape and the idle dropped. I just ran it to temp and took temp readings at various placed. If the iac is supposed to get to 150+ it doesn't look like thats happening.

below stat - 175f
above stat - 140f
top radiator tank - 140f
bottom radiator tank - 110f
water pump coolant distribution housing tube - 175f
black hose going to iac - 126f
actual iac housing - 88 f

I tried to unscrew the iac plate and two of the screws rounded off. So if I can't get the plate off, do you think a guy could shoot silicone inside the iac port to block it off, or would that be a bad idea...or is that even my problem

[Trailkick]

I put the duck tape back on the port and adjusted the idle screw to get it around 900rpm for further testing. With the engine idling normal and the port blocked, the iac coolant hose was at 150 and the iac housing showed 128

[fixkick]

175 with any IR pyro gun is 180F. so the stat works. your good,. but what about the ICA tube temps., many times its just a hose blocked.

those 3 screws are a problem.
id find a new TB. (used)
the acutal IAC does not come out. all you can do is see it messup
if trying to get buy, then block the holes, sure RTV.
i find using lots of heat to a screws will get them out. takes care not go get the Alum too hot.
i heat the head real fast for short time then attack them.

---

your IAC IR readings show it blocked, this path
at the hose side or the base gasket under TB is wrong, backward, home made wrong, or blocked.

what if H2O is blocked HERE

http://www.fixkick.com/fresh-air/Slide_S...ge_13.html

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is it a bad IAC or is the water flow blocked.

88F is wrong. (but depend on time running and distance) if 20 miles ran, that is DEAD wrong 88f

you very close to true cause.

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i think the book says it closes at 158f
but every one i measured is 150F. so they do so a tad early, no big surprise.

[Trailkick]

I tested some more after this post. I think when I got 88f I was reading for towards the valve part of the iac, where there probably isn't any coolant flow. I disconnected the hose going to the iac and used a bicycle air pump and pressurized the hose, coolant shot out of the iac. I also did it the other way and coolant shot out of the hose. So it sounds like the iac is junk. I'll shove some jb weld in there, that'l fix anything :-) Thanks for the help.

On another note, would that port being open all the time cause low vacuum? Just wondering if it had anything to do with my weak brakes....

[fixkick]

the ECU likes this air, to start
you will find starting on cold days hard. it will want to flood.
the ECU uses fixed tables for cranking, and expects this valve to be open.
but there are those who have done this , seen 3 .
and they must now crank with foot at 5% throttle.
keep in mind 2, the ECU thinks valve is open and cant use the iSC to control idle (the electric iAC)
so is also a factor after starting
good luck with you car.

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no, the IAC valve will not cause weak brakes.
the vacuum is about 19"
at hot idle.
check vacuum, it will be near that...
weak brakes are , bad brakes, or the booster is dead.
the vacuum check is is very easy the tool is $20
http://www.fixkick.com/tools/vactool1.jpg