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View Full Version : Stuck throttle on '89 SC 5 speed



peacefulruler
08-14-2003, 09:07 PM
Hi, guys;
It'd be great if someone could offer advice on this.
My throttle is stuck, and the engine revs to about 2700 RPM.
I was driving back from lunch and punched it when the light turned green, and now the throttle seems to be stuck.

I shut off the car and restarted it, to no avail.
Any suggestions?

Thanks,
Fred
San Jose, CA

MIKE 38sc
08-14-2003, 09:26 PM
Check and make sure your throttle isnt sticking, if its not your IAC has gone out.

HSKR
08-14-2003, 09:35 PM
Pop you hood and make sure the throttle cable is still attatched to the throttle linkage. If so, check to see if the cable and linkage move freely. Make sure any vacume lines that should be attatched still are(might have blown one off under boost).

peacefulruler
08-17-2003, 12:12 PM
Hi, guys;
I popped the hood, and the whole throttle attachment
and springs still look fine to me. When I flex the spring, the throttle plate sounds like it's flopping inside the housing;
is this normal?
The car is idling about 2200 RPM all the time.

What is an IAC?
Which vacuum lines, and where do they attach?

Thanks for any help you can offer.

MIKE 38sc
08-17-2003, 01:51 PM
No that is not normal.
Pull the intake tube off and look into the throttle body and check the throttle plate it may be loose.

soop
10-22-2003, 04:08 PM
I just bought a '90, 3 weeks ago.

I had the same problem 3 times on the way to work today. I hammered down on the pedal a couple of times and it stopped. Happens when I get into heavy throttle.

What was the cause? Did you find out? I haven't had a chance to check.

BobGPz
10-22-2003, 05:04 PM
Yeah, like Mike said..if it is "flopping" around you need to check out the "Butterfly" (Brass piece) inside of the Throttle Body. Pull intake tube off and see if both screws are still holding the butterfly to the TB shaft. Make sure they are tight. If they came loose you may need to adjust it into place before tightening. Hope a screw didn't get sucked down into the motor. Ouch!

soop
10-22-2003, 10:34 PM
Well...the butterfly is intact. I used spray lube on the linkage and spring and it did it again on the way home. One punch on the pedal and it stopped. What's sticking?

I'm not yet very familiar with the intakes on these yet, and how the boost is controlled.

It seems like a boost thing.

BobGPz
10-23-2003, 08:38 AM
Hmmm..
Beats me, if the linkage, cable, spring assembly is good and the TB Butterfly is fine then it has to be binding up somewhere...foot pedal (Inside the car) isn't sticking on floor mat or something is it?

1QuikV6
10-23-2003, 09:06 AM
Im leaning towards it being his High idle electronic choke that keeps the car at high idle when its still cold. Maybe its hanging up. Could also be a sensor.

soop
10-23-2003, 03:02 PM
Originally posted by BobGPz
Hmmm..
Beats me, if the linkage, cable, spring assembly is good and the TB Butterfly is fine then it has to be binding up somewhere...foot pedal (Inside the car) isn't sticking on floor mat or something is it?

Nah. Wish it were that simple. What regulates the pressure from the blower? Is there a valve or gate?

Lber1568
10-23-2003, 03:24 PM
My 92 SC 5 speed did same thing except mine was about 3000 rpm. Idle Air Controller was broke. Make sure you get the right controller. I looked at 3 different ones before bowing out for OEM. The aftermarket ones were built backwards

Bacondoggy
10-23-2003, 06:18 PM
just replaced my iac today and that was a main cause for my problems. tell you what you do - remove the IAC (it is on the right attatched to the TB) by two 8mm bolts. Now, put a thin piece of cardboard as a gasket kind of but with no holes in to bypass the IAC totally (screw the iac back into the tb so the pressure keeps the cardboard between, sealing off the iac completley from the tb). now see if the car's rpm drops.
Also, while the IAC is out, you can do 2 things to test it.

#1 measure the resistance between the two terminals. it is not plus and minus they are connected. my 2 bad iac's made that beeping sound (to let you know that it is one connection), but the brand new one from ford did also, but I got a 10.0 on the voltmeter. So I realized that the bad ones were shorted out.

#2 this is more practical. put your mouth on the one hole and make sure your lips are sealed and blow... :eek: what's wrong with you guys (perverts)... no seriouslly, if the IAC is bad you will be able to make air go through the other side (make sure it is going from before the throttle plate to the other side, and not visa-versa). both my bad ones did that. if the seal is good, you wouldn't be able to empty your lungs. Oh - heh - and you may want to clean the IAC off b4 you do that - I didn't really care - I like the taste of dirt haha j/k

hope this helps

ps - go for FORD - it may be more expensive, but none of the other ones work right

soop
10-23-2003, 09:10 PM
Hey Bacon, RAM AIR working for you? ;D

Thanks for the info. So you want me to get intimate with an IAC?

Yeah, I've replaced the IAC in the LX. The Neihoff unit just didn't look quality, not to mention it mounts backwards.

This would affect it at 2500-3000 RPM under throttle ya think?



Originally posted by Bacondoggy
just replaced my iac today and that was a main cause for my problems. tell you what you do - remove the IAC (it is on the right attatched to the TB) by two 8mm bolts. Now, put a thin piece of ...

snip

... your lungs. Oh - heh - and you may want to clean the IAC off b4 you do that - I didn't really care - I like the taste of dirt haha j/k

hope this helps

ps - go for FORD - it may be more expensive, but none of the other ones work right

1QuikV6
10-24-2003, 03:38 PM
So Bacon, does your car enjoy getting blown by its driver? muahahaha.. on a serious side thats some insightful advice. mine isnt really acting up but im gonna look into it before it goes to crap on me.

Bacondoggy
10-24-2003, 04:42 PM
since my car is a GIRL I am sure she doesn't mind - I do drive her hard and fast and she seems to enjoy it...

but hes I think the IAC's primary use is just for idling... I think there is a debate wether or not it opens at WOT to allow some extra air in. From what I have seen almost all rough/high idles the IAC is the culprit...


ps. oh and soop - I don't even have ram air on my car - I just thought that was fun to try to be the only one to support a theory because everyone else was believing it (I am not saying its right or wrong I don't care :D ) I root for the Marlins... hahaha I like the underdogs

soop
10-24-2003, 06:03 PM
Originally posted by Bacondoggy
ps. oh and soop - I don't even have ram air on my car - I just thought that was fun to try to be the only one to support a theory because everyone else was believing it (I am not saying its right or wrong I don't care :D ) I root for the Marlins... hahaha I like the underdogs

Yeah, I know. Just messin' with ya. ;)

MIKE 38sc
10-24-2003, 06:27 PM
Your problem is the IAC. When the diaphram ruptures you wi get an idle from 1500-3000 RPM depending on how large the rupture is.
Yours is large. Get a new Ford IAC the aftermarket ones do not work.:)