Idle speed -- too high

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Lincolnlov

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Recently Seafomed then replaced the gaskets on the throtle body intake of my 90 LSC. (150K). Also cleaned the egr valve and port as well as the idle control valve and ports. Prior to this cleaning the car idled at a steady 750 rpm in gear. Now its idling at just over 1000. The voltage on the idle control valve reads 0.98. I'm looking for a way to bring the idle speed back to where it was before I messed things up. :confused:
 
Fast idle

Black87LSC said:
Theres an adjustment screw underneath the throttle body, turn it counter-clockwise. You wont need to turn it much, prob 1/4-1/2 turn should do ya
Click to expand...

Yep, tried that one but seems to have no impact on idle speed. It did seem to make a difference in the downshift position of the accel. though. :eek: Now I'm beginning to think that I may have messed up the idle control valve but I'm still looking for ideas. :(
Lincolnlov
 
The idle adjustment won't change the shift position; I think you played with the TV cable. As I recall you need to disconnect the IAC to get the idle to adjust properly.
 
JoshMcMadMac said:
The idle adjustment won't change the shift position; I think you played with the TV cable. As I recall you need to disconnect the IAC to get the idle to adjust properly.
Click to expand...

OK JMMM,
Thanks.
I'll try looking again today. Yesterday I only found one adjustment screw. Perhaps it could have been the TV cable. But, I'll have a closer look in the daylight and try disconnecting the IAC before I try any adjusting.

Lincolnlov
 
The idle adjustment, from the front of the engine, is out of sight. It is on the "back" side of the throttle body, facing the firewall. I think I remember it being something small like an 8mm, but I'd have to check.
 
Fast idle

JoshMcMadMac said:
The idle adjustment, from the front of the engine, is out of sight. It is on the "back" side of the throttle body, facing the firewall. I think I remember it being something small like an 8mm, but I'd have to check.
Click to expand...

Thanx. JMMM.
Soon as the rain stops I'll go out and disconnect the idle control valve and give the adjustment a turn and see what happens. I seem to recall that years ago there was a little "stick-on" paper on the side of the throtle body that said something to the effect the the idle speed could not be adjusted. You recall ever seeing something like that?

Lincolnlov
 
The screw is actually pretty good size, maybe a 12 mm?? Its a hex head with a slot in it. I forgot its on the back side on the marks, it faces the front on my T/C
 
Fast idle

Black87LSC said:
The screw is actually pretty good size, maybe a 12 mm?? Its a hex head with a slot in it. I forgot its on the back side on the marks, it faces the front on my T/C
Click to expand...

Black/JMMM,

Well, no matter what I did to the adjustment screw while the ICV was connected solved the problem. :mad: I couldn't get the in-gear idle speed back down where it belongs even when the screw no longer touched the stop. However, with the ICV disconnected, I was able to adjust the iidle speed back to normal. :eek: But, a rethinking of what I had done provided some insight to the problem. In the cleaning process I had removed and cleaned the metal spacer between the two gaskets where the ICV connects to the TB. During reassembly I had apparently turned it upside down. I removed the ICV inverted the metal spacer (so one of the set screws is visible) and that seems to have solved the problem at least with the engine warm. Gonna let it cool completely and hope that it works properly from a cool start.
Thanks for all your support :)
Lincolnlov
 
Glad to hear it worked out. Seems that I didn't recall the size quite right; do you happen to remember what size the bolt actually is?
 
JoshMcMadMac said:
Glad to hear it worked out. Seems that I didn't recall the size quite right; do you happen to remember what size the bolt actually is?
Click to expand...

JMMM,

Yep sure do. Tried several. The 10mm is too big, 9mm is too small. But, as Goldielocks said -- 3/8 is just right. ;) Still waiting for the cool start to be sure but I'm optimistic that I have found my error.
 
Fast Idle

Yep, sure can use a screwdriver. Or, in my case it'll turn just using thumb and forefinger. Thanks all you guys for your input :)
 
If you messed with the throttle stop screw, you're going to have to re-check your TPS voltage. Just an FYI.
 
Fast idle

NYC LSC said:
If you messed with the throttle stop screw, you're going to have to re-check your TPS voltage. Just an FYI.
Click to expand...

NYC,
The TPS voltage is reading 0.98v. Hope that's within spec. :( because now "my baby" seems to do what it is supposed to at least regarding idle. Oh, NYC, would you by chance know what that metal part is called that sits between the two gaskets where the ICV attaches to the TB?
 
Lincolnlov said:
NYC,
The TPS voltage is reading 0.98v. Hope that's within spec. :( because now "my baby" seems to do what it is supposed to at least regarding idle. Oh, NYC, would you by chance know what that metal part is called that sits between the two gaskets where the ICV attaches to the TB?
Click to expand...

That's fine. As long as it isn't 1.00 and higher at idle. If it gets that high, the computer thinks you're cruising and the idle will raise and lower and the car surges like a mofo.

That plate is the "idle air adjustment spacer". It was used by Ford to correct surging idle problems. There are two hex head screws in that plate that you can adjust the idle with instead of the throttle stop screw so you don't mess with the TPS voltage. I just put one back on my car yesterday because I had funky idle problems. Turns out it was a TPS with two broken wires where it connects to the wiring harness. If you want, I have a 3 sheets that came with the spacer I could take pics of and post.
 
Fast Idle

NYC LSC said:
That's fine. As long as it isn't 1.00 and higher at idle. If it gets that high, the computer thinks you're cruising and the idle will raise and lower and the car surges like a mofo.

That plate is the "idle air adjustment spacer". It was used by Ford to correct surging idle problems. There are two hex head screws in that plate that you can adjust the idle with instead of the throttle stop screw so you don't mess with the TPS voltage. I just put one back on my car yesterday because I had funky idle problems. Turns out it was a TPS with two broken wires where it connects to the wiring harness. If you want, I have a 3 sheets that came with the spacer I could take pics of and post.
Click to expand...
NYC,
Thanks, good to know about the use of the set screws. The IAAS sounds like a name and a part that Ford came up with after the fact. I would appreciate the pix. I try to keep a file of the various parts that I've replaced or tinkered with on my old car so that I can recall how I resolved a problem. I'm old enough to be getting "halfheimers" disease, ya know! :D
 
LOL no problem. I'll post them up later tonight when I get in from work. And yes, there were TSBs or something out about idle problem, so Ford thought up this plate.
 
NYC LSC said:
LOL no problem. I'll post them up later tonight when I get in from work. And yes, there were TSBs or something out about idle problem, so Ford thought up this plate.
Click to expand...
I didn't know about this for a 90 mark. I have hands on with a 1987 doing it. The poor owner couldn't run the car for more than a couple of seconds as it would start and then race to like 3000 rpms. I had to throw my hands up on that one. He later let me know that he, "Cleaned the entire top end". During reassemply he probably corrected the connections and positioning. If/when mine goes on the 90, it will be replaced.
 
OldSchool1 said:
I didn't know about this for a 90 mark. I have hands on with a 1987 doing it. The poor owner couldn't run the car for more than a couple of seconds as it would start and then race to like 3000 rpms. I had to throw my hands up on that one. He later let me know that he, "Cleaned the entire top end". During reassemply he probably corrected the connections and positioning. If/when mine goes on the 90, it will be replaced.
Click to expand...

My old '87 did that, I could never figure it out...:mad: Sometimes it would be fine, and other times it would rev up like what you said
 
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