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Discussion Starter #1
Please help, I'm fairly handy and car savvy. I was getting an issue where sometimes my car would start then shut off immediately and also start to have a rough idle and almost stall at stop lights.My mpg and power seemed to be taking a hit as well. The problem began to happen more frequently, so I decided to change the plugs, fuel and air filters, not much difference. So today I changed the PCV and IAC gasket and figured I'd clean the throttle body and IAC unit as well. All said and done, when I started it up my idle was way too high and wouldn't go down in park or in gear.. Figuring I made a mistake somewhere I did re did everything, now the idle is not as high but still above normal. It seems like the the throttle is sticking, in the body, not the pedal. I didn't mess with the TPS and the IAC seems clean and moves well, hoses seem ok. No idea what it could be aside from the TPS or IAC, any thoughts, advice or troubleshooting ideas wouuld be greatly appreciated.
 

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Check all vacuum hose connections including at the vacuum bus. You might have knocked one off its connector somewhere. Even that little hose coming off the passenger side manifold can make the idle quite higher if it's dislodged, and it's prone to dry rot too. (I replace it in my '90 every other year.) Don't forget to check the U-shaped hose on the speed control unit on the left shock tower as well.

Also, how thoroughly did you clean the throttle body/intake plenum assembly? I cleaned the one in my '88 wagon years ago, and came to find out the throttle plate was worn around the top and bottom and the dirt I removed was the only thing sealing the gap.
 

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Discussion Starter #4
I unplugged the IAC and the idle stays, also when you pull the throttle, it doesn't return to idle position with out manually pushing the throttle back down (doing this under the hood).

I cleaned the TB very thoroughly, checked for vacuum leaks by placing my hand over the TB, plenty of suction and the engine began to die out immediately. I'm really at a loss to what happened from cleaning the IAC and replace the PCV. All I can think of is the TPS has gone bad some how, but i did nothing to it, so i don't understand why that would be the issue.
 

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Discussion Starter #6
When I unplugged the IAC it sounded like it wanted to drop, but only for half a second. I don't know why the throttle doesn't want to return, I was suspecting the TPS, but not really sure. Not sure what you mean about using smoke for vacuum leak check, It's a cold windy day here and I'm out side so I don't know if it would work.
 

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Discussion Starter #7
Quick update, I went and tapped the IAC with a rubber mallet and the idle speed went up, I'm pretty much assuming the IAC is the problem. It's odd cleaning it made it worse but, there is nothing else I can think of. You guys think I should just spring for a new IAC?
 

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When I unplugged the IAC it sounded like it wanted to drop, but only for half a second. I don't know why the throttle doesn't want to return, I was suspecting the TPS, but not really sure. Not sure what you mean about using smoke for vacuum leak check, It's a cold windy day here and I'm out side so I don't know if it would work.
If you click on the link in my last post it explains what to do. Here it is again:

https://www.youtube.com/watch?v=zMok2y05jNE

Quick update, I went and tapped the IAC with a rubber mallet and the idle speed went up, I'm pretty much assuming the IAC is the problem. It's odd cleaning it made it worse but, there is nothing else I can think of. You guys think I should just spring for a new IAC?
Only if it's a Motorcraft
 

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Discussion Starter #10
I did go purchase a new IAC, from pepboys *shame*, only local place that had it in stock. Put it on and not one difference, so i'm gonna say it's not the IAC. It seems like there is play in the throttle line or something, it doesn't want to come back to idle after i pull on the throttle a little. This is all so odd, I'm a missing something? Everything looks like it's hooked up correctly, is there a line or spring that pulls the throttle back to position? Any pics of the IAC area, front back, side to side would be greatly appreciated.

I did this to my brothers 98 escort a couple months ago and had no problems, car ran much better. I have no idea why I'm having such a problem with this.
 

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Check and unhook throttle return spring. Then manually by hand open and close throttle valve checking for shaft or butterfly binding. check also for smooth cable operation from your pedal to throttle valve.
 

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Has It Been That Long?
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I did go purchase a new IAC, from pepboys *shame*, only local place that had it in stock. Put it on and not one difference, so i'm gonna say it's not the IAC. It seems like there is play in the throttle line or something, it doesn't want to come back to idle after i pull on the throttle a little. This is all so odd, I'm a missing something? Everything looks like it's hooked up correctly, is there a line or spring that pulls the throttle back to position? Any pics of the IAC area, front back, side to side would be greatly appreciated.

I did this to my brothers 98 escort a couple months ago and had no problems, car ran much better. I have no idea why I'm having such a problem with this.
We don't say buy a Motorcraft IAC because it's a nice turn of phrase. It's because the other brands don't even work most of the time. So you haven't ruled out the IAC.


Sent from AutoGuide.com Free App
 

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Would a vacuum leak cause the throttle not to return to idle?
No and neither would an IAC. But you haven't ruled the IAC out by doing the opposite of what was advised either. Did you check the throttle return spring or do a smoke test as was also advised?

No offense but at this point why bother to ask for our input at all?
 
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