I have a 97 f250 heavy duty with the 5.8l 5 speed. I adjusted the throttle stop screw under the black cover on the throttle body. Then looked down on the air intake hose that goes on to the throttle body and saw a sticker that said "DO NOT CLEAN THROTTLE BODY OR ADJUST IDLE STOP SCREW"

I was like OH NO, what did I do now?
My question is: If anyone has this kind of engine, I was wondering if they could measure between the stop plate and how far the screw is screwed in? And please give me the measurement so I can set it back to normal?

My truck has over 245 thousand miles on it and runs perfect, uses no oil, and is a hard worker pulling gooseneck cattle trailers!

Any help please, I'm new to the forum, in the process of updating as soon as possible.

Thanks!

 

The throttle stop screw is set to a position that produces between 0.9 and 0.99v on the TPS sensor, you will have to probe the TPS wires with small pins and connect a multimeter.

 

The truck idles just fine, dont seem to be any difference, I just turned the screw maybe 1/4 inch of a turn. I dont really want to do anything to the wires to mess them up. Thanks for the reply!

 

Why'd you ask how to fix it if you didn't really want to fix it?

You don't have to screw up the wires; just slide the probes into the open end of the plug and set it up right. Or just give me your truck and I'll take care of it

 

The EFI system takes a reading of the TPS when the key is first turned to run and it uses this as the "baseline" for idle adjustments until the engine is shut off again. The motor will run and idle normally as long that base reading isn't above 1.0v.. which it probably isn't. If it is above 1.0v you will get a check engine light eventually.

 

I just did the same thing to fix the idle in my 89 351. So far no lights... i think it'll be alright.

 

I was just wanting to know what the setting was for the screw from the factory.
Can't give my truck away, it's my best friend lol. We work together!

 

Did you turn the screw too, or the wire test like their talking about?

 

Check your TPS. Like these guys say, its not that big of deal. There is a rubber weather shielding behind the plug that plugs into the TPS. Thats the only way you will get it back to where it should be. You can keep your Multimeter there and turn the screw back out until you are back with in range. You will do no damage to the wiring, or the plug. EFI systems work very well, but you have to keep everything in sync with each other, or else you are asking for problems.

If it was having a rough idle, cleaning the throttle body isn't a bad idea. I have done that on plenty of cars without any negative side effects. With EGR systems in place these days, the throttle body should be cleaned out from time to time. However, I never touch the idle stop screw.

When I am building a project car however, I make sure to put the TPS on, and then check it with a Multimeter to get it with in range. It's a pretty simple process and it will make sure your ECU is getting the correct information so it can make your air:fuel ratio right.

So, grab your multimeter, and check your voltage at idle. If its too high, back the screw off until it reads correctly. Simple as that!

 

You guys are right about checking the voltage output to adjust it properly... problem is, if he didn't know what it was originally reading, using a meter to adjust the sensor isn't going to do him any good. However, setting it to read 0.9v is a good reference as Conanski once told me- problem with that is that you'd have to turn that screw a long way inward to get it to read 0.9v.

Check out this page for more info on the TPS- Ford Fuel Injection » Throttle Position Sensor (TPS)

Also, if you don't know, you can clean the throttle body- just make sure to use TB cleaner [some guys swear by carb cleaner] and don't do any scrubbing. There is a very thin gel type coating on the inside of the TB that allows the butterfly valves to seal- scrubbing will remove the coating and it won't seal properly, which in turn can cause performance issues.

 

How to adjust idle speed (official Ford procedure) - FSB Forums

 

But why were you turning on the screw in the first place if your truck idles fine?

 

Thanks for the replies! I guess I'm going to do the multimeter thing on the TBS and see what happens.

 

I listened to an idiot friend of mine.

 

Did the voltage test and it turned out great. The voltage was 0.97 volts.