[TonyPa]

Is this normal? 1989 302FI.
When I first start my truck up, especially in the morning, it goes up to 2000 rpm, and seems to stay there a few seconds or so, until the oil pressure builds, then goes to normal. Just seems high to me. Always idles great, and shifts fine. Just that initial start seems high to me. Unless that is normal?

 

[BroncoJoe19]

2000 seems a little high to me, you may look for a little vacuum leak. Maybe the PCV valve is loose.

I just checked mine and at 33 degrees it started and high idled at 1400 - 1500 rpm

 

[TonyPa]

2000 seems a little high to me, you may look for a little vacuum leak. Maybe the PCV valve is loose.

I just checked mine and at 33 degrees it started and high idled at 1400 - 1500 rpm

I'll check around for a leak. It only goes to 2000 for a max of 3 seconds when cold. Then idles perfect. Seemed high to me also. Kind of scares me...

 

[SCRebel]

Cold start on a frosty morning mine idles at 1700-1800.

 

[Elway]

Sounds pretty typical for an older vehicle. I usually just give it a little rev and it comes right down. My 1980 Pontiac Firebird did the same thing, as did my dad's 74 Camaro. I seem to remember a thread about this a year or so ago. hmmmmm

 

[TonyPa]

Mine does it even when it is warm out. just seems to go to 2000 just for about 3 seconds, then drops down. Then does what is supposed to. Just that first 3 seconds makes me raise my eyebrows!

 

[TheUnforgiven]

where does it settle after that 3 seconds?

many people here have trucks that high idle at 2k rpm. my bronco did, in fact the colder it was, the longer it would stay there. a quick blip of the throttle would bring it down.

 

[Gacknar]

2,000 for three seconds seems a little odd.

Normal would be 1,600-1,800 for 10 to 20 seconds. This is a cold start strategy the EEC uses to use the exhaust to help heat the HEGO up.

I would run a KOEO test.
http://www.oldfuelinjection.com/?p=13

And check the voltage to the TPS.
http://www.oldfuelinjection.com/index.php?p=30

 

[TonyPa]

where does it settle after that 3 seconds?

many people here have trucks that high idle at 2k rpm. my bronco did, in fact the colder it was, the longer it would stay there. a quick blip of the throttle would bring it down.

Okay, I went and checked it. It went to 2000 for the 3 seconds, then drops to 1400, 1200, then after a short period down to 750. very smooth idle.

 

[BroncoJoe19]

Typically a high idle is due to a vacuum leak. Also I've seen 2000 rpm idles due to a faulty TPS.

You might try pulling codes.
You may want to check the vacuum line to the MAP sensor.

 

[TonyPa]

Typically a high idle is due to a vacuum leak. Also I've seen 2000 rpm idles due to a faulty TPS.

You might try pulling codes.
You may want to check the vacuum line to the MAP sensor.

I will have to check it out. Maybe I will have advance down the street here, run the codes. I did start it today, and when it hit 2000, I gave it a quick "blip", and it dropped right away.

 

[TonyPa]

Check base timing (read the VECI label under the hood), then read this caption:



If cleaning helps, replace it. They don't last long after being cleaned.

I will check that article out right now. Thanks very much!

 

[JKossarides]

Tony Pa:

I don't know if you've seen this before,

There is a Ford Racing Performance Parts "idle setting procedure" Instruction Sheet (Techline (800) FORD788) steps 1-9 on How To adjust idle by disconnecting the IAC using the throttle body idle stop screw, drilling out the mounting screw holes on a newer "plug & play" TPS so you can adjust it for voltage setting.

In the past the ideal setting was thought to be .93-.97 volts or just under 1 volt but recently posted information regarding this appears the setting should be between .55v-.75 volts.

Posted by FSB member Jermil01 recently:

Wanted to update this thread based on some TPS adjustment information I got from one of my tuning sites. This goes against the conventional wisdom of setting the TPS closer to .95 range. Thoughts??

Regarding any ECU controlled function (and idling conditions in particular), before any strategy based adjustment can be made by a computer controlled system, it must first run somewhat normally in a default and OL mode.

To do this with a FORD you must first follow a few rules.

You must keep the TPS input above the deadband area and below the "tip in" area. On a FORD this equates to below approximately 0.9V and above 0.45. Anything above 0.90V the ECU thinks the throttle is starting to open. This brings into affect possible dashpot and fuel cut strategies which can turn one grey real fast. Below approx 0.40-0.45V the system suspects an incorrect input and substitutes a default figure.

So first off, the TPS should be set to around 0.55-0.75V. You can also disconnect the IAC then disconnect the battery for 15-20 minutes, reconnect and the computer should default back to factory settings.

Good Luck ~ :thumbup

 

[BroncoJoe19]

JK,
I have read a number of posts that recommend NOT changing the throttle body stop screw.
It seems to me, that recommendation is the absolute last resort, certainly not the first thing to look at.
I don't have any personal experience with that. Most people who I have helped with a high idle found the issue to be something different.

 

[azdesertdweller]

i'm havin the same problems....'cept it stays 13-15 hundred after initial warm-up.....so fer me its probably a vacuum line or 3....on a side note...that initial high idle really annoys me,as there is little oil in the heads....im just sayin

 

[sneal46]

The 351 in my 88 does this exact thing as well. Starts up at 1800 then kicks down to 1000 or so after a few seconds. Never thought about checking for a vacuum leak. Nice little thread. This is the type of thing that forums are so good for...

 

[azdesertdweller]

ya, mines been idleing at 650 700 rpm for years,now after i been working on it ....starts off 1800+...then drops to 1300+ and stays,i'm fairly sure its vacuum lines,problem is ,my hearing is shot,if i cant see it or feel it,its hard for me to locate it,but hey no worries....its just a matter of time till i figure it out....

 

[SCRebel]

Normal would be 1,600-1,800 for 10 to 20 seconds. This is a cold start strategy the EEC uses to use the exhaust to help heat the HEGO up.

This is what mine does on a cold day. However during the summer it starts at 1500, for about 5-8 sec, then slowly and constantly idles down till it hits 600 rpm.

 

[JKossarides]

I've been flamed before regarding this and I understand the "racing application" may not apply with respect to .55v-.75 volt setting for a stock engine though many here have stoker racing style engines where it might apply ? BUT the .93-.97 volt setting has been "touted" by every top guru on this site for quite some time so I don't see an issue with that.

With regards to the throttle body idle stop screw and IAC, that procedure was posted when I first joined FSB by a member who said he was Certified Ford Tech and that's the way they did it at the Ford Dealership but that it was for "baseline idle". As I've always stated if you decide to turn the scew make sure you either count the protrouding screw threads on either side of the TB block or mark it with chaulk for reference in order to put it back the way it was AND I have to believe the screw can be zeroed out to factory spec's, more then likely they way they designed it IMO.

It doesn't take a genius to figure out that Ford Motor Co. wouldn't have wasted money for tool and dye on a small intricate spring loaded screw and threading for tens of thousands of vehicles if it weren't supposed to be "functional", why not just mgf. a "fixed length idle stop STUD" instead and eliminate any confusion.

As for disconnecting the battery to default to OEM factory settings, what happens when you swap in a new battery and the BKO has been disconnected for more then a half hour or so.......?

It's probably better to use a Ford Code Reader to clear codes but I've done all of them a number of times and I've never had any issues or problems so I'll stack my engines performance against anyone's, maybe it's just fear of the unkown....lol lol

Do I get it right all the time, no but neither does anyone else here so perhaps this will make everyone more comfortable: :doh0715:

http://www.fullsizebronco.com/forum/showthread.php?t=203080

Good Luck ~ :thumbup

 

[azdesertdweller]

still on it

ok....assuming i fixed all the air leaks(i'm looking at everything,)timing light goes on driver side bank front plug wire(no.1)disconnect spout at distributor....set to 10 degrees BTDC......if this doesnt drop my idle,i still have an air leak right?...i just did a major trip on my cooling system(radiator fanclutch,thermo,freeze plugs,and i wanna get this idle adjusted right before i road test it,got to get past emmissions(late already)