Fast idle after start up (1 Viewer)

[speyrod]

Fast idle after start up (20 miles after)

Ok, everything was fine when I put her down on Saturday. I was good over the weekend and spent it isn the yard, trimming trees, edging, and mowing.... This morning I get in and she starts (just like every am). I get up to a stop sign and something feels different (idle). Well she is still cold, stop light about a mile away, still feels different. I shift to N and she is Idleing at 1800 (normal was 600ish). 20 miles later at the office 1600. No CEL...

Thoughts?

Oh yeah, I searched (quickly), 96' 118, TB cleaned, plugs, cap, rotor @112k.

I'm going to dig around later maybe lunch and listen for a vac leak?

 

[Kaderabek]

Maybe unhook the battery for a while, let the computer reset.

TJK

 

[speyrod]

Little update, problem still persists. I pulled the EFI relay as I thought I read somewhere reeseating it resets the ECU?. Anyway problem is still there, when I first start the engine after sitting 20 mins or so the idle is almost normal then it jumps up.

 

[semlin]

bad water temp control sensor? Should throw a CEL but not necessarily.

 

[landtank]

check your throttle cable. I had one that was slow to return and got varying idle rpms. When it's idling high just pop the hood and see if you can rotate the butterfly to lower the rpms.

 

[zipastro]

This is another issue that I have seen beat to DEATH on the 80's cool board.
conclusions I have seen
1. Its suppose to do that to warm the engine up faster (Load of BS as they did not do it when new)
2. Vacuum leak somewhere.........
3. Bandaid fix is listed at the 80's cool website, couple of O rings on the idle speed plunger(hides the real problem)
4. Throw money into new electronic parts\sensors till the problem is fixed, caution most people go broke before they fix it.
5. Drop it in gear with a quick neutral drop as soon as you start it up.
6. Pretend you do not notice the problem (this is my personal solution)

 

[Cruisin'Carolina]

I thought until I read your posts again that we are experiencing the same thing, but your high idle condition lasts, mine doesn't.

My truck starts up and sets at 1800-2K!, but when put in gear, driven a couple of hundred yards, and returned to neutral....

it is rock steady, smooth and quiet at 600, maybe 650 rpms.....

 

[Darwood]

I thought until I read your posts again that we are experiencing the same thing, but your high idle condition lasts, mine doesn't.

My truck starts up and sets at 1800-2K!, but when put in gear, driven a couple of hundred yards, and returned to neutral....

it is rock steady, smooth and quiet at 600, maybe 650 rpms.....

Mine is doing that too and I can't remember if it did that before I replaced the throttle cable. When I start the truck it shoots up to 1800-2000 rpms as if my foot was on the accelerator and then settles down quickly to 1000 rpms or less. Once the truck is warmed up it idles smoothly at 600 rpms (that is if I don't have my brake lights and turn signal on at the same time, but that's another matter)

I keep thinking that my throttle cable is a little too tight (I like things tight and probably over did it), but wouldn't that keep it from idling at 600 rpms?

 

[semlin]

This is another issue that I have seen beat to DEATH on the 80's cool board.
conclusions I have seen
1. Its suppose to do that to warm the engine up faster (Load of BS as they did not do it when new)
2. Vacuum leak somewhere.........
3. Bandaid fix is listed at the 80's cool website, couple of O rings on the idle speed plunger(hides the real problem)
4. Throw money into new electronic parts\sensors till the problem is fixed, caution most people go broke before they fix it.
5. Drop it in gear with a quick neutral drop as soon as you start it up.
6. Pretend you do not notice the problem (this is my personal solution)

zipastro you are talking about high start up idle. It has been done to death here as well, but I am pretty sure that is not what speyrod is experiencing. He is still at 1600 rpm after 20 miles and when he starts it stops for a moment at a low rev and then jumps up. The "normal" high idle startup will jump to 16-1800 rpm immediately then drop down to 1000 rpm in 100 rpm increments on its own in a minute or two or sooner if you throw it in gear. There are many many posts on it and its possible causes and cures.

Darwood, and cruisin carolina are also talking about high start up idle I think.

 

[speyrod]

Well problem solved I feel like a I had a split in my rubber floor mat and well you get the rest My girl is back to 600 rpm

 

[semlin]

heh, no one thought of that one. I don't like the princess with a split rubber analogy much but glad to hear you are cured