My engine runs great, plenty of power. However, whenever I shift, I usually shift at about 2-2500 RPM. The problem is this, when i push the clutch in to shift at 2-2500, the engine takes FOREVER to reduce RPMs so that I can let the clutch out and speed/match the engine and tranny for a smooth/quick shift into the next gear. It literally takes 6 or so seconds for the engine to go back to idle when at 2500 RPMs, but only when I shift. If i rev it up to 2500 in neutral, then let it go it comes down normally. If I wind it out and shift at say 4-5 grand, the RPMs come right back down. It only does this at the 2-2500RPM shift range. I do take my foot off the gas when i shift, so it's not me. Is the computer doing something it's not suppose to? This is really annoying because I have the habit of using hte clutch to force the engine RPM down so i can shift at a decent speed(quickness), if I wait, it takes me forever to shift. And therefore I am wearing out my clutch faster than normal. There is no way the engine can coast itself from 2500-700rpm in 6 seconds, something is making it reduce RPMs slowly, so I suspect the computer or something else. What do you guys think?


*this is at normal operating temperature.


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster American Thunder Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

That's it for mods now, saving for a Stang. Check out my Gallery for a look-see.

 

Idle Speed Control sticking? You know the little thing that raises the engine rpm when you have the A/C on? Could be sticking or the throttle body is sticking. Try to lube up the throttle body shaft. Also check the spring while you are at it. Just a couple of thoughts.

 

You know how when you start the truck when it's cold, the computer holds the RPMs at around 1500 for a few molments, and then it comes down. Mine seems to stay at 1500 when it's cold for awhile, longer than my other 95 300/6 did. Could that have anything to do with it? Even if i go to take off while it's still holding the 1500 rpm, it'll go right along in 1st gear at 1500 and not slow down, and if I push the brake to force the truck to slow down, it'll fight it until the computer desides to drop the idle RPMs to 700 after a lil bit. The problem i described above in the other post happens at all times, even when hot. How do I check to see if the idle speed control is sticking? Would reading the computer codes help? And how do I check that spring?


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster American Thunder Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

That's it for mods now, saving for a Stang. Check out my Gallery for a look-see.

 

My f150 was doing the same thing, except it wouldn't idle down at all. If I was driving down the road at 2000 rpm and stopped at a red light, it would stay at 2000rpm until I let the clutch out again. Which was kinda hairy when a cop stopped beside me at the redlights because it has true duals with 12" glasspacks

My TPS sensor was bad. After I replaced it the engine idles down just like it is supposed to. The TPS is attached to the bottom of the throttle body.

Jon
1989 F-150 XL- 4x4, 302, M50D
1995 Bronco Eddie Bauer- 351W, E40D

 

Well, I don't have the problem were it won't go down, it just takes to long to go down. 2000 is abnormal for idle, 1500 isn't, because the computer holds the 1500 when you start it while cold, so it can warm up a minute. It'll hold the RPMs for about a minute or a few seconds more, which I think it abnormal, I don't remember my old truck taking that long so i wondered if that had anything to do with my shifting problem. It's normal to have it hold 1500 for a few seconds when you start it while it's cold, but, I just don't think holding it over a minute is normal for the computer to do.


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster American Thunder Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

That's it for mods now, saving for a Stang. Check out my Gallery for a look-see.

 

I would also say your TB. I had the same problem but it stayed around 2600rpm and the check engine light would not come on all the time. There not that expensive so you mightice well give it a try.

 

How do I lube the throttle body shaft and how do I check the idle speed control? I don't notice any raised RPMs when the A/C is on....never did in my other F-150 either. What do you mean by "i would say it's the TB"... Throttle body, but how? Explain yourself please. Thanks.



Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster American Thunder Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

That's it for mods now, saving for a Stang. Check out my Gallery for a look-see.

 

 

Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

Thats it for now, saving for a stang. Check out my Gallery for a look-see.


Justin

 

I was driving last night at about 40mph, put the clutch in and put it into neutral to coast because there was a stoplight coming up. The engine went down from 1900 to 1500 rpm and just stayed there for about 3-4 seconds until I hit the brakes. Once I hit the brake it went down to idle. How weird is that? Would the computer make a code even if the light on the dash doesn't come on?


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

Thats it for now, saving for a stang. Check out my Gallery for a look-see.


Justin - One Happy FTE Member

 

I would have the computer scanned. Not just a code reader but actually scanned while the problem is occurring.

'fenders

 

Justin:

I can't say I know exactly what's happening with your truck, but mine did have some of the same troubles with what appeared to be the throttle sticking (I'd have to stab the accelerator at a red light to get it to idle down). I removed the plastic cover that houses the throttle shaft at the end of the accelerator cable and coated the shaft with Teflon spray. This seemed to help (I'd already cleaned the throttle body, so I know it wasn't a carbon ridge or anything causing the throttle plates to stick open.) I also noticed that there was an adjustment screw that allowed me to fine tune the idle speed, so I took care of that while I was under the cover. You mentioned something that is making me wonder...... when you hit the brakes, the truck idled down. This makes me wonder that your problem isn't vacuum related (when you stepped on the pedal, the booster drew vacuum from the engine, and you may have either sealed or created a vacuum leak.) I know my EEC raises the engine idle speed to create more vacuum when it doesn't detect enough (I think around 16" is the magic number). Could it be that you have a leak somewhere on the engine or in the booster, itself? Perhaps, when you stepped on the pedal just right, it sealed the leak and made the EEC happy, thus resulting in it lowering your idle speed back to where it should be? Just a thought or two......

 

Well, that braking thing only happeneed once, and I think it was just a concidence that I hit the brake and the RPM went down at the same time. It hasn't happened before or after that.


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

Thats it for now, saving for a stang. Check out my Gallery for a look-see.


Justin - One Happy FTE Member

 

Gotcha..... I can appreciate what a pain that has to be. As mentioned in the prior post, a full blown diagnostic check of EVERYTHING would probably be in order. Your peace of mind (and loss of aggravation) would be worth the money spent.

 

my 89 f150 does the same thing. but when i turn the heat or ac on the truck just goes dead unless you keep it reved up. when i first crank it up in the morning it goes dead. the second time it shoots up to about 1500 and stays for about a minute then goes back down to idle and runs smooth. whats wrong here.