The cursed idle!!!!
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From: Auburn/ Opelika
The cursed idle!!!!
OK, here goes guys; recently replaced my IAC to correct my idle problem- it works. But on start up, it still rises to 1,000 rpm and sticks til you give it gas and only when you give it gas. Last nite I was leaving the movies and it stayed at 1,000 rpm when I had returned to drive from reverse. My dad thinks 1,000 rpm is the normal idle speed- I do not b/c when it stuck last nite it was too much throttle for the 'creeping' speed when leaving the movies. (I was not pressing gas, it was going by itself til I corrected it by shifting to neutral and back to drive.) Sometimes it does it, sometimes it does not, does not seem to be linked with engine temp. So, I have the following questions:
1. What is the correct idle speed for a 351W 5.8L?
2. What else could contribute to the dilema since the IAC is out?
3. When in tunnel-like places (self car wash for example) the engine noise is applified and I hear a plastic ticking from the right side of engine- my car/ truck buddies have said it is a possible exhast leak and I concur. Yay or nay?
4. Is ticking noise a possible culprit?
Thanks for reading this and any info that you can give me.
-William
1. What is the correct idle speed for a 351W 5.8L?
2. What else could contribute to the dilema since the IAC is out?
3. When in tunnel-like places (self car wash for example) the engine noise is applified and I hear a plastic ticking from the right side of engine- my car/ truck buddies have said it is a possible exhast leak and I concur. Yay or nay?
4. Is ticking noise a possible culprit?
Thanks for reading this and any info that you can give me.
-William
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Joined: Dec 2003
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From: Miami
Your butterfly's could be hanging open a little. The next time it happens pop the hood and pull the throttle linkage to the fully stopped position and see if she drops down! I had to put an additional spring on mine to help it. Normal idle for an auto is I believe 675 to 725 in park and 625 in gear. You have a sticker under your hood that has a vaccum diagram for your emmisions. Read that and it will tell you exactly where your idle sould be. As far as your ticking goes, it very well could be exhaust and it could be as simple as a strand from your belt that is slapping something during rotation, could be a noisy injector, could be alotta things. Start crawling around and try to find exactly where it is. I just hope the little ELF'S are'nt back!!!!!!
She Ain't Revved Ti'll The Rods Are Thrown!
Al
She Ain't Revved Ti'll The Rods Are Thrown!
Al
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From: Auburn/ Opelika
Nah, those little boogers got exterminated. 
'Stopped' postion as in wide open throttle or push it to 'close' it? Noisy injector...sounds costly. I'll crawl around next time I can.
Thanks Al.
-William
'Stopped' postion as in wide open throttle or push it to 'close' it? Noisy injector...sounds costly. I'll crawl around next time I can. Thanks Al.
-William
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From: Auburn/ Opelika
Looked under hood for the sticker and it does not have a vacuum diagram. Only has belt diagram, jack instructions and the one about the fuel cut off switch. The belt on there is pretty new, I'd be surprised if it was breaking up......unless the mechanics put a lousy one on there. -William
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From: Miami
Pull the throttle linkage to the closed position. I would find someone on the site with a 5.8 that has the diagram, it is either on the air box or on the under side of the hood. The numbers I gave you are probably it though. Go buy a mechanic's stethascope with a long probe on it, and play doctor! They are very cheap and can pin point the noise. Place it on the injectors, exhaust manifold, valve covers, you find the noise and alot others!
She Ain't Revved Ti'll The Rods Are Thrown!
Al
She Ain't Revved Ti'll The Rods Are Thrown!
Al
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Your idle sounds normal to me. Almost any vehicle is going to idle at a faster rate when the engine is cold. When you get into your truck do you give it time to warm up? After a minute or two the idle should drop down.
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From: Auburn/ Opelika
I've tried that and it doesn't seem to do the job. Maybe I'll give that another shot. It seems to do it always, even after it's warmed up. Who knows. -William
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Joined: Apr 2003
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From: Chicago
Mine does it hot or cold. Obviously, it does it longer when it is cold but on a hot start, I still have to blip the throttle to get the idle down before I shift into gear otherwise it hits hard. I'd love to know what the **** this truck's problem is.
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Long ago when my truck was in warranity, the dealership techs pulled alot of hair with fast idle. They just started changing parts.
Fast idle was solved when they replaced the TPS throttle positioning sensor.
Gosh I miss the carbs. Good luck........
Fast idle was solved when they replaced the TPS throttle positioning sensor.
Gosh I miss the carbs. Good luck........
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Joined: Aug 2003
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From: Sacramento,Ca
Originally posted by Goldenace
Long ago when my truck was in warranity, the dealership techs pulled alot of hair with fast idle. They just started changing parts.
Fast idle was solved when they replaced the TPS throttle positioning sensor.
Gosh I miss the carbs. Good luck........
Long ago when my truck was in warranity, the dealership techs pulled alot of hair with fast idle. They just started changing parts.
Fast idle was solved when they replaced the TPS throttle positioning sensor.
Gosh I miss the carbs. Good luck........
brand new i may add. im gonna have to take it back to my carb guy which is a drive for me, but owell. seems like this is a common problem with the 5.8's. Sean
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From: Auburn/ Opelika
Ok, guys just played around with it literally minutes ago. I turned the idle down by turning that screw on the tb linkage, I noticed an immediate difference in the engine's overall 'attitude'. I don't know if I 'loosened' it too much as I have just done it and I myself haven't been able to adjust to the engine. I can't tell what is normal and what's not (yet), as it is a copmpletely different engine. Here is a list of stuff I've noticed:
1. rpm drops way faster when I let off the gas, it's expected b/c I lowered the rpm. How fast should this be? Any 'red flags' in this area? I really don't want her in the shop.
2. When braking I thought I had to give it more pedal to completely stop, again, I can't tell if this is normal or not. It could be me b/c I haven't adjusted yet so I can't tell.
3. The low end torque I was wondering about has been found, significant increase in acceleration from 0 to 40+. If I did it too much will there be a accel diff. in the 65+ range?
4. Anything else yall can tell me if I've adjusted it too much.
Thanks to all who have posted for the great info!!!! One less thing on the repair list if it doesn't act up over the w/e. lol. Keep me posted. Thanks again.
-William
1. rpm drops way faster when I let off the gas, it's expected b/c I lowered the rpm. How fast should this be? Any 'red flags' in this area? I really don't want her in the shop.
2. When braking I thought I had to give it more pedal to completely stop, again, I can't tell if this is normal or not. It could be me b/c I haven't adjusted yet so I can't tell.
3. The low end torque I was wondering about has been found, significant increase in acceleration from 0 to 40+. If I did it too much will there be a accel diff. in the 65+ range?
4. Anything else yall can tell me if I've adjusted it too much.
Thanks to all who have posted for the great info!!!! One less thing on the repair list if it doesn't act up over the w/e. lol. Keep me posted. Thanks again.
-William
Fleet Mechanic
Joined: Aug 2001
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From: Round Rock, TX
You adjusted the idle air stop. You typically would not adjust this.
What you should probably look into is the TPS voltage at idle. There are three wires going into the TPS--a ground, a reference voltage, and a signal line. I forget right now which one is the signal. With the engine off, check the voltage between the ground and signal wire--should be less than 1.0V. I like to have it around 0.97V. If for any reason (the throttle body doesn't always go back to the same idle rest position, etc.) it is at 1.0V or above, you will get a high/weird idle. My throttle body doesn't always go back to the same position, so I put it around 0.97V. You may want to put that idle air stop screw back where it was originally and check the TPS. If the TPS voltage isn't just right, simply loosen the screws on it and adjust it. You will have to remove the throttle body to adjust the screws, but not to test it.
What you should probably look into is the TPS voltage at idle. There are three wires going into the TPS--a ground, a reference voltage, and a signal line. I forget right now which one is the signal. With the engine off, check the voltage between the ground and signal wire--should be less than 1.0V. I like to have it around 0.97V. If for any reason (the throttle body doesn't always go back to the same idle rest position, etc.) it is at 1.0V or above, you will get a high/weird idle. My throttle body doesn't always go back to the same position, so I put it around 0.97V. You may want to put that idle air stop screw back where it was originally and check the TPS. If the TPS voltage isn't just right, simply loosen the screws on it and adjust it. You will have to remove the throttle body to adjust the screws, but not to test it.
Fleet Mechanic
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From: Round Rock, TX
The TPS is on the bottom of the throttle body. The end of the throttle shaft goes into the TPS. The holes in the TPS that the screws go through are larger than the screws, so if you slightly loosen the screws you can rotate the TPS until it reads the way you want at idle and then you just tighten them down.
It's pretty easy. All you need to check it is a digital multimeter set to volts. If you need to make adjustments, you must need a 10mm socket to remove the throttle body and a phillips screwdriver to loosen the TPS screws. You can probably be checked and adjusted in about 10 minutes.
It's pretty easy. All you need to check it is a digital multimeter set to volts. If you need to make adjustments, you must need a 10mm socket to remove the throttle body and a phillips screwdriver to loosen the TPS screws. You can probably be checked and adjusted in about 10 minutes.
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