Low/rough idle
#2
Look at your throttle Body. The large, rectangular aluminum boc the large air tube which runs from the MAF (where the air filter is), across the top of the radiator, and into. Just above where the air tube enters, on the metal it fits into, there is a large screw, just to the left of center, as you face the engine from the front. Remove the large screw. It's a cover protecting the Idle Adjust Screw. A somewhat smaller screw down inside, under the large screw cover will now be visible. This is the Idle Adjust Screw.
If you tighten the IAS down in, the idle should slow down. If you back it out, or unscrew it, the idle should speed up. If the idle doesn't change properly as you adjust the IAS, try screwing it all the way out, and examining the o-ring on the bottom of it. If it's damaged, or destroyed, replace it, making sure to clean out all the bits and chunks of o-ring down inside the place the IAS is. These o-rings are readily available at most auto parts and hardware stores. Put the new one on, after covering with a thin coating of Vaseline or silicone dielectric grease. The grease or Vaseline not only makes the rubber of the o-ring last a lot longer, it also makes for a much better seal.
Idle RPM should be 800-850. Make sure to use an external tachometer, not the one on the dash panel. The integral ones are notoriously inaccurate. Set the RPM with the IAS, and the install the large cover screw. Make sure the truck is totally warmed up. Drive it around the block a few times, make a run to the store, whatever. Anything to make certain it's good and warm before you try to adjust the idle RPM.
Does this all help any?
Pat☺
If you tighten the IAS down in, the idle should slow down. If you back it out, or unscrew it, the idle should speed up. If the idle doesn't change properly as you adjust the IAS, try screwing it all the way out, and examining the o-ring on the bottom of it. If it's damaged, or destroyed, replace it, making sure to clean out all the bits and chunks of o-ring down inside the place the IAS is. These o-rings are readily available at most auto parts and hardware stores. Put the new one on, after covering with a thin coating of Vaseline or silicone dielectric grease. The grease or Vaseline not only makes the rubber of the o-ring last a lot longer, it also makes for a much better seal.
Idle RPM should be 800-850. Make sure to use an external tachometer, not the one on the dash panel. The integral ones are notoriously inaccurate. Set the RPM with the IAS, and the install the large cover screw. Make sure the truck is totally warmed up. Drive it around the block a few times, make a run to the store, whatever. Anything to make certain it's good and warm before you try to adjust the idle RPM.
Does this all help any?
Pat☺
Last edited by 2ToyGuy; Jun 6, 2023 at 12:04 PM.
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