Hello,
I'm a new member here and was hoping I could get some advice.
My truck is running in high idle after I changed out my sparkplugs in order to correct an engine misfire.

This is everything I did:
- Installed new sparkplugs (NGK plugs)
- Replaced sparkplug wires and coil wire with NGK wire kit
- Replaced Distributor and Rotor
- Replaced PCV Valve

My misfire is now gone however the truck now runs in high idle.
I looked for any vaccum lines that may not be connected and can't see any. The air filter looks clean and I don't see anything obvious that would be causing this. I was thinking that I should try to adjust the idle but I heard never to do that on a fuel injected engine.
The truck is a 1996 Dodge ram 1500 with 3.9L engine V6
Any help is greatly appreciated. Thanks for reading.

 

disconnect the battery for a few minutes to reset the PCM, hook it back up, and restart the motor. See if that doesn't help.

Make sure nothing is holding the throttle open either....

 

I recently changed out my plugs & had the same issue, & I run 3.9 2001 ram. The main vacuum on the side of the TB got left off by me, I checked all other vacuum hoses instead of the most obvious then DER - there I was with a fixed truck.

 

Thank you very much for your advice Peshewa and HeyYou. I suspect a vaccum line maybe off as this morning I noticed my vents will no longer change position, example from defrost to floor etc, it seems to stay in one position. I am assuming this is controlled via vaccum lines?

but I will try your suggestions tonight and write back on how things faired.

 

Vacuum lines will cause high idle. The one on the pass side of intake really like to break - you know, the tiny one....

Also, can I ask why you replaced distributor? Or was it just the cap (hopefully)?

And +1 more n disconnecting battery. Anytime you remove or replace a sensor on these trucks, you need to disconnect the battery first to reset the PCM. It will take a little bit, but it will relearn the sensors.

 

Hi,

Yes at first I replaced the wires and sparkplugs, after doing that I started the truck up and could still hear it running rough and misfiring. At that point I replaced the distributor cap and the rotor inside. After I did that the misfire was gone.

I actually did have the battery disconnected while doing the work if that matters?

 

Idle is controllled by the IAC mountind in the throttle body. If crap builds up in there, it will cause high idle. Disconnect battery again and remove the throttle body. Remove IAC and clean. You can test it to see if it is good. Clean the port real good, but do not tun, twist, pull or push the pintle on the IAC.

You can find instructions to test in the service manual located in the FAQ/DIY section.

 

Ok I've disconnected the battery and left it disconnected for about 3hrs. I looked around for any loose vaccum lines and did find a line that isn't connected to anything. I looked all over for a nipple for it to plug into but for the life of me can't see one. I plugged it with my thumb while I had the motor running but it had no effect. The Vaccum is connected the small vac lines on the passenger side.

I'll take a look at cleaning the IAC.

Here is a pic I took of the Vac Line:
https://picasaweb.google.com/lh/phot...?feat=directli

 

What gdstock said. Mine did the same thing I took it out cleaned it with a cotton swab. Idled like a champ.

 

Hi guys, well I looked around the engine again and it turns out that there was indeed a vac line that fell off while I was replacing my plugs and wires. I must have accidently disconnected it. Its hooked up again and idle is down and the vents are working normally now.

Thanks for all the great advice, really appreciate the help. I really like this forum and will be reading it actively.

Take care.