I have a 90 3.9 and sometimes when I crank it up the idle is really low and other times I crank it it does fine and Idles normal. When it starts and the idle is low it will only last a few seconds then it picks up on its own and idles right. Does anyone know what could be causing it to do that? I have really good oil pressure and have tuned it up (plugs, wires, dist.cap and rotor, air filter). any help would be appreciated thanks

 

Check the Idle Air Control (IAC) connector. If it's okay, pull the IAC and clean it or replace it.

 

Where is the IAC connector an a pre magnum 3.9?

 

also check the EGR, if it's blocked up clean it out

 

I just replaced the EGR about a month ago, so it shouldnt be blocked up. Its just that sometimes it idles really low when you start it. It dont cut out or sputter and it always picks up and idles right on its own. It is just drivin me crazy. LOL I will check it though tomorrow along with the iac connector if I can find it.

 

i think its called the idle speed control switch. its like a carburator with an adjustment screw.

 

yeah I found it today. I didnt get a chance to clean it or anything cause I had lots of stuff to do today. How do I go about cleaning it up? Do I just spray the outside where the screw adjustment is or do I need to open it up and spray all the gears and stuff down with carb cleaner and then lub them up with some sort of lithium grease or graphite lube? Thanks in advance.

 

Wow I was lookin that part up just in case I have to have a new one and the cheapest I found it was $80. That is just crazy for a little part like that. It must be something that goes out pretty often on these trucks. Thats why it is so much. LOL

 

Count your blessings, there are some of us throwing all kinds of codes,replacing parts that don't need to replaced,serious money expenses, with no final results. Do to electrical problems, my dango, runs so inconsistant I begining to think that it has a personality. Headaches and lots of time spent on line troubleshooting. (Just ask) tecs. have me on a don't open this list. PCMS SUCK

 

Now that you mention it, if my truck sits for a day or more it starts up kinda sputtering for a second then idles almost like it has a little miss for a second then grows to a nice idle all in a matter of like 4-6 seconds. Now I know I need a new EGR valve cause the EGR code is the only one to ever come up even after a good cleaning, but could it also be anything else? 95 318 Magnum.