So I've noticed occasionally my truck will idle low, especially in the morning or after the first time I start up. It doesn't usually last long or idle rough, but I'm just wondering if it's something I should be concerned about. Just as a reference, it usually idles just under 1000 and when it's low it's around the second mark.

Thanks!

 

Might be a dirty or malfunctioning IAC (idle air control), or it could be your TPS (throttle position sensor), both of which are on the throttle body. It's pretty easy to remove the throttle body and give it and the IAC a cleaning. Get some carb cleaner spray and remove any crud buildup you see, especially around the IAC rod, throttle bores, and the tiny ports in the bores. When you make a trip to the auto parts store for the carb spray, pick up a new PCV valve and throttle body gasket too. If that doesn't cure it, we can try some other things.

 

I haven't had time to do anything about this yet but am going to try tomorrow.

Also, would this make the oil pressure read high? It's not out of the "comfort zone," but it is almost there. I'm the third owner for this truck and I'm trying to figure out all the quirks.

Thanks again!

 

Too high? That's not a complaint I am used to hearing. If it isn't blowing up oil filters, it isn't 'too high'.

 

Gotcha! I just wanted to check. I figured it wasn't too much to worry about.

 

Mine reads high, almost pegs the needle sometimes, other times it reads low; or normal. Think its the sending unit.

 

Hey pbblaster. Here's something to check. My ol lady has a 94 Lexus that uses a dual coolant temp sensor setup like our daks do .One sends temp to the computer, one sends temp to the guage. We'll the one that sends temp to the computer broke and as soon as that happened it started idling really low on start up, it would even be hard to start and wouldn't start at all a couple times. But you get it running and it wouldn't idle high like normal to bring the engine up to temp. It would sit idling at almost nothing. Put in the new sensor and it went back to normal. You should check that out. The sensors aren't too expensive and you would just need to replace the one that sends signal to the pcm

 

Thanks for the info, I will check that out! I did clean the idle air control and throttle body on Saturday. After I got done then it didn't want to start. I went out Sunday to get a new IAC, brought it home and it started right up. It still doesn't idle like normal, around 200, but maybe I got used to it idling wrong. We'll see how it goes!

 

Azboyinmi, if the OP is experiencing the idle issue at startup, when the system is in open loop mode, isn't the temp sensor ignored by the ECM? I could be wrong about the temp input, but while in open loop the ECM is supposed to rely on fixed parameters. EDIT: The O2 sensor is ignored in open loop, not the temp sensor; I was incorrect.

 

Well, if the temp sensor is unplugged, it'll throw a right wobbly; for instance, my 1988 kicks the idle to about 2,500 RPM (!!!) and kills all advance.

My Cougar does similar, but not that extreme. (And has a "Kill All Advance" plug to set timing with, but remember, it's a Ford.)

RwP