What exactly causes each of these? I've been looking and I can't find a whole lot.

Lets say I start my car.... 15 minutes later (5 min idle warmup) the following happens:

The RPMS go from 1200 to 700-650 after 2-5 minutes
I drive out of my driveway
The idle goes back to the 1200
At the only stop I encounter, the RPMs can either be at 1200 or 700... depends on what day it is
At my destination, the idle RPMs are at 700

My ALDL logs are showing that it never entered closed loop, and frequently issues a "forced to open loop"

I need to know what conditions would cause it to stay in open loop, and what needs to be at certain specs before closed loop starts

(i'm guessing my EGR valve and my o2 sensor... but i'm not sure)

 

coolant temp sensor getting a low or erratic reading would cause that. check the cst in the front of the manifold. The contacts may be corroded or the sensor may just be bad(mine was cracked).

the ecm has to see above a certain temp from that sensor to go into closed loop, so if the sensor is giving erratic readings it could force it to open loop.


Zac

 

Ok, the coolant temp hit 180 by the end of the run with no erratic reading, just a smooth curve. The IAT stayed around 70F the whole time

Is there something else that needs to be at a certain value?

I still think my EGR valve isn't working, but I just realized the ECM has almost nothing to do with the EGR valve

 

Ok, I drove around for 45 mins today and according to WinALDL, I never hit closed loop. The BLMs did their thing. The O2 was varying quite a bit.

The new EGR valve helped out my idle a little bit also.

Do I need to not accelerate or stop for the ECM to enter closed loop? I was on a highway for about 10 mins, but that was all the longer I could go without really going out of my way for a cruise.

As far as i know, it's not throwing any codes