Cold Idle Control issues.

[907DAVE]

Well I thought I had the issue resolved until temps dropped to -40 for the past week or so - and it stopped working again.

Using the Scangauge I monitored the IAT and it was reading 500* (which I now believe is an issue with the Scangauge), so I disconnected the sensor and it defaulted to 68 and the high idle seemed to work normally - when the engine was cold.

Today I spent a bit of time playing with it and was pretty successful controlling the idle with the sensor disconnected, once it warmed up I lost all control of the high idle.

I tried changing the default to 0*F , setting the Cold Idle control to be always on - regardless of temp - and it still wont work when the engine is warm.

When the sensor is disconnected does it substitute a different temp sensor?

As a last ditch effort I plugged the sensor back in, and still no high idle function.

[GTS]

I think I'd make sure your issues isn't the sensor. What makes you think it's something with the Scangauge and not the sensor? I had a bad EOT sensor, or bad wires to it, awhile back, once I hooked a scanner to it it came obvious when it was reading 4 degrees on a warm engine. I'd make sure that sensor is reading correctly before you spend a bunch more time trying to adjust the tuning for it.

[907DAVE]

Reason I dont think it is the sensor is because when it is unplugged the default to 68*(which it displays) - I went in an changed the default - and whenever it is set lower than 0*F it displays 500*.

This leads me to believe the Scangauge is not set up to read below 0*.

[GTS]

That makes sense. Do you have AE where you can verify this?

[907DAVE]

I do have a Genisis and Verus I can use to verify, just haven't felt the need to yet.

I about got this one figured out, but there is still a strange issue. When engine is cold, the idle will raise up to what it should - then suddenly drop back down to base idle. It will continue to do this for a few minutes, then it might decide to work and stay up on the high idle, or might just stay at base idle.

Also, my Autostart is messing with this somehow. This evening I started the truck after dinner - went out about 10 minutes later and it was still at base idle speed. Stuck my key in and turned to the "run" position and after a few seconds it ramped right up to where I had set it...lol.

I will be playing around with it some more in the AM.

[GTS]

I think if there is question at to weather the sensor is reading correctly that would be the first thing I would want to verify so you're not chasing your tail trying to figure it out.

As for the autostart I think I may have an answer for you. I have remote start on my truck as well and though it is a '96 I do have an AIC on it. When I remote start it the wires are tagged that are needed to start the truck but not all accessory wires have power to them. My AIC is apparently one of the wires that doesn't have power to it as it will not idle up without the key in it. I've been going to find the wires needed to fix this but just haven't gotten around to it yet. So you may want to get a wire schematic and trace the wires for what sensors are needed to activate the high idle (e-brake circuit?)

[907DAVE]

Okay, my idle was working perfectly for about a week or so, then the issues came back with a vengeance. The issue is consistent when using the auto-start, so I decided to go after this first.

Just so everyone knows, I installed the auto-start when I first purchased the truck and has worked normal up until this year.

I check voltage drop through the Auto-start for all my ignition wires, and it was .2v, not great, but could be worse. The voltage would stay around 13.7 volts with all the accessories on. Now the real kicker is when the Auto-start times out, and the turbo timer kicks in the idle works normally. The timer is tied into the exact same wires but is only dropping .1v.

Here's a video I took just for giggles.......



Since this still appears to be a voltage issue, and the only time it has ever done this in the past is with low battery's........Does the PCM read system voltage in A/D counts?