Idles high after being in gear.

[1998_K1500_Sub]

ECM assumes if it reads it it's true or if it commands it it's done

Succinctly stated.

 

[BigRedOne]

I'm definitely still learning but have bumbled around in TP enough to know there are too many states/flags in the code to easily connect the dots between cause and effect in some cases. In the early ECMs like these, it seems a lot of stuff is open loop and ECM assumes if it reads it it's true or if it commands it it's done. EG. there is no sense on fuel pressure, ECM assumes it's good and if it's not - you get strange results as ECM is assuming it's good. I think this is what 98_K1500 is thinking about with respect to IAC - maybe IAC is not as ECM thinks for some reason.

When you get TP up you'll see what I mean with respect to all the flags and conditions which the ECM monitors or sets - look thru and see all the "idle" and "IAC" related stuff. In your case, perhaps something easy to check would be "Desired Idle RPM" (which I assume is the RPM the ECM is trying to control to?) and there is a flag on "Idle RPM High" (which I assume is whether the ECM thinks the idle is too high or not?) . I think you should be able to tell whether ECM thinks it's controlling to the correct RPM or not - and whether that "correct" RPM is different in the two cases.

Take what I say here to be perhaps ~50% correct I'm guessing at a lot of this when I get into TP. Good luck!

Yea I'm using ALDLdroid and I'm just getting it set up but I am optimistic looking at all the flags and parameters it supposed to show. The problem I just ran into (like in the last 5 mins) is i'm using a bluetooth cable and it pulls power from the aldl plug. Well it works fine with the key on. But for some reason when you start the engine there is no power to the aldl plug anymore. Key is in the same position except now the engine is running. Checking to see if this is normal or an issue. The cable maker sent a power lead with the proper terminal to hook up to the trucks power and then to the cable but not sure why only power with engine off.

 

[PlayingWithTBI]

but not sure why only power with engine off.

That does sound weird but, I don't use a Blue Tooth cable, I have an ALDL to USB cable so, I can't confirm this.

 

[BigRedOne]

OK. So went out with my power probe and G terminal is ground key off and 11.2 volts key on and ground when truck is running. The bluetooth cable also uses term L for power so there is no wire in the term L slot. So I used the wire provided by the cable maker and put it in the L slot and ran it to ignition on slot in the fuse box and we have power. Neat software on the ALDLdroid and still learning all the features. Definitely a better scanner than the one I borrowed. No weird 1000rpm idle anymore. Now I just need to learn the software and maybe TP and winaldl to see who shows the most info.

One other question I have is what should the IAC count be in gear? I am showing 124 at 750rpm in gear and then back to park it drops to 119 and idles at 1550rpm. When I first start it warm in park it's 19-22 and 750rpm. Definitely belive the IAC is the issue but why is it not being told to drop further?

 

[PlayingWithTBI]

Now I just need to learn the software and maybe TP and winaldl to see who shows the most info.

Get TP RT, Winaldl is old school.

Definitely belive the IAC is the issue but why is it not being told to drop further?

That's the $64,000 question. Maybe do some data logging and look at all of the inputs and commands in a graph?

 

[BigRedOne]

Get TP RT, Winaldl is old school.


That's the $64,000 question. Maybe do some data logging and look at all of the inputs and commands in a graph?

That's the plan. Have to learn this TP software first. Have to figure out why my engine definition is a ADS file and not a XDF file. Right from TP's site.

 

[PlayingWithTBI]

Have to figure out why my engine definition is a ADS file and not a XDF file.

Your .adx or .ads is for data logging/monitoring. The ,xdf is for looking at/modifying your .bin Make sure you get TunerPro RT v5 not just TunerPro the RT can data log where the other can't. I can't remember, is your ECM a 1227747?

Here's the .adx and .xdf files for it.

www.gearhead-efi.com/Fuel-Injection/showthread.php?304-1227747-ECM-Information-42

 

[Schurkey]

That's the plan. Have to learn this TP software first. Have to figure out why my engine definition is a ADS file and not a XDF file. Right from TP's site.

This is why I use a scan tool instead of a laptop + software + cable.

I connect the scan tool, input a few digits of the VIN, and the scan tool pretty-much does all the rest as far as displaying useful info.

 

[BigRedOne]

This is why I use a scan tool instead of a laptop + software + cable.

I connect the scan tool, input a few digits of the VIN, and the scan tool pretty-much does all the rest as far as displaying useful info.

problem with that is I can't find anyone with a scan tool that has the 10k resistor. all of them cause the idle to default to 1000rpm and other parameters aren't correct. That's why I bought the cable. I can change between the resistor or not depending on application.

 

[Schurkey]

Which scan tool(s) are/were you using?

I only have experience with older Snap-On scanners; but I find it hard to believe that there's scan tools out there that don't allow a proper road-test mode with normal (safe) idle speeds.

OTOH, I know that cheap Chinese scan tools are often questionable. And, as I said, I have no direct experience with anything but Snappy scanners in the last 30 years. (I used OTC Monitors back in the late-80s.)

"I guess" your laptop/software/cable solution should enable you to access the same data as a proper scan tool. So maybe all of this is moot. It just seems to me like you're spending too much time getting the tool to work, and that takes away from the time you have to fix the truck.