K2500HD Idle Issues...

[ErikSS]

That sucks man. I hope you have a warm place to do it!

[bartonmd]

That sucks man. I hope you have a warm place to do it!

Nope, not this... I would do the TB in the garage, but this is entirely too long for the garage, at least with the door shut. I do have a carport on the east side of the house that's out of the wind, though, and its supposed to be like 38 on Sunday, so I may do that. If my buddy happens to be down at his dads house, I could probably use the barn, but its not any warmer than outside, really...

Though, what I'll likely end up doing is pulling the front end into my shop and lowering the door on top of the cab, then putting some cardboard around each side of it, and turning on the heat. If it was going to be really cold, or if it was a really big job, I could drive an hour south and do it in my grandparents' insulated concrete floor pole barn, but it shouldn't be either of those things, with any luck.

Mike

[jonbo2002]

That sucks man. I hope you have a warm place to do it!

Nope, not this... I would do the TB in the garage, but this is entirely too long for the garage, at least with the door shut. I do have a carport on the east side of the house that's out of the wind, though, and its supposed to be like 38 on Sunday, so I may do that. If my buddy happens to be down at his dads house, I could probably use the barn, but its not any warmer than outside, really...

Though, what I'll likely end up doing is pulling the front end into my shop and lowering the door on top of the cab, then putting some cardboard around each side of it, and turning on the heat. If it was going to be really cold, or if it was a really big job, I could drive an hour south and do it in my grandparents' insulated concrete floor pole barn, but it shouldn't be either of those things, with any luck.

Mike

hope it warms up enought for you Mike, too bad I'm too far north for you cause it would fit in my barn. I know it's cold as hell here and not getting any warmer soon.

[bartonmd]

It shouldn't be bad, I think/hope... It's only a 1-2 hour job, though, so it's not a big deal even if I have to work 20 minutes then come inside for a bit. I've got all weekend to do it.

Mike

[bartonmd]

This setup actually worked pretty well. The shop heat kept it around 40-45F in there the whole time.

It didn't start out idling well at all, but as it learned the new air characteristics, it got better, "normal" almost, even. I won't know until the next few heat cycles if it's actually fixed, or if it just had a good cycle.

[dvanbramer88]

How long did it take?

Could you see dirt on the gaskets where they were leaking like in that video I posted?

Hopefully this turns out to fix it and this was your only issue.

[bartonmd]

Took me a little over 3 hours of actual work time, but I was being careful and trying to get everything as clean as I could.

Yeah, there was some on a couple of them.

You and me both!

Mike

[bartonmd]

Well, it's better, but it's not fixed. It seems to idle well and not search for idle while sitting still. I still have cold start issues, though it seems to be able to idle for itself much sooner than before. I've pinned down something really interesting that it does. When you are coasting and push in the clutch, it drops to 300 and hangs out around there, until the instant that you come to a stop, when it jumps right up to a steady 600rpm idle. I coasted like 3/8 of a mile down a hill and it stayed at 300-400rpm the whole way, until the instant that I stopped, and like I say, it jumped right up to 600. It always used to hang out at 1200rpm expecting you to go into another gear, then drop to 600 when you came to a complete stop. It's like the 1200rpm settings (starting and idling while rolling) have been replaced with 300-400rpm.

I did the "spray brake cleaner and watch the computer for rich conditions" thing again, and there are no vacuum leaks that I can tell with the new intake gaskets. I also put a throttle position sensor and a MAP sensor on it today, and plugged off the input to the canister purge solenoid. I also cleaned and dielectric greased all the grounds that I could find. Still does it.

I'm starting to wonder if I've got a damaged PCM... The only other thing I can think of is a cam position sensor...

Mike

[KE7WOX]

I'm starting to wonder if I've got a damaged PCM... The only other thing I can think of is a cam position sensor...

Mike

Do you have cruise control? I believe that at least for the 4.2L TB, a malfunctioning cam position sensor, or one that "forgot" the settings will prevent cruise control from working, so I suppose this could be a way to test it.

[bartonmd]

Yep, cruise works.

Mike

[KE7WOX]

Yep, cruise works.

Mike

Ok, I'm starting to think that I got my shafts mixed up and it's the crank sensor that does this.

I figure that the PCM is a lot easier to replace than the cam sensor, but the part itself is a lot more expensive, which kinda sucks.


The other question I have is if these behaviors have been steady between changes or not, because I'm starting to wonder if you have a bad wire somewhere in the system.

[ErikSS]

That Sucks man. I was hoping it was done.

[bartonmd]

No, changes all the time... I doubt it's just a dead wire or something. It's too specific when it happens.

Mike

[KE7WOX]

I think that a bad wire would make the same but intermittent, or the same all the time. But that's not really my area of expertise.

I ran out of ideas, other than maybe see if this continues once it warms up a little bit (Atmospherically) and see if it's temperature related.

On a sidenote, how are those Duratracs working for you in the snow?

[bartonmd]

I think that a bad wire would make the same but intermittent, or the same all the time. But that's not really my area of expertise.

I ran out of ideas, other than maybe see if this continues once it warms up a little bit (Atmospherically) and see if it's temperature related.

On a sidenote, how are those Duratracs working for you in the snow?

No, it's not that kind of intermittent. Also, the wires that usually die are fusable links in the wiring harness, and once those blow, they don't come back. You have to replace them.

It was like 50F today, and it was still doing it. It had been 2 days of below zero before it started doing it.

The Duratracs are AMAZING in the snow!! They are as good as, or nearly as good as snow tires I've had. I'm putting them on the TB for next winter.

Mike

[KE7WOX]

Ok so it's not a temperature thing then.

On the wires I was thinking more along the lines of a frayed wire that was making intermittent contact, or that it was getting "open" on vibration or something like that. That's just experience with my ABS that had a bad wire going from the right front speed sensor; and the ABS would sometimes intermittently fail, or be disabled and intermittently work.

I'm seriously considering Duratracs to replace my SilentArmors, at least for the winter/spring, because the SA's aren't that great when Dublin half-asses the road plowing.

[bartonmd]

Ok so it's not a temperature thing then.

On the wires I was thinking more along the lines of a frayed wire that was making intermittent contact, or that it was getting "open" on vibration or something like that. That's just experience with my ABS that had a bad wire going from the right front speed sensor; and the ABS would sometimes intermittently fail, or be disabled and intermittently work.

I'm seriously considering Duratracs to replace my SilentArmors, at least for the winter/spring, because the SA's aren't that great when Dublin half-asses the road plowing.

I had thought about that, but it's not anywhere close to what I've experienced as wire issues.

Yep, I've been VERY impressed with the Duratracs!

Mike

[Trail X]

Mike, I assume your clutch has a switch that returns a signal to the ECU. Sounds to me like your ECU isn't getting the signal that you're disengaging the engine from the drivetrain. If you're coasting to a stop while using engine braking, the ECU might be demanding an idle speed of around 300 to give you engine braking... but when you push in the clutch, it should understand that there's no longer the momentum of the vehicle keeping the engine revved, and reset the idle to the higher setting. I'd see if the clutch signal is making it to the ECU.

[bartonmd]

Mike, I assume your clutch has a switch that returns a signal to the ECU. Sounds to me like your ECU isn't getting the signal that you're disengaging the engine from the drivetrain. If you're coasting to a stop while using engine braking, the ECU might be demanding an idle speed of around 300 to give you engine braking... but when you push in the clutch, it should understand that there's no longer the momentum of the vehicle keeping the engine revved, and reset the idle to the higher setting. I'd see if the clutch signal is making it to the ECU.

Hmmm... I'll check into that... You still have to have the clutch in to start it, but I don't know if there's 2 switches (1 to the ECM and one that's in the start circuit, or what) or something, or how that all works, so I'll look into it. Also, though, when you coast it down to idle speeds while actually in gear, the IAC catches it at 600rpm and tries to keep it there.

Having said that, I took the stock tune and turned on the rolling-idle setup (higher idle while going over 4mph), as well as kept the high idle longer on startup. I did a download and test run a little bit ago, and while it's still 45F and the engine was at 100F or so, it worked better than it did this morning, so we'll see if it's something that I can tune around, or not.

Mike

[bartonmd]

With the extended high idle that I put in at startup, it started up OK, but didn't like to recover from me pressing the throttle very well, even sitting still, until it was halfway warm.

The dipping still happened when pushing the clutch in while moving.

I ended up turning around and taking the car, because the alternator was making noise, and going back and forth between 14.2 and 15.6V. It'll be a warranty item through Rockauto, but still another irritation.

Mike