Haven't driven my bus in a few weeks. Started it up today to get ready for my next trip. FICM is still pegging at 48.5v, so that's good. And it didn't smoke when I started it and let it idle. However, once I started driving, with EOT still around 100d and basically idling along at about 15mph to let it warm up more, it first smoked grey. Then, after getting warm, it would smoke black when I gave it pedal.

My VGT sits at 85 while stopped at a light, but would go to 50-60 while driving. So, I'm thinking my turbo is messing up again. Going to take my Forscan PC out to see if it commands on. TorquePro didn't give me in codes while driving, but we'll see what Forscan says.

 

OK, my turbo won't command on with Forscan. When I first slid the button towards 100%, it changed sound, got deeper, but after that, nothing. Sliding back and forth does nothing, no change in sound. It's the same deep kinda sound I hear when I first fire it up, for a few seconds.

I'm assuming that means I got a wiring issue or my turbo is frozen. I got 5v Vref. Another strange thing is Forscan shows ECT at 88d when I know it's WOT. Torque showed it correctly while I was driving it, so not sure what that means.

Does the fact that it was driving fine when I parked in last month suggest anything? What would mess up while it was sitting parked? I'm thinking that suggests the turbo is locked up - maybe worked fine while I was driving, but once it cooled down and sat, the unison ring seized up?

Would I get a code when the turbo freezes? Or when it's not commanding on? Maybe I just didn't drive it long enough to set the code?

I hate to tear into this or go replacing parts without having a plan. I can try unplugging the VGT connector, but I'm thinking that's what the Forscan command is doing now. How would I check voltage coming to that connector? Just turn the key on and probe the pins? Can I do that with it disconnected, probing the pins from that side, or do I need to leave it connected and probe through the backside of the connector? I've never been able to make that work, probably because I don't have a thin enough needle on my voltmeter.

 

My money would be on the vanes getting stuck since it was fine prior. Have you tried driving it hard to see if that might free them up? Get the exhaust nice and hot?

 

OK, I still don't know anything. It wasn't wiring; it was the EBP tube/sensor clogged again. Been maybe a year and a half since I cleaned it. When I first got it off, looking at the sensor, I didn't think that was it. It wasn't completely filled with soot like others have described. But I did get some soot out, and then ran a string down the tube - hard to say if it was clogged or not; it's so hard to reach in this Eseries that I wasn't sure if it was hitting a clog or I just wasn't pushing far enough. And not sure how far the string needs to go down - you can't easily see the tube either - but I got about 6 inches into it, then doubled the string (thin type) and got about 5" in with that.

I had no illusion that was going to fix it, but I knew I needed to check it first. Yet, sure enough, runs great and not a whiff of smoke.

 

Thanks, 5O. I wouldn't have taken that bet, seems logical. I thought that Forscan command would make it come on even with a bad sensor. After I cleaned the EBP, and first fired it up, I tried that command again, and I could hear it now, but just barely. Made me wonder if I just wasn't hearing it before. Been so long since I used that command; I was remembering the sound difference being greater. But, I guess not.

I did notice on the Forscan app log screen that adds a line of description for each action you take, that it was displaying a line for each time I tried to command, and saying it was successful. Not sure if it was doing that before and I just wasn't on that screen to see it. Maybe it was saying unsuccessful before.

Dang, that Forscan app for PC isn't user friendly. I remembered having a hard time finding the turbo command last time, and I looked for a long time again today. Most of the buttons don't pop up a little window telling you what they are. The turbo button is worse - it isn't highlighted to let you know the function is available. Instead, it has a big X over it as if whatever that button is for not available. And the icon doesn't remind me of anything to do with a turbo, so I didn't click it. But after clicking every other button on every page multiple times, I tried that one.

Apparently, a clogged EBP doesn't throw a code? Forscan didn't find any either. I wonder what the chances are that it actually wasn't the EBP? What if it's, like you say, just that the vanes finally freed up after driving it here and then idling a while messing with it? While I baby this bus, rarely going over 60mph or pushing it hard, it's still a heavy bus and I pull about 5000lbs of trailer, so it kinda gets a lot of work anyway. And I drive for hours at a time at highway speed - I wonder if that's good or bad for turbo vanes?

 

I think the main issue with the vanes is when they don't get fully exercised regularly, that portion of the housing still start to rust. When you do send the vanes into that part of the housing they can get stuck. The key is using the full range of the turbo.

It's typically the upper range. IE it needs to be floored with max boost every so often so the vanes go full open. It could be worse?