Gary Lewis Posted February 4, 2023 Share Posted February 4, 2023 I'll hopefully get to that tomorrow! In the meantime, I took a video to show the vacuum and you can see/hear the stumbling at fast idle. This isn't the main problem, but it may be adjacent. This video doesn't have the EGR disconnected (that's tomorrows job) https://drive.google.com/file/d/1MZygufOC7WSG52hxLHgggvVgT7gncPex/view?usp=sharing The audio is a little different in person, but hopefully this adds a little more color to what I'm trying to describe at fast idle. But, this item is secondary (but annoying). It's odd, but driving, this isn't noticed in performance, the tach, or in listening to the engine. Driving, it's all good, or when you kick the idle down. That's not much wobble on the vacuum, but I can hear the bobble in the RPM and see it on the vacuum. I think you have an EGR problem. Tomorrow may tell. Link to comment Share on other sites More sharing options...
ckuske Posted February 4, 2023 Author Share Posted February 4, 2023 That's not much wobble on the vacuum, but I can hear the bobble in the RPM and see it on the vacuum. I think you have an EGR problem. Tomorrow may tell. Well, jury is out for me to do another round of testing. First, I capped vacuum line that attaches to the EGR itself. The stumble at fast idle is still there, no question. After I tried each configuration a couple times, either I stopped noticing the difference, or the truck had gotten its way into a better state. I was never able to make it stall, so I suppose that is good. Also tried capping off the vacuum that goes into the solenoid to remove the EGR and solenoid both - again is seemed better but it is hard to say for sure. (Vacuum Source -> Solenoid -> EGR Vacuum Line -> EGR Vacuum Connector) I tried capping some other paths off, no improvement. I also hooked the vacuum gauge up to the EGR vacuum line, and verified there is only vacuum applied through the solenoid after the truck is warm, and you advance the throttle. I guess I should remove the EGR and check it on the bench etc, and make sure everything is clean, seats well (EGR fully closed?) etc. Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 4, 2023 Share Posted February 4, 2023 Well, jury is out for me to do another round of testing. First, I capped vacuum line that attaches to the EGR itself. The stumble at fast idle is still there, no question. After I tried each configuration a couple times, either I stopped noticing the difference, or the truck had gotten its way into a better state. I was never able to make it stall, so I suppose that is good. Also tried capping off the vacuum that goes into the solenoid to remove the EGR and solenoid both - again is seemed better but it is hard to say for sure. (Vacuum Source -> Solenoid -> EGR Vacuum Line -> EGR Vacuum Connector) I tried capping some other paths off, no improvement. I also hooked the vacuum gauge up to the EGR vacuum line, and verified there is only vacuum applied through the solenoid after the truck is warm, and you advance the throttle. I guess I should remove the EGR and check it on the bench etc, and make sure everything is clean, seats well (EGR fully closed?) etc. Yes, I think that would be my next step. Perhaps the valve is, as they frequently are, carboned up and won't fully close. Link to comment Share on other sites More sharing options...
ckuske Posted February 5, 2023 Author Share Posted February 5, 2023 Yes, I think that would be my next step. Perhaps the valve is, as they frequently are, carboned up and won't fully close. Ok, I pulled it. It basically looks brand new still. I pulled vacuum on it and the valve seems to move freely as well. I did notice that the EGR cooler should have a gasket on both sides. I didn't remove it off the manifold yet, but if there is a gasket there, I sure didn't see it. Either it's fallen apart or isn't there. That would be a red flag (I think). If you slide the cooler on the bolts and try to mate it against the manifold, there's a small "clank". You would think if a gasket was there, it wouldn't do that... It looks like the same gasket should be on both sides of the cooler in the drawing below. I felt inside the cooler with my finger and got some carbon out. I guess I'll pull that next (how deep is this onion?). Before I go down that rabbit hole I suppose I should measure the EVP voltage to make sure that isn't throwing the ECU off... Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 5, 2023 Share Posted February 5, 2023 Ok, I pulled it. It basically looks brand new still. I pulled vacuum on it and the valve seems to move freely as well. I did notice that the EGR cooler should have a gasket on both sides. I didn't remove it off the manifold yet, but if there is a gasket there, I sure didn't see it. Either it's fallen apart or isn't there. That would be a red flag (I think). If you slide the cooler on the bolts and try to mate it against the manifold, there's a small "clank". You would think if a gasket was there, it wouldn't do that... It looks like the same gasket should be on both sides of the cooler in the drawing below. I felt inside the cooler with my finger and got some carbon out. I guess I'll pull that next (how deep is this onion?). Before I go down that rabbit hole I suppose I should measure the EVP voltage to make sure that isn't throwing the ECU off... I think the lack of a gasket is the issue. You’ve had a leak there. Link to comment Share on other sites More sharing options...
ckuske Posted February 5, 2023 Author Share Posted February 5, 2023 I think the lack of a gasket is the issue. You’ve had a leak there. Agreed! Fingers crossed. To be clear, there was a gasket mating the EGR to the cooler. From cooler to the manifold is TBD ( an hour or two hopefully), it doesn’t appear so. Link to comment Share on other sites More sharing options...
ckuske Posted February 5, 2023 Author Share Posted February 5, 2023 Agreed! Fingers crossed. To be clear, there was a gasket mating the EGR to the cooler. From cooler to the manifold is TBD ( an hour or two hopefully), it doesn’t appear so. No such luck. There was a gasket there, not in great condition, but it was there. I've ordered two fresh ones from Amazon, they'll be here Tuesday. I took the cooler off and gave it a bath with hot water and Dawn dish soap. It looks much better. There was a fair amount of carbon, but not enough that I thought it would have caused an issue. But it just got Roto-Rootered, so it should be good for years to come. On Tuesday I'll put everything back together, check out the EVP sensor, and unless a miracle happens by then, go down the smoke test route. It still feels like a vacuum issue, so that's the track I'll stay down. Coincidentally with all of this, my original power steering pump gave up the ghost finally. So, putting a replacement on with the rest of my day today... Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 5, 2023 Share Posted February 5, 2023 No such luck. There was a gasket there, not in great condition, but it was there. I've ordered two fresh ones from Amazon, they'll be here Tuesday. I took the cooler off and gave it a bath with hot water and Dawn dish soap. It looks much better. There was a fair amount of carbon, but not enough that I thought it would have caused an issue. But it just got Roto-Rootered, so it should be good for years to come. On Tuesday I'll put everything back together, check out the EVP sensor, and unless a miracle happens by then, go down the smoke test route. It still feels like a vacuum issue, so that's the track I'll stay down. Coincidentally with all of this, my original power steering pump gave up the ghost finally. So, putting a replacement on with the rest of my day today... Well, like Edison you know one more thing it isn't. Bummer on the power steering pump. That's a messy job. Link to comment Share on other sites More sharing options...
ckuske Posted February 5, 2023 Author Share Posted February 5, 2023 Well, like Edison you know one more thing it isn't. Bummer on the power steering pump. That's a messy job. Yep, I know eventually the problem will make itself known. On the power steering thread, I just got the old one off, and got the pulley off too. First time I've ever done that. I used my brake bleeder vacuum pump, that made it much less messy! Link to comment Share on other sites More sharing options...
ckuske Posted February 11, 2023 Author Share Posted February 11, 2023 Yep, I know eventually the problem will make itself known. On the power steering thread, I just got the old one off, and got the pulley off too. First time I've ever done that. I used my brake bleeder vacuum pump, that made it much less messy! Ok, I need to put my EGR/vacuum stuff back on so I can start bleeding the power steering and test it. So, I checked the EVP. My Haynes manual says resistance between VREF and EVP signal pin is supposed to be "slightly less than but no greater than 5000 Ohms". Mine is around 4550. So fail, I think. Next, EVP signal pin and SIG RTN should be "slightly greater than, but no lower than 100 ohms" but it is 1200 Ohms! I think I found the problem? I will take the EVP off the EGR and make sure the pintle isn't stuck somewhere... I imagine a reading this far off could really cause the ECU to do stuff that shouldn't be happening... Link to comment Share on other sites More sharing options...
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