That's bizarre. Good on them for finding something.
Long crank when warm - Issue after valley pan repair
- Thread starter jmanscotch
- Start date
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Isn’t it possible that a malfunctioning EGR valve could cause hydrocarbons in the intake?
I was thinking the same thing about sticky EGR. I haven't really heard of them being an issue on 10-13 models... there are some defective ones on 14-15 models
Hard to imagine it wouldn't trigger a code but who knows
Would a stuck open PCV valve do anything?
Hard to imagine it wouldn't trigger a code but who knows
Would a stuck open PCV valve do anything?
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PCVs have caused issues on other cars but it is rare. Definitely near the end of this problem!
- Thread starter
- #105
Definitely could be the EGR valve sticking open, an issue with the purge solenoid or something wrong in that whole system. I had all those parts unbolted, unplugged and moved around quite a bit during repairs so it wouldn’t be unreasonable to think something went wrong there and could’ve been the cause of this whole situation.
I’m not sure the PCV valve would allow such a condition, but I did replace it during repairs and inspected it again when the intake manifold was off last and the check ball (?) was free and loose.
I’m not sure the PCV valve would allow such a condition, but I did replace it during repairs and inspected it again when the intake manifold was off last and the check ball (?) was free and loose.
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- Thread starter
- #106
Seems the tech working on it feels the same way about troubleshooting it as I do.
That said, I picked the GX up Friday and have it for a week or so. The shop has had it for two weeks and I needed it back for some things. The tech seemed happy to have a break from it anyhow, I don’t blame him and am happy with the work he’s done on it.
What we’ve learned, thanks to his hard work, is the issue is within the intake manifold. When I picked it up, he mentioned he finally was able to find something else that stopped the symptoms, much like blowing air into the intake. He disconnected the short air line that runs from the PCV valve to the intake manifold and let it sit for the 1-1.5 hours and it didn’t long crank.
This connection:
Based on that, today I did the same and was able to replicate it, with that line unhooked and it sitting for the right amount of time, the long crank problem ceased to happen. I then repeated the process, disconnecting the line and plugged the intake manifold port (leaving the PCV Valve output side to vent) and it exhibited the issue. So the issue isn’t fixed by the PCV system venting, it’s the intake manifold venting to atmosphere that solves the problem. There’s either hot air (likely not the problem) or fuel rich-enough air/EGR recycled air collecting in the intake manifold and that’s leading to the long cranks.
What I’m guessing, based on the setup of the system, is the EGR valve is stuck open. That’s a very suspect direct feed supply that routes into the intake manifold. The only other possibilities are the engines intake valves being open from the cylinders and a few possible vacuum line options that shouldn’t offer anything in the way of possible sources of contamination that’d cause this. He did mention the possibility of fuel in the crankcase and those vapors making their way back up into the intake manifold. I find this possibility as unlikely, but plan to perform a premature oil change to eliminate it as a cause anyhow.
The tech did actually accidentally confirm one theory when he mentioned he could send compressed air backwards through the EGR valve, with the GX off, and hear it exiting the exhaust system. He mentioned he didn’t know if that was normal or an abnormal condition. The EGR valve should be closed when the vehicle is off, and it isn’t. At least that’s what I’m finding online and seemingly in the FSM.
While I have it in my possession, I’m going to clean up the EGR valve and try to dislodge any gum and gunk in there, and retest. The tech did find slightly excessive amounts of gum/guke in the intake manifold and intake runners and cleaned it out nicely. It’s not a stretch to think moving the EGR valve around, during the repairs directly prior to this issue, might have shifted some of that and stuck the EGR valve slightly open thus creating the problem.
I plan to flush the EGR valve clean with some brake cleaner or equivalent (have to see if there’s rubber in there or not) or maybe just replace it ($250) then retest. I hope to have an update within a few days.
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Amazing progress. Keen to see if that fixes it.
Looks like that EGR stepper motor has 110 positions according to the FSM. You can also perform an active test with Techstream
There is a stepper motor test as well as some graph based tests in FSM
- Thread starter
- #112
Yep, he gave me some bottles of BG EPR and MOA to run through the system for that exact purpose.
r2m
Richard
Too bad you're waaaay past the lemon law.
- Thread starter
- #114
Pulled the EGR valve and it had plenty of gummy gunk in there, but appeared to be fully seated closed. I also used a poker to push the valve open and closed a few times and it seems to operate smoothly.
Here’s the bottom side, aka the outlet of the valve, where the center plunger extends out from the body of the EGR valve to open. It’s closed in the pic and after cleaning it with carb/choke cleaner.
I also fished a metal snake down the EGR air lines and didn’t find any obstructions in the passages.
I looked around, questioning what else might be a culprit and this purge valve sticks out. Best I can determine, it routes back to the fuel tank/vapor canister and will vent excess vapors from that system into the intake manifold intake runner. Valve and where it enters the intake are highlighted.
I’m waiting to check the EGR cleaning results before moving onto disconnecting the tubing from the purge valve to the intake manifold, plugging the intake manifold opening (leaving the purge valve outlet open to atmosphere) and seeing if the long crank happens or not.
With the fuel vapors not making it into the intake and the intake not venting, it’d tell me if this is the source of what is filling the intake manifold.
Here’s the bottom side, aka the outlet of the valve, where the center plunger extends out from the body of the EGR valve to open. It’s closed in the pic and after cleaning it with carb/choke cleaner.
I also fished a metal snake down the EGR air lines and didn’t find any obstructions in the passages.
I looked around, questioning what else might be a culprit and this purge valve sticks out. Best I can determine, it routes back to the fuel tank/vapor canister and will vent excess vapors from that system into the intake manifold intake runner. Valve and where it enters the intake are highlighted.
I’m waiting to check the EGR cleaning results before moving onto disconnecting the tubing from the purge valve to the intake manifold, plugging the intake manifold opening (leaving the purge valve outlet open to atmosphere) and seeing if the long crank happens or not.
With the fuel vapors not making it into the intake and the intake not venting, it’d tell me if this is the source of what is filling the intake manifold.
- Thread starter
- #115
Well, shy of it being a tease or a change in the amount of time it needs to act up, it’d seem the EGR valve cleaning has cured the long crank, at least in the way it’s happened historically. It’s now started reliably three times after trying to get it to act up.
I’m hesitant to call it fixed, I’ll need to live with it a few days and through enough various scenarios to be more confident, but I’m hopeful.
I’m hesitant to call it fixed, I’ll need to live with it a few days and through enough various scenarios to be more confident, but I’m hopeful.
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r2m
Richard
I think I can say this for everyone on this thread, we're all hoping the best over the next couple of days and that it IS finally fixed!
- Thread starter
- #117
I’ve attempted to get it to long crank multiple times after sitting 30 min, 1, 1.5, 2 and 4 hour marks and cannot get it to act up under any circumstances. A dozen or more successful starts in the exact conditions it’d always act up in over the last several months.
I’m officially calling it and believe it’s now fixed.
It’d seem the gum/gunk buildup in the EGR valve got shifted around during the valley pan repairs and got lodged in a way that held the EGR plunger valve open, just enough to let exhaust gases slowly leak into the intake manifold, accumulating to a critical point over 1-1.5 hours.
The presence of that hot oxygen depleted exhaust gas likely displaced the colder oxygen rich air and is what caused the engine to turn over for several seconds before that less combustible air in the intake was cleared out and it begun getting the fresh air it needed for combustion.
Thank you to everyone who shared ideas, insight and the struggle! I’m elated by the idea of just enjoying the GX again without constantly contemplating the issue.
Cheers y’all!
Jake
I’m officially calling it and believe it’s now fixed.
It’d seem the gum/gunk buildup in the EGR valve got shifted around during the valley pan repairs and got lodged in a way that held the EGR plunger valve open, just enough to let exhaust gases slowly leak into the intake manifold, accumulating to a critical point over 1-1.5 hours.
The presence of that hot oxygen depleted exhaust gas likely displaced the colder oxygen rich air and is what caused the engine to turn over for several seconds before that less combustible air in the intake was cleared out and it begun getting the fresh air it needed for combustion.
Thank you to everyone who shared ideas, insight and the struggle! I’m elated by the idea of just enjoying the GX again without constantly contemplating the issue.
Cheers y’all!
Jake
r2m
Richard
Now that this has been solved, time to get back to the build!! 
That is great news!!! I've only glossed over EGR removal. Do you lose much coolant removing it? This may perhaps be a maintenance item some may want to undertake.
I know now if I have ever have to undertake this project (coolant valley) myself EGR cleaning will part of the job.
I can't say I ever cleaned one before (only replaced). I did have one fail on my old 5.0L Explorer.
I know now if I have ever have to undertake this project (coolant valley) myself EGR cleaning will part of the job.
I can't say I ever cleaned one before (only replaced). I did have one fail on my old 5.0L Explorer.
- Thread starter
- #120
Haha thanks man.
EGR cleaning is pretty straight forward. You don’t have to disconnect the coolant lines that run to/from it just to clean it. Just unbolt the three 12 mm bolts that mount it to the intake manifold (top three circled bolts) and the four 10 mm nuts on the inlet and outlet gas piping (bottom four circle nuts) then the whole EGR valve housing can be moved around, flipped over, etc (there’s enough slack and play in the coolant lines).
The remove the inlet and outlet pipes from the main body (four more 10 mm nuts) and you’ll have direct access to both sides of the plunger valve. I used a few rags underneath and choke/carb cleaner to flush it out and a rag to get a bit more aggressive on the outlet side. Blew it clean with shop air and reinstalled it.
EGR cleaning is pretty straight forward. You don’t have to disconnect the coolant lines that run to/from it just to clean it. Just unbolt the three 12 mm bolts that mount it to the intake manifold (top three circled bolts) and the four 10 mm nuts on the inlet and outlet gas piping (bottom four circle nuts) then the whole EGR valve housing can be moved around, flipped over, etc (there’s enough slack and play in the coolant lines).
The remove the inlet and outlet pipes from the main body (four more 10 mm nuts) and you’ll have direct access to both sides of the plunger valve. I used a few rags underneath and choke/carb cleaner to flush it out and a rag to get a bit more aggressive on the outlet side. Blew it clean with shop air and reinstalled it.
