Surging issue, dumping boost around 12 psi


italianjoe

Well-known member
Apr 9, 2018
180
Dearborn Heights Mi.
Well I can tell you that I had the correct oil filter crack, and the car almost bled out completely. Was back in 2019. I was REALLY lucky that it happened on the street of our shop. Made one hell of a mess inside the shop, once safely parked and shut down. Ill still use the correct Motorcraft filter. Next change will be switching from Castrol to Motocraft.

GT power, thanks for joining us, and your insight that you have provided, so far! I hope some members don't dissuade you from sharing more.








0
Just curious was the filter that failed the one that cracked at the seem? I have only seen two filters fail one was at the seem towards the bottom and the other was at the top where the oil filter wrench goes.

And just an F.Y.I. for the guys who do there own oil change please look at the filter closely. I have had a filter with the inner rubber seal off center. So please look at them before installing them.
 
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nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,176
I'm not an engineer, and my brainpower is limited for this topic at this time, or honestly most other times. But why are you gonna argue about this with a guy who just said "I was tasked with launching the Ford GT engine line" about this topic?"

1. Only that it would take more than 300psi to balloon the metal casing of a spin-on oil filter and wondering how a NFGT would accomplish that - especially when the rubber seal would seemingly fail well before that pressure.

2. Other high performance Ford motors - like the 3.5 Ecoboost in the Raptor and the 8200rpm 2016/17 GT350/GT350R both spec the FL500S filter, seemingly without trouble. Does the NFGT generate substantially more oil pressure than these cars?

Not challenging that there's a reason that the NFGT specs a different filter - but can't believe it is pressure-related failures because then it would also be failing in these other (similar or greater pressure) applications.
 

GT Power

Ford GT Team Alumni
Mar 17, 2021
12
Force = pressure x area. The seal is not the weak point.

The GT350 does not use the FL500 filter. An FL-2069-ST is used on that vehicle.

You are once again comparing a basic wet sump design to the GT’s superior, purpose built dry sump system. Apples and oranges comparison.

The GT went through a considerably more aggressive durability test cycle than any other Ford engine. Issues get identified that would never manifest themselves on other platforms, especially not on a truck engine.

I’ve wasted enough of my time on this. Over and out.
 

extrap

GT Owner
Mark II Lifetime
Jul 16, 2020
1,751
Gainesville FL
...

I’ve wasted enough of my time on this. Over and out.

For what it's worth I enjoyed reading all you wrote, good info coming from the source 🍻 I don't actually own a NGT, but I've been thinking about getting one.
 

Special K

GT Owner
Mark IV Lifetime
Aug 23, 2016
1,775
Franklinton, LA
Getting back on topic... I did hear from the concierge late last week that a vacuum line to the waste gate which runs very close to the turbo was found damaged (one source said melted another said cut). They have not yet driven the car to see if that was the culprit. Just passing the info along as it comes my way.
 

fjpikul

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Jan 4, 2006
11,475
Belleville, IL
Cut? Who would do that?
 

Special K

GT Owner
Mark IV Lifetime
Aug 23, 2016
1,775
Franklinton, LA
Cut? Who would do that?
I’m leaning toward melted, just passing on the raw info.
 

nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,176
I'll create a new thread in the future to continue the "discussion" on the oil filter. Hopefully I'll have some cut-aways of several related filters to illuminate some of the differences.

Special K - I'm glad you are getting some feedback on the diagnosis of your car and I hope it is back in your hands soon at 100%!
 
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nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,176
Getting back on topic... I did hear from the concierge late last week that a vacuum line to the waste gate which runs very close to the turbo was found damaged (one source said melted another said cut). They have not yet driven the car to see if that was the culprit. Just passing the info along as it comes my way.

Special K - thanks for giving us updates. I happened to take a look at the service manuals for the GT yesterday and looked up some diagnostic information on the problem you described.

In the engine diagnostics there is some guidance on troubleshooting problems like no start, long cranking, rough idle, etc. But there is also a section on reduced power and some reference to diagnosis through specific sounds. A discernable "chirp" sound points to the blow-off valves. As ItalianJoe accurately pointed out, there are two of them on the GT. That's kinda interesting (the fact that there are 2) but perhaps even more interesting is the fact that they are electronically controlled. Hence, I suppose the reason that ItalianJoe was referencing the importance of engine management software. (In a lot of different applications, blow-off valves are completely mechanical.) Anyway, based on a very, very, long arm's length diagnosis, my gut still says issue is in the "charge-side" turbos. Despite that the blow-off valves are electronically controlled, they are still physically opening a valve (when commanded) and my bet is on the mechanical side of one of those valves not fully closing. It may get pushed closed and sealed under higher, but not so good under partial boost.

In terms of the findings of the broken/melted/cut vacuum line(s) to the wastegate, that is a good find. Vacuum leaks are never good and really need to be dealt with before continuing further diagnosis. I'm skeptical that this is the root problem because an errant wastegate control will compromise the creation of boost... but typically doesn't having anything to do with releasing charge-side pressure (save for the fact that a vacuum leak could obviously be problematic.) Typically a vacuum line to the wastegate is originating from an ECU-controlled boost solenoid as opposed to true manifold vacuum. I'll explain. For example, let's say that the target maximum boost for a Ford GT is 20psi. The wastegates would have a physical spring of about 1/2 of the target maximum boost pressure - so say, 10psi in our example. It means that under hard acceleration, the turbos would generate 10psi of charge pressure and then the wastegates would start opening to vent the exhaust gasses and boost pressure would level off at 10psi. (This is what is meant when engine builders say the car was running on wastegate springs.) But, in our example, we may want 20psi of boost. What happens is that there is an ECO-controlled boost solenoid. The ECU will control this solenoid to add pressure the wastegate diaphragm. This pressure becomes additive to the resistance of the wastegate spring. So, at full song, the turbos will ramp up to 10psi.... but then the ECU can add 0 to all of this 10psi back to the wastegate resistance and now the boost pressure between 10psi and 20 psi is being completely commanded by the ECU via the boost control solenoid.

So, coming back to your car/problem. If the vacuum line(s) that they found are true manifold vacuum, they need to be corrected and there is the possibility of this being the entire problem.. Fingers crossed! But two things that can throw a curve at this.... if the vacuum line that is cut/broken/melted is coming from the boost control solenoid, then it is not true vacuum and would more likely compromise maximum boost attainment as opposed to an un-warranted release. Th other nagging issue is that the sound sure sounds more like the bypass valve "chirp".

Anyway - I wrote way more than I was planning but maybe it provides a little more insight into the foundational elements of turbocharged engines.
 
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Special K

GT Owner
Mark IV Lifetime
Aug 23, 2016
1,775
Franklinton, LA
Special K - thanks for giving us updates. I happened to take a look at the service manuals for the GT yesterday and looked up some diagnostic information on the problem you described.

In the engine diagnostics there is some guidance on troubleshooting problems like no start, long cranking, rough idle, etc. But there is also a section on reduced power and some reference to diagnosis through specific sounds. A discernable "chirp" sound points to the blow-off valves. As ItalianJoe accurately pointed out, there are two of them on the GT. That's kinda interesting (the fact that there are 2) but perhaps even more interesting is the fact that they are electronically controlled. Hence, I suppose the reason that ItalianJoe was referencing the importance of engine management software. (In a lot of different applications, blow-off valves are completely mechanical.) Anyway, based on a very, very, long arm's length diagnosis, my gut still says issue is in the "charge-side" turbos. Despite that the blow-off valves are electronically controlled, they are still physically opening a valve (when commanded) and my bet is on the mechanical side of one of those valves not fully closing. It may get pushed closed and sealed under higher, but not so good under partial boost.

In terms of the findings of the broken/melted/cut vacuum line(s) to the wastegate, that is a good find. Vacuum leaks are never good and really need to be dealt with before continuing further diagnosis. I'm skeptical that this is the root problem because an errant wastegate control will compromise the creation of boost... but typically doesn't having anything to do with releasing charge-side pressure (save for the fact that a vacuum leak could obviously be problematic.) Typically a vacuum line to the wastegate is originating from an ECU-controlled boost solenoid as opposed to true manifold vacuum. I'll explain. For example, let's say that the target maximum boost for a Ford GT is 20psi. The wastegates would have a physical spring of about 1/2 of the target maximum boost pressure - so say, 10psi in our example. It means that under hard acceleration, the turbos would generate 10psi of charge pressure and then the wastegates would start opening to vent the exhaust gasses and boost pressure would level off at 10psi. (This is what is meant when engine builders say the car was running on wastegate springs.) But, in our example, we may want 20psi of boost. What happens is that there is an ECO-controlled boost solenoid. The ECU will control this solenoid to add pressure the wastegate diaphragm. This pressure becomes additive to the resistance of the wastegate spring. So, at full song, the turbos will ramp up to 10psi.... but then the ECU can add 0 to all of this 10psi back to the wastegate resistance and now the boost pressure between 10psi and 20 psi is being completely commanded by the ECU via the boost control solenoid.

So, coming back to your car/problem. If the vacuum line(s) that they found are true manifold vacuum, they need to be corrected and there is the possibility of this being the entire problem.. Fingers crossed! But two things that can throw a curve at this.... if the vacuum line that is cut/broken/melted is coming from the boost control solenoid, then it is not true vacuum and would more likely compromise maximum boost attainment as opposed to an un-warranted release. Th other nagging issue is that the sound sure sounds more like the bypass valve "chirp".

Anyway - I wrote way more than I was planning but maybe it provides a little more insight into the foundational elements of turbocharged engines.
Never too much information! I read it all and there is a lot to digest, but it’s discussions like this that get the thoughts flowing. Thank you for taking the time to research and opine. I’m hoping to see this resolved soon for all.
 
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