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Discussion Starter · #21 · (Edited)
Also, you need to figure this out! We, the forum, can't afford to have you exchanging your car for something else, unless it's another Mustang Ecoboost. 馃馃徏
Hahaha! I'm heavily leaning towards the new downpipe having a fundamental effect on my blowby. I just got back from picking up my daughter again from my parent's house. No CELS. Hooked up my OBD dongle. No codes. Car drove just fine.

It is going to be in the back of my mind though, just like @FreedomPenguin said. I'm either going to spring for a whole new PCV solution (upr dual valve with radium plate) or may put the OEM downpipe back on. Don't want to drive around worrying about a puddle of blowby accuumulating in my hotside pipe. But I'll check my catch can again in about 2 or 3 weeks.

Lastly, as far as going for another Ecoboost Mustang. Trust me, this car has been PLENTY FUN. I've enjoyed driving it and I've enjoyed modding it. But one of my life mantras is 'fool me once, shame on you; fool me twice, shame on me'. The entire reason I got this car in the first place, was because I could mod it with a warrantied FP tune. I've meticulously researched every subsequent mod to ensure that I was being as safe as I could with it. After all, it still needs to be my daily driver. But if its not even able to last me 60K miles (I'm expecting 100K), then it would be time to cut my losses. FWIW, I browse the CArmax inventory here and again, and am in love with the Toyota Camry & Avalon TRD versions. I also really like the turbocharged Mazda6's with the skyactiv technology.

This is definitely a to be continued story....for now.....
 

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Did you keep the oem downpipe in attic etc? curious, in the sections in rear, go out and wipe your finger, it is it covered in black soot? mine was, it literally changed my grabber blue ti like dark. it was on the black plastics a little too. I use Degreaser 9 or whatever its called, and washed it all off.

but in 25k miles, I didn't have any soot build up, and in the few thousand miles, I had a ton built up.
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Your going to get a soot build up on any car.

Fuck me dead when I was OEM and I was washing it nearly every week there was always a fine/thin layer of soot built up around those areas and the Exhaust.

The worse ones by far were the turbo Diesels. But even then that was more because I was more lazy and couldn't be arse to clean it all the time.
 

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Your going to get a soot build up on any car.

Fuck me dead when I was OEM and I was washing it nearly every week there was always a fine/thin layer of soot built up around those areas and the Exhaust.

The worse ones by far were the turbo Diesels. But even then that was more because I was more lazy and couldn't be arse to clean it all the time.
I get that soot builds up, but during that time IT WAS CAKED on. I had to scrub the **** out of it, since I went back to OEM downpipe, ive never see it discolored again. 3k miles now
 

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@gatornek and @FreedomPenguin , forgive me, but what tunes are you guys running? Are you both running Ford Performance tunes? I'm wondering if that is part of the issue with you guys running downpipes? I don't think the FP tune can account for a downpipe like an aftermarket tune can. Just spit balling here to see what you guys have in common.
 
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Discussion Starter · #26 · (Edited)
@gatornek and @FreedomPenguin , forgive me, but what tunes are you guys running? Are you both running Ford Performance tunes? I'm wondering if that is part of the issue with you guys running downpipes? I don't think the FP tune can account for a downpipe like an aftermarket tune can. Just spit balling here to see what you guys have in common.
Yes. FP tune.

No forgiveness necessary bro. I've been trying to hash this out since yesterday, endlessly reading on what could cause this much blowby now. Not sure how adding a PRESUMABLY higher flow downpipe could do this. It's not uncatted, just a (again...presumably) higher flowing cat.

From what I understand, adding an UNCATTED downpipe simply allows the tuner to be more aggressive in the tune since he doesn't have to control exhaust gas temps, which could be detrimental to the cat behind it. If the tune stays the same from the OEM downpipe, all your really doing by adding a 'higher flow cat' is changing the exhaust note, and possibly allowing your turbo to spool up a tad bit faster.

What I don't understand, and I'm still trying to do some reading, is how it could possibly affect the PCV system. And it seems to be BOTH the 'cleanside' and the 'dirtyside'. My catchcan on the dirty side was the MOST FULL I've ever seen it....which would seem obvious now from the amount of 'smoke' and 'blowby' that was exhibited in the video, with my dipstick out. With the dipstick seated, and at idle (as it was), one can only assume that this smoke/blowby is now exiting out the PCV breather plate and into my dirtyside catchcan. The increased blowby was also obviously exhibited by the picture of my splashshield where the hotpipe meets the intercooler. It seems obvious that there is blowby also coming through the top pcv valve on the passenger side, entering the intake, and getting blown out by the compressor and into the hotside pipe...which ended up causing my hotside pipe silicone couplers to slip off.

I'm really trying to understand this so I can make an informed decision on how to move forward. Right now my options are either redoing my PCV plate and catchcan system, or putting the OEM downpipe back on, and seeing if things don't return to normal. Would never have thought that much smoke would exit the engine on idle. That plus the puddle told me something is wrong, or at least different, than it was before.

I'm all ears for any facts that I might be missing and a logical explanation into how the new downpipe allowed this to happen.
 

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all I can contribute is, FP + oem downpipe = barely ANY oil.
FP + downpipe = 3-4-5x as much in less time.

Not sure why, but I also had full 3 inch exhaust. I didn't have it taper from 3 inch to 2.25 after downpipe.my theory is more flow, lets more pressure, means more oil can be sucked up into air.

the soot thing, was another by product I noticed. 25k miles= my rear valence was always blue. few thousand miles, my car had black soot caked up on the valence. 3k miles later with oem downpipe, it hasn't changed colors since. could be coincidence...

but I also had that terrible CPE CAI on it, and that thing I had ridiculous IAT's and never really noticed, I put oem back on same time I put oem downpipe back on. Maybe higher temps from IAT caused more richness ontop of downpipe? possible.
 

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The whole thing doesn't make a ton of sense to me either. I'm just trying to find the correlation. It's gotta be the downpipe combination with the FP tune. The tune just likely isn't optimized to run a downpipe. In all honesty, I've been on the fence about a downpipe myself. I know I could grab some more ponies, but I don't know if the juice is worth the squeeze for me.
 

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Discussion Starter · #29 · (Edited)
my theory is more flow, lets more pressure, means more oil can be sucked up into air
Let's think about this. Blowby happens (only happens??) when 'excessive' pressure from the ignition event is able to leak past the piston rings and into the crankcase. During this event, both the exhaust valves & intake valves are shut. I think it boils down to what is causing this amount of pressure, that escapes past the piston rings, to increase? The only way(?) to increase pressure is to have a much stronger ignition event. If the theory about the FP tune + aftermarket downpipe is correct, then theoretically, the FP tune could be injecting more gas than what is needed. But the FP tune is basing its fuel delivery on the MAP sensor at the throttle body, load, rpm, etc....so is the lessened backpressure of a freer flowing exhaust able to dramatically increase the amount of air inside the cylinder during the intake stroke, after it made its calculation? I don't see how, because the exhaust valve is closed and the intake stroke is basically dealing with a volume of air that it already took into account without the exhaust having any effect on its 'flow' into the chamber. The only thing I can think of, in this regard, is that the chamber is able to evacuate the exhaust gases much better than the FP tune is thinking. In which case, then yes, then the intake stroke is loading up much more on clean air, then the FP tune is accounting for! I wanna say that I remember reading some where that at idle, the engine almost expects for there to be some exhaust gases lingering around.

Anyway, just food for thought. I don't know. I'm grasping at straws.

I spent all day yesterday and today reading this 58 page thread thread from Mustang6g that deals with downpipes and the PCV system...but I don't really feel it applies to this issue. Everyone there is complaining about 'smoke out the tailpipe' when adding a downpipe. The conclusion was, in particular with the 2015 Mustangs which had an older PCV plate that was apparently more restrictive than the one I have (and everyone has now because Ford revised it https://www.mustang6g.com/forums/attachments/tsb15-0192-pdf.56878/), the pressure from the crankcase was able to overcome the lessened pressure from the exhaust, and would allow droplets of oil to push out the turbo seal, into the turbine, and then get burned up in the exhaust, thus causing smoke. In essence, the PCV system was not doing what its supposed to. This is almost the opposite, the PCV is working, its just possibly being overwhelmed. I have checked time and again, there is no smoke coming out my tailpipe.

Blue smoke out of exhaust

I'm going to do some serious datalogging from here on out. Make sure I have my AFR's, fuel trims, and crankcase pressure recorded. I may also have to start connecting my dongle before actually starting the car, so I can record my startup event and transition into idle. In the meantime, I may re-purchase the passenger side FP catchcan or go with the UPR. I need to make sure that the air/oil is being separated before being shot back into my intake, pre-turbo.

Once I get more information and data, I'll make a decision on whether to ditch the downpipe.

I appreciate all the feedback. Honestly, I still have about a year left to pay off this car, and while I am no longer underwater on it (according to KBB), I was really looking forward to having no car payment. I'd really like to get to that point, and be able to enjoy that for some time.
 

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@gatornek Glad this turned out fine so far for you. Lots of food for thought in this thread.
Please keep us posted as the days goes by. Carmax and so on are good if selling but it's not a buyers market :)
As long as everything checks out might be best to stay with the devil you know.... for a while! :sneaky:
 

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Havnt got a clue about technical aspect. What you said blew over my head. Your bumper valence that I posted a photo of, is it really sooty? more than you remember it being? wondering if you also had that issue like I did, or if that was a combination of the super heated air temps from my old intake. maybe more fuel to cool it down lol
 

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I think the vapor escaping the oil filler port while at idle is a red herring. You don't get significant piston blow by at idle. The increase in oil quantity in the intake systems, however, is telling. Running an aftermarket downpipe without modifying the PCM software to account for it is not a good idea, because significant changes to exhaust backpressure can adversely affect the turbocharger, specifically maximum turbo RPM. The PCM modulates boost using the wastegate. Wastegate actuation is based on variables, or engine indications that change with conditions and power demand, and constants, which are things the PCM expects never to change. One of those constants is exhaust backpressure. The PCM can safely demand a given maximum boost without fear of over-speeding the turbo because it expects sufficient backpressure in the exhaust system to control turbo RPM. Remove that backpressure, however, and the turbo is free to spin faster. Fast enough to cause damage? That's where I would be looking if I were you.
 

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Discussion Starter · #33 ·
@gatornek Glad this turned out fine so far for you. Lots of food for thought in this thread.
Please keep us posted as the days goes by. Carmax and so on are good if selling but it's not a buyers market :)
As long as everything checks out might be best to stay with the devil you know.... for a while! :sneaky:
Agreed. If this as simple as either installing a better PCV system or removing the downpipe, then all is good.
 

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Discussion Starter · #34 ·
Havnt got a clue about technical aspect. What you said blew over my head. Your bumper valence that I posted a photo of, is it really sooty? more than you remember it being? wondering if you also had that issue like I did, or if that was a combination of the super heated air temps from my old intake. maybe more fuel to cool it down lol
Valance is not sooty. Not so sure if its because my Borla mufflers stick out a decent distance past the valance. But I've also been religiously watching the tailipe for any hint of smoke, and there has been nothing.
 

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Discussion Starter · #35 ·
I think the vapor escaping the oil filler port while at idle is a red herring. You don't get significant piston blow by at idle. The increase in oil quantity in the intake systems, however, is telling. Running an aftermarket downpipe without modifying the PCM software to account for it is not a good idea, because significant changes to exhaust backpressure can adversely affect the turbocharger, specifically maximum turbo RPM. The PCM modulates boost using the wastegate. Wastegate actuation is based on variables, or engine indications that change with conditions and power demand, and constants, which are things the PCM expects never to change. One of those constants is exhaust backpressure. The PCM can safely demand a given maximum boost without fear of over-speeding the turbo because it expects sufficient backpressure in the exhaust system to control turbo RPM. Remove that backpressure, however, and the turbo is free to spin faster. Fast enough to cause damage? That's where I would be looking if I were you.
FWIW, it wasn't the oil filler port, it was the dipstick hole. Not sure if that makes it better or worse though, lol. I get the whole overspeeding the turbocharger. Remember that the PCM also uses the throttle plate to shape the boost curve as it is more responsive than the wastegate. I've been monitoring boost pressure ever since adding the downpipe, and its been nominal. I was just commenting on another thread about how I feel that there is zero lag in the car. My pedal goes down, boot pressure goes right up. So if anything, there could very well be a much faster spool up to achieve peak boost. Again, the question in my mind, is how any of this would increase blowby. Because I'm skeptical about the fact that the turbo spooling up faster would lead to increased blowby, even at idle(?). I'm still leaning towards the PCM injecting more fuel than necessary. My gas mileage was never the greatest because of my heavy foot and the urban stop/go nature of travel around here, but the past couple of months its gotten a bit worse. Down to about 16 mpg (I was steady at about 18-19 mpg before). I just figured I was LOVING hearing the new exhaust note from the new downpipe and resonator, so maybe I was being extra aggressive on the throttle...but maybe there is something to that?

I do agree that this is something I need to keep an eye on and make a decision on. Finding a puddle of oily residue on my splash shield is precisely why I freaked out and titled this thread as I did. But again, the car is running as it always has from behind the steering wheel. No weird noises. No shaking. No pinging. No smoke out exhaust. No CELS. And absolutely no codes that I could pull. If the turbo were overspeeding, then that's a definitive code that would have reared its head by now, no?

My next steps are as follows:

1) Install a catchcan solution on the cleanside valve (passenger side). I need to know for sure that the oil deposit is coming from blowby out the valve, and not the turbo itself.
2) Start datalogging every trip for fuel trim, crankcase pressure, boost pressure, etc
3) Based on my findings from the first two, I'll make a decision whether or not to remove the downpipe.

I will keep this thread posted.
 

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I know you likely chose the FP tune for a reason (warranty), but have you considered going the route of professional tuning to compensate for the downpipe. I'm with @MWSletten on this one, I think it's due in part to a tuning issue.
 
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I've been monitoring boost pressure ever since adding the downpipe, and its been nominal.
That's not the issue. The issue is the relationship between boost pressure and back pressure. I don't know all the ins and outs of how the software manages turbo RPM, but there is no direct measurement of it. That means the software has to make assumptions--that's the constants. You can still overspeed the turbo with nominal boost pressure if assumptions about other constants are wrong.
 

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Discussion Starter · #38 ·

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Discussion Starter · #39 ·
I know you likely chose the FP tune for a reason (warranty), but have you considered going the route of professional tuning to compensate for the downpipe. I'm with @MWSletten on this one, I think it's due in part to a tuning issue.
It may be an option. I just need to understand the issue before I chase it. Even if I gotta throw a little money at understanding it.
 

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From the looks of your plugs, plug holes in the head, I don't think it's an engine issue. I hoping that your engine is okay. I'm more concerned with the turbo for the reasons @MWSletten listed above. I think that is your smoking gun if you will. I think if you either tune for the downpipe, or replace it with stock, a lot of your issues will disappear. I would not, continue to drive the car as is, however. You may have caught this early enough to fix it, prolonged use will not be your friend. You can always do a compression check to make sure, but I don't honestly believe that is the issue here. Just my $.02
 
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