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Weehe Weehe is offline
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Default Bent Rod, Cracked Ring, or? - 10-15-2017, 05:21 PM

At ~98k miles I installed a Pure Stage 2 and have been running 20psi with E30. For the first time since owning the car (46k miles), I got the low oil, add a quart light. Thinking it was a fluke the first time, I didn't document the mileage. I have gotten the low oil light 3 more times now, every 1500-2000 miles.

I started getting a stumble at idle, so replaced my plugs (they had 12k miles on them). All plugs but cylinder 4 looked new.


The base and insulator has carbon deposits, while the electrode is crusty white.

This made me pretty concerned so I did a compression test:
C1-200
C2-160
C3-190
C4-185
C5-200
C6-160

Not really what I was expecting, now I'm concerned about C2 and C6 as well. I also took pics of the new plugs after 300 miles. C4 already had deposits.

The rest looked brand new:


My next thought was a bad PCV valve in the valve cover causing oil vapors to get sucked into C4. I pulled the intake manifold, but there was no oil residue on the intake track or valves. I also confirmed the main PCV valve is fine with the vacuum test. So oil is coming from after the intake valves.

Lastly, I checked all cylinders with a scope. C4 piston was dark brown, burnt oil. All the others looked normal with a little carbon deposit on the sides. There was no visible damage on any cylinder wall, or on the edge of the pistons/rings.

So I am at a loss. The car still drive great, only with the occasional stumble at idle. I know these engine can bend rods and oil consumption is the only indicator.

Is there anything else it could be? I'd rather not wait for it to pop to find out.
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bNks334 bNks334 is offline
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Default 10-15-2017, 05:40 PM

That looks like oil coming from above (oil is all the way up the threads)... like a leaking valve cover gasket...

Compression test makes you wonder though. I've heard you can drop a bit of oil down the spark plug tube (wet test) to rule out piston rings.
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Default 10-15-2017, 05:44 PM

Quote:
Originally Posted by bNks334
That looks like oil coming from above (oil is all the way up the threads)... like a leaking valve cover gasket...

Compression test makes you wonder though. I've heard you can drop a bit of oil down the spark plug tube (wet test) to rule out piston rings.
Carbon is from cylinder up. When I removed the old C4 plug it was hand tight. So gases were going up the threads. There is no leak from the VC.

But that does make me want to check the injector seal. I can't remember if oil could get in and leak down that.
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Default 10-15-2017, 07:12 PM

How the hell are you running 20 PSI on stock fuel system with PS2?!
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Default 10-15-2017, 07:19 PM

Quote:
Originally Posted by Marlinman
How the hell are you running 20 PSI on stock fuel system with PS2?!
I have a stage 2 fuel pump, E30 isn't too big a demand. Actually run AFR in low 12s too. Will probably drop it to 19psi for winter.
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Default 10-16-2017, 10:41 AM

My car had similar symptoms a while back. A month later after those symptoms Boom! Bye Bye Cyl #4

Don't wait like I did and just get it fixed.


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Default 10-16-2017, 11:19 AM

Quote:
Originally Posted by alexis485
My car had similar symptoms a while back. A month later after those symptoms Boom! Bye Bye Cyl #4

Don't wait like I did and just get it fixed.
The thing is, I've been consuming oil ever since I installed the PS2. So I'm not sure if the turbo is leaking oil, or if I damaged the engine as soon as I installed it. I have been running with oil consumption for 10k+ miles and has been pretty consistent. The stumble at idle is new, I'm wondering if they are unrelated and it's just an injector.
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bNks334 bNks334 is offline
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Default 10-16-2017, 11:30 AM

uhhhhhh you should not have oil on your spark plugs. You have SOMETHING that you need to address whether it's related to your stumble at idle or not... There really aren't that many ways for oil to get into the cylinder.
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Default 10-16-2017, 11:36 AM

Quote:
Originally Posted by bNks334
uhhhhhh you should not have oil on your spark plugs. You have SOMETHING that you need to address whether it's related to your stumble at idle or not... There really aren't that many ways for oil to get into the cylinder.
I appreciate all help in this situation, but I assure you it is not normal oil on the spark plug. It is dry carbon deposits coming from the cylinder going up the threads. The plug was only hand tight, so would make sense that gases were going up the threads.
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Default 10-16-2017, 12:38 PM

Those compression test results are alarming. Generally they should be within 5 of each other, although the absolute value can vary by kit/temp. I would get them confirmed with compression and leakdown tests from a good Bimmer shop.
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Default 10-16-2017, 12:43 PM

Quote:
Originally Posted by Weehe
The thing is, I've been consuming oil ever since I installed the PS2. So I'm not sure if the turbo is leaking oil, or if I damaged the engine as soon as I installed it. I have been running with oil consumption for 10k+ miles and has been pretty consistent. The stumble at idle is new, I'm wondering if they are unrelated and it's just an injector.
The reality is this cars consume oil and even more when they are pushed. It really hard to take that foot off the accelerator when running PS2

Anyhow, IMO your car symptoms doesn't sound like anything related to oil leak from the turbo. Its more like piston ring about to collapse. I had that same stumble at idle and carbon deposit in the plug in cyl 4 only. Also, I did a compression test and cyl 4 didn't look that bad (185) compare to the others. Then, I replaced the plugs and the car ran normal after but, it was a matter of time until the worse happened.


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Default 10-16-2017, 01:12 PM

Quote:
Originally Posted by alexis485
Anyhow, IMO your car symptoms doesn't sound like anything related to oil leak from the turbo. Its more like piston ring about to collapse. I had that same stumble at idle and carbon deposit in the plug in cyl 4 only. Also, I did a compression test and cyl 4 didn't look that bad (185) compare to the others. Then, I replaced the plugs and the car ran normal after but, it was a matter of time until the worse happened.
That seems pretty premature to think there is impending failure. Also, care to elaborate more on your prognosis? I don't think you actually meant piston ring collapse.
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Default 10-16-2017, 01:41 PM

my car consumes about 1 quart every 2500 miles (19-22 psi e30) I think its pretty normal cus cylinder pressures are much higher with the PS2. I do drive my car hard usually multiple WOT pulls every time I drive it. have you considered maybe a leaky injector?


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Default 10-16-2017, 04:31 PM

Quote:
Originally Posted by JETmn
That seems pretty premature to think there is impending failure. Also, care to elaborate more on your prognosis? I don't think you actually meant piston ring collapse.
I meant to say based on the symptoms similarity with my car, there is an indication of worn piston rings.


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Default 10-16-2017, 08:04 PM

Quote:
Originally Posted by Newguy123
my car consumes about 1 quart every 2500 miles (19-22 psi e30) I think its pretty normal cus cylinder pressures are much higher with the PS2. I do drive my car hard usually multiple WOT pulls every time I drive it. have you considered maybe a leaky injector?
Before I installed the PS2 I only had the low oil light come on once when I went 8k with an oil change. As soon as I installed it the 1500-2000 needing a quart started. So that's why I'm not sure.

I actually just bought a new injector as it seems plausible. My AFR goes rich at idle when it stumbles, so seems promising.
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Default 10-17-2017, 12:13 AM

Quote:
Originally Posted by Weehe
Before I installed the PS2 I only had the low oil light come on once when I went 8k with an oil change. As soon as I installed it the 1500-2000 needing a quart started. So that's why I'm not sure.

I actually just bought a new injector as it seems plausible. My AFR goes rich at idle when it stumbles, so seems promising.
Could also be increased cylinders from running higher boost with PS2 which could cause higher crank case pressure so more oil going through the pcv system, or piston rings to be more compressed allowing oil by. On my other cars with larger turbo upgrades and higher boost they always burned alot more oil, it also seemed to get a bit better on low boost.

That's why im looking at getting a stage 3 turbo for my m2 as i'll be able to make as much power as stage 2 turbos at significantly lower boost levels (~15 psi range) which will be friendlier on rods and pistons and internals in general.


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Default 10-17-2017, 06:25 AM

Agreed, it could be more blow by. I haven't noticed any more oil residue in the intake track though. Also, if it was the turbo it probably would have gotten worse by now. I don't want it to come across as bashing the PS2, was just listing my thought process.

I've ordered an injector that should be here this week. Will see if it fixes it.
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Default 10-17-2017, 08:19 AM

I had more consumption with my PS2 as well. Had good compression though. I would have a plug loose every now and then. I went stage three for many reasons. The cost is so low not and I would take a EFR over a hybrid any day. PS2 is still a hell of a bang and seriously quality work if you are CERTAIN you want <500 whp. People push them to get good numbers, but a engine is a air pump, there is only so much you should push from the stock turbofold.

So you have a great problem, choosing between quality well priced options. Good time to have a N55/N54!


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Default 10-17-2017, 02:30 PM

Quote:
Originally Posted by jturboawd
I had more consumption with my PS2 as well. Had good compression though. I would have a plug loose every now and then. I went stage three for many reasons. The cost is so low not and I would take a EFR over a hybrid any day. PS2 is still a hell of a bang and seriously quality work if you are CERTAIN you want <500 whp. People push them to get good numbers, but a engine is a air pump, there is only so much you should push from the stock turbofold.

So you have a great problem, choosing between quality well priced options. Good time to have a N55/N54!
+1

Btw not bashing pure at all, it just won't hit my goals on pump gas alone, and if it could it can't hold that boost level till red line. I also prefer low boost to help prolong the internals.

Plus since my m2 is going to undergo a full track conversion it'll really help out having a less restrictive exhaust manifold and low boost in terms of heat, and it'll even be a bit easier on my internals too at 480-500whp.


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Last edited by Lowon; 10-17-2017 at 02:35 PM..
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jturboawd jturboawd is offline
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Default 10-17-2017, 03:07 PM

I'm right there with you, speedtech kit sitting on the shelf already sold my ps2


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Default 10-17-2017, 05:45 PM

Quote:
Originally Posted by jturboawd
I'm right there with you, speedtech kit sitting on the shelf already sold my ps2
I thought it was F-series only for some reason. Am I mistaken? In the description it says 2012-2015
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Default 10-17-2017, 09:44 PM

Quote:
Originally Posted by KevinC39
I thought it was F-series only for some reason. Am I mistaken? In the description it says 2012-2015
They have an E-series n55 kit now too.


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Default 10-17-2017, 09:45 PM

Quote:
Originally Posted by jturboawd
I'm right there with you, speedtech kit sitting on the shelf already sold my ps2
Lol hurry up and install it with some images already!
Can't wait to see how that goes man.


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jturboawd jturboawd is offline
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Default 10-18-2017, 05:35 AM

I know i am dying to put this thing on. I have a e series kit on the shelf with SSP clutches, m4 flywheel, a2w intercooler,meth, etc. Ill have it on by the end of the year for sure.

cylinder pressure will be higher like for like on the PS2 for many reasons. larger turbo should make less torque at equal HP because the air pump is much more efficient, all this goes into why its easier on the engine and pretty much always a better idea to go a little larger then increasing HP. The stock turbofold is designed for quick spool, they open up the part right at the turbine but they cant open up the vains in the turbofold.


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Default 10-18-2017, 08:18 AM

Quote:
Originally Posted by jturboawd
I know i am dying to put this thing on. I have a e series kit on the shelf with SSP clutches, m4 flywheel, a2w intercooler,meth, etc. Ill have it on by the end of the year for sure.

cylinder pressure will be higher like for like on the PS2 for many reasons. larger turbo should make less torque at equal HP because the air pump is much more efficient, all this goes into why its easier on the engine and pretty much always a better idea to go a little larger then increasing HP. The stock turbofold is designed for quick spool, they open up the part right at the turbine but they cant open up the vains in the turbofold.
+1, btw what air to water intercooler are you going to get? And I didn't know they sold any for n55's.

Horse power stays the same or increases at a lower boost level with a larger turbo because it's able to flow a larger volume of air at lower boost pressures. Sure torque does drop a bit but not too much.

Now what does this mean for a track focused car?

1) we know compressing air generates heat, therefore higher boost means more compression means more heat in the form of charge air temps. What else do we know? These F series BMW cars run really lean, this leans to high cylinder temps, high exhaust gas temps, and high water temperature + oil temperature as a result aka bad news for a track car.

2) the exhaust manifold on these stage 3 turbos are really good, and able to flow a larger volume of gas than stock. This will lower restriction in the exhaust portion and allow exhaust gases to flow more freely. As a result lower cylinder temps can be expected compared to the restrictive stock exhaust manifold. (Bmws dump fuel to try and cool egts by making the afrs richer as part of the stock ecus function causing hpfp to crash, read Rwalkers thread for that). Again this helps ensure track reliability.

3) lower boost psi or kpa means less pressure (unless you max out a stage 3 turbo but that's a different story) on the internals of your motor, what does that mean? More engine reliability and less chance can of bending a rod.

4) like many others have said, I personally prefer a Borgwarner efr turbo to a hybrid turbo because imo every part of the efr was meant to support it's intended power level.


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