NefMoto

So my 1.8t is now a 1.9t with 83mm pistons. Pistons I bought were 9.6:1 compression supertech pistons. Turbo is a gt2860rs.
OEM all sensors, same locations, oem injectors for now. No doubt lots will need to be tuned to make sure things run correctly.
Currently I'm getting a 17705/P1297/004759 - Pressure Drop between Turbo and Throttle Valve (check D.V.!) code. Gonna check for leaks tomorrow.
This is the first set of data I gathered.
It appears the idle rpm is hunting, unsure why.
Lambda regulation for o2 sensor before catalyst is seeing highs of 19%, not sure if that could be potentially because of the leak. AFR during idle and PT seems stable though which is good.
After break in, I'll limit boost and get some WOT data.

Does anyone see what needs to be done to stabilize things?

What maps did you change already to fix displacement difference?

none yet, that data was the maiden voyage.
I have not calculated intake volume yet, how precise does that need to be? The only way I can think to do that simply is remove intake manifold, Close throttle body and fill intake with water, then remove and measure. Is there a better way?....perhaps a way without taking the intake off?

also: "Vs is intake volume from throttle plate to intake valve." Vs is in liters?

No, Vs cant be in liters.
In my HS file KISRM is .119100. Solving for Vs in the equation posted on the wiki yields 53.8337531.

Intake volune from valve to throttle plate is definitely not 53.8337531. Does anyone know the unit of measurement?

The goal here is to find the volume of the OEM intake manifold, find the units of Vs, subtract the found value from the manifold from Vs, this will yield the intake runner volume of all 4 cylinders. Then find the volume of my new intake manifold, add the runner volume and plug it into the variable Vs in the equation on the wiki.

also, looking through a translated version of the FR for BGSRM, they determine the equation to be KISRM = zkorr/[(Vs/VH) x z] which places priority for solving Vs/VH before multiplying by z, on the wiki, your equation has it as Vs/VH x z which would prioritize multiplying VH x z before dividing it by Vs.

Let me redo the equation with this new order of operations.

yea you must prioritize (Vs/VH) before multiplying by z.
for me, it yielded 3.36460957 which makes sense in liters now.

Translated FR:
"Vs is the intake volume from throttle plate through to the inlet valves, typically 1.5 to 3.0 x VH"

3.36460957 falls within this range. Good

ok so an oddity,

I have a welded larger intake manifold (which i will take an actual measurement of the volume of later)

so my OEM Vs is 3.364, I guesstimated the new one to be around 3.75.
My OEM displacement is 1.781 liters, my new displacement is 1.870 liters

my OEM KISRM is .1191

plugged both into the equation to calculate my new KISRM and got .1122. Not that far off. Perhaps when I measure the actual volume of my new intake manifold and recalculate I may get something a bit different but as per how the equation operates, if engine displacement goes up, KISRM goes up, if intake volume goes up, KISRM goes down.

also this:


What is this factor?

1870 % 1781

gracias

You should not really need to make big changes. Any drastically strange behavior you see is likely not displacement (or even intake size) related.

Logged after tuning KISRM, KUMSRL and MLMAX. Rpm is still hunting, sometimes it sputters a bit at idle.

lambda regulation before catalyst is still above 10% occasionally, it's fluctuating alot (viewed in VCDS).

I'm also still getting a 17705/P1297/004759 - Pressure Drop between Turbo and Throttle Valve (check D.V.!) code. Sprayed all silicone couplers and hose joints with brake cleaner to no effect. Did not spray compressor of turbo with brake cleaner yet but I doubt that's it. I also have 21" hg vacuum at the gauge at all times which doesn't really reflect an air leak. Is there a better way to hunt these leaks down or could it be something in the software?

Any ideas on how to fix these 3 issues? maps inside the "Idle LTFT and idle misfires" of the wiki?

Likely mone of that is tune related, IMO

Anyone have any ideas?

Its block 033 lambda regulation sensor before catalyst thats outside of range + or - 19% swinging. What does this block record? I dont believe this is stft is it? What does vcds mean by lambda “regulation?”

Aside from retorquing exhaust bolts and ensuring there are no exhaust leaks before lambda o2 #1, im out of options pretty much, blasted every intake joint with brake clean, tightened up all clamps, kinda stumped if its a hardware issue.

Could these symptoms be a stuck hydro lifter? Not quite perfectly sealing valve? Something else internal?

Compression test and leak down test would help you figure out if you have a cylinder low on comp.
Youre using stock maf sensor and stock sensor housing? Also using stock injectors? Using brake clean to check for vacuum leaks anyplace besides tje intake manifold is not going to do anything. The high vacuum is on the back side of the throttle valve. You need to pressure check the charge pipe


Used compressed air and set a regulator at 20psi and feel around with leaks soap and water gelp to fimd leaks

Try unpluging the maf and see if idle clears up. If it does you have a intake path / maf issue.

Pics of your setup would help too. What ku d of dump valve are you using? Do you have it plumbed into some kind of turbo inlet pipe?

Ok so unplug the maf, check if idle smooths, compression test, leakdown test, pressure test the charge piping (i always forget about those tests).

I’m running a TFSI electronic solenoid VTA BOV so it only opens upon accelerator pedal lift (not under intake vacuum like a pneumatic BOV would). I used to think this was the leak a little while ago but i put the oem pneumatic diverter valve back in place, cleared DTC’s and the code came back.

I have not upgraded my maf housing yet (will need to eventually) i have not upgraded my injectors yet (will need to) all sensors are oem and are in the percieved oem locations, ie: map is after intercooler but before throttle plate. Maf is before turbo, n75 is plumbed to pressure pipe, TIP amd wastegate actuator. Wastegate actuator (turbosmart) has oem pressure spring in it (7psi) oem injectors, oem iat sensor, after throttle plate, in plenum, etc.

Here’s the setup:

https://m.imgur.com/gallery/cus1m (https://m.imgur.com/gallery/cus1m)

This may have had something to do with the weirdness, although I haven't had time to test it, its very cold and snowy out here.

My primary wideband o2 was in a bung in the downpipe, that was almost facing downwards (damn chinese $100 downpipes) so condensation may have been pooling inside the baffle housing of the sensor. I moved it up next to the turbo to the new bungs facing upward and it seems things are running a tad smoother from feel.

will confirm later.

tune the car mafless or have the dv dump back into the tip

I would love to properly tune the MAF out, I've been studying how to for a while now but have come to no comfortable conclusion yet. I'm not sure if I'm educated enough on the limitations, perimeters and potential of ME7.5 yet to be able to do it, unless you can clue me in to something you know that could give me an edge.  ;) ;) ;) :P

I hear some people (Prj is one i know of) run it with a map sensor pre and post throttle body (two map sensors)? How do people calibrate for this? Can this compensate for temp changes in some way/emulate true speed density?

1) all this MAFless talk is insanely naive
2) WTF BOV to atmo? Really? Cmon.

1: yea i wasnt really serious about that undertaking.
2: could you explain a bit more on the symptoms of the loss of metered air and are they apparent in my logs because i’m not seeing an issue other than my dtc and that dtc comes back with recirc. I understand that a loss of metered air could create a rich condition after shifting back into gear and accelerating. Do i have that right? Am i not looking at the correct data that reflects this?

FVPDKLDUS?

Not just shifting. Any off throttle, even during part throttle application.

I’ll reiterate, electronic BOV. So only opens upon a negative pedal % change of an amount i forget (i calibrated it a while ago).

https://m.imgur.com/gallery/cus1m (https://m.imgur.com/gallery/cus1m)

But yes, it does release the backpressure of air as it builds up against the closed throttle plate. When the bov closes and the engine begins to reingest that air, yea it’s missing an amount that was metered (not sure how much precisely) but that loss is not reflected in my AFR’s so i’m perplexed. (And if it is, please point it out to me because my eyes and inexperience are missing it)

Heres the kicker. With stock maf and injectors regardless of over bore ajd intake manifild volume the car should run just fine and lambda reg sgould be within 5% at idle. Your dump valve isnt plumbed right and you know thst but continue to argue that is fine. What kind of magic answer are you looking for? I said before install the dump back into the the turbo inlet or tune the car mafless. Its really not as hard as some make it out to be

no I understand, I'm not arguing, this is peaceful and primarily educational. If I am informed, I can make better decisions, I'm learning every day and I hope others can also learn from the [hopefully more than] turd threads I start. I'm just looking for evidence because connecting the dots between hardware changes and software evidence is easier when I can see it in a graph or when someone points my head at it and screams HERE IT IS! (lol sorry about this, that's just how I need to operate)

But currently, without any fueling calibration whatsoever, the car FEELS pretty good. Apart from block 033 which I don't fully understand yet, I believe block 032 STFT and LTFT's were both aprox 2.4-3% fluctuation (need to check again).

But reiterating, I know my BOV, electric or not, is releasing metered air at times that it should not and constructing an ideal fuel injection system with a draw through MAF would require this to be rectified, I don't believe my idle hunting is related to this however. Knowing and seeing the evidence of what a VTA BOV is causing to ECU is important to me, because cause and effect is how I can learn.

Also relating to MAFless, the execution through ME 7.5? totally over my head right now. The principles of why alpha-n is not a good idea and TRUE speed density is? I get. I'm not sure anyone here has published openly a calibration strategy for atmospheric temperature influenced or true VE map speed density modified ME 7.5 yet, so I'm waiting for that. In the meantime, I'll continue studying.

Because it simply isn't worth doing. There is absolutely zero advantage to speed density over MAF/torque based EFI (let alone BOV to atmo, which you were told from the VERY START is a bad idea), unless you have severe packaging restrictions.

If you really want speed density, go standalone and call it a day.

Have fun calibrating part throttle!

I really don't understand why you insist on complicating your build where it isn't necessary, especially since you don't have the experience or knowledge to make it work.

The excuse of "I just want to learn" is bull. You need to learn the basics first. Do that with a simple build, if only to eliminate possible sources of problems. At your level, it will prove impossible to make head or tail of any issues you come across if you stack one unknown on top of another. It is pure insanity.