Conflicting load measurement

[Breeze1]

Hi guys,

It's been a long time since I've been here, pre-covid actually so I hope you and your families haven't been affected or at least not too much, and this stupid thing soon becomes history, with a lesson or two learnt along the way.

I'm (still, for those of you who'll remember) having an issue with load values on my car and trying to figure it out after dealing with some more pressing mechanical matters. I'll share as little opinions as possible on the possible reasons, and stick to facts AMAP.

- For a long time I thought that lower than normal loads at WOT were due to a faulty MAF sensor, because I was basically (and stupidly) disregarding any load values not logged at WOT, wondering why they'd peak at 500mg/ stroke while they should be more around 630/650 for my engine (M52TUB28)
- I logged the MAF sensor values in volts, to determine whether the MAF sensor was not reaching 5v: it doesn't, and peaks at around 4.5v
- The MAF sensor's voltage doesn't peak at WOT, but rather anywhere between idle and mid-throttle, neither do the load values (which makes sense), which peak at expected WOT values (650ish) but again, anywhere between idle and mid throttle
- fuel injectors and FP are fine, judging by the engine's behavior and the fact that my AFR's reach as low as 11.5 @ 6500 rpm when I disconnect the MAF sensor and go WOT (12.5 with MAF plugged in)
- When I scan for errors with INPA, I'm getting the code below

signal error.jpg

- My MAF sensor isn't a stock one; it's strictly identical to the stock one visually speaking but happens to be for a volvo 2.0T engine ; those of you who'd think I should get it replaced already are 100% right, but : that still doesn't explain why peak load isn't reached at WOT (or does it? I'd think not because even if its scale is off, it should react to throttle input in a linear fashion, no matter what?), neither does it explain the error code, which was there ever since I swapped my engine, initially equipped with a stock sensor
- My max throttle position value, when WOT, peaks at 68.8°.
- for some reason beyond my understanding(because it should be related to load), peak power remains consistent with my setup (Around 230hp at the crank)
- My setup: M52TUB28 from an E39 auto (hinting at that error code here??), M54B30 intake manifold with adapter plate for the TB, E39 catless headers, M54B30 exhaust line, 323i (3.07) diff, 215cc injectors (stock, professionnally cleaned and blueprinted).

Looking forward to your inputs on that one guys, not so much because the car needs it but because this load measurement issue has been messing with my head for too long now!

[dworthy]

Sounds like there is a restriction somewhere in the intake path, for at WOT you are not getting the full voltage or max mg.

BTW, the code is showing sporadic and wasn't current at the time you pulled it.

[Breeze1]

Thanks for your reply dworthy. A restriction as in, possibly, a very small leak around the adaptor plate/ Throttle body for e.g., or a real restriction, like something blocking part of the air's path? Or like for e.g. a throttle body plate not fully opening (which I have verified several times that it does and is not restricted by the adaptor plate, but what do I know...)

I'd think a leak would "show up" as abnormal AFR's, but they seem fine if getting 14.4/14.5 instead of 14.7 when cruising/on light throttle is considered fine (at mid/full throttle they behave normally as far as my AFR gauge is concerned, although it's hard to track a 0.1 or 0.2 discrepancy anyway).

Do you rule out the MAF sensor for this or could it still be responsible? I'd say no because if it was the voltage would never exceed the one at WOT, which it actually does.

Thanks for the heads up about the code, I had missed that!

[dworthy]

Yes, a leak would show up, but if you have a plugged air filter, or too small of a pipe going to the intake, that too would make it struggle.

Another thought came to mind, check the foot pedal, is it showing up in INPA when you go WOT 100%?

[Breeze1]

It's currently being tested by my Indy for a possible leak or physical restriction of the intake tract (making sure the TB plate opens fully and that there is nothing blocking the air's path), although leaks have been checked for very recently. The intake boot is stock, so is the manifold except for the adaptor plate (which edges have been properly sealed with silicon last time we took the manifold off).

About throttle pedal, I'll hook up INPA at the end of the day and check it out. About that, I can already tell from my logs (using romraider) that the thing never goes above 68.8 degrees (not %) even when at WOT. I have already tried to -reasonably- tighten the throttle cable, to no avail. Even with the TC tightened it remained at 68.8°. I thought it's just the way it's supposed to be, which at the time seemed to be confirmed by some research I'd made on forums (but could be wrong).

What I still can't get my head around is: why does the MAF's voltage peak at mid throttle and not full throttle? I'm thinking a restriction in the intake tract would affect breathing at all throttle levels, and in any case the voltage would always be higher at FT than mid throttle.

As far as my limited understanding goes, I'm leaning towards a very small leak that would only show up when FT because of the added pressure, but I could be wrong.

Will share my Indy's findings here tonight.

[dworthy]

Just like having a clogged exhaust system, the car will idle fine, run okay up to say 3k and then just turn into a dog at 4k. Think of a water hose and how the different sizes contributes to how much water can flow based on the diameter of the hose, larger equals more flow. Also any turns/bends the air has to make can cause turbulence thus slowing down air flow. The motor is a big air pump, and if it cannot get all the air it needs, you will not get max power at WOT.

[Breeze1]

Just like having a clogged exhaust system, the car will idle fine, run okay up to say 3k and then just turn into a dog at 4k. Think of a water hose and how the different sizes contributes to how much water can flow based on the diameter of the hose, larger equals more flow. Also any turns/bends the air has to make can cause turbulence thus slowing down air flow. The motor is a big air pump, and if it cannot get all the air it needs, you will not get max power at WOT.

Makes sense, thanks. I'm sure the filter isn't clogged, and the intake tract is stock (except for the manifold which is larger than stock and an CAI, which lands the same results as the stock airbox +/- 5mg, recently tested for that purpose). Right now I'm thinking adaptor plate/TB "plate", or very small leak that robs pressure away when WOT. Will keep you posted!

[Breeze1]

Ok so we did find 3 issues (2 of which thanks to your guidance), but they do come with 2 "but's"

- small leak around the TB; fixed, better idle than before and about 5mg more at WOT

- The "circle" (opening) in the adaptor plate is slightly off-centered as compared to the TB's one; which could very well explain lower load values than expected at WOT (restriction in the air's path, as you mentioned); BUT while it happened very rarely, I had already made a few logs (months ago) where the load DID reach 635mg if I remember correctly (way more than 600 for sure). Which is why I hadn't considered the adaptor's plate or any other possible restriction until you put me back on that track; I'd think if it reached it a few times, the adaptor plate isn't faulty, but maybe I just "got lucky" or my logger felt really optimistic those days lol

- I hooked up INPA with ignition on (engine off) and monitored "status full throttle" while fully pressing the gas pedal: it stays off even if my indy was at the same time making sure the TB's blade was fully opened! So in all logic the DME isn't recognizing the FT condition BUT when I log runs at WOT with romraider, the lambda integrators turn off, which as far as I know is consistent with a WOT condition, which is also triggered by any amount of input to the throttle blade superior to 65°...

My plan of action unless advised otherwise will be to test another TB to see if I'm getting the ON status, in which case I'll make other logs to see if the load goes back up. I'm also planning on finding a good turner who will make another plate with 100% correct dimensions this time (to think I've been running this one and getting robbed of whatever amount of power for years now, just don't get me started on that ), but that will come after the TB's status issue.

[dworthy]

Sounds like a plan. You should see a percent valves for the gas pedal in INPA, for it has to tell the DME how much you want. Typically you will get the WOT effects around 98% or higher, so this has me thinking that the pedal maybe the problem as it has a potentiometers that can fail over time as this is a drive by wire system.

[Breeze1]

Sounds like a plan. You should see a percent valves for the gas pedal in INPA, for it has to tell the DME how much you want. Typically you will get the WOT effects around 98% or higher, so this has me thinking that the pedal maybe the problem as it has a potentiometers that can fail over time as this is a drive by wire system.

Perhaps I was looking at the wrong parameter then, because I checked the "status full throttle" one, which is either on or off but doesn't display a percentage. In terms of degrees WOT is triggered at 65° if memory serves well, but in any case at the time I made sure 68.8 was enough, which is partially confirmed by the deactivation of lambda integrators (they actually turn off past a certain throttle input, and not necessarily FULL throttle contrary to what I said before). I will check the analog section of INPA for that "percentage" parameter you mention.

About the gas pedal, the M52TU engines' generation has a drive by cable/by wire system. There is a conventional throttle cable attached to a "by wire" throttle body with a potentiometer. I will swap the TB with another one to see if that makes a difference.

Thanks for your help dworthy, will keep you posted!

[Breeze1]

Some "news". I hooked up INPA again, looking for an analog parameter that'd move with the throttle pedal. I found two:

PWG Angle, which peaks at 84.49 and seems to refer to the throttle pedal
DKP-angle, which peaks at 82.48 and seems to refer to ?? The throttle's body blade?

And I note that they're both in degrees rather than percentage.

On the other hand, under romraider I have a table that relates to full throttle detection, is expressed in percentage of TPS and set to a value (68%) inferior to the one I log with my car (68.8%) when I go WOT.

So based on the romraider value my logs indicate that WOT is indeed triggered, but I don't know how that interacts with the INPA value and the "minimum 98%" you mentioned in one of your replies.

IMG_20201031_155003.jpg

[dworthy]

I will go out and look today at the wagon with INPA and see where I can find the percentage I noted above. But from what it looks like, it maybe a differance in DME's as I have MS45.1 and you would be running MS42 I think.

[Breeze1]

I will go out and look today at the wagon with INPA and see where I can find the percentage I noted above. But from what it looks like, it maybe a differance in DME's as I have MS45.1 and you would be running MS42 I think.

Correct, I'm running an MS42. Thanks!

[dworthy]

I found it in MWB-3 under "Fahrpedalwert" aka gas pedal. Never understood why German is just one big word, as they take two or more words to make another one.

When I get to WOT, it shows 99.6 percent, which is close enough in my book.

[Breeze1]

Thanks for your help dworthy. It seems that I have a different version of INPA than you do.

I couldn't find that parameter expressed in % after double checking every page I could find. Actually and as per my previous sharing, mine indicates the throttle pedal's position in terms of degrees rather than %(the "PWG angle" parameter I have).

I have also noticed that my pages' layout is different than yours. For e.g. my lambda integrators are on a dedicated, different page than my engine speed...

So unless I can somehow download and install your version of INPA on a laptop, I guess I'll have to take my logs' word for the fact that the 68.8% throttle input being superior to the 68% required, WOT does engage when I fully press the pedal.

I'll keep looking for other ways to bring that load back up, as mentioned before.

[dworthy]

Yes, and I think that would be because of the different DME's, as I have a much newer version. Think of it like differance between the early E-36 and the later E-36's.

There will also be different data that is getting pulled, like for example I have a wide band oxygen sensor, and you won't IIRC on the MS-42. I wouldn't sweat it too much, as I am not really sure what the degrees should be for your pedal though, would think 90, as that is what you would get from the throttle body. Would be worth just looking to see if the throttle plate does open all the way.

[Breeze1]

I'd love to have a stock wideband to log AFR's, but I'm stuck with an external one which I can only peak at when I'm driving lol (it's not one of the aftermarket sensors compatible with romraider).

About the throttle plate, it does open fully when I press the pedal to the floor. With that and the fact that my lambda integrators go off when I go FT, I'll conclude that the DME does recognize the WOT condition and look elsewhere for the cause of my suboptimal loads (@ WOT because like I said, at mid throttle they do reach 630/640 or more, on a regular basis, go figure...).

Namely, throttle body's adaptor plate (for the M54B30 intake manifold) dimensions and MAF sensor.

[Breeze1]

Hello,

So I'm still tracking down that load measurement issue, and I have found something odd when removing the fuel rail's plastic cover: this aluminium pipe which isn't connected to anything. I mentioned it to my Indy and he says it's supposed to be like this. That doesn't sound right to me, unless it's some kind of breathing valve (which doesn't seem right either, because a fuel rail venting next to ignition coils...no ).

I want to set things right and put back whatever hose is seemingly missing there, but given my Indy's answer I'd rather tell him where it should go on its other end than let him figure it out. Any ideas? I looked it up on realoem, but there is no indication of a hose going there either:

https://www.realoem.com/bmw/enUS/sho...diagId=13_0644

[dworthy]

I do believe that there's supposed to be a vacuum line connected to that, as it's supposed to pull any fuel vapors from the injectors that doesn't get injected into the engine. I would have to pull a cover to see exactly where it would go on the wagon, but I think it goes down to the side where you have all the vacuum ports on the intake.

[Breeze1]

So that could explain at least partly why the load figures are below normal? Not because of that "hoseless" pipe but rather because of its other end which remains open. I'll try to find an open port on the intake and connect it to it. I'll let you know my findings, hopefully by the end of the day!

[Breeze1]

Ok so we found not only the abovementioned hose missing and its port plugged, we found another one that was supposed to go from the fuel rail (the one that normally attaches to the backside of that aluminum pipe) to the fuel pressure regulator missing and the PR basically regulating nothing but itself (I don't even want to think about where that excess fuel was going if not to the PR) and (yes, there is more... ) the 3/2 directional control valve unplugged both from its electrical plug and the hose that goes to the intake...

How that engine was running without misfiring or creating major damage will forever remain a mystery to me... all thanks to the "really nice guy" who sold me the replacement engine back then, and was supposed to "have taken care of everything".

This got me thinking that I should probably consider changing my career's path and opening a small garage because although I'm not a mechanic by trade I am 100% sure that I can do better than that, as anyone who actually gives a sh*t probably could.

P.S.: I didn't want to rush him for putting the car back together so I'll only be able to test drive it tomorrow (fingers crossed) and make some logs after tomorrow to see if that makes any difference regarding load figures.

[dworthy]

How that engine was running without misfiring or creating major damage will forever remain a mystery to me... all thanks to the "really nice guy" who sold me the replacement engine back then, and was supposed to "have taken care of everything".

Well that's a nice way of putting it... lol

Now that we have gone down the rabbit hole, I wonder what else isn't connected properly or not working right.

This is why I do all the work myself and take the time to buy the tools that I need. I have found that any special tool that's needed will pay for itself typically after it's first use.

[Breeze1]

Well that's a nice way of putting it... lol

Now that we have gone down the rabbit hole, I wonder what else isn't connected properly or not working right.

This is why I do all the work myself and take the time to buy the tools that I need. I have found that any special tool that's needed will pay for itself typically after it's first use.

I understand 100% and as I'm slowly gathering knowledge about the car and the fact that most mechanics where I live either lack the knowledge or don't care enough to do things by the book (there are some really good ones but the issue is basically finding them amongst all the others LOL), I'm inclined to do more and more by myself as well. Honestly I still lack confidence for those more serious issues, but now I'm thinking that with a brain, repair manuals and the appropriate tools there is no reason for me not to do it, especially with some really good help such as the one you have been providing me with.

About the car, all has now been fixed and I'm happy to report that lambda integrators are now down to virtually 0 whereas they used to hover around the 2% mark, but load levels and the behavior of the car are unchanged, except at idle, which is now consistently stable and doesn't "dip" (and sometimes stall) as it used to do when the engine was really warm.

The only things left to get satisfying load results (which BTW and odly don't even seem related to hp levels according to romraider's dyno figures) are replacing the MAF sensor (I ordered one and will have to wait a few weeks thanks to covid..) and getting that adaptor plate perfectly aligned to the throttle body's opening. Other than that there is nothing I can think of...