[torqueisking]

Ran a Rheingold Intake Soot Test on my 335D looking for the cause of poor low end power and below is the result.






Red is the measured flow, blue is the calculated flow. Here's what a typical test result looks like. It's from my 195,000 KM X5 35D.




Air flow is higher than it should be in the 335D graph. Thought it may be a bad MAF. Swapped out the MAF from the X5, no change.

I was thinking it could be a swirl flap issue. They are tested within the intake soot test but the actual swirl flap position has always read zero when testing the 35D or 335D. I've read conflicting information about a positional feedback system for the swirl flap. I can't find any positional swirl flap sensor. The schematic shows three wires going to the actuator; power, gnd and control. When I run the swirl flap test, the rod/flaps are moving but Rheingold isn't indicating any change.




Maybe it's the turbine or compressor bypass but if so, I would think the graph deviation would be much greater. Still looking....

Has anyone experienced a similar intake soot test result?

[torqueisking]

Found some similar test results in this thread:

https://www.e90post.com/forums/showthread.php?t=1195370

[M5_1of400]

Have you reset your adaptations?

[robnitro]

If no leaks, having a higher reading is fine. If deleted, that would explain it because there is less back pressure and more fresh air.
Also if your small hp turbo is not being spooled, as you have low end boost issues that will decrease back pressure too and show more fresh air flow in this unloaded test. Of course under load with less boost will mean less air, but this test is done in P/N

[torqueisking]

Originally Posted by DieselDemonDM

Have you reset your adaptations?

Hadn't reset them when I ran the soot test in both vehicles but I did reset them when I swapped the MAFs.

[torqueisking]

Originally Posted by robnitro

If no leaks, having a higher reading is fine. If deleted, that would explain it because there is less back pressure and more fresh air.
Also if your small hp turbo is not being spooled, as you have low end boost issues that will decrease back pressure too and show more fresh air flow in this unloaded test. Of course under load with less boost will mean less air, but this test is done in P/N

Haven't found a leak but the other thread mentionedboost leakage through the swirl flaps which my pressure testing wouldn't catch so I'll look there next.

Not deleted but both vehicles have the high pressure EGR removed and EGR valve pin disconnected (EGR always at 0%).

Even at idle, same RPM, same coolant temp, the 335D MAF reading is higher than the X5 (2.8 vs 2.2 g/s).

[robnitro]

At idle there is so little boost generated that I'd be hard pressed to think the flaps would do that. But of your hp turbo is bypassing exhaust flow (Im not sure if it's vnt or wastegate), the much lower exhaust pressure would allow for more fresh air flow.
From my torque monitoring, warmed up in D 0.7 psi boost and 1.8 exhaust psi.
In N about 0.5 psi and 1.6 exhaust.
If you are seeing 0.0, then yeah your hp turbo might be bypassed (vnt or wg fully open)

[torqueisking]

Thanks for the data points. They are very helpful.

Unfortunately won't have a chance to test the 335d until the weekend.

My X5 full load measurements were I27PSI/E42PSI on the highway today. Sound about right? Idle measurements were close to your numbers.

[robnitro]

Full load boost looks good, I get about 29-30 max but it depends on tune.

Exhaust depends on rpm and whatever equipment dlf/scr etc you have.

Your lower rpm issues is either the change over flap or hp (small turbo) control. There's ista test for those that I ran through but I couldn't see where there change over flap is, just the control for hp which I saw moving during the test.

My x5 with only DOC showed a similar result to your soot test. My ports weren't cleaned but they looked very good around the time my egr took a permanent vacation. I only cleaned the intake then and kept the ccv stock.

[torqueisking]

Originally Posted by robnitro

Full load boost looks good, I get about 29-30 max but it depends on tune.

Exhaust depends on rpm and whatever equipment dlf/scr etc you have.

Your lower rpm issues is either the change over flap or hp (small turbo) control. There's ista test for those that I ran through but I couldn't see where there change over flap is, just the control for hp which I saw moving during the test.

Change over flap issue sounds about right after measuring -3.6PSI intake and 0.9PSI exhaust pressures at idle in N on my 335D. To be confirmed... thx!

[robnitro]

Negative intake pressure could be hp turbine control. The turbo is "open" on exhaust side making no boost.

The bypass is on the compressor side, which also could do this.

How did you determine it was the bypass?

[torqueisking]

I confirmed the negative intake pressure and low exhaust pressure cause by applying full vacuum to the turbine control valve with my manual vacuum pump while watching the pressures rise to 0.6PSI IN, 1.5PSI EX. The problem was the vacuum hose from the pressure converter to the turbine control valve. Although I couldn't find it, it had a leak in it.

Thinking that this was the cause of my odd intake soot test results, I re-ran the intake soot test and the results still not correct.

I took a dentist type mirror and looked at the underside of the intake manifold around the swirl flaps. Four of the six had oil residue on them. Two were dripping. Off with the intake manifold.

Findings

1) There is a boost leak through some of the swirl flaps shafts. Time for plugs!

2) The round port gaskets do not appear to be sealing well. The head side of the sealing surfaces were all covered in oil and soot. Looks like another potential boost leak source.

3) The flaps toward the front of the engine were partially closed in the rest (open) position. The flap closest to the actuator is fully open. Each next flap is progressively more skewed from the fully open position and the ports+flaps have more carbon caked on them.




Not sure if this is the cause of my odd intake soot test result but these flaps need attention so I will plug them up, replace all the gaskets and re-run the test.

[robnitro]

Glad you found the low end boost issue!

Your result is good, as I said, I got similar results when I ran the test. The test is not run with much boost so leaks will not influence it much, if at all.
If you run dpf, keep the flaps. Eliminating them increases particulate emissions which make regens happen more often. They are easy to clean with a toothbrush and some diesel or kerosene.

[torqueisking]

I will take my chances with the flap delete on my 335d. My flaps are leaking around the shafts, it appears as though I can't recondition the bushings/seals and buying a new intake manifold is pricey!