745i: No boost at all :-(

[gigi]

Hello all!

I've do some tests on the engine yesterday...

First, I've test my boost gauge with a air foot pump (sorry for the picture quality but a was alone to pump and take picture :-))
This is not exactly the same pressure, but boost gauge follow air foot gauge with approximatly 0.1b difference (maybe it's the air foot pump gauge not correct....I don't know...)
20180402_192256.jpg

After that, I wanted to do a leak test of the whole system.
Ideally, with all admission valves closed.
So I have slided the 6th intake rocker on its shaft in order that the intake valve stay closed when the camshaft turn
20180402_183913.jpg

Only the 6th rocker can be slide enough to skirt the cam of the camshaft because ther is more place on the 6th cylinder compared to the other cylinders.
And I finally turn the engine (manually of course) to have only one intake valve open with the exhaust valve on the same cylinder closed.
In my exemple, cylinder 3.
20180402_183935.jpg

I removed the air flow meter, installed a plug with a tube and air gauge to an air compressor, and plugged breather hose:
Sans titre.jpg

And start the leak test.
I have detected a air leak at the no return valve that going to the knock box, you can heard this on this video, this is a little leak, I think it is no enough to disturbe the boost :
https://www.youtube.com/watch?v=B-qO8DIsx_8

So I plugged the outlet of this valve:
20180402_184845.jpg

And after this, I do another leak test and here is the result:
https://www.youtube.com/watch?v=pxABAC7Kvqo

You can heard a leak, this leak is appears above cylinder head...I think air leak on 3th piston rings...because as you know piston rings are not "waterproof", especially on cold engine...
And then air rises through the oil ducts to the cylinder head.

How do you think of the leak test and result?

Thanks a lot :-)

[Hit Man X]

Hello!

I have installed the LJ Wastegate...without boost solenoid to simplify the system and avoid the causes of additional breakdowns...
I have used the metalic pipe to connect turbocharger to wastegate directly, like LJ
Turbocharger shaft is not broken, I rebuilt it with new parts and it turn freely

Motronic system needs that boost solenoid to work correctly.



http://turboboostleaktesters.com/ Look at that website.

[gigi]

Ok but....I don't understand why...

[nikoor]

Are you sure you got Ljet wastegate? Unknown Motronic wastegate connected like that could give little to no boost. If you need two thumbs to push valve down, it is a Ljet.

There is one-way valve for Hvac system too, if you put boost gauge wrong side no boost is seen. This valve is for keeping boost away from Hvac vacuum system on charge.

[gigi]

Are you sure you got Ljet wastegate? Unknown Motronic wastegate connected like that could give little to no boost. If you need two thumbs to push valve down, it is a Ljet.

There is one-way valve for Hvac system too, if you put boost gauge wrong side no boost is seen. This valve is for keeping boost away from Hvac vacuum system on charge.

Yes it's Ljet wastegate, it's the wastegate of the M102 I had before, and I have tested it, it open at approximately 0,6 - 0,7 bar.

The motronic wastegate is stuck :-( , it's the reason I use the Ljet one...and to increase boost too...but this maybe later...

And boost gauge is connected directly to intake manifold, no one-way valve or something else.

It's not a boost gauge problem, but a boost problem because there is no much power AND no boost on the gauge...

It's an enigma...

[nikoor]

Ok, it is clear then. Can you list all parts transferred from old M102 to the new M106 engine? Your fault got to be found there on list, as your issue transferred over too.

Dont give up yet.

Edit: In reverse it could be something that stayed fixed in car too, clogged exhaust? Intercooler?

[gigi]

I dont give up easily :-)
The transfered parts are:
-all the intake from air flow meter to throttle body (including all piping and intercooler)
-turbocharger
-Wastegate
-exhaust system after turbocharger
-fuel supply
-all the transmission (manual conversion)


Intake piping and intercooler are not leaking.
I have changed turbocharger one time, and rebuilt another one.
I tried to drive without exhaust (only with the M102, no yet with M106 because neighbour don't really like that :-), but I have to...)
And I have to test without intercooler too (with direct piping from turbocharger outlet to throttle body)

[nikoor]

I dont give up easily :-)
The transfered parts are:
-all the intake from air flow meter to throttle body (including all piping and intercooler)
-turbocharger
-Wastegate
-exhaust system after turbocharger
-fuel supply
-all the transmission (manual conversion)


Intake piping and intercooler are not leaking.
I have changed turbocharger one time, and rebuilt another one.
I tried to drive without exhaust (only with the M102, no yet with M106 because neighbour don't really like that :-), but I have to...)
And I have to test without intercooler too (with direct piping from turbocharger outlet to throttle body)

How is your intake box with air filter? How car feels while driving compared to another 745i? Did you try all gears through, not only 1st?

As someone stated here already no small leak is going kill all boost if turbocharger is pushing air strong.

Only component i can think that can affect that strongly boost is Wastegate.

Edit: How are your fuel injectors and wiring? Correct ones are green top bosch #0 280 150 200. BMW cuts off fuel injection to limit boost on both M102/M106 engines for protection. It kills compression effectively.

[nikoor]

One more thing, does your throttle plate move freely and open fully horizontal pedal floored?

[gigi]

I tried without air filter ... no results ...
I can't compare to another 745i because I never drive another one.
But the car is ... smooth, no really powerful and no "kick boost" impression.
I try all gears, from 1th to 5th
Injectors are green bosch #0280150200, and the flow rate is correct.
Cuts off injection appear only when boost is too high or when knock appears, is not it? And only on M106, no M102?
And of course, throttle valve move freely and is flat when pedal floored

[gigi]

As you know, non-return valve or check valve to knock box (part #11651288340 ) is NLA.
Sans titre.jpg


No panic!


I found an equivalent valve at Opel, it's a check valve for brake booster, for Opel Corsa B or Astra F, part #90588175:
20180405_181326[1].jpg

[Hit Man X]

M102 only cuts fuel when over boost due to Hobbs Switch, that is all. Those cars pretty much always run. M106 is much more complex with knock sensors, magnetic solenoid, etc. Not having a magnetic solenoid is not helping your situation, it belongs in the system. I swear when mine was dead I had no power enrichment.

You need to boost leak test the turbo side of the things, not the cylinders. http://turboboostleaktesters.com/how...ost-leak-test/ That is what you need to do.



Motronic wastegate has lower case 'B' cast into base by part number. Ljetronic, does not.

[gigi]

What is and where is Hobbs Switch on M102 ?
i don't remember to have this on mine...

[nikoor]

I tried without air filter ... no results ...
I can't compare to another 745i because I never drive another one.
But the car is ... smooth, no really powerful and no "kick boost" impression.
I try all gears, from 1th to 5th
Injectors are green bosch #0280150200, and the flow rate is correct.
Cuts off injection appear only when boost is too high or when knock appears, is not it? And only on M106, no M102?
And of course, throttle valve move freely and is flat when pedal floored

M106 cuts fuel at 0,7 bar boost normally. In short, knock regulation only retards ignition in steps (not severe kncock) or decreases boost pressure (severe knock).

How is your engine wiring with new M106 setup?

[gigi]

It's stock engine wiring, I have only the wastegate valve disconnected because I have the Ljet wastegate....but I'll modify this like Hitman said

[nikoor]

It's stock engine wiring, I have only the wastegate valve disconnected because I have the Ljet wastegate....but I'll modify this like Hitman said

It is good idea to zero any changes to original. I don’t think it is your issue either. Take care connecting small hoses correct way, i attached BMW instruction for this.

620D8C7A-298D-438E-ACA9-5D1E79EBAE5B.png

[gigi]

Ok thanks a lot.

And i realized I forgot to say you something important...

I don't have the stock intercooler, but a Ford Focus ST intercooler, like this:
2013-2015-Ford-Focus-ST-Turbo-Intercooler-Air-Cooler-OEM-13-14-15-232218500863-5.jpg

Same inlet and outlet diameter than 745i IC, but different form (thin and long)

So the piping and compressed air circuit is longer than original 745i.

I do not know if it can be the cause of my problem ...
This is why I want to try without IC...

[Hit Man X]

Pressure test the system.

[nikoor]

Motronic wastegate has lower case 'B' cast into base by part number. Ljetronic, does not.

This is not always true, i have three Motronic WGs without ’b’.

86719924-1BBB-4B14-8535-04417C043655.jpg

[Hit Man X]

Wow, learned something new today. I thought that was the way to ID the Ljet versus Motronic wastegate!

[gigi]

You need to boost leak test the turbo side of the things, not the cylinders. http://turboboostleaktesters.com/how...ost-leak-test/ That is what you need to do.

Hello all!

So I do a pressure test, rather several pressure tests.

But in the link above, it's not mentioned in what position must be every valve ... and it's very important!

The first test, with all intake valves closed.
I have succeed to have all intake valves closed by sliding intake rocker # 6 and # 3.
I have pressured 0.5b, and counted time to go down to 0.2b.
In this case, it takes approximatly 28s.
https://youtu.be/igwbm0AoRhI

After this, I have slided back rockers in their normal position.

I have done a second test with intake valves # 1 & # 5 open, exhaust valves # 1 & # 5 are closed.
0.5b to 0.2b takes approximatly 11.5s
https://youtu.be/c_a-kDxJZfo

And I have done this with the other 5 combinations, and the results are:
# 5 & # 3 open: 10s
# 3 & # 6 open: 9.5s
# 6 & # 2 open: 10.5s
# 2 & # 4 open: 5.7s
# 4 & # 1 open: 5.5s

All values ​​are average 10s, except apparently for cylinder # 4, the leaking is most important.

And for the fun, with the valve overlap on cylinder # 1:
It's impossible to pressure! Because all air go directly to the exhaust because intake and exhaust valve are in overlap position
This is the reason that the positionning of the camshaft is important to do the test ...
https://youtu.be/dZ-InkRmIug

So, in the link above, it's write "if you lose 1 psi per second (1psi / s), then your system is in good shape."

In my case, the biggest leak (cylinder # 4) is 0.3b in 5.5s => 0.78psi / s
All other cylinders leaking is approximately 0.43psi / s

So I conclud that all the engine is not in so bad condition, maybe with something wrong on cylinder #4, but not important because leaking is less than 1psi/s

Is this right?

[gigi]

Hello all!

Not very inspired by my pressure tests... :-)

Something I don't understand...
Attachment 626846
On this scheme, I have draw a vacuum line in green.
This vacuum line goes from intake manifold to the rubber elbow after AFM.
So, all pressure in the manifold goes directly in the elbow between AFM and inlet turbocharger...which is permanently in vacuum!
Do you have one-way valve on this line?

Thanks

[yert315]

That line should go to your FPR. The vac line on the intake boot goes to the boost solenoid.

The solenoid lines go to the Compressor housing, wastegate, and intake boot.

[gigi]

That line should go to your FPR. The vac line on the intake boot goes to the boost solenoid.

The solenoid lines go to the Compressor housing, wastegate, and intake boot.

Ok but there is another one:
20180412_222140.jpg

20180412_222250.jpg

And this line connect boost from intake manifold to vacuum of intake boot, isn't it ?

[Hit Man X]

Yes. Intake manifold to the breather is correct.