Peugeot Forums banner

MAF and Turbo measurments, are they correct?

4K views 12 replies 3 participants last post by  BiGK 
#1 ·
Hello guys
I'm driving Peugeot 407 2.2HDI 170hp Bi-Turbo. Last weekend I tried to remap my car in a local tuning garage.
When we put the car on the dyno, she maked 178hp on the engine and 146hp on the wheels, everything good and working perfectly. When we put the custom software that was made from the tuner. The car started to overboost @ 4000rpm to 2 bar of pressure. The requested pressure on map was 1.8 bar. The guy told me that I need to check the turbos, because something is happening.
I was wondering, because everything is fine with the stock software, the car runs perfectly and there is no issues, there is no faults according to my Lexia, which I'm using with DiagBox.

I runned some test and I want your opinion, here is the videos, as follows:

Turbo measurment

MAF measurment

As you can see, in the video "Turbo measurment", on: 1:21min, you can see that the turbo does 2.6 bars of pressure, which is way more of 2 bars, what my tuner said.
In the video "MAF measurment", on: 2:44min, you can see that the MAF setting is 1000mg and the measured valued is: 1500mg, is that normal?

Thank you!

Sincerely,
Alex
 
See less See more
#2 ·
To me (not an expert), it sounds like the map is wrong or the wastegate can not flow excess air out. Engines are simple. More air + fuel = more power. More power = more exhaust flow and if the wategate can not handle this extra load, it will cause the turbine to spool up faster, causing boost creep.

At some point, even though it is overboosting, the ECU isn't requesting the wastegate solenoid to open more than ~50%. So it's possible a wastegate solenoid issue, or the map causing the wastegate solenoid not to open more.

That's where I would start.
 
#3 ·
So, the values from the clips are okay?
As I remember, the mapper, made the software and requested the wastegate to be opened in 35%, he told me that, he can make it to be open at 25%, but this will not resolve the issue with the overboosting.

Can you tell me how to check the wastegate selenoid, if it's working properly?
 
#6 ·
If it's only a stage 1 map normally the N75 (duty cycle) maps on the turbo can be left near standard and the boost pressure raised in the limiter maps only (dependant on ECU type). Not done a bi-turbo, could it be that the turbos are compounding due to the changes in N75 and giving the over boost.

Changing the N75 maps can often cause overboosting especially with VNT turbo if the actuator is being driven more than the standard max values . Has he also checked that he is using the correct factor and has not inadvertently used relative and not absolute boost values.
 
#7 ·
Reviewing the video again there is something wrong with the map. Look at the waste gate duty. 98% at idle dropping to to around 30-40% as the rev's rise that a massive jump back to 98% at 3500 rpm which will 100% spike the turbo and overboost.

The only time i have seen a spike like that was on a normal map with a leaking swirl valve diaphragm which as the swirl valves where opening it would leak vacuum making the boost drop, ecu would increase duty to maintain boost and that would trigger swirl to close which restored vacuum and restored 100% boost which triggered overboost and limp mode
 
#8 ·
Actually, this is the values with the stock software. The mapper told me that there is discrepancy between the two turbos and I should make a bench flow test on turbo's. Probably, I'll give them to the proper service and I will make them hybrid in the future months.

But, I have a question regarding the MAF sensor, which makes me wonder, the actual value is more with 300-400-500mg/impulse than the requested, which is 1000mg/impulse. I've tested 4 different MAF's from hit cars, and the results are familiar. I will clean the EGR valve this weekend, but do you have any suggestions, why this is happening?

Because, when we've put the custom software, the values on the MAF was 1500mg/impulse permanent and there was constantly error P0100.

With my MAF, with the values from the video, I've got an error 3 times for 8 months... in the other time, there is no error.

What should me the perfect value for the MAF?
 
#9 ·
If the maf stays at a fixed value the map is wrong they must be changing the maf map in error I think they are using the wrong map data I would get them to double check firmware and software versions.

I have not looked at the bi turbo so maybe due to the twin turbos it works in a different manner. If it runs fine on std map I'm sure your turbos are fine.

Rule of thumb for air flow per stroke for normal air density (0.84mg).

So rough airflow if everything was 100% should be single cylinder capacity 545cc/0.84 x boost in Bar gives weight of air in cylinder in mg.

Expected value will be around this less any egr that is requested. Higher than expected is normally lack of egr or over boosting and lower under boost or excess egr (low or over boost should show up in the expected boost pressure readings)


Sent from my SM-T830 using Tapatalk
 
#10 ·
Great explanation!

So, let's take for example the video for the measurements above (it's with the stock software of the car).

At 2200/2300rpm:

Turbo reference valued: 2494 mbars
Turbo pressure value: 1506 mbars

MAF:
Air Flow Setting: 1000 mg/impulse
Measured Air Flow: 1324 mg/impulse

So, we have under boost, that why the MAF shows those values, is that correct?
 
#11 ·
Guys,

It's me again.

Because everybody told me that my MAF measures are too high at 2200 and 3200rpm. I spoke with two representatives from Sofia France Auto (the Bulgarian dealership for Peugeot) and they confirmed that 1500mg/impulse - Measured Air Flow is too high ,because the Air Flow Setting is 1000mg/impulse.

So, I bought brand new MAF today, VDO (VDO is now Continental) and it is the same situation.

Any advise?
 
#12 ·
Obviosly, I am going to speak to myselft in this topic, but I hope that I will help other people with 2.2HDI 170hp.

The problem was in the FAP filter was drowned. We removed the filter and the car became alive from 1500rpm! And there was no problem with the control of the turbo charges!

The problem when the FAP is drowned is that when the turbos made they pressure, the FAP makes a back pressure and confusing the control of the turbo charges. Of course, the selenoids tried to compensate, but they can't fully.

After that, a new guy made the remap and now the car is 207hp and 452Nm with a catalyc converter. If we had removed the catalyc converter and made the boost a little bit more and the fuel a little bit more, the car can produce around 215hp and 470Nm.

Thank you all for the help and may the horse power be with you!

Sincerely,
Alexander
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top