Lack of power after a remap

Busternaut

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Joined
Apr 3, 2021
Location
Bulgaria
TDI
Golf Mk 4 ASZ
Hello everyone, I own a mk 4 tdi 131 hp PD. The car has a FMIC and a 1752vb hybrid. It has been remapped and makes 1.8 bars of boost however the performance is very underwhelming. I suspect that the fuel is not enough but the mapper tells me that this is the maximum fuel he can do. I only know that it is 75mg. but as far as I have read there are other factors such as duration? Is there a way I can check with vag com and post the results here so you can confirm my suspicion of not enough fuel? The car doesn't smoke at all, even if I floor it at very low rpm to intentionally make it smoke. I don't want smoke it is just really odd to me and confirms my theory.
 

QuickTD

Veteran Member
Joined
Feb 25, 2002
Location
SW Ontario
TDI
2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
Log IQ with VCDS and see if it ever hits the 75mg/stroke value. There a several limiters that may restrict the max IQ and they all must be adjusted during a tune, perhaps he forgot something? 75mg/stroke at 4000rpm should be over 200hp, probably more fuel than that turbo can provide sufficient air for.
 

Busternaut

Member
Joined
Apr 3, 2021
Location
Bulgaria
TDI
Golf Mk 4 ASZ
Log IQ with VCDS and see if it ever hits the 75mg/stroke value. There a several limiters that may restrict the max IQ and they all must be adjusted during a tune, perhaps he forgot something? 75mg/stroke at 4000rpm should be over 200hp, probably more fuel than that turbo can provide sufficient air for.
Hello, I have logged the charge pressure and the IQ. However it doesn't show more than 70mg, but the mapper told me that it is actually 75mg and the program just doesn't show it. The log shows the car achieves the boost required and it shows 70mg. This is under "max IQ" if it is not the correct place to look let me know.
So on paper everything looks fine but the car is sluggish, nowhere near 200hp.
One thing that is important and I forgot to mention is that the car was remapped with a 2.5bar map sensor (it was a mistake, the sensor came with the fmic and the guy tld me it was 3bar.) Right after the remap the car would smoke a little under full acceleration. I then thought about that sensor, removed it and saw it was actually 2.5bar. I then swapped it with the original 3bar and the car stopped smoking at all. Still sluggish though. I told this to my mapper and he said that it couldn't be the reason and everything should work fine. It is really suspicious to me the whole wrong sensor situation.
 
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QuickTD

Veteran Member
Joined
Feb 25, 2002
Location
SW Ontario
TDI
2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
It appears your tuner did not raise the diagnostic limit for IQ. It maxes out at 70, so the logs won't really show what is actually going on above 70mg/str. Also, you are only logging IQ based on MAF (smoke limiter), IQ based on drivers wish and IQ based on RPM (torque limiter). You need to log actual IQ, not the limiters. They only show you what is allowed, not what is being injected.

I think you will find actual IQ around block 15 on EDC15P. We need to see the actual IQ. If it is low, you need to find the limiter that your tuner missed and correct the diagnostic limiter so you can see what is actually happening.
 

Mozambiquer

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Mar 21, 2015
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1998 VW Jetta TDI. 1982 VW Rabbit pickup, 2001 VW Jetta TDI

Busternaut

Member
Joined
Apr 3, 2021
Location
Bulgaria
TDI
Golf Mk 4 ASZ
I'm wondering if the tuner didn't correctly disable the maf sensor. Is the maf unplugged and removed, or plugged in?
It is currently plugged in. I tried to unplug it and test the car but it was the same. I could try again?

Is it possible to be a boost leak? Even though both my boost gauge and vcds show that I am reaching full boost.
Woudn't the car smoke alot if there is a boost leak? Or it will just limit the fuel? But then again it shows actual IQ is the same as requested.
Possibly a vacuum leak? I don't know what to think anymore.
 
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QuickTD

Veteran Member
Joined
Feb 25, 2002
Location
SW Ontario
TDI
2003 Audi A4Q 5spd 2.0 TDI 2056VK R783, 2006 Audi A4Q 6spd 2.0 TDI, 2007 A4Q 6spd 2.0 TDI
IQ is hitting the 70mg/stroke diag limit, so you're getting that much fuel at least. If it isn't smoking, the car should be making at least 180-190hp. If it isn't, you need to look at external factors that would limit IQ, bad lift pump, plugged fuel filter, low tandem pump pressure etc.

What MAF code is it? I've seen MAF codes set by a bad MAP sensor or bad MAP scaling. The switch to change from MAF to MAP smoke map is a simple bit switch, one digit. Pretty hard to screw it up. But is does not mean you can remove the MAF, it is used in other calculations (EGR etc.)
 

tdi_my live

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Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
Here is a log from block 015: https://log.tunezilla.com/s/8HI1cLSF

I noticed that the car keeps throwing a MAF error code even though the MAF is disabled. Is that normal or?
What did you expect to actually get a different IQ value? The information comes from the ECU and not from a sensor that measures the actual amount. Since the diagnosis has not been expanded, you will not see a value higher than 70.
 

tdi_my live

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Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
It is currently plugged in. I tried to unplug it and test the car but it was the same. I could try again?

Is it possible to be a boost leak? Even though both my boost gauge and vcds show that I am reaching full boost.
Woudn't the car smoke alot if there is a boost leak? Or it will just limit the fuel? But then again it shows actual IQ is the same as requested.
Possibly a vacuum leak? I don't know what to think anymore.
Why was the MAF trying to deactivate. You don't need that up to a loose 1700mg air mass. If it starts to reach the maximum voltage then you have to switch over to MAP based and deactivate the LMM, but correctly without an error message. And beforehand you can increase the maximum voltage and create some tolerance for it.
 

tdi_my live

Veteran Member
Joined
Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
Take a look at the boost pressure curve. The turbocharger is supposed to bring high boost pressure early on, and it doesn't do it. Then at 2600rpm skin over it, the VNT counteracts and opens. Then closed again. What do you mean, what does that decrease in performance and dynamics if the N75 control does not fit well. Your remapper has to go back to this.
 
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