Adjusting fuel IQ for when the AC is on.

ytk

Active member
Joined
Dec 6, 2014
Location
IL
TDI
MK3
When the AC is running there is some lack of power , is there a way to adjust the fuel IQ or some other method to adjust it for when it is running?

Thanks!
 

Steve Addy

Top Post Dawg
Joined
Aug 7, 2002
Location
Iowa
TDI
97 Mk3
You'd have to ask performance tuners whether they can do it or not, there's no mechanism that's available other than pulling out the VAG-com every time you wanted to turn on the AC, which isn't practical.


Steve
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
top kek,

To answer your question, NO, but in a long way, yes. If your Q.A. is too low you could see a bit harsher idle roughness when the AC is on vs off.

If you can feel or measure a power loss more than 1-5HP on a dyno on an engine with about 100HP stock, you have a SERIOUSLY F'ed up thing going on and any feeling you have of MORE POWER is clearly a placebo effect. Now thats not to say that at idle or about 1.5HP output that yes the engine should see a noticeable difference and the ECU should be correcting the GPH input and Q.A. of the IP's IQ.
If i remember right, the procedure calls for the AC to be off when doing your hammer mod or adjusting your Q.A. but its been a while so i dont remember more am i looking it up.
 

ytk

Active member
Joined
Dec 6, 2014
Location
IL
TDI
MK3
Thanks guys, perhaps I will try to play a bit more with the IQ or observe it with vcds when it is on.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
If your car is noticeably slower with the A/C on I think there's something wrong beyond the IQ. Injector issues, weak pump, air leaks in the fuel lines, poor boost or a boost leak...could be any number of things. But I've had two MK3s and now have a B4, and it drives the same, A/C on or off. Your car should, too.
 

Digital Corpus

Top Post Dawg
Joined
Mar 14, 2008
Location
Ontario, California
TDI
'97 B4 w/ 236K mi body, 46K mi soul
Pump Voltage > Injection Quantity

If you want to understand why, read this:
http://forums.tdiclub.com/showthread.php?t=393474

There is also a relay under the center console that turns off the AC compressor’s clutch once you have a significant enough engine load. Not everyone likes that behavior and some bypass it. These details aside, IBW is correct though with the caveat that during partial load , you’ll notice *some* reduction of power, but nothing dramatic.
 

KLXD

Top Post Dawg
Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
A better question would be "how much does your IQ increase with the AC on? Mine increases x."

Maybe something's going wrong with your AC pump/system that's causing the lack of power. If so your IQ would increase more than normal with the AC on.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
one thing i do know is that while observing Scangauge II the GPH goes from 0.08 at idle to 0.11 when the AC is kicked on. Not sure, never hooked up VCDS for that.
 
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