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Adjusting/setting IQ?

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17K views 3 replies 2 participants last post by  kmveedub  
#1 ·
I saw the FAQ on this on Fred's, but I want to make sure I'm talking about the right thing here. As usual, not much help on Fred's page.
At idle - pretty much most of time, I'd say 90% of the time - my car sounds horrible, unbelievably loud, and the entire motor feels like it's shaking vigously. I was told the IQ probably needed to be adjusted/fixed. Does this sound right?
Honestly, I can't say I've seen much of a difference in performance, though. When accerating, the car isn't any slower - from what I can tell. Maybe I'm wrong, though. Also, I will say that when I am having this issue (which like I said, is 95% of the time) that when I rev it up, the RPM's fall down a lot slower. The needle on the tach literally falls down slower, it's weird.
Now, when it's running fine and not having this problem (which is rare), then the revs fall down quite normal and pretty quick.
So, if this indeed simply means my IQ is jacked, here are my questions.
1)Is a VAG-Com the *ONLY* way to adjust it? Will any other scan tool do it?
2) What is an ideal setting to have the IQ set at?

Before you mention the injection pump going out, I highly doubt that's it. It has a brand new 11mm injection pump in the car now. Shortly after installing (and putting the injection timing in correct time) the pump, it ran fine. This is a recent problem.

Thanks a lot for the help!
 
#2 ·
Re: Adjusting/setting IQ? (kmveedub)

IQ is relative to the car. On a stock TDI it is roughly 3.0. A TDI with a chip and nozzles would probably have an IQ of about 9.0. If your car has only the 11mm pump then your IQ should probably be around 4.5 - 6.0, depending on the smoke levels. Do you have a chip or nozzles? The IQ number is inversely proportional to what you would expect: an IQ of 1.0 is rich while 10.0 is really lean. Below 1.0 your engine will throw codes and go into limp home mode. Above 10 or so the car begins to be difficult to start. This depends on the car, though.
There are two basic ways to adjust the IQ on a pre-'04 TDI: the mechanical adjustment, AKA Hammer Mod, AKA the coarse adjustment, is done with a Torx T25 bit and a special socket to loosen the tamper-proof bolt. Once the tamper-proof bolt and the proper Torx bolts are loosened you move the top of the pump either to the left or to the right. I always forget which direction richens and which leans. The amount of movement is extremely small: 1mm of movement can take your engine from so lean that it won't start to so rich that it is idling at 2000 RPMs or more. They call this the Hammer Mod because the original person who posted about this suggested that you use a hammer to gently tap the pump head in the desired direction with the Torx bolts just snug enough to allow the part to move under some control You will actually see the IQ change as you tighten the bolts!
The second way, the fine-tuning way, is with VAG-COM. You go into Adaptation then go to a value of 00, I think. You will see the IQ itself and the adjustment value. The factory value is 32768. If you adjust this value downwards you can raise the IQ value by about 1 point (from 3.0 to 4.0, for example). The limit is about 32686, I think. Anything below that number will not affect the setting. The upper limit is about 32798 and this will give a slight decrease in IQ to about 2.8 from 3.0, for example. HTH!
 
#3 ·
Re: Adjusting/setting IQ? (MeanGreenTDi)

Good info, thanks a bunch!
To answer your question about the mods, it currently only has an UP chip and 11mm pump. It is getting 520's in a few weeks, though.
 
#4 ·
Re: Adjusting/setting IQ? (kmveedub)

VAG-COM got it taken care of.
Thanks to Jim at Dieselgeek! http://****************.com/smile/emthup.gif