Adjust IQ with VCDS then perform hammer mod?

JohnTso

Veteran Member
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Jul 27, 2004
Location
Wisconsin
TDI
2003 Desert Jetta & 2015 Passat SEL
Background - I'm not new to TDI's. I've done all maintenance, repairs and mods since 1998 - except for TB. Now that I own a VCDS I'm looking to fine tune my TDI's.

Does it make any sense to adjust the IQ value using the VCDS to find the sweet spot (performance & FE); then do the hammer mod to mechanically set the value?

The Desert Jetta (stock engine) is running well, but the IQ is 2.5 and timing is very slightly advanced. My thinking is both could be tweak somewhat.
 

BobnOH

not-a-mechanic
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May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
According to the old old "How it Works" section in our FAQ, you should first try adjusting
the IQ with the VCDS first and only hammer as a last result.
 

JohnTso

Veteran Member
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Jul 27, 2004
Location
Wisconsin
TDI
2003 Desert Jetta & 2015 Passat SEL
According to the old old "How it Works" section in our FAQ, you should first try adjusting
the IQ with the VCDS first and only hammer as a last result.
Thanks for the reply Bob. I'm sure I came across that information in the FAQ's section previously and it planted the seed.
 

compu_85

Gadget Guy
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Location
La Conner, WA
TDI
... None :S
If you go for the mechanical adjustment set the adaptation back to stock. Adjust it as close as you can get it. Then fine tune with the adaptation.

-J
 

mk3

Veteran Member
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Sep 13, 2005
Location
Wisconsin, USA
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03 Jetta GLS 5-speed
sorry but if it is running well why do anything at all?

from my memory, the IQ at idle should be checked with everything nominal - 70F outside and we don't have that now.

that said, for stock it is not supposed to be that low.


I've made some mistakes in over-maintaining my car. Best things I've done in recent memory:

1. new/reman starter so cranking is faster and obviously it starts better
2. Frostheater. even better starting even though it would always start anyway.

I also replaced the thermostat a few years back - age had caused it to keep the coolant a bit low. That will hurt fuel economy.
 

BobnOH

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May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
sorry but if it is running well why do anything at all?
from my memory, the IQ at idle should be checked with everything nominal - 70F outside and we don't have that now.
that said, for stock it is not supposed to be that low.
I've made some mistakes in over-maintaining my car. Best things I've done in recent memory:
1. new/reman starter so cranking is faster and obviously it starts better
2. Frostheater. even better starting even though it would always start anyway.
I also replaced the thermostat a few years back - age had caused it to keep the coolant a bit low. That will hurt fuel economy.
Yes.
Although IQ can cause issues, the ECU is constantly adjusting from sensor input.
I think IQ is one of the most over diagnosed things we see here.
 

03TDICommuter

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Dec 8, 2016
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So. Cal
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01' NB, 5spd
that said, for stock it is not supposed to be that low.
When I rented a VCDS cable to check my car I saw on my bone stock '03 Jetta that the IQ value was really low and not knowing any better I thought that was a good value for fuel economy. (I think the value was 0.8). This vehicle I bought from someone that only ever had the dealer work on it.

Now I know better and it's the inverse for this setting but my car seems to run fine and I'm getting 50mpg all freeway. Do I mess with it?
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
No, not unless it runs bad or smokes too much or something.
That being said, I'm the type that would mess with it, maybe use VCDS to bring it up to 2.2.
The spec is 2.2 to 9.0, most folks like it around 4.0. The ECU will have it all over the place as you operate the car.
Verify that the car is in fact at 0.8 before you mess with it.
 

turbovan+tdi

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Yes.
Although IQ can cause issues, the ECU is constantly adjusting from sensor input.
I think IQ is one of the most over diagnosed things we see here.
That's because people adjust it without a scanner or just adjust it and hope they get it right. Also, every car is different, no 2 are ever the same so X car might be getting poor mpg and his IQ is set low from the factory and Y car, exactly the same is getting great mpg and his IQ is set higher.
 

Owain@malonetuning

Associate Vendor , w/Business number
Joined
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Location
Vancouver
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PD jetta wagon
Center adaptation value is likely 32768

If it's at 2.5, I'd just move it up to 3.5-4 electronically for the time being then raise it higher later. 2.5 is low enough to cause a little bit of slow down shudder for most cars. If you plan to leave it bone stock 5-7 would be better and requires physical adjustment.
 
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eddieleephd

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Joined
May 27, 2012
Location
Battle Ground, Wa
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2002 jetta Wagon
Read the hammer mod completely and set the IQ to 32768 before adjusting the pump as said before.
As it says in the hammer mod, up is down and down is up. So if the number in the space is higher than 32786 I would put that number in and see what the IQ is there. The more fuel you add the more power, and possibly smoke, you get.

Fuel mileage is not always better at a lower IQ. Engines are most efficient in their optimal fuel range.

My Tacoma was most efficient between 3200 and 3600 rpm, no messing with injection quantity on it. I could pull a 3200lb trailer up a hill going 75mph at 3600rpm, any less and I was lucky to get up the hill at 45.

Remember to keep a log of your original and any modifications you do so you can fine tune it if you want to play with it.
 

Enabled

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Apr 23, 2013
Location
Houston, TX
TDI
2003 Jetta TDI Manual, BMW 328d SW
The better the adjustment with hammer mod, the better control your ecu has over the pump. Adaptations are there to correct what is maladjusted physically.

Set stock 32768 adaptations, then hammer mod to get it as close as possible.
Should you get tired of micro adjustments by hammer mod, then I guess use adaptations to correct it.

I set my pump to 4.0-4.2 using ONLY hammer mod.


Any additional adjustment via adaptations will now reduce the ECU's capacity to adjust as written in tune.
Pump can only move position from 0-5Volts. Adaptations only adds or subtracts a few millivolts for correction. Every time you have to add/subtract volts, you lose total range.
 

Nevada_TDI

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Location
Reno, sort of...
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2001 Jetta TDI
My IQ was set at 3.8 and my FE was terrible; 31 MPG. So I set the adaptation to 32768 and used the hammer mode to get to 5.8-6.2; I need more miles on this tank, but it is obvious mt FE this tank will be significantly better. Raising my IQ may have cost me a little power, but I am not racing her so it is no big deal. She still pulls incredibly hard with the new tune and I may even get my Hwy mileage back into the 50's like it used to be.
 

Enabled

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Apr 23, 2013
Location
Houston, TX
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2003 Jetta TDI Manual, BMW 328d SW
My IQ was set at 3.8 and my FE was terrible; 31 MPG. So I set the adaptation to 32768 and used the hammer mode to get to 5.8-6.2; I need more miles on this tank, but it is obvious mt FE this tank will be significantly better. Raising my IQ may have cost me a little power, but I am not racing her so it is no big deal. She still pulls incredibly hard with the new tune and I may even get my Hwy mileage back into the 50's like it used to be.
Make sure you are not running too much start of injection advance... 31mpg is way too low for just IQ to be a lone factor.

What is your hardware timing set at on the graph? Then in adaptations, what is your actual vs. desired SOI timing, and duty cycle?
 

Nevada_TDI

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Reno, sort of...
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2001 Jetta TDI
TDTuning tuned me. Timing is set at 78 degrees and I haven't checked the others, I am sure Mike set them where they should be.About 100 miles ago I set my IQ up to 6 and according to fuel gauge my mileage is much better than it was at 3.8 IQ. In another 200 or so miles, I will top up the tank and see how much difference if any there is in FE.
Tires are properly inflated, brakes are not dragging--those are the first two things I checked. My car does haul a$$ now, but not 11 MPG worth of lost FE for the performance I now have. I am only running 24 PSI of boost and my fuel curve is conservative by most standards; just the slightest haze at WOT. But it all comes back to no two cars/engines with the same equipment and similar driving styles are not going to have the same FE, sometimes not even close
 
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red16vdub

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Aug 26, 2013
Location
(617) City of CHAMPIONS
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03 JSW 5spd
My IQ was set at 3.8 and my FE was terrible; 31 MPG. So I set the adaptation to 32768 and used the hammer mode to get to 5.8-6.2; I need more miles on this tank, but it is obvious mt FE this tank will be significantly better. Raising my IQ may have cost me a little power, but I am not racing her so it is no big deal. She still pulls incredibly hard with the new tune and I may even get my Hwy mileage back into the 50's like it used to be.
Nevada we have similar mods, my IQ is set at 5.5 with the adaptation at 32768 and timing advance to the green line, but within spec like DBW suggested. Slight smoke on tip in but that's it. I usually get 800 miles to a tank at 75mph min. Unless i'm trashing it, My worse ever was in the 650 range.
 

BakoTDI

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Joined
May 5, 2005
Location
Bakersfield, CA
TDI
Jetta, MK7
So I have been reading about others' IQ values for their cars and I have not seen yet anyone mentioning whether each of the cylinders should have a different IQ value or not. I rented the VCDS from ifixmyvw to program a couple of new keys for my car (great page btw) and started to check a few other things in my car. Noticed that each cylinder has a different value ranging from -0.09 to 0.16...is this normal?? should I be seeing such range between cylinders? here is a screenshot of the VCDS. Your input is appreciated.

PS: I have discovered a totally new world by renting the VCDS cable and I'm seriously thinking about buying one but will need more help on what kind of mods I can do with it. :rolleyes: Therefore, there are a lot of things (including in this pic) that I do not understand yet...anyone up to tutoring?! :D

 

turbovan+tdi

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Yes, those values will be different as no 2 cylinders will use the same amount of fuel. Those are nice and even, but if say one was 1-2 points out, then that cylinder/injector would have an issue.

Also, the IQ is a bit high, unless its not warm and/or you have the a/c on. You could lower it to around 4.5 and you'll have more power.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
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Aug 16, 2004
Location
South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
The Desert Jetta (stock engine) is running well, but the IQ is 2.5 and timing is very slightly advanced. My thinking is both could be tweak somewhat.
Those sound like good settings. I'd leave it alone. IQ in the 2.0 -3.0 range is usually good. You may want to advance the timing a bit more, but I'm not sure you'll see much benefit.
 

BakoTDI

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Joined
May 5, 2005
Location
Bakersfield, CA
TDI
Jetta, MK7
Yes, those values will be different as no 2 cylinders will use the same amount of fuel. Those are nice and even, but if say one was 1-2 points out, then that cylinder/injector would have an issue.

Also, the IQ is a bit high, unless its not warm and/or you have the a/c on. You could lower it to around 4.5 and you'll have more power.
Thank you for the reply...The car was idle, no AC, no other power-sucking functions on, and the coolant temp was about 65C. I will check the IQ adjustment how-to's and/or youtube for help with this. Seen a lot about the 'hammer-mod' being used if the VCDS adjustment is not enough.

this is where I was at:
 

turbovan+tdi

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2003 TDI 2.0L ALH, auto, silver wagon, lowered, Colt stage 2 cam, ported head,205 injectors, 1756 turbo, Malone 2.0, 3" exhaust, 18" BBS RC GLI rims. 2004 blue GSW TDI, 5 speed, lowered, GLI BBS wheels painted black, Malone stage 2, Aerotur
5.4 isn't bad. If you are happy with the power, leave it alone.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
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Aug 16, 2004
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South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
If the car has stock nozzles (in good condition) I think 5.4 is too high. You'll lose low end torque and it could potentially be harder to start. I'd move it back to 2.4.
 

Nevada_TDI

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Reno, sort of...
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2001 Jetta TDI
Nevada we have similar mods, my IQ is set at 5.5 with the adaptation at 32768 and timing advance to the green line, but within spec like DBW suggested. Slight smoke on tip in but that's it. I usually get 800 miles to a tank at 75mph min. Unless i'm trashing it, My worse ever was in the 650 range.
Error post.
 
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oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
I will comment on IQ settings from my various experiences with them. Most of the time, a stock, healthy, in good order, properly timed ALH will have no need of tweaking anything. They'll start good, they won't smoke, they will have good power, no slow down shudder, and good fuel economy.

But a higher mileage (and by higher, I mean 250k+ miles or more) engine, a modified engine (bigger injector nozzles, bigger pump head, tune, etc.) may require some slight tweaking to find a sweet spot. Usually the need arises from a complaint of slow down shudder, but not always.

In those cases, it quite often becomes a seat of the pants type of thing. And even then, it can really depend on who is wearing the pants. Because not everyone drives exactly the same.

I think a lot of people go looking for problems that do not really exist. If the car is performing well, and has no issues, best to leave it be. Or at least, if you have no other car to compare to, leave it be until you do. Or until you have someone that has driven a lot more of them weigh in on his or her opinion of how the car runs.
 
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