Adjusting IQ. Which way???

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
I just got VCDS, so I am very new to the program. I purchased it so I could adjust my fuel injection pump after doing a timing belt job. VCDS worked great! Got it done in 2 tries. I’m a little advanced ( about halfway between the middle and upper line on the graph), but it seems like that’s where a lot of people set theirs.

I saw a video on adjusting the IQ, and I thought I’d use VCDS to check what mine was. It shows as 1.6, which I’m guessing is low, as I read it should be 3-5.

Im confused, though. Some people adjust the IQ with a value in VCDS, while others use the hammer tap method. What’s the difference? Which is better? What am I missing?
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
do you have stock nozzles? you can adjust via engine adaptation. click Login button in engine module, enter 12233. then you can adjust "IQ" up/down a certain amount. being as low as 1.6 you will likely need to hammer mod. the question is why is it that low. for a stock tdi, 3.5-4mg at hot idle is likely most accurate, imo. if you lower it, it's going to be a little overfueled, which is may or may not be fine for your particular car.

you should make sure channel 04 for timing is at the default value of 32768 . you should not mess with that. it's really meant for testing purposes only. if you advance timing, the higher fuel amounts will be too advanced.

you should take some logs 011 only, as well as 011-001, and 011-001-003 to get a good idea how well your tdi is performing. take healthy long logs like a whole commute etc. from start to finish. will be most informative :)
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
do you have stock nozzles? you can adjust via engine adaptation. click Login button in engine module, enter 12233. then you can adjust "IQ" up/down a certain amount. being as low as 1.6 you will likely need to hammer mod. the question is why is it that low. for a stock tdi, 3.5-4mg at hot idle is likely most accurate, imo. if you lower it, it's going to be a little overfueled, which is may or may not be fine for your particular car.

you should make sure channel 04 for timing is at the default value of 32768 . you should not mess with that. it's really meant for testing purposes only. if you advance timing, the higher fuel amounts will be too advanced.

you should take some logs 011 only, as well as 011-001, and 011-001-003 to get a good idea how well your tdi is performing. take healthy long logs like a whole commute etc. from start to finish. will be most informative :)
As far as I know, I have stock nozzles. The only modification I’m aware of is a rocket chip.

After that, you lost me. Remember, I’m a total newbie to VCDS. Can you walk me through the steps for “checking channel 4 for timing“ and for “taking logs”? And if you’d be so kind, also tell me why I’m doing those thing.

Is there a VCDS for Dummies out there that explains procedures step by step and the “why” of it? I’d love to become proficient at using VCDS. And due to an upcoming surgery, I’ll have plenty of time to study as I sit around.
 
Last edited:

JohnB

Member
Joined
Sep 28, 2018
Location
Michigan
TDI
2003 Golf TDI GLS ALH 1.9T
As far as I know, I have stock nozzles. The only modification I’m aware of is a rocket chip.

After that, you lost me. Remember, I’m a total newbie to VCDS. Can you walk me through the steps for “checking channel 4 for timing“ and for “taking logs”? And if you’d be so kind, also tell me why I’m doing those thing.

Is there a VCDS for Dummies out there that explains procedures step by step and the “why” of it? I’d love to become proficient at using VCDS. And due to an upcoming surgery, I’ll have plenty of time to study as I sit around.
Instructions for checking timing


Step by step:

  • Make sure you are using thecurrent version of VCDS or a fully registered version of VCDS-Lite)
  • Start your engine and make sure the coolant is up to normal running temp. TDI engines may take a long time to warm up at idle.
  • Start VCDS or VCDS-Lite
  • Click [Select]
  • Click [01-Engine]
  • Click [Meas. Blocks - 08]
  • Go to group 000 (Group 004 for V6 TDI - VCDS-Lite does NOT support this)
  • Click [Switch to Basic Settings]
  • Click [TDI Timing]
  • Select your engine code from the drop-down menu

(continued in link)




Instructions for where to go to access the various available Channels for logging:

Ross tech website has a ton of great information to reference.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
actually if you have a rocketchip tuning your adaptation for timing (channel 04) is likely set to 32900 - for +1.4deg advance across the board for timing, and that's what he likes to set it at on his tunes from what i've seen. so should probably leave that. i personally think that's too much advance for the mid-high/high end at lower rpms... also, iirc, he usually likes to set IQ a bit on the lower end, maybe 3-3.5. that you just have to expirement with.. i would *highly* suggest taking some logs like i mentioned and see how the car is doing - at the very least boost-wise
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Not to supersede burpod's commewnts, as he is way more knowledgable than myself,.
Always thought it was a bit goofy, but it seems the hammer mod is the preferred solution. Adaptation may not allow to you to kick it up high enough (4 or5).
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
a rocketchip ecu may have IQ adaptation set from non-stock value of 32768 as well. for a tuned ecu, where "IQ" is would be generally suggested by the one who tuned it, and you would take logs and see how things are and maybe fine tune. this fine tuning likely could be done with adaptation
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
I drove my Jetta around today for the first time since I did a ton of work on it over the last month: timing belt, water pump, crank and cam seals, intake cleaning and new gasket, motor mounts, fuel filter, new thermostat and housing, new hard pipe coolant o ring.

The car will not come up to temperature. It was 30F out today, so a little cold, but I’ve driven in far colder and the car has always come up to temp in 20 minutes or so of driving. The only thing I can think of is that the new thermostat is bad.

1. Is there another possibility? If I put the thermostat in upside down (not backwards), could that cause this? Is there anything else that I should look at?

2. without my vehicle unable to get up to temperature, is it pointless to look at VCDS?
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
Quite the opposite. First of all does the hose to the radiator feel hot after a drive? Perhaps the coolant sensor is bad and not reading correct. Next drive log 011 and 001

When car has been sitting over night, check block 007 when car is at known ambient temps, key on car off and screenshot it or report the temps, they should all read the same or very close
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
Quite the opposite. First of all does the hose to the radiator feel hot after a drive? Perhaps the coolant sensor is bad and not reading correct. Next drive log 011 and 001

When car has been sitting over night, check block 007 when car is at known ambient temps, key on car off and screenshot it or report the temps, they should all read the same or very close
The hose coming out from the thermostat was not at all hot after a drive. The other hose that connects to the coolant flange was warmer, but I could easily touch both hoses after a drive. I was wondering if the coolant sensor was bad too, but wouldn’t I still get heat from the dash?
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
Actually, I would take a log 011-001-007 next time you drive it.
Can you walk me through how to do that? I don’t have any idea what logging means or how to do it.

If I share a log, is that something the people in this forum can help me to interpret?

How do I educate myself on how to get the most out of the usefulness of VCDS
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
with car on (key on at least) go to engine module. click measuring blocks. in the first row, enter 011 in first block for measuring boost and click "go", then 2nd row 001 for fueling, then 007 in the 4rd row.

then rename the logfile name in the text box to something unique and meaningful. i usually just pre-pend the name with a just a date/time + short descriptor. "Jan5-errands-test-LOG-01-011-001-007.csv" for example. vcds will append log data to an pre-existing file, so if you don't rename it, it will appened new data to the last log you took of these channels, which is really annoying... it's best to always give the file a new, unique name before starting the log

then click start and then drive, stop log at the end. you can click stop and the resume, but logging just the whole drive

if your hoses were cold, it sounds like t-stat physically isn't working, which is strange. in which case logging likely won't provide much help...

to see how good boost control is, log 011 only. 011-001 will give a good idea of boost + fuel.
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
This morning I did my first log, thanks to help from burpod!

if I’m interpreting the data correctly, my intake air, coolant temp and fuel temp were within 2•C (intake air was -0.9, coolant temp was 0.9, fuel temp was 0) before startup.
Even though my laptop battery was full, it died after 7:51 minutes, so the log wasn’t completed for my whole trip, but the data did save until that point.

GROUP 007
By the end of the (unfinished due to laptop battery death)log, my fuel temp was 21.6, intake air was 9.9, and coolant temp was 45. I assume this indicates that my coolant temp sensor is working, indicating that my thermostat is not working. Would you agree?

GROUP 001
At initial startup, my injection was 8 mg/str, and after 10 seconds or so, the rpm’s leveled off at around 966-987, and the injection was around 7 mg/str. Another 10 seconds is dropped to 5.2. Another ten seconds later it was in the mid 4’s.
During the drive when I’d be idling, sometimes it read 3.0-3.2, other times it was 2.2-2.6, and while driving through various speeds it was all over the place (I assume this is normal).

GROUP 011
At idle, the boost specified was 969-979, actual was 938.4, charge pressure N75 was 19.9.

The highest logged rpm’s was 3024, boost specified was 1815.6, boost actual was 1795.2, charge pressure was 63.8.

The highest logged boost actual was 2315.4 (specified was 1836), with charge pressure at 87.3 and rpm’s at 2793.

The highest charge pressure was 80.9. (Rpm’s: 2751, spec:1183.2, actual:1366.8)

How do I interpret this data ?
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
sent a pm - you can email me the logs or post them up somewhere like google drive

- the 4th column in block 011 is n75 duty cycle (%) - the higher that number, the more the vanes are open - 100% means would be vanes wide open.

- your temps look fairly normal given what ambient temps likely are and barely an 8 minute drive. coolant tepms looks a bit low,..

- unless you're at very high altitude, your boost looks low at idle for a vnt15 with n75 @ 19.9% (rod length too long? bad n75? low vacuum?)

- if you're spiking boost to 2315 when target is 1836, that's some huge boost spikes. you don't want to be mashing the pedal if boost control is looking like that.
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
sent a pm - you can email me the logs or post them up somewhere like google drive

-
Thanks, I emailed them to you.

- the 4th column in block 011 is n75 duty cycle (%) - the higher that number, the more the vanes are open - 100% means would be vanes wide open.
Is 100% the ideal? Does this indicate stuck vanes?

- your temps look fairly normal given what ambient temps likely are and barely an 8 minute drive. coolant tepms looks a bit low,..
My temp gauge on the dash barely moves up, and the heat coming from the dash vents is lukewarm. My whole drive was 20 minutes, but of course, the laptop battery died...

- unless you're at very high altitude, your boost looks low at idle for a vnt15 with n75 @ 19.9% (rod length too long? bad n75? low vacuum?)
My altitude is around 700-800, so not high at all. How do I investigate to determine which one(s) are the culprit?

- if you're spiking boost to 2315 when target is 1836, that's some huge boost spikes. you don't want to be mashing the pedal if boost control is looking like that.
I do mash the pedal at times to see how the boost is doing. What am I in danger of damaging? How do I fix that?
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
2300mbar is OK for a vnt15 - but i think spikes that high aren't great for it. and there's a good chance it's spiking higher if you tested/logged it more. IMO, a vnt15 is good for 22psi (not up to 5000rpm tho), perhaps @ 3500, but when it's spiking and vanes are bouncing around more erratically from poor boost control, i think that's probably unhealthy for it. EMPs could be all over the place too.

do these checks:

-for sanity, hook mityvac up to brake booster line at idle - healthy vac should be 29-30hg. if you have a leaky nipple, that often causes a 1-3hg drop depending where it's wiggled at

-also for sanity, take a phone pic of the top of the set screw for the actuator, on the turbo. for garrett vnt15-17 i believe it should be about 2-3 threads showing. if it's never been messed with, hopefully it's just at the correct factory setting, else "rod length" below will be off

-mitvyac hooked direct to turbo actuator. pump up, vanes move smoothly of course through the whole range, and should hit set screw at 18hg. use feeler gauge, flashlight and eyes and/or finger to see when it hits. should never bind up anywhere when applying or releasing vac.

-mityvac hooked to n75 outlet (or teed into vac line to turbo), idle car, go to engine module, basic settings, and select "charge pressure control test". car will run a program that revs engine between 903 and 1400rpm or so, and cycles between 0 and 100% duty cycle. when it shows 0% duty cycle, you should see 25hg - that's what an OEM n75 puts out when all is healthy. if its <24.5hg either n75 is "bad" (or miscalibrated somehow, sticky, bad electronics etc), or could possibly be electrical issue to the n75. if it reads lower than 25hg, it likely can still be used if other things are fudged (rod length, tune). as long as the electronics are good in an n75, they can be cleaned and put back together rather easily.

if the above check out, turbo/n75 should be good.

depending on how boost/etc logs look, you can certainly adjust rod length in the direction it may need to go in to account for variations from car-to-car
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
2300mbar is OK for a vnt15 - but i think spikes that high aren't great for it. and there's a good chance it's spiking higher if you tested/logged it more. IMO, a vnt15 is good for 22psi (not up to 5000rpm tho), perhaps @ 3500, but when it's spiking and vanes are bouncing around more erratically from poor boost control, i think that's probably unhealthy for it. EMPs could be all over the place too.

do these checks:

-for sanity, hook mityvac up to brake booster line at idle - healthy vac should be 29-30hg. if you have a leaky nipple, that often causes a 1-3hg drop depending where it's wiggled at

-also for sanity, take a phone pic of the top of the set screw for the actuator, on the turbo. for garrett vnt15-17 i believe it should be about 2-3 threads showing. if it's never been messed with, hopefully it's just at the correct factory setting, else "rod length" below will be off

-mitvyac hooked direct to turbo actuator. pump up, vanes move smoothly of course through the whole range, and should hit set screw at 18hg. use feeler gauge, flashlight and eyes and/or finger to see when it hits. should never bind up anywhere when applying or releasing vac.

-mityvac hooked to n75 outlet (or teed into vac line to turbo), idle car, go to engine module, basic settings, and select "charge pressure control test". car will run a program that revs engine between 903 and 1400rpm or so, and cycles between 0 and 100% duty cycle. when it shows 0% duty cycle, you should see 25hg - that's what an OEM n75 puts out when all is healthy. if its <24.5hg either n75 is "bad" (or miscalibrated somehow, sticky, bad electronics etc), or could possibly be electrical issue to the n75. if it reads lower than 25hg, it likely can still be used if other things are fudged (rod length, tune). as long as the electronics are good in an n75, they can be cleaned and put back together rather easily.

if the above check out, turbo/n75 should be good.

depending on how boost/etc logs look, you can certainly adjust rod length in the direction it may need to go in to account for variations from car-to-car
Awesome. I will give all of these a try at some point this coming week and report my results.
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
2300mbar is OK for a vnt15 - but i think spikes that high aren't great for it. and there's a good chance it's spiking higher if you tested/logged it more. IMO, a vnt15 is good for 22psi (not up to 5000rpm tho), perhaps @ 3500, but when it's spiking and vanes are bouncing around more erratically from poor boost control, i think that's probably unhealthy for it. EMPs could be all over the place too.

do these checks:

-for sanity, hook mityvac up to brake booster line at idle - healthy vac should be 29-30hg. if you have a leaky nipple, that often causes a 1-3hg drop depending where it's wiggled at

-also for sanity, take a phone pic of the top of the set screw for the actuator, on the turbo. for garrett vnt15-17 i believe it should be about 2-3 threads showing. if it's never been messed with, hopefully it's just at the correct factory setting, else "rod length" below will be off

-mitvyac hooked direct to turbo actuator. pump up, vanes move smoothly of course through the whole range, and should hit set screw at 18hg. use feeler gauge, flashlight and eyes and/or finger to see when it hits. should never bind up anywhere when applying or releasing vac.

-mityvac hooked to n75 outlet (or teed into vac line to turbo), idle car, go to engine module, basic settings, and select "charge pressure control test". car will run a program that revs engine between 903 and 1400rpm or so, and cycles between 0 and 100% duty cycle. when it shows 0% duty cycle, you should see 25hg - that's what an OEM n75 puts out when all is healthy. if its <24.5hg either n75 is "bad" (or miscalibrated somehow, sticky, bad electronics etc), or could possibly be electrical issue to the n75. if it reads lower than 25hg, it likely can still be used if other things are fudged (rod length, tune). as long as the electronics are good in an n75, they can be cleaned and put back together rather easily.

if the above check out, turbo/n75 should be good.

depending on how boost/etc logs look, you can certainly adjust rod length in the direction it may need to go in to account for variations from car-to-car
Results:

1. brake booster at idle is around 27-28. HOWEVER, if I wiggle thehose coming from the vacuum pump, it drops and moves all over the place. Do I have to replace the entire pump, or can just that nipple be fixed?

2. I have around 6 threads showing

3. unable to do this one today (See below)

4. I ran the test as suggested. Mine switched back and forth between 99.6% and zero. The rpms did not change at all during the test, and stayed around 903. When the n75 opened, the vacuum went as high as 22, which is lower than was suggested as normal. If I wiggled the vacuum pump hose around, this number of course worsened.

I tried number 3 last, and tried to connect my mityvac to the hose going down to the turbo actuator. However, the VAC OUT line on the n75 itself cracked off. So now I have to get one of those….
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
Any suggestions where to get a good quality n75? Dealership has it in stock at $175!!
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
idparts has pierburg ones for $40. if yours is original, it wouldn't be a bad idea to have an extra one even if yours is OK. you might just be having vacuum issues.

you can fix the pump nipple without replacing the whole pump.

6 threads on the stop screw is definitely out of whack, try to take a phone pic, you should be able to reach your hand back there and snap a pic. that would throw off the "rod length"

 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
idparts has pierburg ones for $40. if yours is original, it wouldn't be a bad idea to have an extra one even if yours is OK. you might just be having vacuum issues.

you can fix the pump nipple without replacing the whole pump.

6 threads on the stop screw is definitely out of whack, try to take a phone pic, you should be able to reach your hand back there and snap a pic. that would throw off the "rod length"

Does ID Parts have the vacuum pump parts I need too? What is it called?
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
that pic is of the actuator rod, there is a set screw that the lever hits, it's on the turbo itself, it's a threaded allen insert bolt
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
that pic is of the actuator rod, there is a set screw that the lever hits, it's on the turbo itself, it's a threaded allen insert bolt
Sorry about that, I’ll have to take another look for that
 

sixmenn

Veteran Member
Joined
Dec 2, 2014
Location
West Michigan
TDI
2001 VW Jetta TDI manual transmission , 2000 VW Jetta GLS TDI manual transmission
I looked on IDParts and can’t find anything to fix the swivel fitting on my vacuum pump that is “leaking vacuum”. Can anyone point me in the right direction?
 

braddies

Veteran Member
Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
There's a few threads around here dealing with that... Basically the vacuum pump can be taken off the motor and then tap the lip with a brass hammer to pean it back down tighter against the wiggly nipple, some folks have encapsulated the joint with jb weld
 
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