IQ

spacekup

Member
Joined
Feb 6, 2024
Location
Hillsdale mi
TDI
2001 mk4 Jetta TDI
Okay, so I bought a mk4 TDI that had been manual swapped, new head, new cam. Whole top end is new, was told I had bigger injectors. Bought it loping like it had to much fuel so I believed the bigger injector part. Fast-forward few weeks of driving it like that. Pulled the injectors to find out they are still stock automatic injectors.. but have a 11mm pump and a ecu I pray to God, got switched. But havent checked, but being a stock untuned ""manual" and a 11 mm would it still think it's getting to much fuel? Because of the 11mm? And a manual ecu? Now fast forward some more put 216s in and a tune will be here in a few days. The lope is obviously heavier with the nozzles, but will a simple tune fix my IQ. Or do I have to have my IQ specifically tuned through vsds? And will I hurt my car driving it with that much fuel untuned? Other then maybe my turbo vains?? 17/49 Garrett vnt
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
The ECU is the same, it's just the soft coding that gets changed... there are three different "slots" in the ECU: manual, automatic, and 4Motion (which is AWD, and on those by default were all manuals anyway).

But to answer your question directly, for best results yes a tune will help the engine run at its best.

Normally, though, t he 01M-->02J conversions I've experienced, they just change the soft coding and nothing else, and they run perfectly fine. So you may have some other issue altogether. Pump timing, etc.
 

spacekup

Member
Joined
Feb 6, 2024
Location
Hillsdale mi
TDI
2001 mk4 Jetta TDI
The ECU is the same, it's just the soft coding that gets changed... there are three different "slots" in the ECU: manual, automatic, and 4Motion (which is AWD, and on those by default were all manuals anyway).

But to answer your question directly, for best results yes a tune will help the engine run at its best.

Normally, though, t he 01M-->02J conversions I've experienced, they just change the soft coding and nothing else, and they run perfectly fine. So you may have some other issue altogether. Pump timing, etc.
Well I appreciate the response and understand it. New to this TDI stuff. After I tune it today or tomorrow hopefully. If it still acting funny I was going to assume pump timing also. That would be my next tackle anyway. Thank you dude!!
 

spacekup

Member
Joined
Feb 6, 2024
Location
Hillsdale mi
TDI
2001 mk4 Jetta TDI
The ECU is the same, it's just the soft coding that gets changed... there are three different "slots" in the ECU: manual, automatic, and 4Motion (which is AWD, and on those by default were all manuals anyway).

But to answer your question directly, for best results yes a tune will help the engine run at its best.

Normally, though, t he 01M-->02J conversions I've experienced, they just change the soft coding and nothing else, and they run perfectly fine. So you may have some other issue altogether. Pump timing, etc.
And can I still drive it like this? For a bit? Tell I get it figured out?
 

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.. :/
if you switch to coding 2 and you adapt IQ or hammer mod to be normal healthy 3.5-4.2mg, the car should run very close to stock - not exactly the same - fueling/timing will be a little bit off . as 10mm/.185s (manual) vs 11mm/.158s (auto) is not simply a flat/linear change to the fueling ("IQ")

be aware , some "name brand" tunes do not actually give you a tune for your specific fueling hardware, despite their claims. you get the same exact maps in the tune regardless of what fueling you say you have. and you simply have to approximate it (poorly) by altering IQ one way or another. so do your research :) unfortunately, also a lot of misinformation and misunderstanding out there regarding all of this...

you can read all about "IQ" and fueling as it pertains to your above situation (switching code) in the "Fueling" section HERE.

idle loping can be caused by hardware issues, but also wrongly done fuel/timing maps in the tune. with a healthy pump and large injectors, idle should be butter smooth
 

GTiTDi

TDIClub Enthusiast, Macht Schnell! Vendor , w/Busi
Joined
Oct 18, 2010
Location
3 Spruce st Wareham, gateway to Cape Cod Massachus
TDI
'91 GTI CJAA swap,'02 Jetta wagon ALH swap, '03 GTI 1.8T rally car, '03 Sprinter 3500
You need to check and adjust IQ aka Hammer mod, Just completed yet another manual swap here at Schnell and for reference the IQ was at ~1.8 after the swap and once warmed up was not smooth so adjusted IQ to ~3.2 and now she is right as rain. Just needs bigger nozzles and a Podtune!
 
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