Nozzle upgrade, IQ adjustment, and Tune

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
I have been digging around the forums a few days now, and I am guessing I am not looking up the right combination of words. I am new to TDI's, but not wrenching.
I am not planing on doing any mods till I get the car all fixed up, but I am always trying to learn what I can to better formulate a plan for the long run.

If you get nozzles/hot swap injectors, from what I have read, you need to adjust the IQ.
If you get nozzles/hot swap injectors, and a tune at the same time, do you still need to adjust the IQ. Or is the IQ adjusted through the tune, by the tuner already?
Or
Am I miss reading some threads, and to adjust the IQ you have to do the hammer mod, because there is no software adjustment, or because the proper way is the hammer mod?

I have a lot to learn about vag-com inspections and adjustments. Reading tables and charts.

My plan for the car: 99.5 Jetta
get vag-com
injectors PP520
malone stage 2

I know once I start down this road it is going to morph into a custom stage 5 for the end game. I did the same thing with my 02 bugeye, before I knew it, I was full STI bolt on with a custom tune.................. darn it cars are addicting. :)
I do things very slow to start, it would probably be six months of research and asking and learning before I even start to purchase any items. But then when I do, I get everything at once.

Thank you for your time,
Jared
 

Nero Morg

Veteran Member
Joined
Oct 19, 2017
Location
OR
TDI
2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
Tune or no, if you change injectors, you have to adjust your injection quantity for smoke control, fuel eco, and slow down shudder :)
 

Jetta_Pilot

Top Post Dawg
Joined
Apr 14, 2005
Location
West Hill, Ont. Nov.12th in Mexico till April 22nd
TDI
2015 Passat Highline TDI Candy White (SEL Premium) long gone 2002 Jetta TDI
You're thinking of doing it in the right sequence, injectors and then a tune. My suggestion would be to also buy the Flashzilla so you can download the OEM ECU file and then install the tuned file. If you go crazy after you can get Stage 3. You can rent or buy the tool.
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
Jetta _Pilot, my understanding is that I need an ecu socket for my 99.5 jetta?
Unless I miss read about the socketing.
 

Nero Morg

Veteran Member
Joined
Oct 19, 2017
Location
OR
TDI
2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
No, you are correct. You'll need to have your ecu socketed to get a tune. Get ahold of Cascade German in Gresham about socketing and tuning. They also sell nozzles.
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
No, you are correct. You'll need to have your ecu socketed to get a tune. Get ahold of Cascade German in Gresham about socketing and tuning. They also sell nozzles.
Awesome, have you used them before?
If not, is there anyone else you would recommend?
 

Nero Morg

Veteran Member
Joined
Oct 19, 2017
Location
OR
TDI
2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
Yes, they're the ones that helped me tune my car, plus I've bought loads of stuff from them. Definitely a verified vendor and well known here.
 

Nero Morg

Veteran Member
Joined
Oct 19, 2017
Location
OR
TDI
2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
It does, but 98 NB and the 99.5 jettas used a different ECM than the 2000-2003 ALH
 

Rrusse11

Veteran Member
Joined
Jan 23, 2014
Location
PA Deutsch Country
TDI
2002 Golf, 5spd; 05 Jeep CRD
"to adjust the IQ you have to do the hammer mod, because there is no software adjustment, or because the proper way is the hammer mod? "

Jard,
There is a certain amount of software IQ adjustment you can do with VCDS, if you make a big jump in fuelling, ie bigger injectors or a bigger pump, then physically adjusting the pump is needed. The "hammer mod" is straightforward enough, a little tap can make a big difference, gently gently is the key, same with adjusting timing. You will need the right Ross-Tech cable coupled with the free software. Not sure about how that works on a 99.5 variant.
 

tdi_my live

Veteran Member
Joined
Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
Hello, every change in the hardware has to adapt the software accordingly. If you use larger nozzles, the SOI and the IQ (duration) must be reset in the ECU software. With a VEP through the pump voltage in volts. The map must be reprogrammed for the new nozzles.
Job from the Tuner.
 

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
Just to clarify a couple points: As Russell posted, you can adjust IQ with VCDS and in fact the adjustment range is pretty significant. If you upgrade nozzles alone, an IQ adjustment in VCDS may be adequate to reduce smoke. A tune is not required.

Having said that, '99.5 and 2000 cars have less sophisticated fuel mapping than later TDIs and can experience slowdown shudder when you upgrade nozzles. This is especially noticeable when the engine is cold. Usually increasing the IQ number with VCDS is enough to correct this. If not, then you may need a hammer mod.

It's surprising to me to see the range of IQ settings with the pump at its default setting in VCDS. I've seen numbers from 1.8 to 3.6. I usually shoot for 2.8-3.0.
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
Thank you everyone, your expertise is much appreciated! Also, thank you for early instructions on VCDS and hammer mod target numbers.

I have worked on a lot of cars. Japanese and American cars you replace the part and go. But I have already "bonded" more with this jetta than any other car. Germans really do know how to engineer dont they. 🤣
 

tdi_my live

Veteran Member
Joined
Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
I would be interested in your software number. With VAG COM you can read them out in the ECU. How old is the car Is that an ALH? What does Stage 2 include for a turbo?
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
Tdi_my live, I do not have a vagcom yet. But the car is a 99.5 jetta alh, I believe the stage 2 is just upping the boost 2 or 3 psi.
 

tdi_my live

Veteran Member
Joined
Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
Sorry, but as a German I can't do anything with the name 99.5. Why enlarge the nozzles but let the loader series?
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
No need to apologize, I think I was not fully understanding your question too.

I am enlarging the nozzles for future modifications as well.
The loader, I believe you are referring to the tune? Please correct me if I am wrong.
 

tdi_my live

Veteran Member
Joined
Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
The question is what year of manufacture is the car? Below 2000 it cannot be flashed via OBD. Then soldering is the order of the day for tuning.
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
99.5 is the model year. At least in the states VW changed ecu's after that. So I have to do different tuning than someone with a 2001.

The loader, I will leave vnt15 till I am ready with the rest of the supporting mods. I have always left my loader as the last part that I upgrade, because I feel that you can overwhelm your engine if you upgrade the loader with out all the supporting mods.
The loader I am considering is the vnt17/22.
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
Yes sir, I will need to solder my ecu. Not the end of the world, just a bit more work to get to the final goals.
 

tdi_my live

Veteran Member
Joined
Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
Hello, I don't want to spam the tread full. Now I understand. But there are 2 PLCC32 EPROMs that have to be unsoldered and reprogrammed. Do you have the equipment?
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
Hello, I don't want to spam the tread full. Now I understand. But there are 2 PLCC32 EPROMs that have to be unsoldered and reprogrammed. Do you have the equipment?
No worries about spamming, these are honest questions. I am here to learn just as much as I can, and you have brought up a few good points that I have not fully thought about yet, thank you.
I do not have that equipment. And honestly I would rather have a tuner do the work, because they do it more often than I ever will.
 

Rrusse11

Veteran Member
Joined
Jan 23, 2014
Location
PA Deutsch Country
TDI
2002 Golf, 5spd; 05 Jeep CRD
So here's a thought, could Jard install a later Mk4 model ECU, (computer). Or would this involve extensive re-wiring?
My understanding is that the motor is essentially the same.
 

Nero Morg

Veteran Member
Joined
Oct 19, 2017
Location
OR
TDI
2003 Jetta wagon, 2001 Jetta TDI, 2014 Passat TDI
Without getting into nit picky details, yeah the engines are essentially the same. As for rewiring, the entire engine harness will have to be changed, since the connectors are different. I think you have to change the dash harness too, to an extent, since wasn't 99.5 the only year that didn't have immo? So cluster would have to be changed too.

Least that's all I know off the top of my head. Never really looked into it.
 

Jard

Member
Joined
Aug 31, 2020
Location
Oregon
TDI
99.5 Jetta
I was thinking about doing the harness upgrade, but there are a few posts that talk about how intensive of an undergoing it is.



It is possible, just a lot of work.
 

Rrusse11

Veteran Member
Joined
Jan 23, 2014
Location
PA Deutsch Country
TDI
2002 Golf, 5spd; 05 Jeep CRD
"the entire engine harness will have to be changed," Nero Morg

Ahhh, forget that then, that'd be a ridiculous amount of work. May as well buy another car.
 

Nevada_TDI

Veteran Member
Joined
Aug 17, 2008
Location
Reno, sort of...
TDI
2001 Jetta TDI
You could send the ECU out for a modification and then whatever tunes you want should be compatible. My ECM has the soldering modification and I have upgraded my tune a couple of times. the .214/.216 nozzles have enough fuel flow for the VNT-17 upgrade to 24 PSI. As is mentioned before (if possible) pick a nozzle size/potential horsepower first. I went from .205's (Stage 3)to .230's,(Stage 4.5) and then realized my turbo wouldn't use up the extra fuel, and my FE was crap. So I bought .216's, and sold my .230's at a loss. Horsepower become a very slippery slope, and gets expensive quickly. Look at Rrusse11's signature: a ton of go fast parts and I am sure there was quite a cost involved. I am sure his car is a blast to drive, and I am sure he has places around him that he can stomp the throttle and bury the tachometer with ease.
 
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