Nozzles/IQ

$600BeaterTdo

Member
Joined
Jun 27, 2018
Location
PA
TDI
2000 gls tdi
Hello all, I have a 2000 jetta tdi that was was converted to a 5 speed, the guy who I purchased the car from claimed he had the “biggest nozzles before need a tune” which he said was .205? Anywho, the car obviously smokes like an old Detroit. As funny as it is, and enjoyable it is to smoke someone out that’s riding your ass, I know it’s very unhealthy. After the swap I adjust the IQ via hammer mod and a bag com. It’s at a steady 4.8-5.2 but still smokes an unhealthy amount. My question is, what are some opinions on a safe IQ to bring it to so that it doesn’t trail behind me when having a load, but yet isn’t making it run too lean? I know it’s more of a trail and error ordeal, I just don’t want to go jacking the IQ up to high, take it for a test run and damage somthing. Any help would be greatly appreciated!
 

KLXD

Top Post Dawg
Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
You can't be too "lean" and cause damage. It isn't a gas engine. Too much fuel gets you smoke and higher EGT's.

Underfueling just yields less power.

Hammer away until it runs properly and don't worry about what the IQ number is.
 
Last edited:

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
The IQ only needs to be within range (2.2 - 9.0). The ECU will change it as you drive.
We've seen it sometimes like to be around 4 or 5, but results vary a lot. The old VEs came with it set to around 2.2.
I've never upgraded injectors, but I believe there may be other adjustments to go with that.
I would diagnose the excess smoke, could be some loose piping, or something else.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
So much interweb guessing. Do you think we can assume the .205s are in good shape?
Keep in mind air is a big part of fueling. Too much or too little will affect combustion.
 

$600BeaterTdo

Member
Joined
Jun 27, 2018
Location
PA
TDI
2000 gls tdi
That’s a good question BobnOh, I have no idea what shape their in. I just removed and cleaned the intake mani last night, it should be breathing good! I just think those injectors, along with the 11mm pump are dumping too much fuel to it. I will play around with the IQ some more tonight and update! Hopefully I get it, I feel like it would have more potential if it ran cleaner. She feels like it’s choking itself out somtimes dumping all that fuel coming up hills
 

PakProtector

Veteran Member
Joined
Jan 5, 2014
Location
AnnArbor, MI
TDI
Mk.4's and the Cummins
She feels like it’s choking itself out somtimes dumping all that fuel coming up hills
The symptoms are at opposite ends of the spectrum. The usual symptom of 'dumping fuel' is a kick in the butt dyno, and a smile...aka the engine makes more power with more fuel as noted. The exhaust needs to be very black indeed before adding more fuel decreases power.

The 'choking itself' is quite another thing...

Douglas
 

2000alhVW

Veteran Member
Joined
Aug 30, 2018
Location
Silver Spring, MD
TDI
2000 Golf
The symptoms are at opposite ends of the spectrum. The usual symptom of 'dumping fuel' is a kick in the butt dyno, and a smile...aka the engine makes more power with more fuel as noted. The exhaust needs to be very black indeed before adding more fuel decreases power.
The 'choking itself' is quite another thing...
Douglas
it's what my car did when the MAF was unplugged and I was in all types of limp modes.

actuator rod was out of adjustment, kicked it into limp mode immediately. MAF was unplugged so it could be semi-drivable, and it would "smoke like a freight train" (as someone put it when they were behind me on a hill, and then caught up with me at a red light).
Basically motor wasn't getting any air because no turbo
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Battle Ground, Wa
TDI
2002 jetta Wagon
I would set it to default IQ and hammer it to IQ as close to 3 as possible and modulate it later with the computer. That's how it's recommended in many places.


Fact is with you saying you have .502 injectors the largest they can be sounds like he put pp502's in. However, without knowing exactly when, how, and an actual receipt you have no idea what exactly was done.


I will ask you now, when was the timing belt done and is there proof? can you contact the mechanic and verify what work was done? Anyone on these forums will tell you that if yo cannot verify these things to do it immediately.


I found I was 10,000 past due when I did finally speak with the original mechanic about my vehicle, not good. It's likely that the belt would live much longer, however, the items it rolls across rarely live to terribly much longer.


We could all say a lot more however I find that introducing you to the link in my signature which is the best thing I can do. What ever you need, search it there and see what you find.
 

joep1234

Veteran Member
Joined
Jan 2, 2014
Location
NC
TDI
former '04 Beetle TDI, now 2x '15 Audi Q5 TDI's, 2007 Dodge Ram 4x4 6.7
A lot of smoke is too much fuel for the air supplied. Is your turbo working popularly?
 

Nevada_TDI

Top Post Dawg
Joined
Aug 17, 2008
Location
Reno, sort of...
TDI
2001 Jetta TDI
I'm with KLXD, due to the fact you don't know if, when, or how far your IP has been re-set, just hammer mod it until it runs right. A can of Diesel Purge might not be a bad idea either...
 

wonneber

Top Post Dawg
Joined
Oct 12, 2011
Location
Monroe, NY, USA
TDI
2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
Did you use VCDS or a generic scannerto check the IQ?
I would log the boost request and boost actual and go for a test drive.
Run the motor up into the 4K range.
If the boost actual is lower then the requested you are not getting enough air.
 

mk3

Veteran Member
Joined
Sep 13, 2005
Location
Wisconsin, USA
TDI
03 Jetta GLS 5-speed
I would set it to default IQ and hammer it to IQ as close to 3 as possible and modulate it later with the computer. That's how it's recommended in many places......
sorry, I think that could be true for a stock setup but if there has been a mod ot increase fueling, such as higher flow injectors and a larger/more powerful pump then you need to trick the system with hammer mod and likely the IQ at idle is going to get quite high. (mine was 5.8 after installing slightly larger nozzles and adjusting)

I wrote this a few years back
http://forums.tdiclub.com/showpost.php?p=4261932&postcount=9

still stand by it as my car is now 304k miles with the same setup - I did the injectors probably more than 100k miles ago.

Frankly, I think the car would be better with a tune and might require it. My mod was pretty minor and in my opinion near the limits of what can be done with hammer mod.

Other than hammer mod, maybe the boost control system needs to be evaluated.
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Battle Ground, Wa
TDI
2002 jetta Wagon
sorry, I think that could be true for a stock setup but if there has been a mod ot increase fueling, such as higher flow injectors and a larger/more powerful pump then you need to trick the system with hammer mod and likely the IQ at idle is going to get quite high. (mine was 5.8 after installing slightly larger nozzles and adjusting)

I wrote this a few years back
http://forums.tdiclub.com/showpost.php?p=4261932&postcount=9

still stand by it as my car is now 304k miles with the same setup - I did the injectors probably more than 100k miles ago.

Frankly, I think the car would be better with a tune and might require it. My mod was pretty minor and in my opinion near the limits of what can be done with hammer mod.

Other than hammer mod, maybe the boost control system needs to be evaluated.
MK3, I Know that you're correct, really the IQ is telling the ECU how much fuel is being injected by the nozzles at a specific pressure, idle.
I do think that the hammer mod would need to be done a few times and driven to see results and get right, as I'm sure you have.

Your post said that you think of it as air, however, think about it as a baseline instead. You're telling the ECM that the baseline for these nozzles is 5.8mg/St. Now the ECM is going to limit additional fuel. I believe that the remaining movement is broken into a percentage of the accelerator pedal and that's what's given by the ECM when you drive.


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