How-To: Hammer Mod w/Pics & Cake!

davidm2232

Veteran Member
Joined
Feb 22, 2011
Location
Gloversville, NY (upstate)
TDI
92 4Runner-ALH Swap In Progress
I can't get a consistent reading for my IQ. I get it to 3.0, then drive it, it has absolutely no power and dies when I push the clutch in. After a hard restart the IQ is at 8 or 9 and slowly drops. I just can't get it dialed in. When I crack the torx screws loose, I get a bunch of air in my fuel line, if I get a decent IQ it starts idling really rough when I tighten the screws. Any suggestions before this thing visits the bottom of the local reservoir?
I'm having the same problem. I have to hold the go pedal to the floor and crank the starter for like 30 seconds to get it to start. I need to drive this to school, how can i get it back to stock?
 

shwagondawheels

Veteran Member
Joined
Oct 29, 2011
Location
Richmond, VA
TDI
98 Jetta TDI 420K and truckin
from what I've been reading it sounds like the IQ needs the be raised when you install larger injector nozzles correct?
or the value your looking at in vag has to be raised

I have an AHU A3 tdi and just installed a set of Bosio P520 sprints yesterday and Im going to a friends shop today to hook up the vag and set the idle injection quantity. It smells pretty rich and I swear I could see the fuel gauge moving on a 50 mile test drive. I did let it idle a while so that didn't help mpg.

But I would like to try this too because my triangle bolt has been ground into a square so somebody has been playing with it before me and that would explain some issues if they didn't us VCDS doing whatever they did in there and the IQ has been off..
 
Last edited:

fastcash43

Active member
Joined
Apr 30, 2011
Location
trenton NJ
TDI
1.9 Jetta 028-906-021-AHU.lbl
Did the original author of this thread forget to mention loosening the 4th triangle bolt or is the point of the article to show that the hammer mod can be done without loosening the triangle bolt. Can I get some confirmation from folks that hammer mod can be done without loosening the 4th bolt ?
 

VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
Joined
Jul 2, 2000
Location
Springfield, VA
TDI
‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
It can be done without loosening the 4th bolt.
 

fastcash43

Active member
Joined
Apr 30, 2011
Location
trenton NJ
TDI
1.9 Jetta 028-906-021-AHU.lbl
Thanks VeeDubTDI, I'm going to give it a try today. Btw does going the 3 bolt method increase potential for pump gasket damage etc does anyone know ?
 

fastcash43

Active member
Joined
Apr 30, 2011
Location
trenton NJ
TDI
1.9 Jetta 028-906-021-AHU.lbl
UPDATE: I did the hammer mod the other day, loosening ONLY 3 pump head bolts (ignored the special triangle bolt) with success. The 3 bolt method does work or at least so far anyway. The question now is has anyone who's done the (3 bolt) hammer mod not had success ? Are we all wasting time and money diggering around for that special triangle socket for nothing ?
 

VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
Joined
Jul 2, 2000
Location
Springfield, VA
TDI
‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
I suspect that there is an increased risk for gasket damage by only loosening 3 of the 4 bolts. If you have a very old pump, you may want to consider loosening the 4th bolt or sucking it up and doing a pump re-seal (it probably needs it anyway).

We've had varying success by only loosening 3 bolts. Some pumps are fine, others leak afterwards. Who knows if loosening the 4th bolt would have saved the gasket - not really worth trying in my opinion... if it leaks, re-seal it because it's going to leak eventually anyway.
 

acesneights

Veteran Member
Joined
Feb 19, 2012
Location
North East Ct
TDI
2000 Golf TDI auto 2dr
if you are good you can have the car running with VCDS displaying the IQ reading while you whack it. (not hard!) that takes the guesswork out of it

if you loosen the bolt too much, it squirts you with fuel... :) tighten it a little.

altho pay attention as you tighten the bolts, the IQ value may change...

it would also be a good idea to get the special bit from metalnerd to loosen the 4th bolt, makes the job much easier.

Good How to BTW
Metalnerd ?? Can you expand on that ?
Thanks.
 

TTR 21

Member
Joined
Feb 26, 2012
Location
Snohomish, ID
TDI
2002 Super J
I recently did this mod and while the engine was running i tapped the pump towards the driver side until the idle became poor. I then slightly tapped it back to where the idle just cleaned up. It feels like i have definately picked up a HP from doing this. The exhaust has a slight puff of black smoke when you tap the throttle or quickly accelerate from a stop.
 

thesupercat

Member
Joined
Jan 15, 2013
Location
Onalaska, WA
TDI
1998 Jetta TDI, 1996 Dodge Cummins 4x4, 1991 Dodge Cummins.
I recently did this mod and while the engine was running i tapped the pump towards the driver side until the idle became poor. I then slightly tapped it back to where the idle just cleaned up. It feels like i have definately picked up a HP from doing this. The exhaust has a slight puff of black smoke when you tap the throttle or quickly accelerate from a stop.
I did this exact method, just out of common sense, then had my IQ checked with VCDS, it was running at 1.0. There was TONS more power and absolutely no smoke except a light haze at idle when cold. I have done almost every airflow related upgrade I can think of, 3" DP & exhaust, k03/k04 turbo, ported head and exhaust manifold, port matched intake, egr delete, 1.5" intercooler piping, etc... My question is: Is there anything wrong with running at 1.0 with my setup? I have not upgraded injectors yet, that will come soon. But is there a danger of over-stressing the pump or overheating the:confused: turbo, valves, piston, etc. when running at 1.0? Once again absolutly no smoke when I had it at 1.0. Mileage seemed to be fine until I used the power, but I never did run it that way long enough to burn through a tank and then refuel. If I got on it and then looked at the gauge it would sometimes have dropped noticeably. Have it set at 3.2 now and really miss the power!

TIA for any input!
 

VRTn

Member
Joined
Jan 6, 2015
Location
NB canada
TDI
00 Jetta TDI, 2x 01 jetta TDI, 91 jetta AAZ, 95 GTI VRT - sold
NB_TDi :

I followed your procedure for the hammer mod on my 01 jetta which had a real bad case of the slowdown/idle shudders.

After 1 small tap I went from 2.4 to 9.1. So I gave it a small tap back and it was within spec. No more shudder but I now have a small leak (gasket must have got compromised). I still have a real rich smell from the exhaust and my pump timing is good as well. I have bosio .205 nozzles but no other mods.

My question does the IQ # being lower mean more fuel (and higher the number less fuel?). Because I have experienced a loss in power from bringing the IQ up to spec which doesn't make sense to me lol. Going to tinker with it again tomorrow evening, I may need to source out a new gasket.
 

SFHGolfTDI

Veteran Member
Joined
Nov 3, 2003
Location
Ventura, CA
TDI
2002 Jolf GLS TDI - Reflex Silver (purchased 2011) | Previously: 2001 Golf GL TDI - Indigo Blue (sold 2005)
NB_TDi :
My question does the IQ # being lower mean more fuel (and higher the number less fuel?). Because I have experienced a loss in power from bringing the IQ up to spec which doesn't make sense to me lol. Going to tinker with it again tomorrow evening, I may need to source out a new gasket.
Yes, this is how it works.
 

Jpontiac68

Veteran Member
Joined
May 13, 2015
Location
Naperville, IL
TDI
2003 Jetta GL TDI, 5 speed manual galactic blue w/ 101k miles
So true growler me and my friend were messing with IP it squirted all over the windshield and engine luckily no windshield hazing, and engine was fine but it ruined the stock markings. The IP tune is always cool at first until you fill up and got 350 miles and about 29 mpg. And my brakes are sticking as well so I'm trying to set the IP back to stock. If anyone can slove my brake problem I'd be so happy check out my threadhttp://forums.tdiclub.com/showthread.php?t=448238. Thanks
 

rotarykid

Top Post Dawg
Joined
Apr 27, 2003
Location
Piedmont of N.C. & the plains of Colorado
TDI
1997 Passat TDI White,99.5 Blue Jetta TDI
What is the mechanical reason why this is happening?

I picked up a low mile 99.5 Jetta which seems to have started having this issue recently. What is the mechanical reason why this is happening?

I also have a friend with 300k+ miles on the same car purchased new around the same time that is also suffering from the shudder & hard hot start issue. What is the mechanical problem which is causing this problem?

Is the pump timing & fueling control not moving the same distance as it did when the pump was newer due to wear or other age related reasons???

Thanks...
 

m.fessler

Member
Joined
Dec 31, 2017
Location
Austria
TDI
AFN
Hello,

my A4 with an AFN Diesel had stuttering problems at low revs specific under 1500rpm down to idling.
Very annoying especially in the city at low speed and stop & go traffic.

I then checked the IQ with vcds - it was at 32768 - 1,2mg.
32686 is the smallest possible value what led to 2,8mg.
Its much better now but not yet perfect.
Because the electrical adjustment is fully exhausted, I would have now
do the hammer mod to increase the value further.

Do you think the effort is worth it?
Or is the expected improvement from 2,8mg to the optimal 4-5mg not really a big deal?

Because I have read of pumps which be leaking after the adjustment.
And my pump is bone-dry so... hmmm maybe I should rather keep my fingers off?!
Is this a common problem or rather rare?

Thank you,
greetings

Martin
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Martin, you adjust in order to achieve proper operating performance. If you don't have it, and you've exhausted the available range via Adaptation (VCDS) then, yes, you'd need to do the Hammer Mod to further achieve a change. Always set the Adaptation value back to stock before performing a Hammer Mod.

If your pump is "bone dry" then you've got much bigger problems than a simple IQ problem.
 

m.fessler

Member
Joined
Dec 31, 2017
Location
Austria
TDI
AFN
Hi UhOh,

with "bone dry" I meant it does not leak but I am scared that it does after the hammer mod because who knows how old the gasket is and if it take the move without beginning to leak.

The question is if the effor is worth the risk.
If the expected improvement from 2,8mg to the optimal 4-5mg is really noticeable or after all I have more trouble as now because I have to reseal the pump.

Greetings,
Martin
 

m.fessler

Member
Joined
Dec 31, 2017
Location
Austria
TDI
AFN
Had anyone else a so such "small" deviation (2,8mg to the optimal 4-5mg) and
can describe the positive change that I can assess better if the effor is worth the risk or not?

Thank you,
greetings

Martin
 

m.fessler

Member
Joined
Dec 31, 2017
Location
Austria
TDI
AFN
IIRC, 2.8 is the nominal value from the factory for a VE type pump. At least, it is for the ALH engine.
My source says "2,2..9" for both engines (your ALH and my AFN).
Ross-Tech (VCDS) says 2.5 to 9 mg/h.
The official workshop manual for the AFN says 2,0-9.0 mg/h.

Greetings,
Martin
 

UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Hi UhOh,

with "bone dry" I meant it does not leak but I am scared that it does after the hammer mod because who knows how old the gasket is and if it take the move without beginning to leak.

The question is if the effor is worth the risk.
If the expected improvement from 2,8mg to the optimal 4-5mg is really noticeable or after all I have more trouble as now because I have to reseal the pump.

Greetings,
Martin
Martin (if you're still out there), sorry for the late reply (missed the update to this thread). Buy a reseal kit and have it on hand. Plan to hammer mod when you have time to install a couple of the seals (which would be ones of interest here).
 

m.fessler

Member
Joined
Dec 31, 2017
Location
Austria
TDI
AFN
Hey UhOh,

I'm still here. :)
Yep, that's how I'm gonna do it, I am too curious if there is
a noticeable improvement when I change the value from 2,8mg to the optimal 4-5mg.

Thanks and Greetings,
Martin
 

Steve777

Veteran Member
Joined
Dec 1, 2003
Hi all. A newbie (on adjusting IQ at least) question for someone.

So from all that I have read, if you want less fuel getting to the engine, you want a higher IQ value, and a lower software adaptation number (this more or less a quote from myturbodiesel.com's writeup).

What puzzles me is the IQ value is mg of fuel per stroke, so a higher IQ value would seem to mean more fuel going in each cycle/stroke, no? What am I missing???

I am asking because I am about to diagnose some IQ issues and would like to understand this before I start changing things around.


TIA
 

eddieleephd

Top Post Dawg
Joined
May 27, 2012
Location
Battle Ground, Wa
TDI
2002 jetta Wagon
Hi all. A newbie (on adjusting IQ at least) question for someone.

So from all that I have read, if you want less fuel getting to the engine, you want a higher IQ value, and a lower software adaptation number (this more or less a quote from myturbodiesel.com's writeup).

What puzzles me is the IQ value is mg of fuel per stroke, so a higher IQ value would seem to mean more fuel going in each cycle/stroke, no? What am I missing???

I am asking because I am about to diagnose some IQ issues and would like to understand this before I start changing things around.


TIA
My explanation is that the ECM uses an equation to adjust from. It cannot measure how much, so you must tell it the base line. X+Y=Z. X = amount Injectcted by an Injector at standard test condition (what standard is exactly who knows) Y = increase of fuel based on maps and Z = actual injected quantity.
So if the ECU thinks an Injector is going to Inject 2mg/St and wants to Inject 12mg/St it adds 10mg/St 2+10=12, however, in the injectors are injecting 4mg/St and the ECM adds 10 you end up with 14mg/St meaning 2mg/St because 4+10=14.
Again the ECM cannot measure the quantity, it only uses the equation and if its assumptions are incorrect then the injection is incorrect.

Now the equation above is poorly written as it doesn't account for true difference, it's just an example. Reality is that the 14 stated earlier is probably closer to 15.5, or something like that.
 
Last edited:

DukatiW

New member
Joined
Feb 19, 2021
Location
Kuna, Idaho
TDI
2003 1.9 ALH
I don’t have access to VCDS, but I do have an autell scan tool that I’m able to watch IQ with. Can’t make any adjustment, but I can see it. Would this work to use to do this?
I’ve heard of people just doing it blindly and hoping it works right, but I don’t want to do that, don’t feel like ruining stuff yet.
 

bmwM5power

Veteran Member
Joined
May 3, 2007
Location
Rochester NY
TDI
15 GSW TDI S 6MT / 02 JETTA TDI GLS 5MT 15 GOLF TDI 6MT
I might if you have the hands of a neurosurgeon, but you said you dont wanna do this, so whats the point?
 
Top