Injector Gasket Replacement - Won't idle - Rough Start

MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
Hey there.

2000 model. The car sat due to covid and then wouldn't start.
Investigating, I could see from the clear fuel line we'd lost the fuel. I vacuumed but wasn't getting anywhere so I figured there might be an air leak in the ancient fuel lines. Replaced both lines from the filter to injector, vacuumed again and got the car started to the usual idle but found fuel leaking from the injector gaskets. Seemed pretty simple. Replaced gaskets from a Bosch kit, checked all my work to get the male into the female plunger etc. Vacuumed again but the start is difficult and won't idle. Cracked all the nuts and getting fuel at each. What has happened? No leak at gaskets but I'm stumped for what seemed simple. VCDS said their gadget won't work unless car idles. I can get it to start with a lot of work and run with a lot of foot to throttle but dies immediately. Any ideas? (tired cracking all 4 nuts but still not running as normal).Thanks in advance.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Check wires to the pump. Mice maybe? If the wires looks in good shape (really check them) try running the pump directly from a small container of clean fuel. If that does not yield a change, then I would suspect that maybe you scuffed or damaged the tip of a nozzle or 2. They are very sensitive. If you cant rule it out to electrical or fuel conditions, I would pull the injectors and inspect the tips. Did you drop them or leave them out over night (not soaking in fuel)?
 

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
The injection quantity (IQ) needs to be modified. Look up "hammer mod" for how to do it.

You need to use VCDS to monitor the IQ while you perform the mod. Most likely the pump is over fueling the motor.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
If by "injector gaskets" you mean "injection pump gaskets" and you didn't know to scribe a sharp line between the pump body and the lid before taking the pump apart, so that the lid could go back *exactly* where it was.... yup, IQ adjustment (otherwise known as a "hammer mod") is a very reasonable explanation for your symptoms.

If you search around a bit you should find lots of great threads on what this means and how to do it.

It really does involve tapping the top of the pump with a hammer. Very gently. :)
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Hey there.
2000 model. The car sat due to covid and then wouldn't start.
Investigating, I could see from the clear fuel line we'd lost the fuel. I vacuumed but wasn't getting anywhere so I figured there might be an air leak in the ancient fuel lines. Replaced both lines from the filter to injector, vacuumed again and got the car started to the usual idle but found fuel leaking from the injector gaskets. Seemed pretty simple. Replaced gaskets from a Bosch kit, checked all my work to get the male into the female plunger etc. Vacuumed again but the start is difficult and won't idle. Cracked all the nuts and getting fuel at each. What has happened? No leak at gaskets but I'm stumped for what seemed simple. VCDS said their gadget won't work unless car idles. I can get it to start with a lot of work and run with a lot of foot to throttle but dies immediately. Any ideas? (tired cracking all 4 nuts but still not running as normal).Thanks in advance.
Hey mark
im not that far away and i could stop by and lend a hand. i have VCDS and cable. PM sent
 

MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
The injection quantity (IQ) needs to be modified. Look up "hammer mod" for how to do it.

You need to use VCDS to monitor the IQ while you perform the mod. Most likely the pump is over fueling the motor.
i think that's exactly it. I did mark the injector pump so it lined up exactly were it was before. I scratched it in several places X & Y. I replaced the gaskets almost instantly so there was no time for anything to get scratched or weathered. It's a simple switch. I watched all the YouTubes before hand. Thanks for all the suggestions. I know the pump can slide left and right. Is there a movement that can reduce fuel to get an idle and then link a VCDS to it can maintain idling. I don't forum much so I'm not sure how to reply one at a time. I'll get there. (Hey - stop with the eye-rolls)
 
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MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
Hey mark
im not that far away and i could stop by and lend a hand. i have VCDS and cable. PM sent
That would be sweet. They say I need to get it to idle first for the software to work. If you have a cable - - I'd be happy for any help, rentals of your gear or brains.
 
Last edited:

MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
If by "injector gaskets" you mean "injection pump gaskets" and you didn't know to scribe a sharp line between the pump body and the lid before taking the pump apart, so that the lid could go back *exactly* where it was.... yup, IQ adjustment (otherwise known as a "hammer mod") is a very reasonable explanation for your symptoms.

If you search around a bit you should find lots of great threads on what this means and how to do it.

It really does involve tapping the top of the pump with a hammer. Very gently. :)
I scratched that sucker up top and sides. It went back to exaclty the same spot. I was a swift and beautiful job so I'm flummoxed with this after. I watched all the YouTubes so doesn't that make me ASE certified? :p I'll look up the IQ adjustment - hammer mod tonight. thx
 

MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
Check wires to the pump. Mice maybe? If the wires looks in good shape (really check them) try running the pump directly from a small container of clean fuel. If that does not yield a change, then I would suspect that maybe you scuffed or damaged the tip of a nozzle or 2. They are very sensitive. If you cant rule it out to electrical or fuel conditions, I would pull the injectors and inspect the tips. Did you drop them or leave them out over night (not soaking in fuel)?

I simply opened the top of the injector pump and replaced the top gasket and then replacing that lid and the same for the main/lower part. The kit came with many gasket but all I needed were the largest two. It was simple. Ran fine before this seeming simple switch of the gaskets. I did my darnedest to put everything back in exactly the same spot. I marked everything. It wouldn't start. I checked everything again and rechecked the male to female plunger alignment. It now starts with furious footwork - runs at 1.5-2k RPM but dies once foot is lifted. I think it's over-fueled that's my feeling. Can the injector pump slide either way and change this fuel flow. I see the screw slots allow for some side to side variation and could that get it to idle long enough to run VCDS (which I don't have). Thanks for our help. I'm at a loss.
 
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Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
That would be sweet. They say I need to get it to idle first for the software to work. If you have a cable - - I'd be happy for any help, rentals of your gear or brains.
yea
happy to help, i sent you a PM (personal message) with contact info
 

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
i think that's exactly it. I did mark the injector pump so it lined up exactly were it was before. I scratched it in several places X & Y. I replaced the gaskets almost instantly so there was no time for anything to get scratched or weathered. It's a simple switch. I watched all the YouTubes before hand. Thanks for all the suggestions. I know the pump can slide left and right. Is there a movement that can reduce fuel to get an idle and then link a VCDS to it can maintain idling. I don't forum much so I'm not sure how to reply one at a time. I'll get there. (Hey - stop with the eye-rolls)

Research hammer mod in google. This is what I found right away. You want to raise the IQ.

 
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jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
This is the tool you are supposed to use. It's not that expensive.

Expensive is hacking and breaking stuff. You are already saving a ton of money doing it yourself.
 

MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
This is the tool you are supposed to use. It's not that expensive.

Expensive is hacking and breaking stuff. You are already saving a ton of money doing it yourself.

Can you feel my shame at the moment for making my own. I only expected to use it once after all. I extracted that bolt too many times. I'll get it out today.... I hope. I've learned my lesson the hard way.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Nothing wrong with making a tool, as long as it works.
 

BigAndy

Veteran Member
Joined
Apr 19, 2002
Location
Northern BC
TDI
99 A3
There was a great writeup on how to make a tool for that 3 sided bolt here. You may need to drill a small pilot hole in the bolt and get an easy out in it - or maybe you could weld something to it...or build it up and file a slot..there are ways. Mongler, from everything I've seen is very creative so you got some good help on the way.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
My creativity is out of necessity and frugality!
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
Thanks. I will work on this. Hit a snag. I managed to rounded the anti-tamper head so now I can't get it off. I'll be back when I conquer that issue. Holy crap!
What, that triangle bolt on the top? Easy fix. I have a few tools to fix this. If you want to swing by? It's not a difficult one to fix. I can weld a nut to it and then replace the bolt!
 

MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
Finally back after a long time burying my head in the sand and panic that I wouldn't get the nut out. Today back to it and it came out easy pushing what remained with a tap but the long sit with WD40 probably helped the most.

Updates: I raised the IQ nothing - No start. Lowered it and got a good start and idle. Tried driving it but a lot of smoke. Do I keep pushing IQ or is it best to get it on VCDS? Thanks for all the help everyone.
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
you can push the QA all the way one direction left or right, you cant harm anything by maxing it out.
the fact that you have lots of smoke tells a different story. regardless of how far you hammer mod it won't change the smoke levels. the ECU's map dictates how much fuel you get regardless of the QA position, hammer mod only changes the initial starting position of the idle to low rev fueling map. same thing with your timing graph in VCDS. once you get past idle the ECU figures out whatever it wants vs what you set it at. granted timing and QA need to be set correctly ion order for max efficiency and power because it sets the start of the MAP and that in a nut shell raises or lowers the entire area under the curve.


long story short, if it's smoking, something else is the problem, not the position of the QA.
VCDS will help drastically in setting things up right to narrow down the issue.
 

KLXD

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Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
Nah. Changing the QA position position is a recalibration of the pump that affects the whole range of its travel.

The ECU thinks it's setting the IQ at some level, but since the QA's been moved the the actual amount of fuel it's injecting is either more or less depending on how it's been moved.

Idunno for sure whether there's any feedback from the QA about the IQ or whether the ECU just sets its position by applying a certain voltage but either way moving the QA changes the amount of fuel over the whole RPM range.

At idle the IQ setting won't cause smoke since the ECU sets the IQ at whatever it needs to be to maintain the programmed idle speed. This is why you can see a different IQ. Off idle it will.

I was playing with it once. Hammered it so far it left a soot spot when starting up my driveway. Went the other way and no smoke.
 

MarkF67

Member
Joined
Jun 20, 2020
Location
Washington DC - Virginia
TDI
2000 Golf
Tweaked with the hammer mod back a few ticks until the start became a little hesitant - tiny taps to what seemed to give me my center point. It now seems to run and idle well without the smoke experienced last night. Has what I consider it's typical smoke upon hard acceleration - as before. Thanks given by the owner/wife - not much - surprise!. Thank you everyone for the help and support. I'll pursue a VCDS next. The whole car is at 21 years so it seems everything is failing, cracking - needs replacement. Cheers.
 

Mongler98

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Joined
Mar 23, 2011
Location
COLORADO (SE of Denver)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
not sure what your going on with this getting it to start with hammer mod, you are supposed to hammer mod it when its running. once you get to rough idle, go the other way a tiny bit and your good. sets you around 2 to 3, rough idle is about 1.4 to 1.6 or lower you want 3 to 5 is idea range.
 
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