ALH 90hp ticking on acceleration

90hp_ALH

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May 9, 2021
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TDI
Audi A3 - 90 HP ALH
Hey mates.
First time poster, long time lurker.
Got an Audi A3 1.9 tdi 90hp ALH. Have it since mid 2020, replaced injection pump in December 2020. Became kinda paranoid, so now every little sound is a foreshadow of something horrible to come. Noticed a few months back a tick on acceleration (couldn't tell you if it developed right after changing injection pump or before, as I never noticed as I either drive with someone in the car, windows down, music, etc...). It immediatly disappears when taking foot of the pedal. Took it to a trustworthy mechanic and asked if it could be the "new" injection pump, to which he said it probably wouldn't make such a sound, and it was probably a dirty/clogged injector. Told me to try it first with some additive (which he doesn't trust but advised since it's a low tick), before probably preparing for a pricey repair.

From your experience, could it be the "new" used injection pump that's ****ed? Would it make a ticking sound that stops on acceleration? Can't hear it in neutral at all.
Still has a 2 month warranty left on it, it's just in a pretty far town I was living at the time, so that's why I don't wanna go there unless I have to.
And if it is an injector, how ****ed am I lmao.

Thank you beforehand.
 

Steve Addy

Top Post Dawg
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Aug 7, 2002
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Iowa
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97 Mk3
Not sure how to approach this, but first off, the Audi A3 with ALH is more akin to the Golf / Jetta Mk4 cars. The Mk3 (A3) Jetta we got in the US never came with the ALH. The ALH was only on the Mk4 Golf / Jetta in the US from 1999.5-2005.

As for the ticking noise, you could try and use a stethoscope to determine where the sound is originating from although that can be tough sometimes. Since injection is operating all the time, even with foot off the go pedal it would be unlikely to be related to IP although I cannot say for certain. If it's present at idle then you may be able to isolate the sound to the culprit.

With situations like this it's very difficult to diagnose noises without being in the presence of the vehicle with the problem. Even with video one doesn't get the subtleties that you would with an in person observation / diagnosis.

Good luck

Steve A
 

Hinzipwo

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2001 Jetta TDI (auto)
the ticking could be your injectors, i'm not sure how to diagnose though

maybe do a vcds log of your injectors while doing a pull?
 

90hp_ALH

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May 9, 2021
Location
Portugal
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Audi A3 - 90 HP ALH
Did the screwdriverscope, didn't help pinpoint it. Added 75mg of additive to the ****en thing to see if it's just dirty, and it did help numb it down actually (first time one of these worked).
Is cleaning these things a hefty process? Thanks for the reply mate
 

Hinzipwo

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2001 Jetta TDI (auto)
well what you could do is a diesel purge and fuel filter change and see if that helps. cleans all the crud out of your injectors. there is countless videos on youtube showing this process. may be worth a try.
 

Mongler98

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IMO, until you diagnose it properly, the only $ you should be spending is on tools. VCDS and a vagcom cable for logging, an actual mechanics stethoscope (screwdriver trick is basically useless compared to that), and oil pressure gauge,
I see the reasoning behind the additive but honestly you're wasting money with little more than a guess as to what's going on. diagnose the issue.
then fix the issue. if its the injectors, go a hot swap with kerma after diagnosing them properly and ruling everything else out. only thing else that is typical to tap like that is lifters due to low oil pressure at higher revs..
 

90hp_ALH

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May 9, 2021
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Portugal
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Audi A3 - 90 HP ALH
IMO, until you diagnose it properly, the only $ you should be spending is on tools. VCDS and a vagcom cable for logging, an actual mechanics stethoscope (screwdriver trick is basically useless compared to that), and oil pressure gauge,
I see the reasoning behind the additive but honestly you're wasting money with little more than a guess as to what's going on. diagnose the issue.
then fix the issue. if its the injectors, go a hot swap with kerma after diagnosing them properly and ruling everything else out. only thing else that is typical to tap like that is lifters due to low oil pressure at higher revs..
Hey! Surprisingly, the additive REALLY helped, which I didnt expect at all. I still hear the tick, barely tho only when at max revs in 2nd gear.
I don't think it's the lifters for one reason only, when I take the foot of the gas it immediatly stops. Doesn't matter if i'm at 5k revs. If it was lifters it would've continued, right? I understand what you saying about spending money, I just had the additive laying around.
Don't have VCDS, probably will take it to a friendly mechanic tuesday. From your experience, could it be the injection pump?
 

90hp_ALH

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Portugal
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Audi A3 - 90 HP ALH
well what you could do is a diesel purge and fuel filter change and see if that helps. cleans all the crud out of your injectors. there is countless videos on youtube showing this process. may be worth a try.
Hello mate. Fuel filters were changed 3k km ago. Sorry whats diesel purge? When I search it on google all I see is additives.
 

Hinzipwo

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Hello mate. Fuel filters were changed 3k km ago. Sorry whats diesel purge? When I search it on google all I see is additives.
its by liquimolly, you basically run your engine off of this diesel purge and it basically cleans out your fuel system, especially your injectors. for more info refer to this https://mercedessource.com/problems...-purge-the-best-medicine-a-sick-diesel-engine they are doing it on a mercedes diesel but the concept still remains the same.

although Mongler is right, you should get a vcds scan and actually figure out whats going on, but in my opinion a diesel purge cant hurt.
 

90hp_ALH

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Portugal
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Audi A3 - 90 HP ALH
its by liquimolly, you basically run your engine off of this diesel purge and it basically cleans out your fuel system, especially your injectors. for more info refer to this https://mercedessource.com/problems...-purge-the-best-medicine-a-sick-diesel-engine they are doing it on a mercedes diesel but the concept still remains the same.

although Mongler is right, you should get a vcds scan and actually figure out whats going on, but in my opinion a diesel purge cant hurt.
That's exactly the additive I bought I think but I'm adding it to my fuel, as it says I can do on the instructions (250ml for 75l, added 1/4 of the bottle for 20l)
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
it could also be a tapping valve or valve float like ting with a very weak spring or broken spring.
Here is a good way to find out if its engine or fuel related...
go for a drive, accelerate and hold the pedal still, now at the same time press the brake pedal. on the mk3 and mk4 platform TDI's they all have a "Defuel" mode that will basically turn the cam arm on the IQ of the IP's QA back all the way to idle fuel quantity. If you have a fuel or injection issue that goes away from less fuel and NOT just reverse pressure from decelerations of the engine, this will show it.

my best is still on non fuel delivery relation.
typically a "tapping" injector does not last long if at all and the results is usually extreemly high EGT's and or melted or burnt pistons from the added fuel from a buggered tip. the tapping sound is ALWAYS from interference of metal parts and for it to be that loud from an injector?????????? yea your car would NOT be running.. as far as i know, same with the IP. and if you DO, you WILL see it on VCDS fuel logs on how much each injector is using.

If you insist it might be the IP (more likely) the tapping is from, scribe a line on the QA and the pump, take it off and inspect the cam and lobes of the head plate and the cam itself. make sure you follow the write up on the IP seal replacements for the QA to do so.

just by putting a fuel additive into your engine, you could have changed the cumbusiuton enough to smooth out any valve issues as well, but less likely.
What additive did you use?
 

90hp_ALH

Member
Joined
May 9, 2021
Location
Portugal
TDI
Audi A3 - 90 HP ALH
it could also be a tapping valve or valve float like ting with a very weak spring or broken spring.
Here is a good way to find out if its engine or fuel related...
go for a drive, accelerate and hold the pedal still, now at the same time press the brake pedal. on the mk3 and mk4 platform TDI's they all have a "Defuel" mode that will basically turn the cam arm on the IQ of the IP's QA back all the way to idle fuel quantity. If you have a fuel or injection issue that goes away from less fuel and NOT just reverse pressure from decelerations of the engine, this will show it.

my best is still on non fuel delivery relation.
typically a "tapping" injector does not last long if at all and the results is usually extreemly high EGT's and or melted or burnt pistons from the added fuel from a buggered tip. the tapping sound is ALWAYS from interference of metal parts and for it to be that loud from an injector?????????? yea your car would NOT be running.. as far as i know, same with the IP. and if you DO, you WILL see it on VCDS fuel logs on how much each injector is using.

If you insist it might be the IP (more likely) the tapping is from, scribe a line on the QA and the pump, take it off and inspect the cam and lobes of the head plate and the cam itself. make sure you follow the write up on the IP seal replacements for the QA to do so.

just by putting a fuel additive into your engine, you could have changed the cumbusiuton enough to smooth out any valve issues as well, but less likely.
What additive did you use?
Thank you for the response. Liqui Molly.
It's not a tapping, it's a small tick. Kinda like a chirp. Nowhere did I say it was a loud tap lmao, and nowhere did I say it was even loud. I literally can't hear it if I have my radio at 10/100 volume. 100% does not sound metalic parts coliding, and the reason I'm inclined towards fuel injection problem is because the sound IMMEDIATLY stops when you take the foot off the gas. Doesn't matter the RPMs. If it was valves, it would be RPM related, correct?
 

Hinzipwo

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Location
North Bay (ON)
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2001 Jetta TDI (auto)
That's exactly the additive I bought I think but I'm adding it to my fuel, as it says I can do on the instructions (250ml for 75l, added 1/4 of the bottle for 20l)
it works better when you do a proper diesel purge rather than just putting it into the fuel tank. search up diesel purge on YouTube and it will show you what i mean
 

Mongler98

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98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
OH... ok, thats different.
Noticed a few months back a tick on acceleration
Ticking is tapping to me, chirping or squealing.. that's a completely different box of frogs.
that does sound like a bad fuel spray pattern to me... i would definitely recommend you replace the fuel filter and fill it up with liquid molly diesel purge. DO NOT ever use fuel from anything other than a filtered source (2 micron filter) to fill a filter for use..
Or bypass the filter and run it in a closed loop with the return line.
 

90hp_ALH

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May 9, 2021
Location
Portugal
TDI
Audi A3 - 90 HP ALH
OH... ok, thats different.

Ticking is tapping to me, chirping or squealing.. that's a completely different box of frogs.
that does sound like a bad fuel spray pattern to me... i would definitely recommend you replace the fuel filter and fill it up with liquid molly diesel purge. DO NOT ever use fuel from anything other than a filtered source (2 micron filter) to fill a filter for use..
Or bypass the filter and run it in a closed loop with the return line.
Thank you! From what I've seen I need to disconnect the fuel lines and put them in a container with liquimolly, or can I just add it to the fuel filter as you've said?
This is the video I saw: How To Do The Liqui Moly Diesel Purge On a Volkswagen TDI - YouTube
Currently only used a bit mixed with fuel as I've said previously, but if it worked just that tiny bit (100% worked not placebo), maybe it'll be completely silent if I do a purge

EDIT: btw out of curiosity, why is this a big nono "Or bypass the filter and run it in a closed loop with the return line" saw a youtube video of someone doing it
 
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90hp_ALH

Member
Joined
May 9, 2021
Location
Portugal
TDI
Audi A3 - 90 HP ALH
it works better when you do a proper diesel purge rather than just putting it into the fuel tank. search up diesel purge on YouTube and it will show you what i mean
Thank you! See my response above for the video I've seen on how to do it, just to see if thats how you'd do it too. Ty again guys
 

Hinzipwo

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Thank you! See my response above for the video I've seen on how to do it, just to see if thats how you'd do it too. Ty again guys
100% correct, thats exactly how to do it. it may not solve your problem but it can never hurt, as long as you do it right ;)
 

Mongler98

Top Post Dawg
Joined
Mar 23, 2011
Location
Northern MD (HAGERBUSH)
TDI
98 Jetta TDI AHU 1.9L (944 TDI swap in progress)
Thank you! From what I've seen I need to disconnect the fuel lines and put them in a container with liquimolly, or can I just add it to the fuel filter as you've said?
This is the video I saw: How To Do The Liqui Moly Diesel Purge On a Volkswagen TDI - YouTube
Currently only used a bit mixed with fuel as I've said previously, but if it worked just that tiny bit (100% worked not placebo), maybe it'll be completely silent if I do a purge

EDIT: btw out of curiosity, why is this a big nono "Or bypass the filter and run it in a closed loop with the return line" saw a youtube video of someone doing it
When ever replacing the fuel filter, you should never use anything other than pure filtered fuel, nothing from a pump or a can. so using this diesel purge is ideal. Otherwise, if your just treating the nozzles, just do a closed loop, it's easier and les $$ and hassle.
hence the 2 ways to do it.
I always just a mityvac to prime a fuel pump though the IP return line though so ............
 
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