Injectors Enigma

YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
Hi Everyone,

I drive a 2014 MK7 Golf (with R body) with CLHA engine (1.6 TDI 105hp) modded to 215hp and 420nm on roller test bench. I really like this car and the drivability is amazing, all the mods are well supported and the car gives power and torque from low RPM to high RPM. The car is fuel efficient (4.5L/100kms to 6.5L/100kms).

But from my last mod (207hp-->215hp with almost no smoke, finally ! ) I'm experiencing injectors knocking and I will need your help to find the bad injector(s) to replace.

First, that's the mods :

- Original turbo (GTD1244vz) has been replaced with the MK7 GTD's Turbo (GTD1449vz)(max press. 1.8bars)
- DPF and Catalyst and EGR has been removed (complete downpipe, original rear muffler still here)
- Oil Catch Can
- BMC Carbon Intake
- Original Injectors (04L 130 277 G - Bosch system) has been replaced with the MK7 GTD's Injectors (04L 130 277 AE - Bosch system) (the purpose in this was not to get more power but to reduce diesel smoke thanks to bigger nozzle and pressure increase, we can shorten injection duration and so reduce smoke).

The last mod is the why I'm coming on this forum.

During Injectors replacement, all seals has been replaced and correctly inserted. All things has been cleaned before inserting injectors.

Injectors has been adapted with their respective IMA-ISA codes using VCDS and all went well.

After replacing injectors with the GTD's ones, the ECU has been remapped by my Tuner (the same who follows and tunes my car since always.

The problem is :

- When engine cold, I hear a really loud knocking and I can feel a lack of power on low RPM. Everything is fine after 1800-2000rpms. Noise appears on middle and full throttle. Never on idle.

- When engine warm (coolant 90 to 100 °C and oil 95 to 110 °c) it disappears but still appears sometimes for few minutes. Always on low RPM and only when full throttle. Never on idle.

- Engine cold start makes a knocking injection noise on the first RPM then it idles normally.

- Cold start AND warm start sends a tiny white-grey smoke at exhaust pipe (see video down this message)

- Sometimes, I can hear the knocking noise when the car is downhill with no injection (for example engine brake on 3rd gear) but the noise is way quieter and you really need to listen carefully. It's not systematic.

On EDC17 and Bosch injection system there is no Basic setting of injectors (only the IMA-ISA codes but that's OK) so I decided to investigate and I have some doubts on injector 2.

1/ I ran a VCDS log session of injectors deviations on idle on cold start and warm start. Nothing looks suspicious to me.

Cold start :


Warm engine :


2/ I then ran physical test of injectors deviation. On idle and warm engine only. (maybe do you have suggestions ?).
All bottles got filled to exact same level (Test duration : 5 mins)




3/ I decided to take the VCDS on road and perform a test under load :
I drove to a big hill, started 1st gear then 2nd gear and finally engaged 3rd gear on a really low RPM ( 1100 rpms) and full throttle. That was the only way I found to force my engine to send maximum fuel possible. The car really slowly took RPMs and I've been able to see injector 2 with big and positive numbers.



4/ Took originals injectors back to double check... and all noises went back to normal (after IMA-ISA adaptation). But the car is laggy as this injection map is not adapted for such little nozzles.

I then put back the big injectors (and IMA-ISA), and the noises are back...



What are your thoughts please ? I have ordered a new injector and it's on his way, but I don't know which one should I remove to put the new one in.

Why is it impossible to get a concluant test on idle ? What is this strange noise I can hear on downhill on engine brake with no injection ? (it disappears with the original injectors)
I don't understand the - and + values. What does it mean ?

Can I rely on my step 3 ? As I never saw this method mentioned in any forum...

Thanks a lot for you future replies !

The video of cold startup with the little smoke :

 
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Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2015 Sportwagen; Golf GLS 2002 (swap from 2L gas); 2016 A3 e-tron
Way outside my area of expertise, but I'd like to welcome you as our first (I'm guessing) member from Reunion Island!!
(I had to look up where it was.)

 

YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
Thanks ! Haha You've got an amazing forum. Sorry if my English is not always perfect as I'm French. Will do my maximum :)
 

YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
I will try an other physical test of injectors deviation this day but this time with a cold engine on first start of the day.

Will let you know.
 

YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
Ran a physical test of injectors deviation this monring on a cold engine.

I'm almost sure the problem is on the injector number 2 and only this one. I was about to order an other one in doubt but I will let the order like this with just one new injector and will replace the number 2.

Then I will tell if the noise is gone or not...

I add you a video and a screenshot where you can see :

- The very light black smoke (on cold statup engine, probably the map being "rich" to warm up engine ?)
- You can hear the rattle noise at the very beginning of the video
- You can see the deviation numbers on VCDS showing number 2 is really in "positive" value
- You can see there is no difference level in bottles at the end of the test... :(




 
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tdi_my live

Veteran Member
Joined
Jul 24, 2011
Location
Germany
TDI
Skoda Fabia
Has the tuner taken over everything relevant from the GTD INJECTORS in your file?
SOI, injection time and rail pressure
 

YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
I know he had to adjust many parameters when I fitted the GTD injectors because the car was going into limp mode, smoking a loot and was doing combustion noises but I couldn't tell you what did he change exactly, I rely on him.. he must know his job.

Limp mode was coming with fault code "fuel pressure too low". (My opinion is that the fuel pump was not able to give in the same time 1/ long injection duration + 2/keep high pressure on such larger nozzles than expected in the mapping, am I right ?)

As soon my tuner modified the map to take benefits of GTD injectors, the car stopped smoking and pushed well (no limp mode anymore). Combustions noises have been drastically reduced. No loss of power, and I can tell I noticed a light torque improvement in low rpm and a noticeable power gain in high rpm (with much less smoke than before with the originals injectors :love::love: thanks to reduced injection duration compensated by larger holes injecting more fuel in less time, right ?)

All these good points tend to make me believe my tuner achieved a good job.

My questioning concerns this fuc***g rattle combustion noise I can hear on engine cold startup and during engine warm-up under full throttle and low rpm. I feel like I'm driving a tractor ! I tried many additives and noticed a better noise but still not normal to me and what I was used before.

There is also this little white-grey smoke on idle when cold and/or accelerating on warm engine.


I expected to get more participations of guys on here but there is not so much talk haha !

Has the tuner taken over everything relevant from the GTD INJECTORS in your file?
SOI, injection time and rail pressure
Thanks a lot for your message. I think all I can do for now is to wait to get this new injector and replace the injector n2... Then I will see. If it doesn't change I'll consider a 2nd injector (maybe the 4th or 3rd... I would make some other tests...).

Then I will consider ask my tuner to have a closer look.

Thx again for reading and do not hesitate to participate guys !
 

adjat84th

Veteran Member
Joined
Dec 13, 2008
Location
Virginia Beach, VA
TDI
'01 Jetta TDI/'15 Golf TDI
Are these brand new injectors or used? If used, did you have them tested?
The below is from my CRUA manual which has the 'AC' injectors, not the 'AE' ones from the GTD which are certainly different in flow rates and power capability. Also, your car is not stock or the same displacement size, so take the below with a grain of salt...you're in somewhat uncharted territory!

Per the CRUA manual checking quantity of fuel at the main return line (goes back to the filter, so includes fuel from all 4 injectors which for you seems consistent across all 4 injectors per your testing):
Start the engine and let it idle for two minutes.
• Specified value in two minutes: 0 ml to 50 ml (0 to 1.69 oz) - again this is total returning fuel from all 4 injectors
– If the specified value is reached, increase the engine RPM
from 2000 to 2500 for approximately two minutes.
– Then check the return quantity again.
• Specified value in 2 minutes: less than 250 ml (8.45 oz)
If the specified value is exceeded, this means one or more injectors
are faulty. Check the return quantity of each injector.

Based on the first test above at idle for 2 minutes and comparing to your 5 minute test would equate to 125ml (4.23oz) as your maximum allowed return amount. So if you had over an ounce of fuel in each of those containers in your pictures, it could mean that all 4 are tired.
 
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YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
Injectors are used units but I skipped the testing step.... maybe that was a mistake. Injectors are only 12 600kms old.

Tommorow I’ll do the return test you asked me to. I will then tell you more about it.

Anyway today I had an other VCDS log and the values completely changed...
The engine doesn’t knock anymore on first RPMs at the first start of the day.
It doesn’t knock anymore on cold engine with low and middle throttle (only if full throttle).
Knock sometimes even when warm and hot engine....

VCDS still indicates normal values on idle but now indicates injector 1 out of specifications. Test conditions are the same : warm engine, a hill, 3rd gear, 1000rpms and full throttle.



The more it goes the most I feel lost. I’m thinking about getting all injectors off again and change seals... clean all perfectly again etc... Anyway will have to do it when I get the new injector, but I still don’t know which one to remove :(
 
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adjat84th

Veteran Member
Joined
Dec 13, 2008
Location
Virginia Beach, VA
TDI
'01 Jetta TDI/'15 Golf TDI
Just keep in mind, the "specified value" in my post above is for the 2.0 CRUA. I would see what the service manual states for your particular engine, and ask your tuner if the IQ at idle is still same as stock in order to perform an accurate test.
 

YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
I ran the test of the main return lines on cold engine. Returned 30ml of fuel (test duration exactly 2 mins as asked). Looks like all is ok this side ??

I got injectors removed for cleaning and injectors were having white and blacks marks on the nozzles... never seen it before, don't know what it means. But they come back really clean. I swapped injector 1 and 2, and will see what VCDS says on next test.

Cleaned them and installed them back. For the moment I didn't drive so I can't tell you if anything changed. But engine started immediately with no smoke.

Tu be continued...

Fuel return qtity after 2 minutes idling on cold start :








 

YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
Ok first time I drove the car so smoothly since the injectors upgrade.

I think my cleaning operation of yesterday got things better.

Cold startup didn't make any hard noise of knocking. There were no grey/black on cold idle like before and absolutely no knocking noises on road during cold engine. But still some black smokes on moderate accelerations. These smokes disappear when engine warm... I bet the ecu cold map is too rich isn't it ??

I then had few knocking noises on warm engine and full throttle but didn't last a lot. I think this is some symptoms of thus stupid injector being faulty.
I drove in city and narrow streets ---> the engine is much much quieter than before. Even if I put full throttle on 2nd or 3rd gear I get a smooth noise and no rattle anymore.

Also remember I have swapped Injector 1 with injector 2. And now VCDS show me cylinder 1 balances well but cylinder 2 is now out of specs.
I do not have rattle noise anymore but I still can hear a very light rattle noise downhill on engine brake with no injection... Does this noise can come from the faulty injector ?

SO.... I BET I CAN RELY ON MY TEST TO TELL THE INJECTOR 1 (originally the 2nd) IS THE FAULTY ?
We can also put aside the suspicions of defective cylinder and compression?


I'll receive the new one by postal services soon. Will replace the number one with the new one. I'll tell you how it goes then !


 

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
Explain what I feel is physically wrong with your nozzles. I explain what I feel is physically wrong with your nozzles.

Picture #34 shows a nozzle that is possibly overheated/ overfueled and may have nozzle damage. Also note, seal has cut that nearly bisects the seal surface.

Picture #27 is also interesting, as there is a cut into the nozzle just below the copper seal. I don't think it's affecting the operation of the nozzle at this time. What is remarkable is, in all of the injectors I have seen, I have not seen this kind of damage.

On your graph, the # 2 injector is out of range. Is that also the injector in picture #34? That would make sense.

Used injectors can be polished, but shiny does not make them new.
 
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YanCT

Active member
Joined
May 7, 2021
Location
Reunion Island
TDI
1.6 TDI - 207hp - 420nm
Thx for this message. @Franko6

Picture 34 effectively shows burnt marks that I never seen before too.... But the nozzle is not properly burnt or affected as I got them all perfectly clean as new with some laquer thiner use (5 mins each) as shown on picture 47.

Picture 27 is just a little black mark of carbon deposit. I had a closer look too when it was in my hand and it went off by cleaning it. No worries.

I don't know if these white marks are due to some additives uses or too high temp ?

Anyway I won't investigate more as I'm waiting for the injector replacement. Then I'll see.


I noticed my engine fan is more often activated than before and particularly when I get home after engine off... I alway respect cooling time before switching it off. That's since I made the I injector upgrade and tune adaptation.

My tuner said he will Kindly have a look and make necessary to adjust things but he is asking me to replace my bad injector before.
 
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Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
Injector in picture 34, is that the same injector that was removed from the #2 cylinder? That sure seems to be the issue.

I don't recommend people buy somebody else's 'problem', when they buy used injectors. It's not universally true, but it happens so often, I don't think it's worth the risk. You have to ask yourself, "Why is the previous owner selling?" 'Because they upgraded' is not a good answer. They might be upgrading from worn out injectors, just like I believe is what happened in your case.

Rebuilt or new common rail injectors are not that expensive. Especially when compared to installing an over-fueling, used nozzle that could be melting a piston.

The fact there is a lot of carbon on the suspect nozzle and there is some white accumulation is not normal. That is indication of problems. Each nozzle's appearance should be equal. There should never be a build up like picture #34.

We have talked before, I believe. It was over some Sun Pistons, which although the claim was 'Korean' or Taiwanese, I never used any of that brand. I have seen some negative information, as in all I have to hear is, 'Sold by Hans Auto' and that's enough for me.

" The Bitterness of Poor Quality Remains Long After the Sweetness of Low Price is Forgotten"... Benjamin Franklin
 
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