Help Troubleshooting Fuel Delivery...

Stealth TDI

Pre-Forum Veteran Member
Joined
Feb 13, 1998
Location
Newport News, VA
TDI
2017 GTI APR Stage 3 (395 hp/376 lb-ft)
Hi,

I offer the following points/observations:

1) While the hardware issues presented above seem plausible, I fail to understand how it can still be considered a possibility if the car drives almost perfectly with RC3 loaded into the automatic file location (S001). If hardware was the issue, I believe the car would ALWAYS have a problem.

2) You didn't get shudder during your test drive of my car because we were flogging it, testing for smoke, and taking VAG-COM plots. Ask Oliver what he thought of my shuddering. I'm not exaggerating when I say it's BAD. Hot-coffee drinkers beware! <joking> The intensity of the shudder is proportional to the amount of fueling delivered by the program (eg, RC2 is worse than UP2, RC3 is worse than RC2, RC3+ is worse than RC3...) or the size of the injector nozzles.

3) I hardly consider autocross as the type of "racing" that would require the pulling of the head from time to time. Quite frankly, a morning of VAG-COM logging is more stressful on the engine than 4-minutes of cumulative cone-dodging in a weekend, especially if you recognize that my foot is in the floor for only 20-30 seconds of all of that. If anything is being abused, it's the chassis, suspension, and wheels/hubs.

4) I agree with 'Meister in that I do not believe I'm laboring the engine. The shudder occurs when I'm NOT laboring the engine... light climbing, slow acceleration, or while pulling my 500-lb trailer.

5) I'm not sure if we're talking about the same "slow down shudder." Imagine nearly any ground speed at which one is driving below 2000-rpm. Yes, I know some prefer driving at 2800-rpm in third instead of 1800-rpm in fourth. But I'll cruise through neighborhoods at 1800-rpm before choosing to rev through quiet neighborhood. FWIW, I cruise at 1800; but not 1500. Anyway, my slow-down shudder isn't just about when coming to a stop. It happens through the normal, minor fluctuations of speed such driving at 1800-rpm, but minor grades or turns require lifting off the pedal a touch to maintain speed. I'm not talking about letting up all the way... I'm referring to letting up 1/8-inch. The engine doesn't necessarily shudder, as in the type to vibrate the car. Instead, it sounds like it's "missing" in these scenarios... perhaps TINY pulses felt in the car. If Aligator can fix this and maintain the highway manners, they've found GOLD.

Now that I know progress can be made via software, I'm just BARELY interested in blowing precious time and $$$ by pulling the head just to take a look. I have 570-psi on all four cylinders, Oliver ensured the injectors were balanced, and the IP and ECU are new. I haven't found a mechanic yet who thinks the head should come off knowing those things. The only other thing I can consider is the possibility that one or two of my intake ports have more caked soot than another (from pre-EGRectomy days). I'm not talking about a huge difference... perhaps 1/16-inch... just enough to see it. But that could be a bit of a stretch. HERE'S A PHOTO.

I tend to believe that OEM tuning may not be the best route in light throttle conditions since the injectors are not OEM. Perhaps Aligator has reduced fueling in light throttle conditions to compensate for the extra fuel flow. I'm not sure. I'd like to see some comments from DI and/or Aligator.

Take Care,

Scott
 
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jsrmonster

Veteran Member - TDIClub Enthusiast
Joined
Apr 22, 2002
Location
Red Lion, PA
TDI
15 Golf SW DSG, RC3 piped, 99.5 Jetta Rocket PD150 6spd 4motion, 2000 ASV110 RC6 "Silverbullet" 5spd Race Car, 2003.5 Cummins QCLB 4x4 "Blue Monster" Jeep CRD juiced, MB Sprinter van juiced up
[FONT=times new roman, new york, times, serif]Hi Scott,[/FONT]

[FONT=times new roman, new york, times, serif]I am still not convinced your problem is not hardware related. I work on these cars every day, and tune a bunch with very good success. You mention about RC3 in auto vs 5spd map blocks, I'm not sure the two map blocks are functioning exactly the same. See if you are getting the same fueling in both map blocks with vagcom. Drive along where the shudder occurs and vaglog 1, 4, and 11. for each at the same rpm, same road, and same mph. If you don't feel like logging data, we can meet and do this.[/FONT]

[FONT=times new roman, new york, times, serif]I will be glad to sit down and show you a side-by-side comparison between the two tunings. The shudder you mention spilling coffee is not the tuning, it is just being multiplied somehow by the tuning. I would also like to investigate your maf sensor, throttle pedal, and look at field 013 during shudder. [/FONT]

[FONT=times new roman, new york, times, serif]I hear everything you say about replacing hardware, etc, but you could easily have replaced bad hardware with more bad hardware. You've never had the head off the car correct? A bad valve guide and/or seal could leak boost into the crankcase on one cylinder making that cylinder run rich during part throttle, but not show up at full throttle, cuz the volume is so much greater than the bleed off. Is your motor using any oil? The oil level shouldn't change over 10000 miles. Diesels actual add some fuel to the oil thru blowby over time making up small amout of oil lost to scavenging. Obviously leaks and oem ccv hockey puck will consume oil too, but worn valve guides or bad seals will increase oil consumption.[/FONT]

[FONT=times new roman, new york, times, serif]btw, I didn't understand your type of competetion doesn't require full power acceleration and high duty cycle performance. I guess you are doing parking lots and manuvering cones on a timed course. That weekend sport seems very popular in md as I recall living in columbia. Road courses like summit point and are much more demanding on the engine/drivetrain, imho. I can easily install a hard switchable dual chip too if you like, so you can switch between 2 tunings on the fly. Also with vagswitchable, it allows a total of 4 tunings to be run in one ecu. I don't normally provide this to the masses, but off road and racing applications are no problem.[/FONT]

[FONT=times new roman, new york, times, serif]Jeff[/FONT]
 

Aligator

Registered Vendor , w/Business number
Joined
Apr 19, 2003
Location
Poland
TDI
AGR, AVF, AMF, BLB
Based on my experience the part-load shudder is caused by quantity adjuster voltage imbalance. The imbalance may appear on both sides - adjuster and the ECU.

The adjuster imbalance occurs when the adjuster is dirty and at a constant delivered IQ the voltage indicated by adjuster fluctuates. The ECU regulate IQ and this causes shudder. It most cases it can be cured by quantity adjuster cleaning. More info here (unfortunatelly in Polish) http://forum.tdi-tuning.pl/viewtopic.php?t=1741
This is the primary reason for slow-down shudder. I've seen many suddering 1Z/AHU running stock software that were 100% cured after cleaning the adjuster.

On the ECU side the shudder may be caused by the way ECU controlls idle (slow down shudder) and maps controlling quantity adjuster voltage. Auto coding shudders less or does not shudder at all because of a different way of controlling idle. The A3 ecu does not have as good A/D converters and it does not read quantity adjuster voltage as good as A4 ECUs. Therefore if voltage maps in the ECU are modified in a wrong way the engine will shudder at light throttle.

IMO Stealth should clean the adjuster first and then fine tune the ECU maps.

Other things like a slow spoolup can be fine tuned by remapping.
 
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greenskeeper

Top Post Dawg
Joined
Mar 10, 2003
Location
USA
TDI
1998 Jetta TDI
If someone could tranlate that page it would be helpful.

I'll admit my IQ and voltage varies a surpising amount at a steady idle.

However Aligator cured the light throttle shudder that my RC3 had.
 

Stealth TDI

Pre-Forum Veteran Member
Joined
Feb 13, 1998
Location
Newport News, VA
TDI
2017 GTI APR Stage 3 (395 hp/376 lb-ft)
Jeff (and all),

I appreciate your patience. I hope I do not appear antagonistic. As stated to someone else, this isn't a chip war for me. It's a search for answers, gaining the insight of several veterans. Please understand that if I type anything that insults your TDI expertise. My writing style is direct and can come off as offensive. However, it is not my intent. You've seen my demeanor and know I can speak with a smile even when I am frustrated. :)

Although I haven't done much logging in the past few days, I have played with the car a bit. But, first, let me address Aligator's comment - I do not suspect the quanity adjuster. The IP has less than 10,000-miles on it. It is remanufactured by Bosch. Please read further for why I still lean toward programming over the IP.

I was able to meet up with "A3TDI" today. He, some other forum members, and I are going to meet at Maryland International Raceway for some drag racing fun tomorrow. His car is equipped nearly identically to mine with the exception of programming and the fact it has 90,000-miles less on the odometer. It's even the same color and still has 14" wheels. :cool: This was a rare opportunity for me to swap ECUs with a similar platform to compare the difference.

First, I recoded my ECU to RC3-002 so he could experience my shudder. I think he was surprised although it wasn't as bad as I had experienced at higher speeds. Next, we swapped entire ECUs and went for a drive in HIS car with RC3-002. NO SHUDDER! Well, there was just a touch on one hill... but there was definitely a change and the miniscule amount of shudder was acceptable. We talked about the possibility of chasing an issue in the head. However, I likely wouldn't chase it. Instead, I'd swap in a rebuilt head to get fresh valves/springs and rid myself of soot deposits.

Next, we drove my car with his Aligator ECU. Again, NO SHUDDER. I cannot recall if there was just a tiny bit on the same hill as RC3. But it was definitely a good drive. Even better, this program eliminates the "slow speed" shudder apparent in the other Aligator program I'm testing.

Now that I've driven another TDI similar to mine, I have more observations. Boost response with Aligator is not as slow as I suspected. It is apparent my Isspro boost gauge has a smaller restrictor in it than A3TDI's VDO gauge. I used to use VDO. So I've suspected my new Isspro gauge behaves differently since the day I installed it. In fact, it doesn't show spikes the same way Joe's VDO gauge does. I'm not inclined to make a switch. But at least I know I have a slow gauge.

My next observation could be important. I discovered one difference between our cars: I have an Autotech 10-lb flywheel and his is stock. I am certain I've read over the years that flywheels are designed to dampen oscillations. I've read a few reports about "drivability issues" with lightweight flywheels, including a report from "Clay," one of TDIClub's A3 tuning pioneers. In fact, I decided to search for his report as I typed this message. Check this out:

Clay said:
...I did have a lightened flywheel in my TDi until yesterday. I was using the Centerforce clutch kit which requires some machine work on the flywheel. Since that needed to be done I had it lightened at the same time too. Since then, the car had a very bad shuddering problem at a particular engine load & RPM. I got really tired of this so I replaced it with a stock one & a new Sachs sport clutch which corrected the shuddering problem... <snip> ...the engine load that my shuddering occured at was 10-12 psi boost & around 2000 RPM but it could occur at much higher rpm under the *right* load. The shuddering started as soon as the lightened flywheel was installed, and stop as soon as a stock one replaced it.
This is EXACTLY how my shudder can be described! His flywheel was "lightened" to 18-lbs at a machine shop. I suppose his problem could have been a result of poor machining. But this idea and his post is perhaps my most promising discovery. Is it possible that THIS is the hardware issue that is exacerbated by software variations? I imagine it's a lot less-expensive of an experiment to have my stock flywheel resurfaced and pay someone to swap it for me than it would be to check or replace the head.

In closing, I'll say today's test drives support the possibity of a minor hardware issue that responds differently between one program and another. I will check out a potential issue with the flywheel. But, if I have a problem in the head, I'm inclined to run with what I have until it's time for another timing belt. RC3-001 is working fine and I can chase this particular hardware issue later. I wonder how annoying it would be to replace the flywheel and head; and still have a shudder? :eek: ;)

Take Care,

Scott
 

paramedick

TDIClub Enthusiast, Vendor
Joined
Jul 29, 2001
Location
Versailles, Kentucky
TDI
2015 Audi Q5 TDI
As the former owner of Clay's A3 TDI, I have heard his mechanic speak of the lightened flywheel. He won't install them anymore because of that experience.

Sounds like you"re on the right track. I do know that there was never an issue with the stock flywheel/Sachs sport clutch. GOK, I abused it while I had the car. I tried EVERY chip/nozzle combo (except race nozzles) during my exploration phase.
 

Stealth TDI

Pre-Forum Veteran Member
Joined
Feb 13, 1998
Location
Newport News, VA
TDI
2017 GTI APR Stage 3 (395 hp/376 lb-ft)
Okay,

The more I analyze this, the more sense it makes. Check out my "mod history" and the story falls together:

Date ......... Odometer
02/02/01 ... 101988 ... Replaced Muffler w/Straightpipe
03/03/01 ... 105110 ... Upsolute Chip Installed

The two items above are irrelevent to my problem. They just give the history. I was pretty happy with the car and had zero problems at this point.

10/25/02 ... 139760 ... Replaced Fuel Injectors w/.205s

This was slightly before Charlie was making his PP nozzles widely available. At this point, I had a mild shudder at 70-mph. This was HIGHLY regarded as normal at the time. The standard practice was to adjust IQ to a "higher" value via hammer-mod.

11/16/02 ... 140861 ... Mechanically Set IQ to 5mg/l

The IP was "hammered" to 5-mg, then the IQ was further adjusted to 7.5-mg via VAG-COM adaptation. Sometime in June 2003 as I traveled across the country to a new duty station, flawlessly towing a 1000-lb trailer, Upsolute provided a "Stage II" chip that was "optimized" for B205 injectors. The fact was the programming only dialed back the fueling to reduce smoke.... and power. :(

03/28/04 ... 162222 ... Installed Sachs VR6 Clutch and Autotech Flywheel

I suspect I did not detect a problem due to the mild UP2 programming and smaller B205 nozzles.

08/01/04 ... 168680 ... Installed Upsolute Stage III kit
04/11/05 ... 178752 ... Installed PP520s

Did not detect a shudder on the highway since the car was usually in "limp mode." :mad:

04/23/05 ... 180537 ... Removed Stage III Kit, Returned to Stock Turbo and RC2

THIS was when the shudder immediately surfaced, but only under certain conditions. Other than the shudder, the car was operating properly for the first time since having the LW flywheel AND heavy fueling mods at the same time. I am confident this problem may go away with a stock flywheel. :)

MY NEW QUESTION: Obviously, the clutch will be fully-exposed in order to remove the LW flywheel. Although the clutch has performed flawlessly for 65,000-miles, should I replace it while I'm there? Someone in another discussion board said, "It sure would suck if it's the CLUTCH that's causing all of this headache." I do not suspect the clutch. But it seems reasonable, if not at least convenient, to replace the clutch since the labor is already in progress. For the record, my clutch is a VR6 clutch by Sachs, purchased from Dieselgeek.

Thoughts?

Thanks!

Scott
 

mojogoes

Top Post Dawg
Joined
May 1, 2003
Location
england
TDI
mk3 tdi golf
Stealth TDI said:
Hi,

Thanks for your input. The injectors were checked last Fall. However, I feel I've ruled out the injectors by borrowing a set from Paramedick. They had about 3000-miles on them. Driving characteristics of the shudder are described in the OP.

I am open to trying out another program. But I'll not hold my breath for miracles. The car is operating far outside its intended purpose. So I accept that I may be doomed to drive on the automatic maps. Should I sell the car some day, I am extremely certain that returning the car to RC2 or less with smaller injectors will nearly eliminate the problem. Even with RC3 and B184s, the shudder is how TDIMeister describes: "a threshold of noticeability." Those who've owned A3s understand that behavior is almost normal... especially at 1600-rpm.

Charlie - Thanks for the package, an unsolicited act of support. I look forward to seeing it (I'm assuming it's a program and not another set of nozzles... either is okay with me ;) ). Just to let you know, I only go to Newport News on the weekends. If I don't see the package tomorrow, then I will not be able to report results for about 10-days.

Thanks Again, Everyone!

Scott

I'm at this same shuddering state because i've changed the ip 1 / 2 the turbo and 3 the nozzles again so i expect to get this until its remapped , but it will not smoke at when done.....something like first stage programing at most.

P.S.........have you asked Aligator to do you a map , just send him your logs.
 
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greenskeeper

Top Post Dawg
Joined
Mar 10, 2003
Location
USA
TDI
1998 Jetta TDI
I thought about the flywheel/clutch causing the shudder before Aligator cleared it up compared to RC3. Nothing against RC3 but that's what happened with my car.

HOWEVER, when I had RC3, the shuddering was not consistent. It could go all day without any shudder and then the next day do it everytime like clockwork at 50mph/1500rpms. Heck it would even not do it, downshift to 4th, shift back into 5th and get the shudder. Which to me sounds like it could be a flywheel/clutch problem depending on how the clutch "lined up" with the flywheel when it grabbed...that "contact" changes everytime you shift.

Maybe RC3 is just more "sensitive" to flywheel/clutch vibrations or the extra torque that RC3 puts out at low rpms when compared to Aligator is making the shudder in the flywheel/clutch.

RC3 definately has more torque at low rpm, at least with my experience in my car.
 

Stealth TDI

Pre-Forum Veteran Member
Joined
Feb 13, 1998
Location
Newport News, VA
TDI
2017 GTI APR Stage 3 (395 hp/376 lb-ft)
Well,

My shuddering is consistent. It doesn't matter when I engage the clutch, the phase of the moon, or anything else. ;) I'm still researching the whole clutch/flywheel decision. For me, it represents a lot of work, time, and $$$ (especially since I need to pay someone to do it for me), not to mention the fact I'd have to surrender half or all of a weekend with my family (I work near Washington DC during the week and drive home to the family on the weekends). Convenience-wise, it makes more sense to fix this via programming (either RC3-001 or Alligator) and replace the clutch/flywheel when I really need to.

I thought about the flywheel/clutch causing the shudder before Aligator cleared it up compared to RC3. Nothing against RC3 but that's what happened with my car.
I, too, have pondered this issue. If the flywheel is 100% responsible for the problem, then why did Joe's Alligator ECU run well in my car? Why do these flywheels work in other TDIs? If the programming is the issue, then why did my RC3 ECU run well in Joe's car? Does the software amplify the flywheel problem or does the flywheel amplify the software problem? It's the whole "chicken vs. the egg" scenario. :rolleyes:

I have not yet sent VAG-COM logs to Alligator. His method of testing requires me to log in an area where it is safe for me to drive 25-mph as well as 70-mph. I cannot do that around DC. I expect to be able to log plenty of data this weekend when I return to SE VA. I have a few I-64 entrance ramps that'll allow me to start 3rd gear runs at 25-mph and blast all the way to 65-mph or so.

BTW, last weekend's AHU DRAG EVENT illustrates little difference between my RC3 car and Joe's Alligator car. Check the thread for our times. They're VERY close. The small difference could be provided by a combination of my Ford intake, LW flywheel, and one-inch lower stance. In the arena of speed, the "chip shootout" appears to be a draw. :cool:

Take Care,

Scott
 

Ballina

Well-known member
Joined
Dec 25, 2005
TDI
99 Passat TDI Wagon
99 AHU Passat 90hp 90,000 mls.I have this shuddering problem too.It occurs mainly between 1800 and 2000 rpm.Main ECU is Upsolute chipped, got this remapped but no cure. Bought second stock ECU and still no cure. Funny thing is , this shuddering now appears to come and go.Im wondering if it could be related to the outside Temp or even the fuel Temp.New MAF.Timing within range.IQ of 4mg.Im at a complete loss to understand the cause. No DTCs. Its ruining the driving pleasure. Is there any cleaner that can be run throught the pump to clean the Quantity Adjuster without dismantling the pump?
 
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Stealth TDI

Pre-Forum Veteran Member
Joined
Feb 13, 1998
Location
Newport News, VA
TDI
2017 GTI APR Stage 3 (395 hp/376 lb-ft)
I'M CURED!!!

I finally made it to someone's place for a clutch/flywheel swap out. Thanks to Mark, aka "AHU TDI", for doing the work. I managed to take some photos of the work and the two flywheels (FW) side-by-side. To be honest, I really thought Autotech FW was just made of a lighter material. Instead, it looks like it was simply lightened by machining. I didn't recognize this when I purchased the FW since I didn't know what the stock one looked like. By the time I had the stock one in hand, I didn't remember what the Autotech looked like. I never saw them side-by-side since I dropped the car off for the servicing. But here's the difference:





The amount of meat removed is amazing. I'm not sure if the shuddering was caused by a huge lack of dampening from the lighter weight or if the FW is misbalanced. But, given the amount of hassle, time, money, and aggravation spent on this thing, I'll never mess with an aftermarket FW again. I have tested the car at a variety of cruising speeds/RPMs between 45-80 mph, with and without the trailer (additional loading). All is well. I'm even on my five-speed maps again.

I want to thank Jeff/Rocketchip for his ongoing assistance and PATIENCE, Joe/"AThreeTDI" for bringing his equally-equipped car down for some comparison testing (this is what led me to consider the possibility of a FW issue), Mark/"AHU TDI" for doing the work, Bruce/"Paramedick" for the use of some spare injectors, and everyone else who has contributed to my efforts.

Now I just need to get to the root of a timing issue. But that's another topic. ;)

Scott

PS: Here are more photos of the clutch/FW install if you're interested:













 

jsrmonster

Veteran Member - TDIClub Enthusiast
Joined
Apr 22, 2002
Location
Red Lion, PA
TDI
15 Golf SW DSG, RC3 piped, 99.5 Jetta Rocket PD150 6spd 4motion, 2000 ASV110 RC6 "Silverbullet" 5spd Race Car, 2003.5 Cummins QCLB 4x4 "Blue Monster" Jeep CRD juiced, MB Sprinter van juiced up
Hi Scott,

Glad to hear your shudder problems are solved. btw, I dyno'd my boys 98-A3 last week, RC4 10mm, pp520, vnt17 (22psi) oem exhaust. We went to Extreme motorsports in Ft Meade (same as last balto dyno day gtg) and got 124hp/259hp. It was 96deg too, so we got quite a bit of smoke. Tim is happy with the car but wants more now.

Let me know when you are ready for RC5.
Jeff :)
 

Stealth TDI

Pre-Forum Veteran Member
Joined
Feb 13, 1998
Location
Newport News, VA
TDI
2017 GTI APR Stage 3 (395 hp/376 lb-ft)
Jeff,

jsrmonster said:
Glad to hear your shudder problems are solved. btw, I dyno'd my boys 98-A3 last week... got 124hp/259hp.
Thanks for the note. I'd love to see the dyno printout. Although your numbers are very similar to mine (I got 122-whp and 258-lb/ft on a chilly day), I'll bet you have more area under the curve.

Scott
 
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