Shuddering at low rpm and cruising.

Mk2Tyler

Active member
Joined
Jul 31, 2023
Location
Richmond, VA
TDI
B4 passat
Hey y'all, I'm experiencing this shuddering issue. I've come across entire threads with many other people with the same problem. 1z cars in the VW and Audi community. But in all my reading it seems no one has posted a concrete solution. Maybe I haven't read enough or dug deep enough. But all the threads just seem to fall off with no closure. So here I am to resurrect the topic.

Fellow shudderers, sound off!
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Los Angeles
TDI
1997 Jetta TDI (1Z)
Shuddering at low RPM is usually caused by some combination of the IQ being a little bit off and the nature of a diesel operating at low RPM. It's not a gasoline engine.

Your tune, clutch, flywheel, accessories running and injector nozzle choices will all factor into how the engine runs. Is it a stock engine? And are you talking about the engine shuddering while letting the clutch out or just generally shuddering in low-RPM scenarios?
 

JordanTr

Veteran Member
Joined
Mar 28, 2022
Location
Kimberley, BC
TDI
1996 B4V x2, 2006 Dmax, 2005 Allroad, 2005 BHW
I recently pulled the RC3 chip and put a stock ECU back in. 0.205 injectors are still installed. The car definitely seems to have more torque at low rpms than with the rc3 tune and no shuddering in the 1600-1900 range. Burpod could probably chime in but it’s likely some mishmash as stated above. It makes sense to me that there’s too much advance and that’s what causes the shudder. For now, I’m enjoying saving the clutch and no more shudders.

Calling @burpod for an opinion.
 

HardToHandle

Well-known member
Joined
Aug 31, 2021
Location
Washington State
TDI
1996 Passat wagon 1z
I had the same issue with my car, what fixed mine was changing the timing adaptation on channel 4 from 33000 back to the default 32768

Now it happily cruises at 60+ in 5th gear
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
With the injector balance as bad as it was and actual timing in the pump acting jumpy like it was as well, that's surely he ciae of the shudder
 

Mk2Tyler

Active member
Joined
Jul 31, 2023
Location
Richmond, VA
TDI
B4 passat
Shuddering at low RPM is usually caused by some combination of the IQ being a little bit off and the nature of a diesel operating at low RPM. It's not a gasoline engine.

Your tune, clutch, flywheel, accessories running and injector nozzle choices will all factor into how the engine runs. Is it a stock engine? And are you talking about the engine shuddering while letting the clutch out or just generally shuddering in low-RPM scenarios?
Hey y'all, I probably should have been clearer. I've spent hours reading threads where all these people with the same problem have tried EVERYTHING and found no solution. Reports from people with stock stuff and modded stuff. Timing, nozzles, tune, IQ, etc. Nothing cures it. The closest I've found which is really only a bandaid, is cutting the vss signal to the ECU. But it also kills the anti surge programs. This was on an Audi 80 thread for 1z Audi 80s' but I've seen VW guys describing the same shudder. So, saying all this. I've got a tune in the computer from burpod. I've tried just about everything under the sun already. Haven't tried unplugging the vss yet. But it seems to be caused by an electrical issue according to the Audi guys. Dealers apparently have no clue and neither does anyone else.

I'll have to see what Jarod says about the injectors.
 

burpod

teh stallionz!!1
Joined
Nov 27, 2004
Location
cape cod, ma
TDI
82 rabbit vnt ahu, 98 jetta vnt ahu, 05 parts car, 88 scirocco.. :/
unplugging the VSS shouldn't really work (or if it does, that signals something else is wrong). but i have seen firsthand if VSS is NOT working, you can get studder/shudder down low rpm. the ecu does care about what speed the car's going as it does various calculations for things. i suspect it has to do with the ecu trying to compensate for injector differences in the <1600rpm areas
 

HardToHandle

Well-known member
Joined
Aug 31, 2021
Location
Washington State
TDI
1996 Passat wagon 1z
Another thing I've seen mentioned is the IP istelf is going bad, or rather the quantity adjuster causing this @TDIMeister mention it in post #8 of this thread

Might also be worth checking the pressure relief valve in the pump to see if the bottom of it is pushed out
 

Mrmolasses

Well-known member
Joined
Jul 18, 2023
Location
Pa
TDI
None
Hey y'all, I'm experiencing this shuddering issue. I've come across entire threads with many other people with the same problem. 1z cars in the VW and Audi community. But in all my reading it seems no one has posted a concrete solution. Maybe I haven't read enough or dug deep enough. But all the threads just seem to fall off with no closure. So here I am to resurrect the topic.

Fellow shudderers, sound off!
Same problem with my b4. New pump and injectors no difference from old ones. The cutting out reminds me of how the brake pedal cuts out the throttle. Im thinking ecu fault possibly. And just wondering do you have a aftermarket radio?
 

Mrmolasses

Well-known member
Joined
Jul 18, 2023
Location
Pa
TDI
None
unplugging the VSS shouldn't really work (or if it does, that signals something else is wrong). but i have seen firsthand if VSS is NOT working, you can get studder/shudder down low rpm. the ecu does care about what speed the car's going as it does various calculations for things. i suspect it has to do with the ecu trying to compensate for injector differences in the <1600rpm areas
in this case vss removal does fix it. Which is odd somewhere along the way the signal is getting affected or ecu fault
 

Mk2Tyler

Active member
Joined
Jul 31, 2023
Location
Richmond, VA
TDI
B4 passat
Same problem with my b4. New pump and injectors no difference from old ones. The cutting out reminds me of how the brake pedal cuts out the throttle. Im thinking ecu fault possibly. And just wondering do you have a aftermarket radio?
I've wondered about the brake pedal thing, I get an occasional "brake pedal monitoring" fault but never looked into it. I do have an aftermarket radio but I had it before the problem started.
 

Mrmolasses

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Joined
Jul 18, 2023
Location
Pa
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None
I've wondered about the brake pedal thing, I get an occasional "brake pedal monitoring" fault but never looked into it. I do have an aftermarket radio but I had it before the problem started.
Yeah i tried unplug brake sensor and it seems to do nothing
 

Mrmolasses

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Joined
Jul 18, 2023
Location
Pa
TDI
None
I've wondered about the brake pedal thing, I get an occasional "brake pedal monitoring" fault but never looked into it. I do have an aftermarket radio but I had it before the problem started.
Im gonna look at vss signal with oscilloscope might show me something
 

Mrmolasses

Well-known member
Joined
Jul 18, 2023
Location
Pa
TDI
None
I've wondered about the brake pedal thing, I get an occasional "brake pedal monitoring" fault but never looked into it. I do have an aftermarket radio but I had it before the problem started.
Im gonna look at vss signal with oscilloscope might show me something y
Let me know, I'm waiting on my injectors to come back before I can tinker more.
yeah i havent seen a solution besides cutting vss to ecu. Kinda disappointing lol lookd at threaded from 20 year ago
 

Mk2Tyler

Active member
Joined
Jul 31, 2023
Location
Richmond, VA
TDI
B4 passat
Im gonna look at vss signal with oscilloscope might show me something y
yeah i havent seen a solution besides cutting vss to ecu. Kinda disappointing lol lookd at threaded from 20 year ago
Same, I saw someone say they solved shuddering with new motor mounts and axles cause they had play. I'll be looking into that this week.
 

Mrmolasses

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Joined
Jul 18, 2023
Location
Pa
TDI
None
Same, I saw someone say they solved shuddering with new motor mounts and axles cause they had play. I'll be looking into that this week.
i had the same problem when i threw a new motor in my b4 lol so its car side problem for sure not the motor
 

Mrmolasses

Well-known member
Joined
Jul 18, 2023
Location
Pa
TDI
None
unplugging the VSS shouldn't really work (or if it does, that signals something else is wrong). but i have seen firsthand if VSS is NOT working, you can get studder/shudder down low rpm. the ecu does care about what speed the car's going as it does various calculations for things. i suspect it has to do with the ecu trying to compensate for injector differences in the <1600rpm areas
[/Q
cruise control problem possibly as well. vss does surge dampening not sure what else the ecu uses signal for.
 

JordanTr

Veteran Member
Joined
Mar 28, 2022
Location
Kimberley, BC
TDI
1996 B4V x2, 2006 Dmax, 2005 Allroad, 2005 BHW
The short answer is yes… There are lots of posts about the ECU swaps. My B4 runs a stock GQ ECU, it came with the plastic case BK ECU, and I have a JB (mk3) ECU with a GQ chipset as well.
 

Mk2Tyler

Active member
Joined
Jul 31, 2023
Location
Richmond, VA
TDI
B4 passat
My b4 had a socketed aluminum case ECU when I got it. I'm assuming that's the GQ. Admittedly I haven't done much research on the ecu's.
 
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