Author Topic: S4 B5 Knocking/Quick Juddering when coming into boost  (Read 503 times)

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Offline maxpearson

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S4 B5 Knocking/Quick Juddering when coming into boost
« on: November 15, 2017, 12:04:33 am »
Only happens when you get into boost in say 4th and 5th fear and you put your foot down halfway or so, as it builds up the car starts almost boost cutting, but if you just plant your foot it gets into boost fine. Has anyone has this happen to them? Cheers
2000 S4 B5
1997 A4 B5

Offline Brett

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Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #1 on: November 15, 2017, 09:05:29 am »
Check the throttle body boot. Probably torn
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Offline 00quattro00

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Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #2 on: November 15, 2017, 04:34:43 pm »
Did you buy that one from chch with the built engine?
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Offline GLIDN

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Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #3 on: November 15, 2017, 05:02:08 pm »
This issue can be related to all the following possibilities.

Faulty/worn/incorrectly gapped spark plugs
Boost leak
Faulty Airflow sensor
Failing coil packs
Failing Ignition amplifier
Failing/faulty N75
Failing/faulty EGT (exhaust gas temperature sensor)
Failing/faulty Primary 02 Sensors
Possibly sticking wastegate on OEM turbos
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Offline maxpearson

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Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #4 on: December 12, 2017, 03:54:58 pm »
Did you buy that one from chch with the built engine?

sorry for very late reply but yeah I did
2000 S4 B5
1997 A4 B5

Offline Turbo

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Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #5 on: December 20, 2017, 08:51:15 pm »
Second Brett's comment on throttle body boot.
Also possibly diverter valves. if they haven't been changed, get them done as a matter of course. 710N or better.
or MAF sensor. - VAGCOM would pick up a fault.

Do you know about using the climate control unit to check fault codes?
press recirculation button at the same time as either the airflow up or down button (can't remember which)
If there are no faults, it will show '0'.
You can do a bunch of other stuff in there too, pressing up or + to check specific codes. from memory, selecting '17' gives you true road speed (as opposed to the 5-8% extra that gets put on your dash speedo)
« Last Edit: December 20, 2017, 09:05:06 pm by Turbo »
2000 S4, MTM stage 1, Oettinger RE's, Bilstein Sports, Vogtland springs, H&R Swaybars, DBA 4000 rotors, EBC Yellow stuff pads, 710N DV's, F1 tints, RS4 clutch

Offline maxpearson

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Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #6 on: December 20, 2017, 09:51:18 pm »
Hey cheers man for the info, the car has started holding revs when changing gears at any rev. Is this something to do with the throttle body?

Second Brett's comment on throttle body boot.
Also possibly diverter valves. if they haven't been changed, get them done as a matter of course. 710N or better.
or MAF sensor. - VAGCOM would pick up a fault.

Do you know about using the climate control unit to check fault codes?
press recirculation button at the same time as either the airflow up or down button (can't remember which)
If there are no faults, it will show '0'.
You can do a bunch of other stuff in there too, pressing up or + to check specific codes. from memory, selecting '17' gives you true road speed (as opposed to the 5-8% extra that gets put on your dash speedo)
2000 S4 B5
1997 A4 B5

Offline maxpearson

  • Posts: 28
Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #7 on: December 20, 2017, 09:53:27 pm »
Car has a HPX MAF sensor
 
Second Brett's comment on throttle body boot.
Also possibly diverter valves. if they haven't been changed, get them done as a matter of course. 710N or better.
or MAF sensor. - VAGCOM would pick up a fault.

Do you know about using the climate control unit to check fault codes?
press recirculation button at the same time as either the airflow up or down button (can't remember which)
If there are no faults, it will show '0'.
You can do a bunch of other stuff in there too, pressing up or + to check specific codes. from memory, selecting '17' gives you true road speed (as opposed to the 5-8% extra that gets put on your dash speedo)
2000 S4 B5
1997 A4 B5

Offline Turbo

  • was going to call myself bi-turbo, but i don't root blokes. sorry.
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  • Twin snails - see my S-car go!
Re: S4 B5 Knocking/Quick Juddering when coming into boost
« Reply #8 on: December 21, 2017, 09:03:48 am »
Hey cheers man for the info, the car has started holding revs when changing gears at any rev. Is this something to do with the throttle body?

sounds like it might be haunted... ;D
2000 S4, MTM stage 1, Oettinger RE's, Bilstein Sports, Vogtland springs, H&R Swaybars, DBA 4000 rotors, EBC Yellow stuff pads, 710N DV's, F1 tints, RS4 clutch