N75 DIY Thread - Overboost or surging fix
#1
N75 DIY Thread - Overboost or surging fix
I had issues with 'Surging' and overboosting on my stock K16 996TT - it would boost to 1.3 bar on occasions but mostly 0.9 or 1.0. It then dropped into the 'default ECU map' due to overboost errors and started to run like a bag of spanners (lumpy/jerky at low throttle)
I read up on the overboost and tracked it down to N75 or MAF, tried the MAF and it wasn't that so onto the N75. Swapped it and all is fixed - boosting solidly to 0.6
I then disconnected the battery for 10 mins to clear the codes and get the car back to the proper ECU map. The car is so smooth to drive now in addition to the boost being fixed.
I didn't find any DIY's for this and its fairly straightforward having done it so I thought I'd drop a few pictures and a 'How to' down here to maybe help and guide others.
Step one
Remove airbox by removing MAF plug and taking out main retaining bolt near boot release then undoing jubilee clip.
Twist airbox anticlockwise as you remove.
Step two
Undo intercooler pipes as shown below by sliding out the clips.
Step three
Remove all pipes and connectors attached to the 'Y' manifold carefully and push out of the way. (NB - Picture below shows airbox which would be removed by now)
Step four
Undo jubilee clip at top of 'Y' manifold just before the throttle body as shown below (Stumpy screw driver or socket set required here)
Step five
Gently wiggle and twist 'Y' manifold - it will pop off. You only need to move manifold to the left half an inch or so once removed to get access to N75 valve - it remains attached in place. You will now see the N75 valve as below
Step six
Slide off the 3 x pipes attached to the N75 valve
Sldie the valve off its mounting and lift it out a little
Unplug the connector below after removing the metal retaining clip
Step seven
Reverse the above process
The only tricky bit is getting the pipes back on to the N75 valve - you really need a pair of these or its a PITA to do.
The bottom pipe needs to be pushed on using the pliers through this gap (it will make sense when you do it)
Step eight
Have a REALLY good check over to make sure you have reattached everything correctly and no snags or rubs exist.
Step nine
Disconnect battery for 10 mins to clear any fault codes from before the fix (turn ignition on if UK car to avoid alarm before disconnecting battery) - ensure you have radio & nav codes in advance.
Here's the old and new N75 side by side:
P/N of N75 is 996.605.155.00 cost of part is about £20!
I would allow 2hrs for the first time you do this and prob 45 mins if you needed to do it again.
Disclaimer - In line with common sence, this DIY is entirely at your risk, no guarantee of a fix is given or implied!
Cheers,
Jim
I read up on the overboost and tracked it down to N75 or MAF, tried the MAF and it wasn't that so onto the N75. Swapped it and all is fixed - boosting solidly to 0.6
I then disconnected the battery for 10 mins to clear the codes and get the car back to the proper ECU map. The car is so smooth to drive now in addition to the boost being fixed.
I didn't find any DIY's for this and its fairly straightforward having done it so I thought I'd drop a few pictures and a 'How to' down here to maybe help and guide others.
Step one
Remove airbox by removing MAF plug and taking out main retaining bolt near boot release then undoing jubilee clip.
Twist airbox anticlockwise as you remove.
Step two
Undo intercooler pipes as shown below by sliding out the clips.
Step three
Remove all pipes and connectors attached to the 'Y' manifold carefully and push out of the way. (NB - Picture below shows airbox which would be removed by now)
Step four
Undo jubilee clip at top of 'Y' manifold just before the throttle body as shown below (Stumpy screw driver or socket set required here)
Step five
Gently wiggle and twist 'Y' manifold - it will pop off. You only need to move manifold to the left half an inch or so once removed to get access to N75 valve - it remains attached in place. You will now see the N75 valve as below
Step six
Slide off the 3 x pipes attached to the N75 valve
Sldie the valve off its mounting and lift it out a little
Unplug the connector below after removing the metal retaining clip
Step seven
Reverse the above process
The only tricky bit is getting the pipes back on to the N75 valve - you really need a pair of these or its a PITA to do.
The bottom pipe needs to be pushed on using the pliers through this gap (it will make sense when you do it)
Step eight
Have a REALLY good check over to make sure you have reattached everything correctly and no snags or rubs exist.
Step nine
Disconnect battery for 10 mins to clear any fault codes from before the fix (turn ignition on if UK car to avoid alarm before disconnecting battery) - ensure you have radio & nav codes in advance.
Here's the old and new N75 side by side:
P/N of N75 is 996.605.155.00 cost of part is about £20!
I would allow 2hrs for the first time you do this and prob 45 mins if you needed to do it again.
Disclaimer - In line with common sence, this DIY is entirely at your risk, no guarantee of a fix is given or implied!
Cheers,
Jim
#5
Very nice info, rep point for you Thanks a lot!
Just want to share the info I just found about the function of the N75 valves....http://s4wiki.com/wiki/Wastegate_bypass_regulator_valve
Just want to share the info I just found about the function of the N75 valves....http://s4wiki.com/wiki/Wastegate_bypass_regulator_valve
Last edited by jpflip; 03-26-2010 at 04:45 PM.
#7
Cheers
Jim
Trending Topics
#9
I had issues with 'Surging' and overboosting on my stock K16 996TT - it would boost to 1.3 bar on occasions but mostly 0.9 or 1.0. It then dropped into the 'default ECU map' due to overboost errors and started to run like a bag of spanners (lumpy/jerky at low throttle)
I read up on the overboost and tracked it down to N75 or MAF, tried the MAF and it wasn't that so onto the N75. Swapped it and all is fixed - boosting solidly to 0.6
I then disconnected the battery for 10 mins to clear the codes and get the car back to the proper ECU map. The car is so smooth to drive now in addition to the boost being fixed.
I didn't find any DIY's for this and its fairly straightforward having done it so I thought I'd drop a few pictures and a 'How to' down here to maybe help and guide others.
Step one
Remove airbox by removing MAF plug and taking out main retaining bolt near boot release then undoing jubilee clip.
Twist airbox anticlockwise as you remove.
Step two
Undo intercooler pipes as shown below by sliding out the clips.
Step three
Remove all pipes and connectors attached to the 'Y' manifold carefully and push out of the way. (NB - Picture below shows airbox which would be removed by now)
Step four
Undo jubilee clip at top of 'Y' manifold just before the throttle body as shown below (Stumpy screw driver or socket set required here)
Step five
Gently wiggle and twist 'Y' manifold - it will pop off. You only need to move manifold to the left half an inch or so once removed to get access to N75 valve - it remains attached in place. You will now see the N75 valve as below
Step six
Slide off the 3 x pipes attached to the N75 valve
Sldie the valve off its mounting and lift it out a little
Unplug the connector below after removing the metal retaining clip
Step seven
Reverse the above process
The only tricky bit is getting the pipes back on to the N75 valve - you really need a pair of these or its a PITA to do.
The bottom pipe needs to be pushed on using the pliers through this gap (it will make sense when you do it)
Step eight
Have a REALLY good check over to make sure you have reattached everything correctly and no snags or rubs exist.
Step nine
Disconnect battery for 10 mins to clear any fault codes from before the fix (turn ignition on if UK car to avoid alarm before disconnecting battery) - ensure you have radio & nav codes in advance.
Here's the old and new N75 side by side:
P/N of N75 is 996.605.155.00 cost of part is about £20!
I would allow 2hrs for the first time you do this and prob 45 mins if you needed to do it again.
Disclaimer - In line with common sence, this DIY is entirely at your risk, no guarantee of a fix is given or implied!
Cheers,
Jim
I read up on the overboost and tracked it down to N75 or MAF, tried the MAF and it wasn't that so onto the N75. Swapped it and all is fixed - boosting solidly to 0.6
I then disconnected the battery for 10 mins to clear the codes and get the car back to the proper ECU map. The car is so smooth to drive now in addition to the boost being fixed.
I didn't find any DIY's for this and its fairly straightforward having done it so I thought I'd drop a few pictures and a 'How to' down here to maybe help and guide others.
Step one
Remove airbox by removing MAF plug and taking out main retaining bolt near boot release then undoing jubilee clip.
Twist airbox anticlockwise as you remove.
Step two
Undo intercooler pipes as shown below by sliding out the clips.
Step three
Remove all pipes and connectors attached to the 'Y' manifold carefully and push out of the way. (NB - Picture below shows airbox which would be removed by now)
Step four
Undo jubilee clip at top of 'Y' manifold just before the throttle body as shown below (Stumpy screw driver or socket set required here)
Step five
Gently wiggle and twist 'Y' manifold - it will pop off. You only need to move manifold to the left half an inch or so once removed to get access to N75 valve - it remains attached in place. You will now see the N75 valve as below
Step six
Slide off the 3 x pipes attached to the N75 valve
Sldie the valve off its mounting and lift it out a little
Unplug the connector below after removing the metal retaining clip
Step seven
Reverse the above process
The only tricky bit is getting the pipes back on to the N75 valve - you really need a pair of these or its a PITA to do.
The bottom pipe needs to be pushed on using the pliers through this gap (it will make sense when you do it)
Step eight
Have a REALLY good check over to make sure you have reattached everything correctly and no snags or rubs exist.
Step nine
Disconnect battery for 10 mins to clear any fault codes from before the fix (turn ignition on if UK car to avoid alarm before disconnecting battery) - ensure you have radio & nav codes in advance.
Here's the old and new N75 side by side:
P/N of N75 is 996.605.155.00 cost of part is about £20!
I would allow 2hrs for the first time you do this and prob 45 mins if you needed to do it again.
Disclaimer - In line with common sence, this DIY is entirely at your risk, no guarantee of a fix is given or implied!
Cheers,
Jim
#10
nice write up. i've replaced mine before as well.
__________________
#TeamAIM
997TT SilverSpool - 210.8 mph 1/2 Mile WR Apr 2019, 9.2 @ 168 mph 1/4 Mile Manual World Record , 3.15 60-130 mph , 2.72 100-150 mph , 1400whp E85
996TT SpoolBus - 204.6 mph 1/2 Mile 996TT WR Aug 2018, 9.5 @ 154 mph, 3.23 60-130 mph, 2.5 100-150 mph Manual Porsche World Record, 1400whp E85
997TT SlowBerry - 205.0 mph 1/2 Mile WR Nov 2018, 9.7 @ 170 mph 1/4 Mile , 3.2 60-130 mph , 2.4 100-150 mph , 1420whp E85
ESMOTOR | DO88 | TPC DSC | SYVECS | COBB | IPD | KLINE | XONA | AMS | ID | ERP | SACHS | TURBOSMART | CSF | DODSON |
#TeamAIM
997TT SilverSpool - 210.8 mph 1/2 Mile WR Apr 2019, 9.2 @ 168 mph 1/4 Mile Manual World Record , 3.15 60-130 mph , 2.72 100-150 mph , 1400whp E85
996TT SpoolBus - 204.6 mph 1/2 Mile 996TT WR Aug 2018, 9.5 @ 154 mph, 3.23 60-130 mph, 2.5 100-150 mph Manual Porsche World Record, 1400whp E85
997TT SlowBerry - 205.0 mph 1/2 Mile WR Nov 2018, 9.7 @ 170 mph 1/4 Mile , 3.2 60-130 mph , 2.4 100-150 mph , 1420whp E85
ESMOTOR | DO88 | TPC DSC | SYVECS | COBB | IPD | KLINE | XONA | AMS | ID | ERP | SACHS | TURBOSMART | CSF | DODSON |