Boost Spiking??

0151rhys · Nov 9th, 2015, 08:34

Hi All, I have recently purchased a c70 t5 which supposedly had been remapped. Anyway this weekend I changed the PCV unit and pipework, replaced the turbo vacuum lines and it has had a full service oil,plugs,rotor arm and cap etc. Prior to this it would occasionally pull aggressively and other times not. Now it boost all the time and feels good, however I noticed the boost gauge is now hitting almost 1.5 bar and dropping to about 0.9 bar. Does any one have any ideas what could be causing this. In addition to the above work I removed the nasty badly modified inlet pipe and fitted an original between the air box and turbo. Could some on assist me and tell me which connection go where so I can ensure I am correct.

0151rhys · Nov 9th, 2015, 08:42

Quick video I recorded of the issue:

https://youtu.be/VPGq2Skr5LM

martin_r_smith · Nov 9th, 2015, 15:00

Try doing another video but in say 4th gear so the boosts is held far a while. That looks to me like a fairly normal spike then the boost drops off because there isn't enough load to sustain it.

0151rhys · Nov 9th, 2015, 16:25

Hi Martin, thank you for the reply, it is an automatic if that makes any differences?

PNuT · Nov 9th, 2015, 16:35

Can you select a high gear manually on your box? like the W mode?

You ideally need to see what the boost is doing right through the rev range at wide open throttle.....

0151rhys · Nov 9th, 2015, 17:34

I will do this on my way to work tomorrow. What does the w do exactly?, I guessed it changes gear earlier to prevent wheel spin in the ice.

Nov 9th, 2015, 08:34	#1
0151rhys New Member Last Online: Jan 10th, 2016 21:35 Join Date: Nov 2015 Location: Wirral	Boost Spiking?? Hi All, I have recently purchased a c70 t5 which supposedly had been remapped. Anyway this weekend I changed the PCV unit and pipework, replaced the turbo vacuum lines and it has had a full service oil,plugs,rotor arm and cap etc. Prior to this it would occasionally pull aggressively and other times not. Now it boost all the time and feels good, however I noticed the boost gauge is now hitting almost 1.5 bar and dropping to about 0.9 bar. Does any one have any ideas what could be causing this. In addition to the above work I removed the nasty badly modified inlet pipe and fitted an original between the air box and turbo. Could some on assist me and tell me which connection go where so I can ensure I am correct.

Nov 9th, 2015, 15:00	#3
martin_r_smith Premier Member Last Online: May 10th, 2022 21:01 Join Date: May 2009 Location: Wiltshire	Try doing another video but in say 4th gear so the boosts is held far a while. That looks to me like a fairly normal spike then the boost drops off because there isn't enough load to sustain it. __________________ 1983 244

Nov 9th, 2015, 16:35	#5
PNuT MaDMaN Last Online: Nov 26th, 2022 18:47 Join Date: Sep 2006 Location: Red Lodge	Can you select a high gear manually on your box? like the W mode? You ideally need to see what the boost is doing right through the rev range at wide open throttle..... __________________

Nov 9th, 2015, 08:42	#2
0151rhys New Member Last Online: Jan 10th, 2016 21:35 Join Date: Nov 2015 Location: Wirral	Quick video I recorded of the issue: https://youtu.be/VPGq2Skr5LM

Nov 9th, 2015, 16:25	#4
0151rhys New Member Last Online: Jan 10th, 2016 21:35 Join Date: Nov 2015 Location: Wirral	Hi Martin, thank you for the reply, it is an automatic if that makes any differences?

Nov 9th, 2015, 17:34	#6
0151rhys New Member Last Online: Jan 10th, 2016 21:35 Join Date: Nov 2015 Location: Wirral	I will do this on my way to work tomorrow. What does the w do exactly?, I guessed it changes gear earlier to prevent wheel spin in the ice.

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