Does anyone have fluctuating boost?
Thread Starter
Scooby Regular
Joined: Jan 2001
Posts: 2,542
Likes: 0
I have a 96 uk with full decat, blitz cone and bleedvalve. Standard ECU.
I have noticed that my boost fluctuates greatly, most days it's 15psi peak 14 held, but somedays it is less than this.around 13 peak 12 held, yet the other day I hit 18psi momentarily after some hard driving.
the point where the fuel cut comes in seems to vary greatly too, when I hit 18, it didn't activate and sometimes it'll go to 16 all day, yet other times it pops and bangs at 14.
WHAT'S GOING ON???
Rich
I have noticed that my boost fluctuates greatly, most days it's 15psi peak 14 held, but somedays it is less than this.around 13 peak 12 held, yet the other day I hit 18psi momentarily after some hard driving.
the point where the fuel cut comes in seems to vary greatly too, when I hit 18, it didn't activate and sometimes it'll go to 16 all day, yet other times it pops and bangs at 14.
WHAT'S GOING ON???
Rich
Atmospheric conditions are different!
The 18psi moment probably happened on a cold morning or evening?
The 14psi bit probably happened when it was hot?
Something to do with charge temperatures, but I'm not technical enough to explain it!
Cold=Good Peformance
Hot=Bad Performance
Cheers
Andy
The 18psi moment probably happened on a cold morning or evening?
The 14psi bit probably happened when it was hot?
Something to do with charge temperatures, but I'm not technical enough to explain it!
Cold=Good Peformance
Hot=Bad Performance
Cheers
Andy
Thread Starter
Scooby Regular
Joined: Jan 2001
Posts: 2,542
Likes: 0
Cheers for the reply Andy, but if only it were that simple.
The 18psi happened on a hot day when the car had been run hard.
It's not a variance that happens from day to day, it happens within 100s of metres of each other and appears random.
On one run you might floor it in second and hit 15 psi, the next time you do the same (on the same journey), you'll only hit 13 psi.
Still HELP!
The 18psi happened on a hot day when the car had been run hard.
It's not a variance that happens from day to day, it happens within 100s of metres of each other and appears random.
On one run you might floor it in second and hit 15 psi, the next time you do the same (on the same journey), you'll only hit 13 psi.
Still HELP!
Scooby Senior
Joined: Oct 2000
Posts: 3,105
Likes: 0
From: Zurich, Switzerland
Faulty boost guage, or leak in the circuit? Faulty bleed valve?
Is the performance affected - should be able to feel difference between 14 & 18 psi
Does the held always come down cleanly from the peak?
Richard
Is the performance affected - should be able to feel difference between 14 & 18 psi
Does the held always come down cleanly from the peak?
Richard
Thread Starter
Scooby Regular
Joined: Jan 2001
Posts: 2,542
Likes: 0
Richard,
Did suspect a dodgy boost gauge, so will be replacing it soon. Held doesn't always come down. Sometimes it peaks and holds the same pressure, sometimes, it peaks then falls and rises again. It never drops more than 2 psi from its peak level though.
I think change the boost gauge and see how I go (it was only a cheap one).
Andrew,
Your ears recovered yet m8? Are you popping down for NM6? I'm probably about 20bhp up from when I was in the Lakes!!
Rich
Did suspect a dodgy boost gauge, so will be replacing it soon. Held doesn't always come down. Sometimes it peaks and holds the same pressure, sometimes, it peaks then falls and rises again. It never drops more than 2 psi from its peak level though.
I think change the boost gauge and see how I go (it was only a cheap one).
Andrew,
Your ears recovered yet m8? Are you popping down for NM6? I'm probably about 20bhp up from when I was in the Lakes!!
Rich
Thread
Thread Starter
Forum
Replies
Last Post
Mattybr5@MB Developments
Full Cars Breaking For Spares
12
Nov 18, 2015 07:03 AM