Boost Gauge problem
#1
Senior Member
True Car Nut
Thread Starter
Join Date: Sep 2002
Location: Genoa, Illinois
Posts: 4,013
Likes: 0
Received 0 Likes
on
0 Posts
Boost Gauge problem
Always had this, but not too big of a deal because the Autotapping showed a 12.7 psi before rockers and I'm running decent times...however, the boost gauges is not steady. Sometimes while waiting at a stoplight the needle will flunctuate a few millimeters and under acceleration it may do the same if I hold a steady foot. No surging or performance problems, just a wierd gauge. What lines feed the gauge? I'd like to give them a glance and check for a leek of some kind.
#3
Senior Member
Certified GM nut
Join Date: Feb 2003
Location: Georgia
Posts: 2,095
Likes: 0
Received 0 Likes
on
0 Posts
That'll be your map sensor. If you pull the vacuum line to it the boost gauge should go straight to 0. As far as I've found its normal to have it bounce a little above -10 stopped when in drive..
#5
Senior Member
Posts like a Corvette
Join Date: Jan 2004
Location: Montréal, QC
Posts: 1,374
Likes: 0
Received 0 Likes
on
0 Posts
Mine'* quite steading actually, pinned at the end ( :P just kidding). I don't really see any fluctuations. I presume the 97 to 99 are the same for the L67, there are 2 MAP sensors on mine. One for the PCM to read and the other for the boost guage...neat huh?
Cheers,
Cheers,
#6
Senior Member
True Car Nut
Originally Posted by DrJay
That'll be your map sensor. If you pull the vacuum line to it the boost gauge should go straight to 0. As far as I've found its normal to have it bounce a little above -10 stopped when in drive..
#7
Senior Member
Certified GM nut
Join Date: Feb 2003
Location: Georgia
Posts: 2,095
Likes: 0
Received 0 Likes
on
0 Posts
Ya know I browsed my pics and I have one of the map sensor but its a little too zoomed in to make out where it is. Its easy to find though. Its a rectangular box about 1/2" thick mounted just above your rear valve cover (towards the firewall). Its got a somewhat large 3 prong plug going into it and its got a vacuum line that goes to the FRP and branches off to attach to the vacuum splitter on the supercharger.
Look at the vacuum splitter on the supercharger. Its on the top of the */c at the rear (Towards the TB) and has 3 vacuum lines attached to it. Follow the middle one to the back of the car. It splits and one goes to the FPR the other goes to the Map sensor. I pulled that from my memory but I'm pretty sure its the middle one
If you still can't find it I'll go take some pictures, its just raining now .
Look at the vacuum splitter on the supercharger. Its on the top of the */c at the rear (Towards the TB) and has 3 vacuum lines attached to it. Follow the middle one to the back of the car. It splits and one goes to the FPR the other goes to the Map sensor. I pulled that from my memory but I'm pretty sure its the middle one
If you still can't find it I'll go take some pictures, its just raining now .
#8
Senior Member
True Car Nut
Originally Posted by DrJay
Ya know I browsed my pics and I have one of the map sensor but its a little too zoomed in to make out where it is. Its easy to find though. Its a rectangular box about 1/2" thick mounted just above your rear valve cover (towards the firewall). Its got a somewhat large 3 prong plug going into it and its got a vacuum line that goes to the FRP and branches off to attach to the vacuum splitter on the supercharger.
Look at the vacuum splitter on the supercharger. Its on the top of the */c at the rear (Towards the TB) and has 3 vacuum lines attached to it. Follow the middle one to the back of the car. It splits and one goes to the FPR the other goes to the Map sensor. I pulled that from my memory but I'm pretty sure its the middle one
If you still can't find it I'll go take some pictures, its just raining now .
Look at the vacuum splitter on the supercharger. Its on the top of the */c at the rear (Towards the TB) and has 3 vacuum lines attached to it. Follow the middle one to the back of the car. It splits and one goes to the FPR the other goes to the Map sensor. I pulled that from my memory but I'm pretty sure its the middle one
If you still can't find it I'll go take some pictures, its just raining now .
#9
Senior Member
True Car Nut
Originally Posted by DrJay
That'll be your map sensor. If you pull the vacuum line to it the boost gauge should go straight to 0. As far as I've found its normal to have it bounce a little above -10 stopped when in drive..
So when you say to pull it and it shoudl read zero.. is that with engine running or not? Will this cause issue with it?
#10
Senior Member
True Car Nut
Join Date: Jun 2003
Location: Purgatory
Posts: 6,313
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Drifter420
So when you say to pull it and it shoudl read zero.. is that with engine running or not? Will this cause issue with it?