Pennock's Fiero Forum
  Technical Discussion & Questions
  I'm trying to adjust the boost gauge and it seems to be acting weird. Please help!

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
I'm trying to adjust the boost gauge and it seems to be acting weird. Please help! by hercimer01
Started on: 02-01-2014 05:20 AM
Replies: 15 (322 views)
Last post by: hercimer01 on 11-06-2014 11:29 PM
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post02-01-2014 05:20 AM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post
I'm trying to adjust {fix} the boost gauge and it seems to be acting weird.
Maybe someone could tell me if this correct?
Here are some reference voltages.
http://www.robietherobot.com/storm/mapsensor.htm

This is with the key on, engine off.


This is with the engine at idle.
Something seems to be wacked out.



I have a ZZP tune with a 3.4 pulley. Otherwise stock.
If anyone has any ideas, please help.


------------------
Project Genisis Lo Budget 3800SC swap

88 Coupe under construction

[This message has been edited by hercimer01 (edited 11-05-2014).]

IP: Logged
PFF
System Bot
fieroaddicted
Member
Posts: 662
From: aylesford, nova scotia canada
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post02-01-2014 08:01 AM Click Here to See the Profile for fieroaddictedClick Here to Email fieroaddictedSend a Private Message to fieroaddictedEdit/Delete MessageReply w/QuoteDirect Link to This Post
did the needle sweep downward to the negative side, or did it sweep upward to the positive side to get to where it is in the second pic?
IP: Logged
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post02-01-2014 11:25 AM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post
Down. When I bump the gas, the needle goes up towards the positive in the correct direction.

[This message has been edited by hercimer01 (edited 02-01-2014).]

IP: Logged
fieroaddicted
Member
Posts: 662
From: aylesford, nova scotia canada
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post02-01-2014 02:39 PM Click Here to See the Profile for fieroaddictedClick Here to Email fieroaddictedSend a Private Message to fieroaddictedEdit/Delete MessageReply w/QuoteDirect Link to This Post
sounds about right i think, but i am not sure how much vacuum you should be reading on the gauge at idle..it would depend on a # of things actually...so basically i don't know how accurate it is reading. I am still building my swap at this time, so i am unsure what mine will show on my own gauge.... Hopefully someone with one installed already will chime in to help you out better.
troy
IP: Logged
RobertGT
Member
Posts: 101
From: Denver, CO, USA
Registered: Dec 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post02-01-2014 04:03 PM Click Here to See the Profile for RobertGTSend a Private Message to RobertGTEdit/Delete MessageReply w/QuoteDirect Link to This Post
I imagine the engine will pull around 10-11" at idle, that's what my 3.4 DOHC pulls and I imagine they aren't far off.

Have you tried resetting the needle? It sounds like it's sweeping normally. I haven't done this on a Fiero or Sunbird gauge, but one way to do it would be to hold the throttle wide open, engine off but ignition on, with the needle removed. Then push the needle back on where it's reading 0. You're done, now pressurize to a known level and verify it.
IP: Logged
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post02-01-2014 05:46 PM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post



I went to to junkyard and got another MAP sensor for $8.00. It reads the same.
I forgot, I have Torque. It verified the gauge.
I did zero out the needle with the key on, engine off. It was reading 2.22 VDC

I have the Map sensor and Fuel pressure regulator plumbed into the fitting under the supercharger snout from the LIM.
BBV is also deleted.

What is the vacuum supposed to read @ idle?
I just checked my Tahoe. It reads almost exactly the same

[This message has been edited by hercimer01 (edited 02-01-2014).]

IP: Logged
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post02-04-2014 08:25 PM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post
I have looked into it and mine running in specs. I ended up putting a stopper peg at -15.
IP: Logged
fieroaddicted
Member
Posts: 662
From: aylesford, nova scotia canada
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post02-04-2014 08:41 PM Click Here to See the Profile for fieroaddictedClick Here to Email fieroaddictedSend a Private Message to fieroaddictedEdit/Delete MessageReply w/QuoteDirect Link to This Post
IP: Logged
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post09-21-2014 01:35 PM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post
I put a vacuum gauge on it and at idle it does pull around 20 PSI vac @ idle.

The boost however would peg at 20 PSI when I would tromp on it.
I found the problem.
I had ran the Black wire "Ground" the back of the instrument cluster. I changed it to the ECM C1 pin 13 MAP ground and now it still shows idle at 20 psi but boost is around 8 psi. I will have to verify the numbers with an actual vacuum gauge but this seems more reasonable.

I spoke too soon. Its still doing it.

[This message has been edited by hercimer01 (edited 11-05-2014).]

IP: Logged
Lou6t4gto
Member
Posts: 8420
From: Ocala, FL USA
Registered: May 2008


Feedback score:    (7)
Leave feedback

Rate this member

Report this Post09-21-2014 02:13 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
What am I "Missing" here ? A Vacuum/Boost Gauge is Mechanical. how can you adjust it? Most engines (any year) that are running normal (N0 Lumpy Cam) will idle at around 20 PSI vacuum when tuned properly, with a cam with more duration , between 15-17 psi vacuum.
IP: Logged
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post09-21-2014 06:20 PM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

What am I "Missing" here ? A Vacuum/Boost Gauge is Mechanical. how can you adjust it? Most engines (any year) that are running normal (N0 Lumpy Cam) will idle at around 20 PSI vacuum when tuned properly, with a cam with more duration , between 15-17 psi vacuum.


I was showing 20psi boost under acceleration. This is an electronic gauge running off of the MAP sensor.
I in a 5 volt sensor circuit. There is a reference voltage from a known ground or in this MAP ground. I had used the dimmer ground plane on the back of the cluster which is obviously different than the ICM MAP ground.
IP: Logged
PFF
System Bot
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post11-05-2014 07:50 PM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post
I bought an Equus Boost gauge and it does show around 19 vac. at idle and 10 psi boost at WOT.
I think my grounds are wrong or something for the 5v sensors.
I did swap in another known good MAP sensor with no change.

Any one have any ideas?

------------------
Project Genisis Lo Budget 3800SC swap
12.840@104.8 MPH Intense-Racing 1.9 rockers, 3" exhaust, 3.4 pulley, ZZP tune and 18 year old tires.

88 Coupe under construction SOLD

88 formula 3.4L 4t60 swap SOLD

IP: Logged
1fast2m4
Member
Posts: 513
From: Frederick, MD (U.S.A)
Registered: Feb 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post11-05-2014 08:22 PM Click Here to See the Profile for 1fast2m4Send a Private Message to 1fast2m4Edit/Delete MessageReply w/QuoteDirect Link to This Post
Mine runs @ -19in, I'd say put a stopper on it and call it done.

------------------
1986 SE 3800SC/4t65eHD (12.871@104.96)
HX-40, FrozenBoost I/C, 80lb injectors & E85 Coming soon.....

IP: Logged
thesameguy
Member
Posts: 1414
From: California
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post11-06-2014 08:19 AM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
On a fuel injected car, vacuum at idle should be around 18-20 inches. What you're seeing on that gauge seems about right - maybe in the factory application there is a filter to keep it from reading off the gauge?
IP: Logged
thesameguy
Member
Posts: 1414
From: California
Registered: Dec 2012


Feedback score: N/A
Leave feedback

Rate this member

Report this Post11-06-2014 08:21 AM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post

thesameguy

1414 posts
Member since Dec 2012
 
quote
Originally posted by Lou6t4gto:

What am I "Missing" here ? A Vacuum/Boost Gauge is Mechanical. how can you adjust it? Most engines (any year) that are running normal (N0 Lumpy Cam) will idle at around 20 PSI vacuum when tuned properly, with a cam with more duration , between 15-17 psi vacuum.


You're missing that pressure is measured in psi (pounds per square inch), and vacuum is measured in inches of mercury ("/hg) ...
IP: Logged
hercimer01
Member
Posts: 2214
From: Rockford IL.
Registered: Mar 2008


Feedback score:    (9)
Leave feedback

Rate this member

Report this Post11-06-2014 11:29 PM Click Here to See the Profile for hercimer01Send a Private Message to hercimer01Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 1fast2m4:

Mine runs @ -19in, I'd say put a stopper on it and call it done.




Mine too.
I did put a stopper on it because the boost gauge only goes to + or - 15 but it's driving me nuts. It's not accurate.
The mechanical gauge reads -19 @ idle and +10 @ WOT
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock