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.
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
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.
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).]
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).]
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.
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.
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.
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?
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) ...
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