I'm trying to adjust the boost gauge and it seems to be acting weird. Please help! (Page 1/2)
hercimer01 FEB 01, 05:20 AM
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.


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Project Genisis Lo Budget 3800SC swap

88 Coupe under construction

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

fieroaddicted FEB 01, 08:01 AM
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?
hercimer01 FEB 01, 11:25 AM
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).]

fieroaddicted FEB 01, 02:39 PM
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
RobertGT FEB 01, 04:03 PM
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.
hercimer01 FEB 01, 05:46 PM



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).]

hercimer01 FEB 04, 08:25 PM
I have looked into it and mine running in specs. I ended up putting a stopper peg at -15.
fieroaddicted FEB 04, 08:41 PM
hercimer01 SEP 21, 01:35 PM
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).]

Lou6t4gto SEP 21, 02:13 PM
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.