Ok will my 95 ecu freak out if I install a 3 bar map sensor? I did a bit of searching last night, and found a couple of posts that mention a 95 ecu can handle boost when it see's it. This leads me to think that I can possibly install a 3 bar map sensor. If that will work then where can I find one? I did a froogle search last night and came up with a couple of places, but thier 'gm' map sensor did not look like mine.

Originally posted by RxR_Eclipse
Ok will my 95 ecu freak out if I install a 3 bar map sensor? I did a bit of searching last night, and found a couple of posts that mention a 95 ecu can handle boost when it see's it. This leads me to think that I can possibly install a 3 bar map sensor. If that will work then where can I find one? I did a froogle search last night and came up with a couple of places, but thier 'gm' map sensor did not look like mine.

Ok... sets get back to basics here...

The 95 ECU can see boost... but what that means is that it will not freak out if it sees over 4.7V or there abouts from the MAP sensor.
The ECU's on the 96+ cars will usually freak out if the voltage from the MAP sensor goes above 4.7V.
What happens? You get fuel cut.

Ok, so what happens if you install your 3 BAR GM map sensor you ask? Well its easy... you'll advance your timing to crazy levels, and more than likelly blow the heck out of your motor. That's it.

Why will this happen? Well it's all about the voltage curve of the MAP sensors... Most MAP sensors including both the Stock 1 BAR MAP sensor and the GM 3 BAR MAP sensor put out a signal between 0 and 5V.
When they see 0 psig, which is a total vaccum they put out about 0V.
When they see their max MAP signal, they output about 5V. On the stock MAP sensor max MAP signal is 14.7 PSIG (0 on your boost guage) it puts out about 4.7 V. On the GM 3 BAR MAP sensor when it sees 44.1 PSIG (29.4 PSI on your boost guage) it puts out about 5V.
The MAP signals put out a linear signal.

So.. at atmospheric pressure (0 on your boost guage) The stock ECU would expect to see about 4.7V from the MAP sensor when under load... Now... if you have your GM 3 BAR MAP sensor in there, you'll get about 1.6V or there abouts when at atmospheric pressure (0 on your boost guage). The Stock ECU will use this voltage and think that you are under very light load... and will advance your ignition timing to anywhere up to 30 degrees and beyond... BOOM!

So in short using a 3 BAR GM MAP sensor with your stock ECU will do nothing for you. Other than blow up your motor when under load.

Hopefully you'll now know not to do it!

Thanks for listening...
Lee.

Ok then...I was just thinking it would be cool for my super afc to log the boost in relation to all else..O yea im already using the corbin boost mod on my super afc as well, it would just be nice ot read it via the map sensor. not as an adjuter, just another gauge.

You can install as many MAP sensors as you'd like in addition to the stock sensor if you need to use one for something else.