The wierdeist thing is happening my stock map sensor will only let me boost to 4 psi then it puts my car in limp mode. I put a one way check valve in line with the map and now i can boost. The map sensor is working though, i know this because i take it off and the car goes rick and my vaccum goes to zero. I would leave the car like this but the transition from vaccum to boost is a little choppy. I'm running a stock ecu and stock injectors with a fmu.

thanks

 

The stock ECU cannot see boost or will throw a CEL. You need a check valve or missing link if you are not running a standalone.

Sonny

 

but i thought the stock map sensor wasnt supose to throw a cod til 11 psi mine wont let me go pass 4

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bubbahatch92 &raquo;</TD></TR><TR><TD CLASS="quote">but i thought the stock map sensor wasnt supose to throw a cod til 11 psi mine wont let me go pass 4</TD></TR></TABLE>

No, the stock map sensor can read up to 11 psi for a standalone. You need some type of check valve or missing link to fool it into thinking there is no boost since you have no standalone. Otherwise, you CEL will get annoying.....quick.

 

Stock MAP won't read to 11 psi, sorry. It's a few psi less than that, OBD specific.

Just because the stock MAP reads it doesn't mean the ECU likes what the MAP is telling it, thusly, CEL 3.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">Stock MAP won't read to 11 psi, sorry. It's a few psi less than that, OBD specific.
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Interesting. I always thought it had the voltage output for 11?

 

or depending on your fuel settings using a VAFC. depending on how lean or rich you have the settings and how much boost you run will determine if u get a CEL. like right now on my current settings i can run 10 psi with no CEL.

 

OBDI MAP's output 2.8 volts at atmospheric. At 11 psi, that comes out to 4.9 volts, which is probably approximately the maximum operating voltage of the MAP. So, 10 or 11 psi should be the max THE MAP CAN READ.

If the ECU sees anything positive, it's going to get angry. Go with a missing link.

 

Honda MAP sensors are limited in their return voltage by physical construction; the diaphragm/wiper that travels across the potentiometer can only travel so far. You'll never get one returning 4.9 volts much less the 5.0 volt referrence.

Hint: Zdyne got it right for OBD0, Hyundaidata got it wrong for OBD1+.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J. Davis &raquo;</TD></TR><TR><TD CLASS="quote">Honda MAP sensors are limited in their return voltage by physical construction; the diaphragm/wiper that travels across the potentiometer can only travel so far. You'll never get one returning 4.9 volts much less the 5.0 volt referrence.
</TD></TR></TABLE>

Really? That is very interesting!

How is the approximate maximum voltage it can output?