I was data logging with a wide band the other day and as part of that we tape in to the MAP Sensor. The Map sensor said I was only boost 8psi when my gauge said I was boost 10 psi.

Which one is more accurate. Map sensor or boost gauge?

-Thanks

 

I'd say MAP sensor. Especially since the ECU uses the MAP sensor for all the fueling.

 

map sensor i say is more acurate

 

What kind of gauge are you using?

 

Autometer

 

haha def map sensor then.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">haha def map sensor then.</TD></TR></TABLE>

what does that mean?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jaker &raquo;</TD></TR><TR><TD CLASS="quote">I'd say MAP sensor. Especially since the ECU uses the MAP sensor for all the fueling.</TD></TR></TABLE>



Who cares which one you're looking at. You're not doing the fueling, the ECU is. Look at the gauge the ECU looks at!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by raene &raquo;</TD></TR><TR><TD CLASS="quote">



Who cares which one you're looking at. You're not doing the fueling, the ECU is. Look at the gauge the ECU looks at!</TD></TR></TABLE>

I care, I don't want a gauge that is not accurate. Then what is the point of even having it?

 

Bling?

There isn't much point, really, unless something is wrong and you're trying to diagnose it.

 

it dosnt matter.. if you ahve the map sensor and the boost guage getting readings from different parts of the manifold they both could be right.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDogg &raquo;</TD></TR><TR><TD CLASS="quote">it dosnt matter.. if you ahve the map sensor and the boost guage getting readings from different parts of the manifold they both could be right.</TD></TR></TABLE>

good point. I thought the would all get pressure the same though.

 

The map sensor has to be calibrated just like when you upgrade to a 2,3 bar map sensor. But the map sensor has be corrected or else your engine will suffer.

Not every map sensor is accurate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx616 &raquo;</TD></TR><TR><TD CLASS="quote">

I care, I don't want a gauge that is not accurate. Then what is the point of even having it?</TD></TR></TABLE>

Well, autometer isnt known for being the most accurate guage...

 

What were you datalogging with?

The MAP sensor just gives out voltage depending on the pressure it sees. The voltage is then converted by your datalogging junk to mbar/psi/etc.

MAP sensors in general are very "precise" but they aren't necessarily very "accurate". You also leave open the possibility that your datalogging hardware/software isn't converting the reading properly. I know Hondata has some issues with this. I even see disagreements between my greddy electronic boostgauge and AVC-R read out... as well as the factory MAP sensor peak voltage (peak hold on my Zeitronix).

 

My autometer does the same thing. The boost gauge says 10PSI while my datalogging values read 8-9 PSI. I just make sure that everything is accurate within the ECU and all the fueling and timing is correct. Either case you will vary more with cold weather when you boost because the spring will get harder .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dustin &raquo;</TD></TR><TR><TD CLASS="quote">What were you datalogging with?
</TD></TR></TABLE>

We are datalogging with Crome Pro and a PLX M-300.

-P

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dustin &raquo;</TD></TR><TR><TD CLASS="quote">
MAP sensors in general are very "precise" but they aren't necessarily very "accurate". </TD></TR></TABLE>

I'd agree with that. I recently decided to trust my MAP sensor over my boost gauge. In the post-mortem analysis of my engine, we figure I was running 27-30 PSI when I melted my pistons from preignition. The MAP sensor showed 20-21 PSI. No detonation at all, we had plenty of fuel, the plugs just got too hot. Trust whichever one reads higher to be safe, and get your gauge calibrated.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by crx616 &raquo;</TD></TR><TR><TD CLASS="quote">Autometer</TD></TR></TABLE>

we call know how accurate auto meter gauges are.

 

how accurate are there EGT guages?
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by integlspwr2k &raquo;</TD></TR><TR><TD CLASS="quote">

we call know how accurate auto meter gauges are. </TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by N20civicB18 &raquo;</TD></TR><TR><TD CLASS="quote">how accurate are there EGT guages?
</TD></TR></TABLE>

I hear those take forever to register / give you a reading.

 

I'm using a VDO gauge and a GM 3bar map. my readings are slightly off too. map sensor reads about 1-2psi less.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ramennoodles &raquo;</TD></TR><TR><TD CLASS="quote">I'm using a VDO gauge and a GM 3bar map. my readings are slightly off too. map sensor reads about 1-2psi less.</TD></TR></TABLE>

How much boost are you running? Mine was close until it got above 18 PSI, then it got more off the higher I went.

 

there are 3 different gm 3 bar sensors, they all have a different calibration and they are NOT linear. the higher you go the more off they get. they were there to protect against an over boost, not provide accurate fueling for running high boost. remember all the cars gm put those things on didnt run much boost at all. if you actually need to read more than 15psi on ur 3 bar i recomend getting an aem sensor, those are way more precise and have a perfectly linear output

 

You should never trust the map sensor for reading boost. If there is a voltage spike or it decides to short out and only read partial boost then your screwed. Alwasy trust the mechanical gauge. Its taking a direct reading from the engine. Think of the AFC hack. The MAP sensor can only read to about 11.8 or 12psi. Any thing above that and the MAP sensor will still only read 12psi when your boosting alot higher. Look at it this way if your runnign 15psi the stock MAP sensor is only going to show 12psi. You have 3psi unaccounted for that need to have fuel and ignition compensated for. Not very safe.