Why can i only reach up to 86 map kpa!! ?? help?

[deathtrapmiata]

I cant figure out what it is...
- Key on / engine not on. MAP KpA gauge reads 86.....barrometer = 99-101
- engine running (idle) = 21-25mapkpa. thats always been like that, even when i would see the right map kpa

- i noticed it while watching my fuel maps while driving. at wide open throttle i only see 86. not a bit higher, its making VEAL throw in crazy rich values in the 80's and making crappy fuel maps.

help please

[Matt Cramer]

What sensor type are you using?

Can you post your MSQ?

[deathtrapmiata]

What sensor type are you using?

Can you post your MSQ?

here it is.
4 bar sensor. i think

[Matt Cramer]

The MSQ is set correctly. What is your MAP sensor voltage with the key on and engine off?

[deathtrapmiata]

The MSQ is set correctly. What is your MAP sensor voltage with the key on and engine off?

how can i tell the voltage?
is this with the ADC gauge displayed in TS or do i need to go get some diagnostics tool to measure it?
also it works; the gauge reads vaccum and @ full throttle map kpa rises to 86 and always 86!
its just like its working but not to the full range.

[Matt Cramer]

Measure the voltage on pin 1 of the MAP sensor header. You'll need to open the case.

[deathtrapmiata]

Measure the voltage on pin 1 of the MAP sensor header. You'll need to open the case.

i will have to get a voltmeter from my local electronics store.
I appreciate your help, and will get that to you as soon as tomorrow morning.

[TheSilverBuick]

Never mind, I didn't see the baro info.

[deathtrapmiata]

Never mind, I didn't see the baro info.

Yea, thats another thing??

The barrometer gauge is perfect in TS.
what gets the barometric reading if the sensors that are in the engine bay (Intake side) are NOT being used by the mega squirt?

Also Matt, I finally got a voltmeter from radio shack today, i took out the ECU, and took the 4 screws off the case and lifted up the white metal cover.
I have never done any thing with circuit boards or used a voltmeter in my life.

So i plug in the red and black leads, and turn the voltmeter to 15 DCV?
then were do i touch them to get a voltage reading?

[Matt Cramer]

The barometric reading is a separate sensor.

Check the voltage on pin 1 of the U2 header - that's the lowest pin of the 6 pins sticking up next to U8 on the main board.

[deathtrapmiata]

The barometric reading is a separate sensor.

Check the voltage on pin 1 of the U2 header - that's the lowest pin of the 6 pins sticking up next to U8 on the main board.

ok, I probably seem dumb enough already, but here is what i see.


can i touch one of these with the leads or do i have to take all of that part of the board off the bottom of the case.
and use the body of the green board that says mapdaddy on it?

i dont have the tools small enough to get to the tiny little nuts off the bolts that fasten it to the case

[Matt Cramer]

You have the numbers backwards; check the voltage on the pin with the red circle around it.

It is OK to probe this with the ECU powered up.

[deathtrapmiata]

You have the numbers backwards; check the voltage on the pin with the red circle around it.

It is OK to probe this with the ECU powered up.

Matt,

I spent the rest of my evening last night removing the seat so I could get leverage on the ecu, Then i took half of the ecu apart to get to were I could see the sensor.

When i probed the sensor i got no voltage. The ECU SHUT OFF!, then comes back on and my fuel pump primes like i just turned off the key and back on again.

needless to say i was running out of time, i plugged in to TS with no vacuum line on the sensor and still got 84 map kpa. sometime it says 86 map kpa when i re-set it.

i accomplished nothing because i had to go back home, so i just had to put it back together and re-assemble my interior and ECU. it sucks because this is my only car, i cant just have a non-running car for 2 weeks to send it off to get a new sensor put in by DIYautotune.

there is actually a pretty good PC repair shop here in town. the guy claims he is very skilled in soldering and circuit board repair/custom computer building etc...
**Here is the deal....I only will only end up running about 9psi of boost once i get this issue straightened out. I don't really think the 4-bar sensor is even necessary other than it may have more resolution??
and the 2.5 bar map sensor is a fraction of the price, the 3 bar map sensor is cheaper too.
i noticed that the 3 bar is wired...would this be easier to install? or is it also soldered to the circuit board? and would the 3-bar still require me to remove the map daddy?

[Matt Cramer]

It sounds like you accidentally hit something that shorted 5V to ground while probing. Pretty easy mistake to make but generally harmless.

If you went with a 3 bar MAP sensor, you'd still need to desolder the MapDaddy, plus you'd need to set up the external wiring.

[deathtrapmiata]

It sounds like you accidentally hit something that shorted 5V to ground while probing. Pretty easy mistake to make but generally harmless.

If you went with a 3 bar MAP sensor, you'd still need to desolder the MapDaddy, plus you'd need to set up the external wiring.

so there will be the 6 holes there when the map daddy is taken off.
then three wires from the GM3bar will go into the hole that the vacuum line was coming out of, and they will be soldered on to the first three pins. the map sensor will be right beside the ECU and connected to my vacuum line that is behind the seat.

is this correct?

[deathtrapmiata]

I ended up getting a mpx4250 map sensor, good for up to 21psi for 20$
my local computer repair shop removed the map daddy and soldered in the new sensor for about 30$
connected the vaccum line, and its working perfectly!
99 mapkpa at KOEO, and with my new supercharger its measuring everything effectivley.

just had to switch pro. properties, the map setting in engine constants, and turn off baro correct. also switched the check box " extra map fitted to X7"