Ok. my other topic talked about how i was having problems with this civic at school. it runs like **** stubbles on accl. miss fires. so we finally figured out what we think it is. We believe its the MAP sensor because EVERYTHING else checks out ok other than the misfires, but we changed dizzys and no change so its not the dizzy. Anyways. i scoped the whole car and sensors and found that the map sensor is only getting a 4.1v reference. and when we hook up a scan to to the car it shows that the MAP sensor is only getting 8Hgs of Vacuum, where we measure it at the MAP port with a gauge and it says 20Hgs... so i checked the wires to the MAP and all are good. Actually back probed the ECU where the MAP comes out and also get the 4.1v reference. I thought it was the ECU so swapped my ECU from my car in there and no change. my ECU also puts out only a 4.1v Reff.... we are dropping a volt someplace and can not figure out why. i checked al the engine grounding points and also the ECU ground on the Thermostat housing.. no dice. HELP!!!

 

Bump

 

tps, iat have a 5v ref?
what year ,model? have u done load testing? probably not so i'll tell u how. unplug both ends of the circuit (ecu and map sensor). get a headlamp bulb (or even a testlight will work). hook one end, say the ecu side. use a piece of wire or a paper clip to prob the pin and connect it to a ground. preferably bat. ground. hook the map side to power. see how bright the light is and see if it flickers or dims. u can also wiggle the wires while watching the bulb. if your not sure how bright the bulb is supposed to be, hook it up to bat. pos. and neg. if i find an open or short, alot of times i'll just run a new wire, unless there are more than 2 involved. what school are u going to?

 

Bump anyone else?

 

wire to MAP is good not shorting out or open. if it was open there would be no voltage. shorted out would show a increase in resistance in the wire and there is none.

 

no one huh?

 

tried swapping in another map?

 

yep swaped the one off my car into it.. no change

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95DxSi-R2 &raquo;</TD></TR><TR><TD CLASS="quote"> what school are u going to?</TD></TR></TABLE>

 

Seek help here:

copy and paste into your address bar

javascriptpenim('send',%20999297933);

 

I go to Elkhart Area Career Center currently and am NATEF Certified in breaks and steering and suspension, soon to be engine performance and electrical. I placed first in our SkillsUSA regional’s competition and am going down to Indianapolis for state competition. I am also working on some ASE certifications. I however have been accepted to Ferris State for Automotive Engineering and will start there next Aug.

Who is ee_chris and why should i seek help from him? Just wondering? has he had this problem?

 

http://www.natef.org

http://www.skillsusa.org

For thos of you wanting to know more info on them.

 

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

copy and paste into your address bar

javascriptpenim('send',%20999297933);</TD></TR></TABLE>
he does know his ****.

the reason the ECU thinks there is 8hg at the manifold is the MAP doesn't have the right reference voltage to send the ECU the right signal.
My guess.... grounds.
the ECU puts out 5V ref for the TPS and MAP. if it's low usually it's a sign that your engine ground is not secure.
It could also be a sign that the output from the ECU is loaded down badly. If it remains at 4.1V even with the MAP and TPS unplugged, search for cuts in the wires.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Relic1 &raquo;</TD></TR><TR><TD CLASS="quote">
My guess.... grounds.
the ECU puts out 4V ref for the TPS and MAP. if it's low usually it's a sign that your engine ground is not secure.
It could also be a sign that the output from the ECU is loaded down badly. If it remains at 4.1V even with the MAP and TPS unplugged, search for cuts in the wires.</TD></TR></TABLE>

So wait.. are you saying it should only put out 4v? or it should be putting out 5v and you just mistyped?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMKid71 &raquo;</TD></TR><TR><TD CLASS="quote">

So wait.. are you saying it should only put out 4v? or it should be putting out 5v and you just mistyped?</TD></TR></TABLE>
sorry... I fixed it. I have fat fingers tonight. I also added a few other comments to the post.

 

haha its all god.. just sacred me there for a second. haha ill ask him later tonight and tell him the situation hopefully we cna get this worked out

 

Alrigt.....

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Relic1 &raquo;</TD></TR><TR><TD CLASS="quote">.........It could also be a sign that the output from the ECU is loaded down badly. If it remains at 4.1V even with the MAP and TPS unplugged, search for cuts in the wires.</TD></TR></TABLE>

loaded down badly like to much voltage to the fuel pump?

we pulled the fuel pump on firday before we left and it was FUCKED. We did a fuel pressure test on it and it was Fine at idle.. but once the engine got a load on it, the fuel press would die down to like 10psi... so were going to change that out.. but could the 4.1v be freom the ECU being over loaded trying to get that fuel pump to work right? maybe not? just popped in my head when you said that.

 

I highly doubt that is it. the ECU switches on the main relay which controls the fuel pump. It draws its power directly from the battery at that point.
Even with the battery at 8volts the ECU should put out the 5Volts needed for this. Logically it should be ok down to 5.5Volts but I don't know how the internal power supply of the ECU is designed so I'm not going to speak for it.

 

well, we will put this pump in and see where were at. this fuel tank is most deff one of the nasty tanks i have ever seen. its got that rust, dirtty look to it and looks like some sort of real real real light soft clay build up. its sick. the pump is deff messed up. the sock thats on the end of the pump was almost black because of all the build up.

 

if the tank is that bad save yourself replacing the new pump in a few months. Clean out the tank, or simply replacing it may be easier.

 

yeah we cleaned it out also