Ok I built a new motor and have been having problems with it running right with the AEM. Me and my tuner have been trouble shooting it and we noticed the voltage on the map sensor reads 5 volts when I just have the key on the start position. So we figured it was faulty, and tried another one. Same thing. He said that it should not automaticlly read 5 volts when starting the car. So now he thinks there is a short in one of the wires and wants to replace all three wires. Now I need to find out which inputs they are on the stock wiring harness for a '99 Si.

What do yall think? Any ideas?
Also it is the same map sensor that was on the previous motor along with the AEM.

 

Anybody?

 

Well, I'm not sure if I quite know what your talking about, but from what I get out of it, you are trying to find out which wires on the stock wiring harness correspond to the wires on the Map sensor... If that's what your looking for it is:

Wire......................GM Code...................Wire Color

GND..........................A.................... .....Green/White
MAP signal..................B......................... ....White
5V.............................C.................. .......Yellow/Red

I got this from hondata's website, you can check this website out for more info at: http://www.hondata.com/3barinstall.html

hope this helps man.

Later,

Sean C.


[Modified by 20lb.teg, 2:23 AM 10/6/2002]

 

Actually we have it wired correctly. I know the question seems confusing. Actually I am confused by it myself? But the main thing I am trying to emphasize here is that my map sensor is reading 5 volts at any throttle level whether it's no throttle, half throttle, or full throttle! I just don't want to take out those three wires and replace them if someone knows of an easier solution to my odd problem.

 

Come on now.....this is honda tech not superhonda!

 

The throttle position won't matter if you're testing the MAP sensor with the engine off, key on. It should read 2.9 volts key on engine off. If you are indeed checking the correct wire. But I would suspect you're probing the MAP sensor power supply wire which is constant +5 volts. But on the other hand if you are indeed probing the correct wire then your mechanic is correct, you have a short between the signal and power wires, somewhere possibly even inside the ECU or at the connector. Check the connectors first before you replace the whole damn harness. I would say cut the signal wire close to the ECU and the MAP sensor and run a separate signal wire to the MAP sensor. See if that solves the problem. If so you know the short is between the two wires not in the ECU or connectors

 

Ahhh one more thing, I forgot you were using an AEM. I would strongly suspect that the AEM ECU inputs aren't configured correctly or the wiring harness wasn't wired correctly.

 

Well the wiring is actually fine. I ran the 3 bar with the AEM for about a month until I blew a piston. Now i drop in a new motor and I run into this problem. WTF!

 

Well actually the wiring is correct. I ran this 3 bar with the AEM for a month until I blew a piston. Now I drop in the motor and I run into this problem. WTF?

 

Beats me then.

 

Maybe you blew the motor because the aem unit fried on the map sensor area? That would explain both areas?

 

Well damn, that makes perfect sense... Hoe that's not it though man. I am stumped...

Good Luck,

Sean C.


[Modified by 20lb.teg, 1:06 PM 10/6/2002]

 

So nobody thinks there could be a short in one of the wires?

 

Anyone?

 

you can usually check for a short pretty easily by just running through all the wire and looking for a ... well a short.

 

Swap it out with another map sensor for testing. like a 1 or 2 bar, if the same problem is about.

i'd supply 5 V to the signal, and ground it, and check the output at the sensor directly, hook a hose up and blow and suck on it, the output voltage should change.

But i'm unfamiliar with the AEM Standalone.

 

Actually we tried another 3 bar and no luck!

 

did you ever figure your reason for blowing the motor? Running lean? Why? Maybe you did fry something in the AEM unit? Identify the problem, then fix it. Maybe that was your problem then! I don't know what else to say,... except it will probably end up being something simple... the most annoying bugs usually are!

Good luck

 

Well the ECU has been sent back to AEM twice since then and they find nothing wrong. Never the less I just got off the phone with Lawrence (my tuner) and he is going to trace all three wires and try to figure it out. If that's not the problem then I'm selling the unit and going with the Accel Gen 7. He's giving me a great price on the unit and he'll have it runing like stock. I only hope I can still use my FJO wideband with the Accel.