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Tuning & Engine Management EPROMS, ECU, MAF, knock, EGT, wideband, datalogging, fuel trims, etc. Read this Forum's Strict Guidelines.

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Old 12-04-2008, 03:50 PM   #1 (permalink)
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From: las vegas, Nevada
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Possible bad ecu?

Well I ran into a brick wall and need a little help with this. I had my car was running alright back and forth to work with no major issues that were pressing. At the time I was running an EVO3 16G factory PSI, stock injectors, stock fuel pump, FPR from an NA car (10 psi over stock). Car was running alright so I was using it to get back and forth to work for a while (3 months or so) when the CEL came on, downloaded and read P0170. so I hooked up my WB02 and my data logger to see what was wrong, the fuel trims were maxing out and was running a tad lean ( around 15ish at idle same under light cruse) and I looked into figuring out why.
First I thought there was a fuel issue so I replaced the filter and installed a pressure gauge, everything looked ok. For some reason I needed to disconnected the FPR vacuum line and found fuel in it, so I put the factory one back on and ran the car. That made it run even leaner. So I changed it back and it went back to running the way it was before for about a week. on my way into work one day I noticed it started running leaner, and by the time I made it home it was really lean(18-19ish at idle and 16ish at light cruse). I started digging into the rest of the fuel system and replaced the fuel pump, which made no change to the way the car ran. So I installed the EVO8 560cc injectors and ran the car, believe it or not it still ran lean, around 16ish.

Then I worked on installing the E-manage I had to try to get it to richen up. That worked for a bit. It was about a month the car ran good then I pulled the harness to clean it up. Then things went to hell. Somehow my MAF sensor went bad. I guess maybe it was had been going bad the hole time and gust finally went after I cleaned up the harness and drove less than a mile. In the process of trouble shooting I somehow managed to break my BOV. So the wife o.k. me to pick up a MAFT GEN2, some tubing, and a GM sensor. After some time of installing and trouble shooting down to a bad ground I finally got it up and running. By this time I pulled the E-manage and installed only the translator. Now here is my most recent problem, it runs but runs like CRAP. At the moment I have a cel for the TPS and engine temp sensor. I plugged in my data logger and the TPS is showing between 90 - 100% at idle. I have switched out with 5 different sensors and checked all the wiring to and from the ECU. At the moment I think I am at the point where I am going to check the wiring one more time disconnect all the sensors and start plugging them in one at a time and see where I get issues. After that I think my ECU might be bad.

I think I am about at my last option, if any one else has anything I can look into please feel free to ad in your advice.

Thanks in advanced
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Old 12-04-2008, 04:22 PM   #2 (permalink)
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Fuel coming from the FPR is a sign that the diaphragm ripped. Replace your FPR.

The diaphragm uses intake manifold pressure & vacuum to control the amount of fuel returned to the tank. At idle the vacuum pulls the diaphragm allowing fuel to return to the tank on the opposite side of the diaphragm. Now say when your boosting, the manifold pressure(or boost) is then used to push against the diaphragm effectively closing off the fuel return port and in a sense rising your fuel pressure. If a crack or tear occurs in the diaphragm - you receive fuel in the vacuum line from the FPR.

The "stock" boost level of a E316G is 14psi i believe just a little FYI.

16 AFR at idle/ under cruise isn't "Bad" but i wouldn't be extremely worried. You create the most damage leaning out under a load(or in boost) anyway.

Look in the service manual for testing the wiring ( ie: which wire has voltage, which has ground, which is signal, etc.) I'm not that familiar if it's a 2 or 3 wire sensor.
Also turn your throttle plate while watching your logger for change, otherwise you can unbolt the sensor and rotate the piece inside + watch.
I know 1gs read about 11% TPS at idle.
See if you can get a buddy with a known good TPS and try swapping it.

You can also test the Temp sensor with an Ohm meter.

All of the proper way to test these sensors and they're specifications are in the FSM.
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Old 12-04-2008, 06:55 PM   #3 (permalink)
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Quote:
Originally Posted by viprez586 View Post
Fuel coming from the FPR is a sign that the diaphragm ripped. Replace your FPR..
i changed the FPR to a good one after i found it leaking so i know it is good.

Quote:
Originally Posted by viprez586 View Post
The "stock" boost level of a E316G is 14psi i believe just a little FYI.
with the ecu controlling boost it seams to be opening at about 10 psi, and i know it is an EVO3 turbo because i pulled it myself while i was in japan. if that isnt right than something else is screwie...

Quote:
Originally Posted by viprez586 View Post
Look in the service manual for testing the wiring ( ie: which wire has voltage, which has ground, which is signal, etc.) I'm not that familiar if it's a 2 or 3 wire sensor.
Also turn your throttle plate while watching your logger for change, otherwise you can unbolt the sensor and rotate the piece inside + watch.
I know 1gs read about 11% TPS at idle.
See if you can get a buddy with a known good TPS and try swapping it.
i have already tried all this. wiring shows correct so far, unless i missed something. moving the throttle only changes the TPS reading from 90% at idle to 100% at full. even with the TPS removed from the throttle body it makes no differance. and i have changed the TPS with 4 others including a brand new one from pepboys.

Quote:
Originally Posted by viprez586 View Post
You can also test the Temp sensor with an Ohm meter.

All of the proper way to test these sensors and they're specifications are in the FSM.
you are correct, all the proper ways to check these sensors are in the FSM and you can find that info the the net if you look around. problem is i dont have a FSM and i am having trouble finding info on how the check the ECU to see if it is good or not.

sorry if i sound a little beat up on this, i have been chasing my tail untill midnight everynight this week and i normally get up at 5am. so i am a little tired and my head hurts.

thanks for the advice though.

mike
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