Strange problem between main relay, main relay harness, and ECU

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aasarsak

aasarsak

New Member
I have been scourning the internet and this site for an answer, and I haven't been able to find one. Her is the situation:

Normally, when I turn the key to position 2 (ignition run), the yellow check engine light comes on for about 2 seconds, then it clicks back off. Normally, I hear the fuel pump humming as it primes the fuel lines during this 2 second period. Recently, I installed a Neptune RTP equipped P28 ECU from this place called xenocron.com for an OBD0 - OBD1 conversion. Ever since I installed the new ECU, 2 things have happened.

1. I have a CEL code for ELD. I have no idea what ELD or how to diagnose the problem. I have replaced the ELD, yet I am still getting the code.

2. The CEL no longer comes on for 2 seconds when I key the ignition on with the engine off (KOEO). Also, I can't hear my fuel pump priming the fuel line before starting the car.

The car starts and runs fine except that sometimes during long freeway trips, the fuel cuts out. I can tell because I have a wideband sensor and it goes to full lean and I can feel the loss of power. If I press the gas pedal in a little bit, it goes back to full rich and it resumes running stoich until I go back to constant throttle cruising.

The fuel cutting problem has been going on since before I did the OBD conversion, so I don't know if any of these problems are related.

The EF service manual gives troubleshooting steps to check the main relay harness. Following the procedures, I found that putting a jumper wire between the #5 and #7 ports of the main harness cause the fuel pump and the CEL to activate when the KOEO.

I followed the recommended procedures for troubleshooting the main relay and it appears to be fine. I thought maybe I performed the troubleshooting incorrectly, so I went ahead and bought a new one anyway, and the problem is still there.

Due to the fact that the fuel pressure regulator indicates constant fuel pressure combined with the fact that the fuel pump activates with the jumper wire on the main relay harness, I have eliminated a faulty fuel pump a a possible culprit.

The only thing left that I think might be causing the problem might be the ECU, but I can't figure out how to diagnose a faulty ECU, or if I have made a mistake somewhere during my troubleshooting process.

Anyone have any suggestions?

Oh, my setup I think is irrelevant to the situation, but here it is just for reference purposes I guess:

89 civic si
b16A
OBD1 conversion
innovate LC-1 wideband kit
drag t3/t04 turbo kit (FMU and MAP bypass removed)
NEPTUNE RTP with P28 (tuned by Church Automotive in Long Beach, CA)
walbro 255lph fuel pump
stock b16 injectors
B&M FPR
 
ok looking at your setup, turbo tuned and using a fmu? for what purpose? why are you still on the stock injectors.

My guess is your peaking out your stock injectors. I dont care if your running less then 5 psi, boosting any car and not upgrading the injectors is just dumb.
 
where did I say that I was running the FMU? I removed the MAP bypass and the FMU. I don't need them any more because I'm tunable now with Neptune RTP. My injectors are not peaking. I had it tuned on a dyno with a wideband in the tailpipe. My mixture is stoich all the way to 7,000 RPM making 200 WHP. Stock injectors are capable of delivering up to 50 WHP per injector buddy. My tuner recommended upgrading if I wanted to turn up the boost, but I'm only running a .5 bar spring.

Why are you flaming? You obviously don't know anything about tuning or calculating the maximum fuel delivery capacity of factory fuel injectors. If you DID know anything about tuning, you would know that if you turn up the fuel pressure, you increase the fuel delivery. Yes, my injectors are near their peak, but running injectors near their peak does not necessarily mean that my injectors are peaking out.

If they WERE peaking out, the fuel would be cutting out at higher engine speeds where the fuel delivery demands are much higher. At constant throttle, constant speed on the freeway, I'm not exceeding any more than 4,000 RPM. Do you even comprehend the problem I'm describing to you? This is happening when the motor is under ZERO boost! The turbo will only produce boost when it is under a load or accelerating, not when it is at cruise speeds with no load on it.
 
first off Im not flaming, if you want me to be an asshole I can be. You a fucking moran if you think that 240cc injecters will properly deliver fuel to you motor. Your faulting out your injectors by running them so hi. You can crank you fuel pressure up all day fo all I care.

O and so you know 3200 rpm is the start of high cam setting. Dont act like you know what your talking about when you have no clue what so ever.

Go fuck yourself and blow your motor for all I care. my d series will blow the doors of your POS b16 all day long
 
I know it has been a long time, but my tuner helped me find the source of the problem. Turns out, the TPS setting in the ECU was off by a few volts. I went into Neptune and lowered it a little. Problem fixed. Turns out that the fuel was cutting out because I was applying too little throttle. Even though I was pressing the gas pedal, the ECU wasn't detecting any change in throttle position at low throttle pressure because the TPS wasn't dialed in correctly. Go figure... :doh:
So I went ahead and dialed it in properly so it actually reads 0% throttle when there is no pedal pressure, and 100% when the pedal is on the floor. Before, it was indicating about -2% when there was no pedal pressure.

Sorry about the confusion before. I hope you didn't get the wrong impression, but I appreciate you trying to help me. :thankyousigna2:
 
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