ECU Question

[ThatOneGuy]

In reference to this thread:

zerothread/159644

I'm having a similar problem in which when I turn on my car the fuel pump does not come on and it won't start. After reading that thread I figured that my ECU was bad and so I took it out to check and see if anything was burned out. Nothing was and so I stuck it back in and everything seemed to work. I took it for a short drive with no problem.

However, just a minute ago I was driving it and it stalled out and now the same thing is happening again (no fuel and no start). I'm not sure whether or not my ECU is bad because sometimes it seems to work and sometimes it doesn't. Is there a definitive way to check and see what the heck is going on here? I'd like to know if I need to get a new ECU or if it is something else entirely. Thanks.

By the way, I know for sure that it is not my actual fuel system that is the problem.

[ThatOneGuy]

Here are some follow-up observations:

Last night I unplugged my batter so that the ECU could reset overnight. This morning I plugged it in and cycled the key in the ignition a few times and finally after about 10 tries, the ECU started working and I could hear the fuel pump. After that, I cycled the key a few more times and every time everything appeared to work. I started the car, raced the engine a few times and it died and now the whole thing is back to square one.

Also, whenever everything is working right, the ECU waits a few seconds to turn off (as can be seen from my AVC-R and SAFCII) when I turn the key off. However, whenever the problem is occurring the ECU (and AVC-R and SAFCII) turn off immediately when I turn the key to "off". So, still not sure what to do, still not sure if I need a new ECU or if it's something else, and still not sure how to check and see (definitively) what is causing problems.

Thanks.

[ThatOneGuy]

I wanted to add one more thing about all this that I'm not sure why I didn't mention before. This kind of all started happening shortly after I connected the second air flow input line of my SAFCII to the O2 sensor input line of the ECU. I did this so that I could try and monitor the voltage being produced by the O2 sensor. After I connected it, I drove the car about a mile and thats when it stalled out and started giving me problems. I'm not sure if that matters or if it's just coincidence but I figured I should mention that I did that.

In addition, I tested the power going to the ECU today as well as the grounds and everything seems to be all right there. The functionality is still on and off with significantly more down time than up.

[ca18detpowered]

sounds like you maybe dont have your computers harness sunk into the socket correctly. I had that problem with my ca...turned out i had the harness sitting crooked

[Blown240sx]

Then logic would say disconnect the second MAF wire from the 02 sensor sense its a Narrow band anyway and you wont get any useful info from it.

[SpeedRacer1]

Could be a few problems. I would highly not suggest connecting that second safc wire to the O2 sensor. It wont read anything useful and is probably messing up the SAFC circuitry. My roomate had an issue with the SAFC randomly resetting itself and causing the Input and Output signals to reset but that wouldnt explain the fuel issue. If the AFC, AVCR, ECU, and Fuel pump have problems then there could be something wrong with the main power wire or its related circuit. Perhaps it is not connected well and has problems under conducting.

If the engine manages to start and run with the ECU still, even if only some of the time, then the ECU shouldnt be the problem.

[ll SR SILVIA ll]

I HAD THE SAME PROBLEM WITH MY ECU BUT INSTEAD OF STALLING INJECTOR 3 WASNT GETTING ANY SIGNAL. I THOUGHT IT COULD HAVE BEEN A BAD ECU BUT WHEN MY BRO OPENED IT UP, IT WAS OK. WE THEN TESTED FOR CONTINUITY WITH HIS POWER PROBE. PUT IT IN AND IT WORKED. NEVER HAD ANY PROBLEMS SINCE. WE COULD ONLY THINK THAT 1) LIKE SAID EALIER, U HAVE YOUR ECU CONNECTOR NOT ON STRAIGHT OR 2) U MAN HANDLED THE CONNECTOR INTO THE ECU AND HAVE EITHER BENT OR BROKEN A PIN.

[ThatOneGuy]

I have since disconnected that second MAFS wire and today I'm going to try and test out several sensors such as the CAS, MAFS, and other things that would maybe cause the ECU to shut down and need to be reset. A buddy of mine told that that might be the problem so I'm hopeful.

As for having the connector plugged in wrong, I'm pretty sure that's not the problem. I checked all the pins and they're all intact and I made sure to plug it in straight and screw it down tight.

Hopefully it's a sensor that I haven't checked and I'll be able to figure it out. I'll let you know if I do but still any input anyone still has would be great. Thanks.

[ThatOneGuy]

I'm checking my sensors and I'm reluctant to take the CAS out and test it so I moved on to other sensors and I'm not getting a reading on the coolant temp sensor. The manual says that it should read something like 2.1 - 2.9 ohms when at around 28 Celsius (68 Fahrenheit) and I'm just getting a reading of no continuity. Is the coolant temp sensor something that could be causing the car to not run? Is that something that would trigger the ECU to not function and need to be reset? Thanks.

[mrzabala]

Sorry if this is off topic but I dont feel like making a new thread so Ill ask here. Will a ecu #63 for a redtop sr20det work with my redtop sr20det with a manual transmission with no problems? Thanks and sorry for the thread jack

[Blown240sx]

Yes now learn how to search and dont thread jack.