Bad ECU, or PCM?

1996Eclipse420a · 05-31-2012, 07:48 PM

So, after a few weeks the "sudden" loss of power is back. It only happens at the snap of a finger... and it regains power. when it happens the radio, and other electronics aren't effected at all. So, could it be the PCM? I find that if I unplug the batter for a while, and hook it back up the problem goes away for 3-4 weeks.

9SECAWD · 05-31-2012, 07:51 PM

Bad ecu will usually give you more problems than that.

1996Eclipse420a · 05-31-2012, 07:54 PM

well, what else could it be? it acts like it's grounding out somewhere in the motor... but it's not. I've traced the wires and everything. So, I don't understand why it goes away after I reset it.

9SECAWD · 05-31-2012, 07:59 PM

By loss of power do you mean the motor shuts down for a second?

96' Eclipse GS · 05-31-2012, 08:05 PM

Have you checked out the possibility your (Charging System) is functioning correct by chance?

1996Eclipse420a · 05-31-2012, 08:05 PM

yes, I mean it loses power for like 1 second. It's hard to describe. It comes straight back though. It can happen up to 3 times in a row. The computer isn't throwing a code, because it isn't a misfire. It's like a loose connection. I've ran a data streaming tool to it and when it loses that connection, it shuts the data stream tool off, and it resets.

jayson427 · 05-31-2012, 08:06 PM

does your check engine light come on? have you done routine maintenance to your car? it could be a few different things.

1996Eclipse420a · 05-31-2012, 08:06 PM

Hey, Omar... I can unhook the battery while it's running, and it runs just fine without it. I'm guessing the alternator is fine, if not then the car wouldn't run... right?

9SECAWD · 05-31-2012, 08:07 PM

does the car spit or sputter, backfire or any crazy stuff like that when it does it? any relays clicking under the dash or anything?

1996Eclipse420a · 05-31-2012, 08:08 PM

jayson427, my check engine light is on.. but for a bad speed sensor... so it stays solid all the time. when this loose connection happens, the light flashes off, but goes right back solid again, until it has that connection issue.

@ 9SECAWD... when it pulls up hill, it jerk the car when it happens... but you can't feel it going down hill. it doesn't backfire or anything.

@9SECAWD and also the relays are good.

96' Eclipse GS · 05-31-2012, 08:20 PM

Yes, the car will run fine without the battery connected for a short while. What you should have listed in the first post is your CEL is on...

Now, this changes the game up.

What exactly is the (CEL) code?

1996Eclipse420a · 05-31-2012, 08:26 PM

I stated above that's it's for my Speed Sensor lol. I should have pointed that out, but that's it. nothing special.

also, I didn't mean to sound like an ass. sorry

Maybe I can clear it up a little. When, I'm driving, it's like the car loses connection to the computer... but gains it back instantly. The electronics in the car don't shut off, neither do the headlights, or interior lights.... so, im about stumped.

DSMinit4life · 05-31-2012, 08:39 PM

A ecu problem will usually throw a few codes, if you check ohms/resistance on coded sensors and they are in spec most likely you have a leaky capacitor on board, ecm tuning has very reasonable cost and will tell you anything else wrong with computer. Give wireharness a good look over. "multi meters are your friend". Check for shaft play. sad to say could be alot of things... good luck keep us posted.

96' Eclipse GS · 05-31-2012, 08:41 PM

No need to apologize, your fine. Thank you though. This however will sound like an ***, what are the four #'s in front of the letter "P." I will try to help, but as you can see I only give what I can with what I have to work with....

DSMinit4life · 05-31-2012, 08:48 PM

N/T sorry when a turbo expescially a large turbo develops shaftplay the propeller will rub housing and couse the car to bog down for a sec. post of wasted space I know sorry....

1996Eclipse420a · 05-31-2012, 08:57 PM

P0501 is the code it throws for the Speed Sensor... if that's what you're asking

if not, then explain a little more please.

96' Eclipse GS · 05-31-2012, 09:16 PM

Now, that we have some ground work laid out. I can give some direction to go on, I should have asked this question before, but is the vehicle a Auto or Manual?

With that said, I would start by fixing the (CEL) code P0501 first. You will need to fix it with time, so get it out of the way now. Then move on to what I would run run along (ECM's) harness and ensure that the harness is correctly connected to the (ECM). If everything checks out fine, then I would start on the problem not being electrical, but Mechanical, like a vacuum leak causing the power surges.

1996Eclipse420a · 06-01-2012, 08:15 AM

hey, omar. sorry for the long wait. it's a manual bud. plan on going turbo soon, but wanna get everything worked out before I start putting money into it.

also, what's the best way to check for vacuum leaks?