Help! Phantom electrical problem!

[Number996]

Thanks to Toybreaker's help, my Galant was ready. I put her on the ground and was letting her warm up before taking her out for the first time. Then, my friend bumped the ecu (was on passenger floor) and she died immidiately then there was a backfire and some electrical sounds like sparks from the engine bay.

Now, when she cranks there is no signal to the spark plugs. I know this because I had my friend hold a timig light while I cranked her; no flash.

At first, when I tried cranking her immidiately after she died, the stock boost gauge would light up when key was in on position but the CEL would not. After unplugging and replugging in the ecu (and bolting it up) the CEL will light up when key is in the ON position butthen goes off. If I crank her the CEL will go off and stay off.

When she was starting fine and idling the CEL would be on and stay on.

The only peculiar things to happen before this were; while pulling on thermostat wires to get ready to rewire the engine coolant temp sensor, there were some electrical spark like sounds from driver side front engine bay area, I couldn't make it happen again so I continued. Then, I heard some more of the same electrical sounds while using a multimeter to isolate the correct wires for coolant temp sensor. These were the same sounds that occured right after she just died in mid idle rigt after the backfire.

Ecu was also opened to inspect for damage. None that I could see.

All fuses good.

Please guys, i'm at my wits end. Thanks

 

[Number996]

Also, I plugged in the old ecu and same thing.

The old ecu is burnt from something on it frying. But the car still started and drove with it before the rebuild but I wanted to replace it so I did.

 

[toybreaker]

... damn thought you had it whupped! /ubbthreads/images/graemlins/banghead.gif



After you're done slapping yer "friend" (don;t let them bleed on anything important), it might be best to just close the doors and go drinkin.


Tomorrow, you can start checking things out, slow and logical like.


Double check the fuses,

... don;t just look at them, check 'em with a meter.

The ones on the positive battery terminal can be checked on the "volts" setting, just open the little side flaps on the terminal box, and meter both sides of the fuses there. (the black lead of the meter on a good ground, and check each side of each fuse with the red lead, one at a time.)

Check the other fuses by touching their test points (the two little metal tabs visible on the top edge of each fuse) with the red lead while the black lead of the meter is on a good ground Be sure to check both sides of each fuse.


If that all checks out, then it's time to check things down at the mpi relay and computer harnesses connectors.


Sorry to hear of your continuing problems, but you'll be boosting soon enough. /ubbthreads/images/graemlins/smile.gif

 

[Number996]

I didn't sleep. Checked fuses. All good.

I was hoping it was all just a bad dream. Nope. Not that lucky

 

[toybreaker]

What kind of shape are the ecu grounds in? (they're up on the "a" pillar)

Did you have them firmly connected when this first happened?

 

[Number996]

The ecu was plugged in right. When inwent to check if nice and tight there was a click like it was snapping into place but my index finger was on the actual clip on the top and it was already in place and disnt move when i heard that click. The plug couldnt be any more into the ecu. Plug pins in ecu look normal no black burnt markes. Plugs look fine, the same.

I have to vfaq where the grounds are for ecu and how to test relays and their locations and i don't know what or where the ''A' pillar' is

You can call my cell phone if you have a couple minutes. I'm in the garage wih the car now. Continplatig making another cup or settig the galant on fire. Hm

 

[toybreaker]

Sean, sounds like you may want to look at the ecu grounds.

I can't honestly remember where the ground leads "come" from, but they both end up under one of the mounting bolt/nuts for the ecu case.

They need to be firmly attached for the ecu to work properly.


Could someone shoot a quick pic of the area, please?

Thanks!

 

[Number996]

I found the ground wires. They are firmly grounded

 

Sean,

I once had a similar problem on my bimmer racecar. I was constantly pulling the ecu out to change/try different chips when I put a new (larger) motor in it. At times it would run, then not run, or run and die. Since I had just replaced all of the sensor on the new motor with new ones, I couldn't believe I had a bad motor sensor. What I found was that the circuit board itself had a wire "ground" (I assume) to the ecu "frame" that had broken off at the board. It was a little stranded wire that I couldn't see unless I really looked - and pulled the board out of the ecu. I'm not sure if the Mitsu ecu boards even have a grounding wire - being a newbie, I'll be pulling my ecu out in a few days to replace the capacitors. Maybe some of the more knowledgeable folks on the forum can chime in here as I might be totally off-base with the Mitsu ecu configuration. Just a thought anyway. . . Good luck and let us know how this works out. I have a feeling lots of us may end up chasing the same phantoms!

Wayne

 

[Number996]

Everything is grounded. All fuses good. All fusable links good. Ecu was removed and re inspected and cant find any signs of malfunction.

What would cause the car to suddenly die at idle, backfire once, and prevent the galant from restarting. Crank but no spark.

When key is turned to on position, turbo gauge lights up at zero (half) and CEL lights up for 5 seconds then turns off. Cranks but no spark.

 

[toybreaker]

Quote:
When key is turned to on position, turbo gauge lights up at zero (half) and CEL lights up for 5 seconds then turns off.



That's good news, as that's exactly what supposed to happen.

The cel on is a selfcheck, when it goes off after a bit, that's a good sign!


Sean reported in by phone that it's running again! /ubbthreads/images/graemlins/applause.gif


It sounds like you may have gremlins in the wiring harness/connectors.


Remember, the your initial no-start was caused by damaged wires for the ecu coolant temp sender down at the t-stat housing.

It's quite possible that other wires in the engine compartment are also heat damaged and/or bodged.


The ones up at the cas deserve to be looked at very carefully[/i]

In addition to the problems with heat baking the harness, people hack into the harness there for their maft/translators.


Inside the cabin, folks often hack the ecu harness for a safc and/or other whizz bang shitarree, so be sure to inspect the harnesses there for "tells".

They also remove turbo timers/alarms, and leave behind a hacked ignition harness, so be sure to drop the lower dash on the drivers side and inspect the ignition harness carefully.

Lastly, the fact that this whole thing started when the ecu was moved may mean that someone may have deformed/spread open some of the contacts of the ecu connector terminals poking at things with a sharp stick.


If it dies again, try wiggling the individual connectors to see if it localizes to just one.


Good luck, and keep the thread updated with your progress!

 

[Number996]

Thanks toybreaker! You're help has been infinitely appreciated.

As toybreaker said, the engine coolant temp sensor was mis wired by previous owner. This caused the engine to start with the ecu thinking it was -40F outside, causing fuel to dump into the engine. After rewiring correctly, the gas/oil mixture in the engine was since drained and refilled twice.

The entire wire harness has been examined. I have determined that when she died and wouldn't restart was a result of me testing continuity and bending a couple connectors in the wire harness. Not so much bent as much as i pushed the black spacers in the connector back into the connector with a multimeter pin and negkected to move them back. They were reseated in correct position and the car starts up fine.

Now, and keep in mind she is running off a 2g MAF, all would be fine until she decides to throw these random fits where she will jump in idle to 2k or 3k rpms. When she does this, if i open the throttle she bogs out. Preventing me from goin anywhere if i'm driving around the neighborhood.

Because all electrical was inspected, this leads me to believe it's the MAF.

SO i deleted the MAF and replugged in the HKS VPC that came with the car. The engine idle sounded worse and when i drove her she would cut out and fall on her face at 4k rpms. I then deleted the VPC. Also, the VPC is plug and play no hacking up the wire harness.

She is now running with NO maf and NO vpc and she seems to drive great minus some bucking in low rpms. Keep in mind the engine IS timed so ignition shouldn't be advanced. When grounded to dignoses mode, timing sits at 5 degrees. When taken out of timing mode she jumps around at 9-13 degrees. She idles at 1k rpms aith biss one full turn outward

Any help is appreciated guys, thanks. Sooo close to being done then i get to go into the regestry hoorah!

 

[turbowop]

I replied to your other thread about the maf/vpc issues.