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Help me Diagnose a wierd problem

Struc

Well-known member
Joined
Nov 24, 2008
Messages
764
Location
Oconomowoc, WI
As a short term solution, I had a circuit breaker in place of my fuse for my trunk mounted battery. Yesterday, while coming to a stop, my battery shifted and pushed the “test” button on the breaker, thus removing connectivity to the battery. The car jerked, I heard the MFI relay snapping on and off several times. Eventually the car died. Figuring out what had happened, I reset the breaker, and started the car.

It started and idled fine, but upon ANY kind of reving, or trying to get power, there was none. I could keep it running by feathering the gas pedal, but couldn’t put hardly ANY strain on the engine – couldn’t even get it into 2nd gear. It felt like I had blown an intercooler hose off, but that wasn’t the problem. I checked SAFC readings, and I was getting a good MAF signal, as well as RPM, TPS, etc. The A/F Gauge that came with the car showed it was running off the scale lean almost all the time, which perhaps explains the running condition.

Got it about 1.5 miles back toward home, all the while it was about to die, and came to a hill I couldn’t get the car over. I came back after about 45-minutes with a different ECU – no help. Came back another 2 hours later with a friend, and towed it home. Upon getting the car home, it was running fine. I “pull started” it on the way home so I had vacuum for brakes, and as I was being towed, I realized the car was running fine. I was able to pull it up into the garage, and today, was able to go out and drive it like normal – NO symptoms remain.

My only guess as to what happened is that the MFI relay got screwed up some how and wasn’t getting enough power to the fuel pump. Any other ideas? I’d really like to have an idea of what happened so it doesn’t happen to me again farther from home. My only other remote idea is a fuel filter issue, but it doesn’t match the electrical issue that started the whole problem.

Specs for 56/1000 are: 2.3l, stock head, ETS FMIC, EVO3 16G, 2G MAS, 560CC EVO injectors, Stock GVR4 ECU (soon to have a Keydiver chip in it), SAFC 2.
 

toybreaker

iconoclast
Joined
Apr 30, 2006
Messages
3,581
With the breaker open, you were running on the alternator.

Did you happen to notice what the voltage at that time?

It's quite possible the alternator/voltage regulator didn't like the sudden change in load, and now it's got some issues.

It might be a good idea to check the charging system out thoroughly before going to much further troubleshooting a running condition... /ubbthreads/images/graemlins/dunno.gif
 

Struc

Well-known member
Joined
Nov 24, 2008
Messages
764
Location
Oconomowoc, WI
I realize I was running on the alternator, and without the battery as a buffer, all kinds of wierd voltage spikes or other wierdness could be happening. I don't have a volt meter in the car, so no clue where it was at. No issues with the charging system at this time - everything checked out. I also NOW have my fuse back in place of the circuit breaker. /ubbthreads/images/graemlins/grin.gif
 

1990ggsxnj

Well-known member
Joined
Nov 21, 2008
Messages
525
Location
Blackwood, NJ
Don't have any idea what could have happened besides the voltage spikes. What's so bad about having the breaker anyways? I have one on top of my battery without any problems but is this not a good idea for some reason?
 

Hertz

Staff member
Joined
Jul 29, 2002
Messages
13,501
Location
Chicago, IL
Fuses don't have buttons. /ubbthreads/images/graemlins/smile.gif

Could have also been a warm-start problem... a rather common issue.
 

1990ggsxnj

Well-known member
Joined
Nov 21, 2008
Messages
525
Location
Blackwood, NJ
Gee thanks Ryan /ubbthreads/images/graemlins/tongue.gif

Pinpoint anything over the holiday?
 

prove_it

Well-known member
Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
If the ecm lost power then all your fuel trims and idle learn was reset. The computer may have needed some time to readjust fuel trims. Hence no power, and running lean. That could explain why it got better.
 

656of1000

Well-known member
Joined
Jan 18, 2005
Messages
292
Location
Phoenixville, PA
Even with the fuel trims reset, the car should still have enough power to go up a hill, or even into 2nd gear for that matter. When you realized the car was running better, were you back to your origonal ecu, or were you still trying the other one? I had the very same symptoms as you the last time I hosed down my motr- I got something wet I shouldn't have. Perhapse a voltage spike caused a similar end result, like something shorting, or a sensor signal overpowered.
 

Struc

Well-known member
Joined
Nov 24, 2008
Messages
764
Location
Oconomowoc, WI
I believe it was towed home with the other ECU in it, but earlier that ECU had no effect.

I never did find the problem. The car has been running flawlessly every since the episode. I'm going to blame it on a random voltage spike that temporarily screwed up "something" electrical, which eventually the "charge" it had wore off. I can't come up with anything better than that. I drove the car a good 75 miles today, and quite a bit over the long weekend, and all is well.
 
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