dies on highway, now wont start

[boostedgsx95]

Earlier today my CEL came on everynow and then for maybe 5 seconds and then went away.(mainly on deceleration in gear) I went home, grabbed dsmlink and went for a little cruise. Everytime the cel came on, it wasnt on long enough to register in the DTC's. But when the cel came on, the logging screen would freeze, and it would backfire a little bit, and my rpm tach would drop 1k rpms or so. So i jump on the highway heading home and i get to 75mph and the car "dies." But its weird bc i could still hear my exhaust and everytime I hit the gas the car wouldnt do anything. It would sound like the rpms would go to 2k maybe, then just drop to 0. But the rpm's wasnt moving from 0. now i towed it home and it just cranking. when i turn the key on the CEL doesnt light up like usual for 5 seconds or so... And I lost communication with dsmlink. it keeps saying "this port is owned by a unknown user" or "IO has timed out..." is this a ECU issue?

Dylan

 

[gofer]

If the CEL doesn't illuminate for 5 seconds with all the other dash lights when you turn the key to the "ON" position the ECU is what you need to look at first. If nothing happens when you turn the key to the "ON" position check your ignition fuse under the hood. Before you toss a new ECU in there test the ISC using a multimeter to make sure its not the reason it blew your ECU.

 

[boostedgsx95]

Thank you for your reply. Last night I switched ECU's to my factory one and still nothing. The problem ended up being the engine fuse under the hood. So I went out and I bought 2 fuses (1 extra just incase)... well I blew 4 today. The first 1 I was just driving down the street and it died. I hopped out, replaced the fuse, and on I went, The 2nd I was on the highway heading home and it just died. I was able to cost off an exit and onto a street and into a strip mall parking lot. since I just used my last one an hour before this one I went out and bought 2 more fuses just to make sure I could get home. well I went to put in the new (3rd) fuse and it sparked as soon as the terminals touched and popped the fuse instantly. So I made sure everything was off in the car and all doors were shut and I put the 4th and final fuse in. Well it sparked and popped instantly too. So now the car got towed home and im a little confused on what and where to start.. This all happened within the last 2 hours by the way. Where should I start?

 

[gofer]

Exactly what fuse is it?

 

[boostedgsx95]

It's the engine 20a fuse in the fuse box under the hood.

 

[gofer]

Alright, let me go through the wiring diagram and figure out what all goes to that fuse and I'll post back up in a bit with the news.

EDIT
I hope you have a printer and a working multimeter to find whats shorted because it can be a few things. You need to unplug and check for shorts to ground from the following sensor connectors/pin numbers.
- The ECU's 26 Pin Connector (Pins 12 & 25)
- MFI Relay (Pins 1, 3, & 4)
- Fuel Injector Resistor Box (Pin 3)
- ISC (Pin 2 & 5)
- Wastegate Solenoid (Pin 2)
- Fuel Pressure Solenoind (Pin 2)
- Evap Emissions Solenoid (Pin 2)
- EGR Solenoid (Pin 2)
- Front o2 (Pin 1)
- Rear o2 (Pin 3)
- MAF (Pin 4)
- CAS (Pin 3)
- CPS (Pin 3)

All of the above Pin numbers are where each sensor/solenoid/relay gets its 12v signal from the ECU (RED wire) so you can just find each of the above and just find where the red wire goes into the back of it. I'd unplug ALL of the above connectors and test from the ECU connector to ground and see if theres continuity that way you know if its wiring or one of the sensors/solenoids/relays is shorted to ground.

 

[boostedgsx95]

Ok thank you. As soon as I get off work if it's not to hot, (heat index is suppose to be 110 today) I will test thoughs. I really appreciate it and I will get back with you asap

 

[boostedgsx95]

yesterday I was able to check out the wiring harness itself by the battery tray and up to the MAF. I heard that it's common for the tray to rub threw the wires. I didnt find anything there so I wrapped it all back up tight in electrical tape. I wasn't able to check those sensors out bc I did not have my DVOM at home. Hopefully I will be able to do that tonight

Ok well I just got done messing with my car. what I did before I was going to start checking those sensors was unplug the mpi relay, plug in the new 20a engine fuse, then plug back in the relay. well when I did that the car fired right up! All I did last night was remove the MAS, battery, and battery tray to inspect the wiring. I didnt find any "bare" or "frayed" wires but however I did find a slit in the tape where the battery had rubbed. I cut probably a 5'' inch area and inspected all the wires. Like I stated above I wrapped it all back up tight. Well Now she's running just fine. I took it down some brick roads and bumpy roads to see if the CEL would flash again and never did. I let it idle down like I used too and it never did it once. So was there possibly a wire barely frayed or something in the harness where I wrapped back up? So I guess my question is, Is it fixed?

 

[gofer]

Here's how I'd tackle this issue with the list of connectors/pins/sensors I typed up above.

1. Unplug ALL sensors from their respective connectors that I listed and the two engine wiring harness grounding points. One is located behind the ECU (towards the firewall) in the center console and the other is bolted to the firewall just under that battery.

2. With the DMM set to audible continuity (

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) test continuity from Pin 12 or 25 of the ECU to a ground (like the chassis of the car).
BEEP If you hear it "BEEP" that means theres a short somewhere in the wiring harness and you need to start chasing that power wire. If this happens let me know and I'll post up a wiring diagram so you can see how the wires are connected between the sensors and the ECU.
NO BEEP If it doesn't beep that means one of the sensors listed above is shorted internally and is blowing that fuse. To test plug in one sensor at a time and check for continuity to ground until you hear a "BEEP" then R&R that sensor.

 

[boostedgsx95]

Ok well I just got done messing with my car. what I did before I was going to start checking those sensors was unplug the mpi relay, plug in the new 20a engine fuse, then plug back in the relay. well when I did that the car fired right up! All I did last night was remove the MAS, battery, and battery tray to inspect the wiring. I didnt find any "bare" or "frayed" wires but however I did find a slit in the tape where the battery had rubbed. I cut probably a 5'' inch area and inspected all the wires. Like I stated above I wrapped it all back up tight. Well Now she's running just fine. I took it down some brick roads and bumpy roads to see if the CEL would flash again and never did. I let it idle down like I used too and it never did it once. So was there possibly a wire barely frayed or something in the harness where I wrapped back up? So I guess my question is, Is it fixed?

 

[gofer]

I'd say yes. That wire rubbing shorted the MFI relay to ground and blew it causing a no start, you could have tested fuel pressure and noticed the motor wasn't getting fuel which would have pointed to the MFI relay. If you tapped up the chaffed wires with JUST electrical tape go get some ribbed split loom from a local car parts store and do it the right way, that way it won't happen again.

 

[boostedgsx95]

Ok I will do that! I really appreciate your help. If it happens again I know what to check for now

Also on a side not: I really like the carbon fiber on your wing. Is that a true CF wing and you painted the top side or is it stick on or what? It looks great

 

[gofer]

Solid CF with paint on the top. Thanks.