Ok, so I disconnected the AEM wideband gauge and sensor and disconnected the signal wire from the ecu. I also disconnected the AEM boost gauge. I also removed the radio (because it's dead and I'm replacing it anyway). I even unplugged the rear o2 sensor because I don't use it anyway. The wideband uses that input on the ecu so I can log it.

I also inspected the engine bay briefly and could not see anything damaged or exposed near the coils, fuel injectors, or any of that wiring. So I drove the car to work today and the way there everything went fine. Drove it home and things were going smoothly until I stopped at a traffic light. I was in the right turn lane with 2-3 cars in front of me. So I slowed to a stop. The front car made the turn so cars were moving up. So I put it in first and went to move up a little. All I can remember is that the car seemed to stall as if I just didn't give it enough gas. So I went to try turning it on again, and the engine will rotate, but it will not fire. I check the fuse, its blown. I replace it and start the car again. I quickly try to move as there is traffic behind me, and same thing, I stall and engine won't start again. I replace the fuse for the second time (blown again), and this time let it idle for a couple seconds before I go.

I had a couple miles until I got home on back roads with plenty of stop signs and traffic lights. So my method was to put the car in neutral as soon as I knew I had to stop and let the car coast in neutral until I had to stop. It seemed like the other times I would let the car go into neutral just before the car came to a stop. This method seemed to work well. I also gave it a good amount of gas and feathered the clutch more than necessary to make sure I didn't stall again.

I'm stumped, I don't know how to diagnose this and I really don't want to take it to a shop. Does anyone have any ideas on what to look for? What can I measure or test?

 

id try a different ecu.

 

Go watch some Pine Hollow Diagnostics on youtube.

 

This guy has a lot of videos. Do you have one in particular that you think might help?

 

He does what you are faced with so I wanted you to see the steps he follows. So, ignore the mechanical repair videos and look at the electrical ones.

 

HUGE THANKS TO Ians06. This dude spent most of his day yesterday on the phone with me helping me track down this issue. It is not fully resolved, but some progress has been made.

Ian helped me trace the ecu circuit and find all the connectors and harnesses, and I happened to come across an issue on the crank angle sensor connector. The signal wire and ground wire had some exposed wiring and it looked like they could touch each other or ground out on the valve cover





Pulling back the brittle plastic covering, you could see a little better how exposed the wires were:



So I started the car and touched the two wires together to verify this was the issue. The car died (for lack of crank sensor signal). However I checked the fuse and it was still in tact. I tried this a couple more times and still no fuse popping. I had then remembered that every time this happened to me while driving, I would immediately try and start the car again. So I got a vice grip and clamped it on the wires to get the car to die and then tried to start the car again. The car did not start, but the fuse also did not blow.

At the time, Ian recommended to tape up the wires and keep looking for other shorts. So I taped up each wire individually to make sure they were insulated. I went to start the car again and it would not start. The fuse was not blown, so I started checking voltage at the connector with the ignition on. The hot wire had about 12v as expected, the signal wire was at about 5v as expected, but the ground wire read about 8v! I must have done something or moved something and now the circuited is currently shorted. I went to un-tape everything, but the ground wire actually broke in two while tearing off the tape. D'oh!

Upon Ian's recommendation (did I mention this guy is the man?) I taped the (now broken) exposed ground wire to the positive lead of my multi-meter and put the black lead to the negative battery terminal. With the multi-meter reading around 8 volts, I was wiggling around the harness and connectors around the coils and injectors. I got the volts to move a bit, at one point I swear I read 0v, but I did not know what I touched or moved. I eventually got it down to 7v while moving the harness for the injectors.

Unfortunately I looked at the clock and realized the day was just about over and I had many errands to run before the day was done. So I left the car there. My plan of attack is to unwrap the wiring harness around the coils and injectors and try to find where it is shorting. The main harness from the fuse box splits, and this line pretty much just has the injectors, crank sensor, and the coils. This is super frustrating, but at least I'm making progress!

Pic of the broken ground wire:


Ian explained to me how to disassemble the connector so I can easily re-connect the ground wire and then put the connector back together.

 

Same problem, same cause.

 

First, thank you for taking the time to look this up to try and help. However, at this point I don't think this video has any useful information for me. As I mentioned in my previous post, I did find some exposed wires on the crank angle sensor harness, but I was unable to get the fuse to blow.

I have a pretty solid direction to go in right now, I just need more time in the garage.

 

I started peeling back the electrical tape and plastic wiring cover on the harness along the injectors, front o2 sensor, crank sensor, coil connectors, etc. No damage found yet. And I'm still getting around 8 volts on the ground wire for the crank angle sensor.

 

So I measured resistance from the sensor ground wire at the connector (in the engine bay) to chassis ground and got a whole bunch of resistance. The meter was on the 2000 ohm setting and readings were in the hundreds. This sensor ground wire goes directly to the ecu. The ecu has a separate chassis ground wire. I measured resistance from the ecu chassis ground to another chassis ground and resistance was near 0. I measured resistance from one end of the sensor ground wire (in the engine bay) to the other side (by the ecu) and resistance was near 0. I measured resistance from the other end (by the ecu in the car) of the sensor ground wire to a chassis ground point, and got a whole bunch of resistance. Same as measuring the other end in the engine bay to chassis ground. I have to look through the diagrams again, but I think that sensor ground wire gets combined from some other input sensors before it gets to the ecu. Additionally, I was able to power up the ecu and read codes via bluetooth OBDII scanner. It resulted in:
P0122 - Powertrain Throttle / Pedal Position Sensor / Switch A Circuit Low Input
P0108 - Manifold absolute pressure / barometric pressure circuit high input
P0113 - Intake air temperature circuit high input

Although, at the time, these sensors were unplugged...

Any ideas? Where do I go from here?

 

Further diagnosis today....

I found that the sensor ground wire that goes into the ecu is the same for the crank sensor, cam angle sensor, and the air intake temperate sensor (in the MAF).

With all sensors connected, I turned the key to the on position. I measured voltage at the crank sensor harness (unplugged from the sensor), and read around 8v. I unplugged the cam angle sensor and the MAF and voltage was under 1! Plugging in the cam angle sensor, voltage shot up to around 10. With the MAF also plugged in, around 8v. With only the MAF (cam unplugged), still read around 8v. Unplugging both, again, yielded less than 1v.

I cleared the codes and with all sensors plugged in again I read the following two codes:
P0108 - Manifold Absolute Pressure / Barometric Pressure Circuit High Input
P0113 - Intake Air Temperature Circuit High Input.

I'll do some research on these codes, but it looks like I'm getting some feedback or something from these sensors when plugged in?

 

After researching the codes, I kept coming up with threads about a bad cam position sensor. I pulled it out of the housing and there as a good amount of oil in there. I wonder if that had anything to do with it?

Either way, I tested resistance between the 3 posts in the sensor. Power and signal pins have infinite resistance (open), but there is a large amount of resistance between the power and ground as well as between the signal wire and ground. I can't for the life of me find information on what the resistance values SHOULD be on this sensor so I can't tell if it's bad or not. Can anyone help?

 

ahhh man i feel your pain. i had a similar issue with my car not too long ago where i parked the car and the next morning car would not start. My ecu fuse was blown too but when i replaced it the car started right up but i saw smoke coming out the valve cover are and it turned out to be my front o2 sensor wire was pinched between my valve cover and the aluminum coil pack cover. good luck with your car bro

 

After trying to start the car a few times, I'm getting the code for crank sensor as well. I'm wondering if I blew the crank sensor when I was touching the exposed wires together trying to re-create the blown fuse issue.

Does anyone have information on how to check the crank and cam sensors?

 

I checked resistance between the signal and ground wire at the plug for the sensor and only read about 600 ohms. I would expect something like 1k or 2k ohms. I'm wondering if that means the crank sensor is in fact toast.

So I decided to remove the old sensor. It looked ok save for some oil on it. I'll order a new one and go from there. *sigh*