So I finally got the car running last night and took it for a drive. As I was pulling up my street it bucked several times then died. Each time it bucked, the headlights dimmed a lot. When I went to restart it, it wouldn't start. I went to check the fuses and the 40A EGI Inj fuse was blown. I put in a new one, cranked for a second, and checked and it was blown again.
From searching, that fuse goes to the fuel injectors and the coils. The coils are just fine with no stray wires. If you have seen my other posts, you know that I have some cracked insulation on my primary injector wires.
My hypothesis is that one of the injector wires grounded on the engine, shorting out and blowing the fuse. Are there other possibilities I should look in to before I tear my intake manifold off again?

 

pressure sensor

 

Random guesses aren't helpful...

The EGI INJ fuse feeds only the injectors and coils, nothing else. If you have a short somewhere you'll be able to detect a continuity between the downstream fuse pin and ground. Disconnect the negative battery cable, pull out the fuse, put one probe in the fuse socket (in the pin with a wire coming out the bottom) and the other probe on the battery's negative terminal. If you have continuity, start looking for a short. Try disconnecting first the leading coil then the negative coil then each secondary injector, repeating the continuity test each time you unplug something. If they're good, pull the UIM and repeat for the primaries.

 

I have no reason to believe that its the coils and every reason to believe that its the primaries. I did a visual inspection and there are no problems with the wires to the coils. In fact the only problem wires I have seen are the under-intake sections of the primaries where the insulation has hardened and cracked. I will go ahead and check the rest of the stuff first since its easier to get to, but my money's on it being the primaries. Its just as well, I really needed to pull the UIM anyway to fix some stuff.

Thanks for confirming my suspicions.

 

same thing happend to me. I found out it was one of the wires I had cut on the emmisions harness that was grounding out on the engine block. After re wrapping the ends I had no more problems...........Viva la standalones

 

the same happened to me, the wires off the BAC touched my BOV and grounded causing it to blow

 

same here. mine died exactly the way yours did. it bucked and dimmed and then just shut off. your going to have to go and look through the harness on your motor. my problem was exactly what you listed and in the same spot. the harness dried and cracked and wires eventually started to touch themselves. i rewrapped each wire and then put new wire looms around it and taped the hell out of it. i was stuck on the freeway so i didnt have time to do what NZ said, but his way makes the most sense and is pretty much failproof.

 

Same. ITs probably the Black wire with white strip (+12VdC) shorting to ground. I would check all around the upper intake including the connection to the BAC and ISC. Also check the injector connectors,wiring.

 

Maybe a stupid question, but are your injector clips cracked and broken? My secondary injector's clips were broken and was wiggling on the injector. This cause my EGI fuse to blow. So you might want to check the clips on your primary and secondary.

 

Well, everything relating to the injectors is in pretty bad shape. There are some fairly sizable breaks in the insulation, so I am confident thats thats where the problem is. I basically threw the motor together with some obvious problems just to make sure that my motor wasn't blown since it had been sitting in a wrecked car for almost a year before it made it into my car. Now that I know its good I am going to tear into the things I need to fix, and one of the main ones is the harness. I have new plugs from summit that I am going to put on to replace them.

 

Did you miss the bit where I said the EGI INJ fuse feeds only the injectors and coils, and nothing else? And this wire is black/yellow.

 

I've got the harness out and am patching up the breaks right now. Hopefully this will fix everything.
While I'm here, what is the best stuff to use to re-wrap the harness?

 

The Scotch Super 33 tape is good. You can also buy wire loom wrap things.

 

Where does one get these items?

 

Hey no didn't think I missed anything. Maybe that is true, but there is a black wire with white stripe that feeds the BAC, and some other things under the hood. Mine was shorting out and I only saw it at night by the sparks shooting from it. But hey we are all trying to help and I dont think anyone misinformed this guy, Im just trying to share my experience.

 

No, you did miss something. There are two completely seperate power circuits feeding the S4 EFI system. The EGI INJ fuse feeds only the injectors and coils via a black/yellow wire. The EGI COMP fuse feeds the sensors, solenoid valves and ECU via a black/white wire. In this case it was the EGI INJ fuse that blew, so anything fed by the EGI COMP fuse is irrelevant to the discussion. That's why I made it clear in my first post that only the injectors and coils needed to be checked.

 

FWIW I redid the primary injector wires and it works great now.

 

Your statement was % 100 correct , my mazda mpv was blowing the 30A fuse after i changed the coils and fuel injectors , ended up removing the plenum (intake) come to find out that one of the injector wires was bare , it was touching the plenum therefore blowing the fuses. Id like to thank you for this forum , for leading me to the the problem keep up the good work

 

Its great to see that this thread was brought back and helped someone...even crazier that it was an MPV not an RX-7!