I'm just trying to figure out what is going on with my car blowing this egi comp fuse irregularly. I will be driving down the road and all of the sudden everything but electrical will die. I will coast to a driveway etc... and get pissed off and get my wife to pick me up, cool off for a little while, go back out and put a new fuse in. the car will fire right up and its off to my garage to start trouble shooting. It's very intermittent, I've read many posts on the egi comp fuse will keep blowing everytime they turn the key to the on possision but this is not that often but still happens everytime I drive the car.

Now here is the thing. THis never happend until the last time I wired in the resistors for the new 890cc injectors (the ones that I did not get ripped off for, thats another story). Anyways could it have anything to do with the resistors or wiring around the ecu? Could the resistors be getting to hot causing other wires to melt?? Does the resistors get that hot? I've checked everything under the hood and as far as physically being shorted etc... I see nothing. Of course if it was shorted on the motor or something like that wouldn't it keep blowing the fuse any time I turned the key to the on possistion? But instead it blows I leave the car alone for a couple of minutes, like 30 or so and come back and it works just fine after putting a new fuse in however if I put the fuse in right after it blows then the new one I put in blows as well???? Crazy ****! Anyways if anyone could help I would appriciate it.

 

a) wires chafing together and causing an intermittent short when the car is warm
b) a solenoid is shorting internally when warm causing the fuse to blow
c) the resistors are adding too much of a load on the EGI fuse, putting in a 40 amp may take care of it but i don't much like changing circuit amperage ratings
d) a wire grounding out on a sharp edge of metal
e) ignition switch could be worn out



these would be the most common things to look at for an intermittent fuse blowing.

 

a)could be, I"ll check to see how it goes.
b)don't have any solenoids left
c)the weird thing about this is the car has had 720cc secondaries since I've had the car back. About 2 or 3 years and when I went to go looking for a resistor, there where none. Well this kind of struck me as odd because the ecu never blew or whatever happens when you run low impedance injectors on a high impedance harness. Needless to say now there are resistors with the 890cc injectors.
d)this did happen on the backside of the alternator possisioning bolt wher it has that peice of metal that held the wires in place was rubbing against the water thermo sensor wires so I cut the piece of metal off and replaced the ends to that thermo sensor and I'll find out if this was the cause but at first all I did was move the piece of metal away from the wires and it still blew a fuse.
e) I just changed out the pigtail portion of the ignition switch about a year ago but I guess this still could be a possibility.

THanks for the reply karack, hopefully I will get this thing running the way it was before I descided to upgrade the ******.

 

personally i would do this:

start the pig up and start pulling on wires and see if the fuse pops, if it does then start cutting open the harness in that location and check for burnt or chafed wires rubbing together.

if that does nothing then i would check the temperature on the resistors, if they seem to be the hottest when the fuse blows and relative to each time they blow then they likely are the cause, moving them to a location where they can cool could cure the problem or you could (weary) up the fuse rating of the circuit.

start with those couple and see what you come up with.

 

EGI COMP fuse is a thirty amp fuse. It has NOTHING to do with your fuel injectors, although it does go to pin 3I on the ECU. The EGI INJ feeds the fuel injectors.

The EGI COMP FUSE, 30amp, feeds the BLACK/WHITE wires that go to numerous solenoids. One of those wires is shorting out intermittently. Outside of the pin 3I on the computer and the solenoids, it also goes to the fuel pump relay/resistor. You might look at your rewire of the pump.

Also, if you have power steering, it also feeds thru a power steering switch. You might disable that switch and see what happens.

I'd pull all the plugs off the solenoids on the rack plus the two off the acv and see what happens.

I notice you have a SAFC. Are you feeding power to this from pin 3I on the computer? Maybe the fault lies there. What else are you feeding off pin 3I????????????????? To much?

I flat miss where if goes to the ignition switch.

 

he doesn't have solenoids anymore.


i didn't trace out the circuit so i was just giving some info to go off of, the ignition has to control the circuit somehow, whether it is directly tied in or not i wasn't sure so i threw that in there.

what about a fuel pump kill switch that is getting worn and having high resistance?

 

No solenoids reduces the search down to *whatever you did to the solenoid plugs* and about three other things like the pin 3I on the ECU and the pwr steering switch and possibley the Main Relay (very doubtful), and the feed to the Fuel Pump Swith/Relay on a turbo car (did a rewire, did you).

 

ok thanks again for the replies guys! I don't have the vac rack anymore so one of the things I just did and call me stupid but there was some wires from the solenoids that where exposed so I cut them and taped each one off indavidually and then taped them all together but this was just about an hour ago so this may have been causing it as well.

Things I've done for the next time I test drive it.

cut off all the solenoid connectors and taped
resoldered new connections for the water thermo sensor
cut the metal clip that was used to hold wires in place in back of the alternator
checked all wiring.

Hailers thanks for the info, I was just wondering where the switch is for the power stearing? Also what do I check with the fuel pump rewire? I have done the rewire and it's been working perfect up until now if that is the problem. The safc is wired up to pin 3i for power witch it states you are supposed to do so that should be cool. I was wiring in something else at the ecu for power but descided that was a dumb idea so I quickly undid that.

 

The 30amp EGI COMP fuse goes to the following:
Power steering switch
Pin 3I on the ECU
Air Supply Valve
Pressure Regulating Control Valve
BAC
EGR
Air Bypass Solenoid valve
Twin Scroll Solenoid
Switching Solenoid
Relief Solenoid
TPS Check connector
Port Air Solenoid
Split Air Solenoid
Boost Sensor
Atmospheric Pressure Sensor
Knock Control Unit
Passes thru the Main Relay

I don't have power steering. It looks like the switch is somewhere near the power steering unit on the engine. Got me.

The above is for a 87-88 series four, not one of those plastic ball joint, plastic cone head afm series five things.

 

ok from that list then the possibilities on my car are.

boost sensor
atmospheric pressure sensor
knock control unit
main relay
power steering switch.

I'll check these, thanks.

 

ATP is inside the car above the passengers feet and to the far right and forward. It is shaped much like the boost sensor but has no vac hose going to it. If you have not messed with it, it should be the next to last thing to look at.

 

cool thanks, I'm guessing it has to do with the selinoids, waterthermo sensor being fubard by the metal hitting it or something having to do with the resistors. Thanks again for the help.

 

hell, you've gone this far you may as well just rip out the whole harness and cut it open and remove the extra wires, inspect them all and rewrap it up all nice.

 

Water Thermo Sensor cannot pop that fuse. Nor the resistors. The resistors/injectors are on another fuse, the EGI INJECTOR fuse. A 40amp one. I hope that is not the fuse you've been popping instead of the EGI COMP fuse which you said you pop.

The problem has to do with a BLACK/WHITE wire as is seen on each solenoid or boost sensor, atp sensor, pwr steering switch , air supply valve, bac, port air solenoid, split air solenoid, etc. Think BLACK/WHITE wire.

 

lol, yeah the egi comp fuse is the one I've been poping so I guess it can't be the water thermo sensor wires but they where broken because of that metal hitting it so I changed them out just because. Hopefully I fixed it while cutting off and taping up the ends of the selinoid connectors. Lol, Karack, I'm not **** enough to do something like that when I could get one used for about 75 bucks however if you want to you can come over here and I'll watch you do it, haha.

 

i did it with mine when i had the engine out, the harnesses tend to get brittle and the insulation starts to flake off after time causing unseen problems like this which can be a real bitch to solve....

 

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/wireing-short-1988-na-408769/

Solved it for me

 

don't have bac or acv so that wire is taped up and hidden. But thanks for the reply.

 

I had a problem where the wiring harness rubbed enough insulation off to cause a short on the metal tab behind the altenator.

 

the only two wires it was rubbing on where the two for the water thermo sensor and from what I've heard those two wires won't cause it???

 

If the fuse has stopped blowing since you cleared those two wires from touching a ground source.............then consider me wrong about that and press on with life.

 

lol, I wasn't saying you where wrong at all man I was just repeating what the masters had told me I really think it has nothing to do with that and everything to do with the shady selonoid connectors touching something.

 

Honda Dude, I go on a week of vacation, come back, and you're still fighting the car, lol...

You're forgetting the basics of troubleshooting a short- isolate...

The BIG clue you have going for you is that the fuse takes a while to blow, and the component takes a while to cool down before a new fuse works. Here's why:

If the fuse takes a while to blow, you don't have a short, you have a current draw problem. Most of the time this happens, it's something like an electric motor on its way out. Any motors in the circuit?

Solenoids act much like motors also, in that they get hot while energized due to the extreme amounts of wasted power they use to operate. As we all know, there are a couple of solenoids on the car that like to cause havoc, the port air and split air solenoids among them. Don't think you have those anymore, though...

Your job is to isolate. We can't do that for you. Hailers gave you the list of things on the circuit. Check them out one by one. Helps if you have a copy of the schematic, too. Karack obviously didn't, lol...

Feel around for any component that gets extremely hot on that circuit after she's ran for a while. That may give you another clue as well.

Have fun, it's like a treasure hunt

 

lol, a treasure hunt huh??? haha nice, the only problem is you don't get a bunch of gold in the end you just get your car working like it should Anyways thanks for shedding some light on the situation. I had no idea thats what would be causing it to do this only when warmed up. Well all my soleniods are gone so it can't be that so I guess it's off to see about those other little obscure things hailers was talking about. Damn I don't wanna go on a treasure hunt lol

oh out of the things hailers said, these are the things I have left

boost sensor
atmospheric pressure sensor
knock control unit
main relay
power steering switch.

witch one would cause the problem of heating up and poping a fuse?

oh and wayne your not alowed to go on any more vacations until my car is finnished

 

I was serious. If the problem has gone away, go about doing something else. I could make a case for that water thermo senors wires touching ground causing the circuit breaker to pop. It'd be a little weak and I'm not about to go out and experiment by shorting mine out to find out if that could cause the circuit breaker to pop.