Another EGR burned engine wire thread... (1 Viewer)

[Iceaxe]

I have an SC'd FZJ80 that has a slowly progressing hesitation upon acceleration @~2,500 rpm. I have fuel filter and fuel pump on the way... But I wanted to check and make sure e EGR didn't melt the cylinder 5 wire.

My question is this... I don't want to buy an entire new engine harness but would rather splice / heat wrap the involve wire(s)... What gauge wire do you use to do this, with what connectors?

Thanks!

 

[inkpot]

Hesitation at lower rpm should not be filter/pump issue. They would be more likely to fail at higher rpm where fuel demand is much greater.

 

[Iceaxe]

Hunh...

 

[NLXTACY]

When the harness goes, at least for me, it took out the injector. For me it was #2. Just killed it. The truck WILL drive on 5 cylinders, for hundreds of miles as it turns out. Just drives like ass but man, the truck just won't stop.

 

[george_tlc]

^ if the +ve feed to the injectors shorts, likely will be to ground. That will take out EFI fuse etc.

Short of injector firing signal (one wire per injector) to ground will keep the injector flowing 100% of the time while ignition is on/run (cat may get unhappy with unburnt fuel setting itself on fire inside the hot cat and melting it). Lots of fuel pouring into the cylinder until the injector dies from 100% duty cycle, then no fuel and dead injector...

cheers,
george.

 

[Iceaxe]

When the harness goes, at least for me, it took out the injector. For me it was #2. Just killed it. The truck WILL drive on 5 cylinders, for hundreds of miles as it turns out. Just drives like ass but man, the truck just won't stop.

That is precisely what's happened! I have a truck that used to be a rocket that is now acting WORSE than before I put the SC in... drives like an absolute pig up the mountains now, and there's nothing I can do about it....!

 

[Iceaxe]

^ if the +ve feed to the injectors shorts, likely will be to ground. That will take out EFI fuse etc.

Short of injector firing signal (one wire per injector) to ground will keep the injector flowing 100% of the time while ignition is on/run (cat may get unhappy with unburnt fuel setting itself on fire inside the hot cat and melting it). Lots of fuel pouring into the cylinder until the injector dies from 100% duty cycle, then no fuel and dead injector...

cheers,
george.

Ok, so how do I tell if the injector is shot?

 

[george_tlc]

IF you actually dropped an injector the vehicle would misfire and you would get a CEL within a VERY short period telling you which injector was misfiring.

cheers,
george.

 

[Iceaxe]

Ok, I got a CEL indicating multiple cylinders misfiring, but cylinder 5 was tagged specifically. Also had a TPS code that went with it. So I replaced the TPS and the CEL went away... but the crappy performance remained... This suggested I should pull the plenum and take a look at those wires under the EGR @ cylinder 5.... At least that was the muddled thought process.

 

[george_tlc]

Yeah, check the harness wiring by the EGR - check EACH and every strand and then fix and wrap with good heat proof insulation and secure the harness AWAY from the EGR. Often the clip breaks due to age etc and the harness moves closer to the EGR.

Also check under the glove box where the harness goes to the ECU - some 80's have that harness rubbing on a sharp metal edge and shorting there.

cheers,
george.

 

[NLXTACY]

Ok, so how do I tell if the injector is shot?

For me it was simple. I got the PO302 (cylinder #2) and I grab my mechanic's stethoscope.

#2 was just "hmmmmmmmm"
#1, 3-6 were "TICK TICK TICK TICK" really quickly.

 

[Iceaxe]

Guys- both of you- thanks for this input. I really appreciate it.

 

[inkpot]

Hunh...

I read your first post to say you bought a filter and pump to hopefully fix the hesitation issue?0

 

[Iceaxe]

Sure- I preemptively did that since older threads pointed to fuel filter replacement t being a solution to "acceleration hesitation"...

 

[Iceaxe]

Ok, found the issue, and I'll post pictures later today. Fried the bejesus out of the harness where Toyota had you stretch the loom across the top of the engine. Spent a half hour with a pick scraping all the melted plastic off the engine.

Anyone know what gauge wire to use for rewiring the engine harness?

 

[george_tlc]

If you use a caliper to measure the diameter of the damaged wires (the copper part) you can just look up wire diameter versus gauge. Most of the wires in that bundle are relatively small (probably in the 22 g range), but measure. If in doubt just go up in size (smaller gauge number) to the next nearest.

e.g. American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire breaking strength

I'd source some decent quality heatshrink with the meltable inner inner to ensure a good water tight seal after you've spliced or soldered new wire segments in. Make sure you do a GOOD job or you'll have issues when possibly not near home etc...

cheers,
george.

 

[Iceaxe]

George,
Thanks for this.... when splicing, are you using an actual connector of some kind or simply binding the wire by hand +/- solder?

 

[george_tlc]

^ There's folk that don't like solder joints on vehicle wiring due to it making a potentially brittle connection (hence EVERYTHING in stock wiring is crimped...). So it'll be your decision whether to solder or to crimp. I'd personally get some un-shrouded (bare metal) crimp 'tubes' and do GOOD crimps to join the wires, the use quality adhesive line heatshrink tubing to seal out the elements. Easier to confirm the splice is secure before covering in heatshrink, but that's just a personal preference.

So, something like -> Crimp Connectors, Butt Connectors | Waytek

or you can use their insulated butt connectors that have the meltable adhesive and heatshrink in one.

One good thing to remember is to cut and butt connect at DIFFERENT positions (staggered) on the harness (say by 1") that way if you repair multiple wires they don't all have the butt splices lining up next to each other to make one big fat/lumpy harness section.

cheers,
george.

 

[Iceaxe]

George,
This is so very helpful- thanks so much.

 

[Iceaxe]

OK, just for fun, here's the picture of what I saw when I opened the hood...