Gentlemen:

Looking for some opinions here on the best kind of fix.

Mr. Grey (sig) ate two relocated (storage bin) Optima Red Tops in less than two years after I had installed a stereo/amp upgrade, alarm, and Greddy boost and 5th injector control hardware.

In addition to the dying batteries, Mr. Grey exhibited the typical FC symptoms of the 3800 shudder, gay idle, and other occasional electrical annoyances we've read about here in cars with electrically driven upgrades like stereos, alarms, etc., which cause the wimp FC alternator to tap out.

The Greddy hardware was all POS or badly installed by Schuler's bottomfeeders at Tripoint (I wasted $$$ there -- chalk it up to noob experience). But even with all of it disconnected, my second Optima was toast earlier this year even after an extra ground was added to the OEM alternator.

All that being said, I concluded Silverotor's FD alternator swap was the solution. However, as I began to swap in the FD alt I began to expect a larger systemic problem with the electrical "grid" of the car: upon careful visual inspection, it seems to me that generally speaking all the wiring in the engine bay is bad, or is approaching bad, and that I should seriously consider rewiring the car if I expect to keep it running right (at least) or making bigger power (desired) or passing emissions (at most) .

It's no different, it seems to me, that the problem that develops with old, cooked brittle vacuum hoses and the problems they cause in these old cars. And let's face it, we are all now dealing with hardware that is verging on 20 years old.

The ECU harness is a prime example. I'm referring to the one that exits the passenger side firewall above the ECU and hangs a left across the engine from the right side strut tower and crosses under the alternator. With about 120K miles of TII engine bay heat and two engine removals (another Tripoint story there) that harness looks cooked. At some point someone has heavily rewrapped the harness with electrical tape and it been sitting there baking on top of the front plate .

Worse though, are numerous cracked and or peeled away insulation and exposed, broken wires near connectors where old brittle wires have been bent and manhandled by under-trained, over-priced mechanic clods. This is obvious right at the connectors to the alternator but no doubt applies elsewhere through the hundreds of electrical connections on the car .

There is also a lot of oily grit and typical engine bay gunk all over the charging harness on the left frame runner between the batter/starter/etc., and on many connectors, such as the solenoid connectors in the rat's nest. That can't help with bad connections and heat soak.

Also, in the course of inspecting everything I found one OEM vacuum hose completely broken off on the back side of the engine near the California ECV (but separate from the group of 4) and I noticed that the connector to the BAC was really loose and sloppy.

So what is the point of an FD alt and adding extra grounds to the car if the wiring throughout is so jacked up?

It's amazing that the car was running as well as it did. But it's not running now, and I don't want to do a half-assed fix.

SO THE QUESTION: HOW FAR DO YOU THINK I SHOULD GO TO OVERHAUL THE ELECTRICAL SYSTEM?

There is a part of me that wants to pull the engine, scrub down the entire engine bay, redo all the electrical with Thermo-tech type insulation and upgraded state of the art connectors. On the other hand, I could for minimal cost patch problem areas by cutting, resoldering, and heat shrink wrapping.

WHAT DO YOU THINK?

Thanks for reading the semi-long post and for your responses.

 

LOL, you sure know how to spin a story...kept me entertained

If and when I ever get to this point (my '88's wiring is still in amazingly good shape), if purchasing a new harness is out of the question, I would pick a system/circuit, say, the 5 or so common ground sensors that feed the ECU, and rebuild that circuit, using new wiring, pins, ground terminals,etc. Next weekend, pick another circuit, and on & on... Obviously the entire harness runs would have to be unwrapped to begin with, but putting some "temporary" tie-wraps around the harness every foot or so would keep everything in place until the project could be completed...This procedure would be a lot less complicated and confusing since you're not tackling the entire harness at once...Then again, if you've got the time to let the car sit for a while (I don't), do the whole shebang at once, like you were saying...Your choice...

 

couldn't you just buy an old wiring harness off of ebay, buy new wires and connectors. then sit at home and redo the one you bought then change out the harness one weekend and see if it works. if not then you have your original one to put back in.

 

step 1: buy a used s4 TII wiring harness (fairly common, atleast much more comman than s5TII harnesses) that is in GOOD condition. maybe out of a low mileage wrecked FC

step 2: strip it

step 3: test for continuity

step 4: make sure EVERY wire ohms out nicely

step 5: buy new connectors for injectors, afm, all sensors, etc. solder them on beautifully. dont use ghetto wire connectors.

step 6: re-wrap the harness to make it pretty.

step 7: profit.

 

jacobcartmill- most modern electrical connectors do not use solder (last time I had to solder an electrical plug was on an A-6 bomber, back in '86 or so, and the planes themselves were about 25 years old at that point). Solder flux is very corrosive, and it's almost impossible to remove it all when you're dealing with a "cold" stranded copper wire that solidifies the solder between the strands before the flux can float. Modern technology has produced for us crimping tools and splices/ terminals/ etc that create a far superior electrical connection compared to soldering, all available at your local well-stocked auto parts store. Not trying to flame, keep on soldering if you like, just trying to educate the masses...With all the cold solder joints we have running around in our cars (and these on strata that were manufactured to accept a solder bead), I rest my case...

 

Ted? Hailers? Silverotor?

Say I don't think I want to go a Haltech or other aftermarket ECU approach and wanted a new ECU harness from Mazda? Is that a really dumb idea? I know the price of it -- about $600 -- is stupid, but since I am not sure I want to attempt stitching together a handmade harness and crimping all that crap together, there seems some virtue in getting a new stock harness from Mazda.

What say you peeps?

Thanks again.

 

are you talking about the front engine harness (main fuse block) or ecu harness or that huge mess of wires that go under the dash?

btw will an s5 front engine harness (one with the main fuse block under hood) work in an s4?

 

My car has been on jackstands for a few months. I decided to go ahead and pull of then re-wrap the engine harness. I have removed all emissions, so there were actually quite a few plugs and wires that I could remove.

After I finally got all the old electrical tape off the crusty harness, I pulled the harness wire loom off to expose the bare wiring. I went through, and pulled off the now non-functional wiring that went to assorted emissions equipment. I followed it back through the firewall to each ecu pin, and pulled them out.

There were a few points where the old wiring was semi-stuck together and I had to gently strip the wires apart from each other. I checked over all the wiring, looking for any wire that might have had it's insulation stripped off. I only noticed a couple of places, and wrapped those wires in those locations with a good amount of electrical tape. Then I wrapped the entire collection of remaining wires in electrical tape, bought entirely new engine wire loom, and slipped the harness in. Then once everything was in I wrapped the wire loom with electrical tape.

It's not in the perfect condition that an entirely new engine harness would be in, but I do have much more piece of mind in relation to the shape that the engine harness is in. As a spare project, I might by a used s4 engine harness, and slowly rebuild it over this next semester, then pop it in over the winter break.

The wiring itself is usually in pretty good shape from my experience, it's just the crusty electrical tape and the cracking wire loom from the original engine harness gives off the perception that the entire thing is bad. From what I've read, it sounds like you have a few areas to clean up, but I'm willing to bet that the majority of the harness is in good shape.

I know you said you don't want to go with an afermarket EMS. Butif you can spend 600 dollars on wiring, why not spend 300 more for a lt8 and not only have a fresh new engine harness but have a faster, and much more flexible ecu.

 

Absolutely no interest in buying an old wiring harness on the internet, nor noobing a crimp job onto it.


I may be a retail sucker, but the way my head works, there is no such thing as a "used S4 TII wiring harness in GOOD condition. It's some kind of contradiction in terms...but then again I may be Joe Retail Sucker. The whole point is to get an electrical system that is as good as and better than the original ECU harness when the car was rolling off the factory line 18 years ago.

Thanks for your thoughts, though.

 

Well, wish I could help you. I've got a beautiful S5 harness brand spanking new I'd sell for $450 + shipping to the first taker. But, in your situation, having an S4, and being all junked up like that, I'd have to think about that.

Getting a new harness is wasteful in my opinion. However, I bought one before I went haltech, and was VERY pleased with that decision until I realized I had to sell it. Nobody wants new harnesses, even at insane losses for the seller (like me). So, if you *do* plan to keep this car for at least a few years, take pride in it, and want to treat it well, buy a new harness. I'm saying this assuming you don't want to rewrap a used but better condition one, as you stated. I would strongly (from a financial point of view) argue that remaking a harness is the way to go BUT for the following: the insulation on the individual wires gets VERY brittle in places. A "well kept" used harness, looking perfect on the outside, may still fracture under the force of simply unwrapping the stock tape!! My '89 NA harness, completely stock, never fiddled with, looked fine on the outside when I pulled it. The individual wires suffered this problem though, and I was unable to use that harness again because of that. Further, new connectors are either very difficult to find, or very expensive, or both. So there is a clear-cut time and frustration advantage to buying a new harness - its clean, perfect, and guaranteed to work (check it nonetheless before you install it).

However... if you buy a new harness, you *WILL* be motivated to completely clean your engine bay. Trust me. You put a gorgeous, supple, smooth, $600 harness into a filthy bay and you instantly become a clean freak. So, if you go that route, definitely plan to clean EVERYTHING and end up feeling damn good about your car, and damn bad about your wallet. You'll likely find more problems lurking under the crap, too, as you clean. So be warned.

That's my two cents about a new harness.

 

oh i am currently rewireing some of my wiring harness. im using 12 guage ( belive most of the stock is using 14) so i get to track every damn wire down and do it. on and old shitty tape sucks ***.

 

I DON'T KNOW ABOUT THE S4/S5 SWAP YOU ASK ABOUT. SOMEONE WILL.

 

Oh, and about the aftermarket ECU... yeah... its not much more expensive. On the outset. But you'll need to spend time tuning it or pay someone to tune it. However, for a turbo engine, like yours, I'd STRONGLY recommend it. You might not like the idea, and I didn't at first, but now that I've stuck that Haltech in my car, I'm pretty damn happy. And I'll be happier the more things I do with it. And you get a brand new harness, that if you ever decide to replace in the future, it will only cost you ~$150 for a flying lead and the connector pack, versus $600. Plus you lose a lot of things that cause trouble. So its a worthy consideration, your fears notwithstanding. I don't think its a bad idea to buy a stock harness (obviously), but I think once you do you'll wish you'd bought an aftermarket EMS too.

 

DIGITALSYNTHESIS, I READ YOU LOUD AND CLEAR ABOUT THAT NEAT FREAKING IT SYNDROME IN THE ENGINE BAY.

YOUR THOUGHTS ARE SENSIBLE. THANKS.

 

See, this is exactly what I don't want to do. HELL is a place filled with crusty, burned old wiring harnesses wrapped in miles of sticky, stinky, annoying electrical tape...But good luck on your project.


Yeah, you've got a point. What's the emissions situation in Georgia? I am pretty sure that going Haltech out in in Cali makes you an outlaw and I don't know if I am that committed...yet.

 

I think your car eating the batteries is most likely due to the battery relocation. What size wire did you use????

You shouldn't use anything higher than 2 gauge, my buddy tried using 4 gauge with the same results that you had, the batteries got eaten for breakfast.. reason, too much current loss in the wire.

I have just done this Mod, However, I didn't take the normal approach. I completely ripped out the power harness and tore it apart. Here's the rub... the Charging circuit, the one that runs from the altenator to your battery looks to me like 6 or 8 gauge wire. Thats fine for the three feet it travels from the altenator to the battery in the stock setup.

However.. when you take that wire, and in essance, add a 15 foot length of 4 gauge wire to it when you toss the battery in the back, things start to get hairy. its kinda like blowing through a coffee stirrer into a slightly bigger coffee stirrer.. 15 feet long. you are still getting the current loss on the 6-8 gauge wire, but now you've also added the loss of the 15 feet of four gauge wire to the mix.. Hence, the battery is going to be stressed when driving the car. Add to that a bumpin system, and things really get cookin!!

My Remedy?? after chuckin the battery in the back, I installed a 140 amp breaker near the battery and then ran a 1 gauge wire directly to the starter from the battery. I then did a 1 foot, 2 gauge ground to the bolt hole already in the body (they have rubber plugs in them, but they are pre-pre tapped if you look). To this bolt, I also ran a 2 gauge ground from the frame below drivers side shock tower where the original cable was grounded. At the original ground point, i bolted the ground cable down with one of those "multi ground points" that you can get off ebay for 20 bucks. I ran all subsequent ground to that point (including the big one from the back of the engine/starter hookup).

Power gets to the front by another 2 gauge wire that hooks from the circuit breaker into a distrubition block. the distribution block goes to the factory fuse block, the haltech fuse block, and the original chargin loop goes in here. However, I ran a 4 gauge wire from the hot out of the FD altenator to the block.

We'll see how my red top reacts to that

PS.. the subwoofer pulls power directly from the battery, before the circuit breaker!

 

it wouldnt be so bad if the person who messed with the harness before me didnt have the wiring abilities of a retarded monkey.

 

HELPFUL POST, YoD! I AM RUNNING A MESS OF 4 GAUGE FROM A DISTRIBUTION BLOCK AT BY THE OLD BATTERY LOCATION BACK TO THE PASSENGER STORAGE BIN AREA. AND THE D-BLOCK USES ONLY 60 AMP FUSES. THIS WAS INSTALLED BY A PRO STEREO/TUNER GUY WHO I FELT KNEW WHAT HE WAS DOING. BUT MAYBE NOT.

YOUR POST GAVE ME LOTS OF IDEAS OF THINGS TO LOOK INTO. THANKS!

 

Hey! That monkey I trained wasn't retarded, he was just "special"!

 

I replaced most of the connectors and rewraped my ECU harness. While I don't have a source for new connector housings, I do have one for the spade connectors (the 1/4" male and female ones that go inside the housing). I posted a link for it a while ago.

As for rewrapping the harness, be prepared for a lot sticky residue left from the original tape. You can use wax/adhesive remover to get it off (just makes it easier when working on it).

The sealed connectors, such as the fuel injectors, CAS, etc, will probably not need to be replaced. Though the insulating boots may have torn over time. You can just wrap tape over the boots and be done with them. The connectors that are uninsulated are the ones that should be replaced. Simply because they're exposed to the elements and can get dirty or corroded.

As for what you should use to rewrap the harness, I'd use a silicone non-adhesive tape available from terminaltown.com for $20/roll. It's an excellent waterproof silicone rubber which can withstand over 300 degrees F, and is flexible. You'll need three rolls to do the harness. Also, to replace the sections that have convoluted tubing, you can just get a kit with 10 feet of each diameter, made by Taylor, from Summit Racing for $12. You won't need more of each diameter than that.

When rewraping, go slow, connector by connector. Also, start the wrapping by wrapping each individual wire run from the connector to the main run of the harness, and then finally wrap the whole harness itself.

I also used heatshink tubing at each exposed connector, where the wire is crimped, to further protect it from corrosion and used dielectric grease to keep out moisture. You can use short lengths of 1/4" heatshrink tubing instead of tape, for the short runs from the connectors to the main wire bundles to save on using the more expensive tape. I also used a heatshrink connector for one of the ground ring connectors that attached to the engine block.

There are instructions on how to use the silicone tape on terminaltowns's website, as well as the dos and don'ts on crimping. I suggest you read them. When replacing the crimp connectors, you *must* have the right tool to do the job.

The resulting product from my efforts looks pretty good (not perfect, since you can see the tape center line), but should last much longer than how it was made from the factory.

 

Oh, the same techniques and materials can be used for the other harness in the engine bay (for the A/C, sensors, lights). I only replaced connectors that were broken or corrded, and left the original wrappings alone.

I also rewraped the connectors that run underneath the car to the starter and transmission. Those at the transmission are especially bad; one was so bad it was fused from the corrosion and had to be cut out. Using sealed connectors, such as weatherpaks or sealed heatshrink connectors, are a must.

 

my bad "special"

 

Thanks cluosborne -- that's good info and I will be looking into many of your recommendations.

 

You're welcome. I'll be finally getting the harness back in the car and running in just a few weeks.

In case you're interested in seeing my redone ECU harness, he's a pic.

ECU harness

In addition to the new crimp connectors, I replaced the TPS and O2 connectors with weatherpaks to improve on reliability.

After taking this picture, I have added a 10-gauge ground to the existing grounds which ends in a ring connector, and soldered inline two 10 OHm resistors for the two primary injectors. Please note: this was ONLY due to finding out that I had two LOW-Impedence fuel injectors. How the car ran for just over two years and didn't fry the ECU is a mystery to me.

I also replaced the main lead from the alternator to the fuse box (using a shorter length of 8 gauge tefzel wire) and separated the one puny 10 gauge lead on the aftermarket positive battery cable into two separate leads. In other words, I used the existing 10 gauge for the interior fuse box and added a length of 8 gauge wire with a ring connector for the underhood fuse box.

FYI, the alternator lead runs from the fuse box (it is fused btw) down along the battery cable, almost down to the starter motor, then up to the alternator. When I replaced the battery cables, I had mistakenly cut this wire thinking it was going under the car. It's part of the CAS/Engine sensor harness that contains the oil pressure, oil level, and water temperature sensor wires. I've since separated them, cleaned, and rewraped them in the silicone tape. Once the engine is back in, I'll finish the final routing and secure it. Oh, the CAS wiring is shielded with a dedicated ground.

 

Well, actually, a properly tuned Haltech can be made to pass emissions as well as or better than a stock system - removal of the 'standard' emissions control devices notwithstanding. I just don't know if the Haltech is CARB legal if you require CARB certification. California is a pain in the *** w.r.t. emissions, so I am not sure at all what your options may be. Georgia for the most part doesn't care. Most of our non-metro counties don't even have emissions inspections, and my area, while requiring inspections, doesn't regulate HOW you pass, only THAT you pass.

Cat, electric smog pump, a carefully tuned map, and you're good to go. You might not need that 50% alcohol tank either!