For whatever reason, the thread I just created about this is locked. It must have been a mistake since I asked a valid question, so here we go-
I think that the wires for the sensors are extremely thin, since they are only as thick as absolutely necessary. Over time, I presume that the resistance of the wires increases as they corrode. I have been having slightly high negative fuel trim, about 10-15 percent at times, so I checked the MAP sensor. The MAP sensor reads 16 IN HG at idle, but a vacuum gauge shows 18. I swapped the sensor out with the one from my 04 Civic with the same result. The oxygen sensor also intermittently works, but is dead most of the time. I think that the wiring is wearing out, so I plan to rewire the important sensors that operate off of resistance with new 14 gauge wire to reduce resistance and help the sensors function better. Can't hurt to have less resistance and could help the sensors function better. What do you think about my idea?

 

There's no reason to perform this. Your assumption that these wires are corroding is pretty high. But they don't change resistance over time. I've got sensors and wiring for over 25 years of Hondas. Nothing corroded.

If you decide to embark on this journey, you do so at your own risk away from Honda Engineering intentions. All I can say is; fortuna favet animus paratus. Praeparato animo fortuna. (Luck favors the prepared. Fortune Favors the Prepared Mind)

 

Thank you very much for the reply. I know that the engineers that designed the car are extremely good at what they do, and that they are much smarter than I will ever be. But the engineers also have a very strict budget, and they do what works well for the average driver. For example, I moved the battery to the trunk because that is what suits MY needs best. I understand that there are very good reasons that Honda didn't install the battery in the trunk for the factory, such as less trunk space. But to me, the space in the engine compartment and the improved weight distribution outweigh the disadvantages to me for what I use my car for. Not everyone will agree with me on that and that's fine. That's just one example of how I customized my car to best suit my needs. That doesn't mean that my setup is "better" than what the engineers at Honda designed, it just means that it works better FOR ME. Maybe incorrect, but I believe that especially on an economy car like a Civic, Honda tries to get the price of the car as low as possible without too much thought about weather things are the best that money can buy. There are definitely things that Honda could have done better on if money wasn't a concern. For example, Honda COULD have used LED lighting that would be brighter, use less power, look cleaner and outlast the car for headlights, tail lights, brake lights, turn signals etc. I converted to all LED lighting and I don't see why Honda wouldn't from the factory besides cost. We can all agree that LED lighting is superior to incandescent lighting as far as longevity, power consumption, brightness, on/off quality etc, but for much more money. Maybe thicker sensor wiring would have benefits also, but obviously at a much higher cost. Do you see what I am saying?

 

What year car are you referring to.

LED auto lighting is only just recently becoming DOT approved and prevalent.

Depending on just how far back you are going with the car will indicate if it was even feasible both legally, timeline wise and economically (not to be confused with cheapest practice).

It's why the lesser durable HID was the main lighting of choice until just recently. It was DOT approved, used less power and lasted longer than cheap halogen's etc etc.

 

You're talking 2004 before any of what you mentioned was even tested to acceptance level testing before it could be used in a production vehicle. It wasn't just because it was to save money for cost; using what they did was so that selling price point would stay relevant to their potential consumer.

Again. in your case, if you want to partake in this, feel free. I just don't see any relevant benefit for the long run for this unless you plan to keep this vehicle for an additional 20-30 more years.

 

It's a 2005. Thanks for bringing up a good point about LED lighting not being common until recently, I didn't even think of that. I was just using LED lighting as an example though. We can all agree that my Civic would be much better built if Honda had unlimited funds and there only concern was building the best Civic that they possibly could.

 

That is not how units fly out of the door. But at least their forward thinking has been brought to the forefront now that the new CEO is in place. I can attest to that commitment from the new 2017 Civic SI my wife has, and the 2018 Accord 2.0 Turbo 6-spd my brother has ordered.

 

Actually, I do plan to keep the car for as long as possible. I have no reason to get rid of this car, it fits my needs perfectly. I legitimately can't think of a car that would fit my needs better. It's very fuel efficient, very easy to work on, very light, drives great and is overall an awesome car for me. I will happily put the time and effort into rewiring the important sensors if there is even a chance of a small benefit, but I don't want to do it if it could somehow cause a problem. What I am worried about is that the computer may be calibrated for the resistance of the factory wiring, and using a thicker wire with less resistance may cause the computer to misinterpret the data it gets, thinking that it is taking into account the resistance of the factory wiring when really it doesn't know that the wires are not what it was calibrated for and then the computer doesn't read the sensor data correctly. Is that a legitimate concern? Is there any way that I could make things worse by rewiring the sensors with thicker wiring as long as I do it correctly? Thanks a lot for the input.

 

There is a possibility of causing damage or having some undesired results with replacement wiring, especially in the harness. Not so much due to PCM signal interference, but reception at all. This is more of a "if it ain't broke,don't fix it" situation. The benefits will be negligible if any at all. Seriously.

 

Thanks. Just curious- What exactly do you mean by "reception at all"? Do you mean that I may have interference if I run the wires right next to the ignition coils like an idiot, or do you mean that reducing the resistance in the electrical system could have undesired results? Sorry for the dumb questions.

 

You're asking me to predict exactly to the letter what could go wrong, and I can only tell you from what I've personally witnessed and worked with when it came to the entire wiring structure. It was just a clusterf*ck of issues, from signal interference to resistance changes to component failure.

I can't give you a crystal ball look, because I honestly don't know all the hazards either. But again only you can say if it is worth it to go into all that.. I found that it just wasn't. Not when more problems could result than successes.

Ever see a car not start simply because of a bad ground, after trying to diagnose 50 other areas after 2 days? That's just the tip-of-the iceberg kind of headache for starters. No thanks...

That's all I can, and am willing to answer any further, as I don't know any more about it.. I stay in my lane and don't screw with good designed stuff out of the box like a Honda wiring harness.... Just try it for yourself and find out.

 

I can add to what Shodan just mentioned.

One user about a year or so ago posted that his car wasn't starting after he changed one of his main ground straps. I think the one on his transmission.

He used a battery cable. The change in the wire caused his car not to start. As soon as he restored that ground strap to an oem wire, his car started flawlessly.

If you get the ETM for your car, you will see how many "shielded" sections the harness has. Those sections the engineers had to add shielding to reduce ElectroMagnetic Field (EMF) transfer after they built the pilot harness for testing.

The process you wish to do, do you have the equipment to monitor all sections for EMF pollution and be able to pinpoint where shielding needs to be added?

This is what Shodan is talking about. You make changes, you open the door to all kinds of things including EMF pollution beyond factory specifications. Which in turn can render your car anywhere from running improperly on any number of areas, to not running at all.

 

Thank you very much, you have been extremely helpful. When I have time, I'll give it my best try and report back. Worst case scenario I just replace the engine harness with my extra.

 

Great information. Also, by the shielded sections of the harness, are you talking about the the wires with the silver strands and foil stuff around them, like the knock sensor wire? I'm asking because none of the things that I would be rewiring has any special shielding, I already looked.

 

I believe that would be the added shielding yes.

The point is, any change you make can potentially change the shielding requirements anywhere in the harness.

I'm not sure if you have had any electronic or electrical education but every wire running alongside another wire with insulation between them basically makes a capacitor. As well as resistance is another factor involved.

Making changes, changes many things in the harness specifications. You may get lucky, or you may not. Or worse, you make things worse but not in any immediate visible sense. i.e. cause the car not to detect fuel trim properly and the car runs rich or lean for the length of time you drive and own it. Won't be noticeable until the engine decides it's had enough and you really won't know that it had to do with your harness changes.

It's precisely why Shodan said he would be unable to predict exactly what would go awry. You just can't know the effects or even see them without the proper testing equipment.

 

Going back to one of your earlier statements, I fail to see how relocating the battery to the trunk is a "need" on a D17, automatic transmission powered car. Unless you had plans to store something in the engine bay, I don't particular see any gain what-so-ever. If this car were destined to spend its days on the track, I'd say that'd be a far better reasoning. After reading that, I have some concerns with the wiring used to relocate the battery itself. What gauge/quality wire did you use to relocate the battery? Where are your grounds for the chassis up front and out back by the battery?

 

Thanks for the comment. I never said I "needed" to relocate the battery, I just wanted more even weight distribution and the extra space in the engine compartment is just a plus. It makes working on things much easier and looks better. I also have an Optima Yellowtop D34 battery from when I lived in Chicago, so it barely fit in the factory mounting location, which is another reason I moved it. I also took off my power steering, so 50 lbs less weight over the front makes it a little easier to steer. As for the way I did it, I used 0 gauge copper wire with crazy thick insulation and a 250 amp car audio fuse right where it connects to the positive battery terminal running from the battery to the front of the car, which is the thickest I could have ran under the interior panels. I have 3 4 gauge copper grounds going from the motor to the body and 2 4 gauge copper grounds going from the transmission to the body, and I thoroughly sanded all the ground connections to shiny metal before installing them. As for the battery grounds, I have 1 2 gauge copper cable going from the negative battery terminal to one of the 3 drivers side rear strut bolts, and I also ran another 2 gauge battery cable from the side post negative battery terminal to one of the 3 passenger side rear strut bolts, and I sanded all those ground connections to shiny metal as well. Is that a good way of wiring the battery? I can't think of how I could have done much better, but if you can, feel free to share.

 

To be fair, you did say you needed to move the battery to the trunk. I understand the "why" you chose to move it, and it seems you did a thorough job wiring it properly.


Removing the power steering and battery won't really have any impact on the car's steering feel, when thinking in terms of weight, because even combined... they're not going to be much more than 30lbs of overall weight loss. If anything, you're going to just make slow-speed turning more of a chore (I did this on my EM2 as well, just for reference).

 

Thanks for the input. I would say that I reduced the car's weight by about 20 lbs by removing the power steering, I made $100 by selling the system, I like the steering feel better, I made more room to work on things and the engine seemed to rev slightly quicker without the drag of the pump. Moving the battery to the trunk did seem to make the car go around corners a little more effortlessly though.