Voltage drop during driving

Printable View

03-04-2013, 04:49 PM
USAF EP3

Voltage drop during driving

Going out on a limb here to reach out to anyone that might have a clue as to was is ailing my electrical system.

Last week I relocated my battery to the rear and also installed the Full-Blown dual pump hangar and ran a dedicated fused and relayed power wire to each pump.

This is how my current relocation setup is:

1. Battery with 4 wires coming from positive terminal (terminal is from an audio store designed to clamp down multiple gauge wires)
2. 1/0 gauge fused wire from battery to starter motor
3. 2 gauge wire to fuse box terminal (where old white power wire went)
4. 2each 8 gauge fused wires to each Aeromotive 340LPH pump
5. 12inch 1/0 gauge wire to ground on chassis. I made this in the pit hole looking part of the ends of the back seat where there are 2 14mm hex head bolts. Was rusted so I cleaned to bare metal before placing terminal.

The battery is an Optima Redtop Model #25. CCA is around 720, more than enough to turn a K20 over.

Also, added 6 grounds to the engine in multiple locations in the engine bay, all end connections have the paint/primer sanded down to bare, shiny metal. Those grounds all are 8 gauge wires and are as follows:

1. Alternator housing from 12mm bolt hole to front chassis (not the radiator core support)
2. Idle pulley bracket to passenger side strut tower
3. Backside of valvecover above VTEC solenoid to passenger strut tower
4. Cylinder head on transmission side with 10mm hex head to driver side strut tower
5. Intake manifold (RBC) near MAP sensor location to front chassis (where battery tie down bolt used to be)
6. Transmission bracket where old ground used to connect to battery is now grounded to where the battery used to ground on the chassis underneath the fusebox.

I believe I have done everything correctly according to what I have researched. Everything points that the wiring is correct.

The problem is that the voltage drops to 12.0V ~ 12.5V varying whenever I am in part throttle or off throttle and coming down to a stop pulling out of gear and into neutral. At the same time the engine wants to die and acts as if it has a vacuum leak with a surging idle.

What makes all of this much more interesting is that whenever there is electrical load on the system (i.e. headlights, A/C, loud radio, etc.) the system sees anywhere between 13.7-14V and it never behaves as I mentioned above. Essentially what I have been doing is driving with my headlights on all the time and it drives just fine with no voltage issues.

There are only a few things that comes to mind that could possibly be bad:

1. Alternator bad, the chassis has over 120k miles and it's the original one, I swapped it over from the A3 when I swapped the engine.
2. The voltage regulator may be bad inside the alternator. Don't see how this might be it since usually when these go bad in the RSX/EP3 platform they make the alternator output TOO much voltage.
3. My wiring? Again, don't see this as very likely since everything is correct size gauge and properly run to each component.
4. My 2 week old Optima battery might be bad. Don't see this as likely since I did a prolonged cranking test for 10 seconds and the engine cranks strong and consistently.

THIS IS DRIVING ME INSANE!!!!

Someone save me before I keep throwing money at it, next part I throw money at would be the alternator.

Forgot to mention that all my vollage readings I was getting through Kpro.
03-04-2013, 05:50 PM
Jpax

Quote:

Originally Posted by USAF EP3

There are only a few things that comes to mind that could possibly be bad:

1. Alternator bad, the chassis has over 120k miles and it's the original one, I swapped it over from the A3 when I swapped the engine.
2. The voltage regulator may be bad inside the alternator. Don't see how this might be it since usually when these go bad in the RSX/EP3 platform they make the alternator output TOO much voltage.
3. My wiring? Again, don't see this as very likely since everything is correct size gauge and properly run to each component.
4. My 2 week old Optima battery might be bad. Don't see this as likely since I did a prolonged cranking test for 10 seconds and the engine cranks strong and consistently.

THIS IS DRIVING ME INSANE!!!!

Someone save me before I keep throwing money at it, next part I throw money at would be the alternator.

Forgot to mention that all my vollage readings I was getting through Kpro.

Have you thought about adding a Cap - to your system to help with the low end voltage problems, having some stored energy might help if it's only during low rpm when the the alternator is not running at consistent speed. Have you changed pulleys on any of them? like added a smaller crank pulley or power steering? sometimes it might provide a lul during the RPM until it passes a cretin point to then speed up? I can't remember there are a few things too you can check using a battery tester, what's the voltage at, should be around 13.5~ 14.7
03-04-2013, 06:08 PM
USAF EP3

I don't have an aftermarket stereo system. No subwoofers, no amplifiers and I have stock speakers. I only have an aftermarket headunit, Alpine with iPod connectivity. I don't think a capacitor would help my situation, and if it did wouldn't it be a bandaid to a more significant problem?

When the voltage is not dropping it fluctuates between 13.7-14V. Ocassionally it will hit 14.1V.

I've been reading that the ELD might be a culprit as well, something else to check.

I haven't swapped any pullies for aftermarket. The only pulley that is different is the RBB crank pulley but that's because I have a K20Z3 shortblock and I'm using a K20A2 head. All the other pullies are from the stock A3.
03-04-2013, 06:40 PM
Jpax

http://www.ephatch.com/forum/showthr...-w-part-(P1298)

wonder if anyone near you has one you can swap out to test see if it helps
03-05-2013, 05:56 PM
USAF EP3

Quote:

Originally Posted by Jpax

http://www.ephatch.com/forum/showthr...-w-part-(P1298)

wonder if anyone near you has one you can swap out to test see if it helps

Ordered a new one, came out to $21. Waiting for it to come in.

Did some more troubleshooting yesterday, it's only happening after the car is warmed up (+160*F) and even when I have every possible accessory and eletrical load bearing thing running my voltage stays steady between 13.7-14.0V.

If there is no load and the voltage drops when I go into neutral, once I DO come to a stop the votlage comes back at idle. But also if I part throttle from a stop the voltage stays between 12.0-12.5V until I either go full throttle or I am cruising at a higher speed in a higher gear (usually 5th or 6th it goes away).

Again, while I'm looking at Kpro and I'm looking at the ELD reading if it's over 15AMPS, the voltage behaves just fine. If it's below those AMPS then it starts misbehaving.
03-05-2013, 06:08 PM
Civic5lug

I think your either getting a little TOO anal about your voltage reading OR your Alternator is on its way out. As long as the voltage increases when a load is applied, I wouldnt sweat it.

And HOLY GROUNDS BATMAN!!!!!! lolz!
03-05-2013, 06:24 PM
USAF EP3

Quote:

Originally Posted by Civic5lug

I think your either getting a little TOO anal about your voltage reading OR your Alternator is on its way out. As long as the voltage increases when a load is applied, I wouldnt sweat it.

And HOLY GROUNDS BATMAN!!!!!! lolz!

Well considering the engine gets to such a low RPM that it dies when I pull into neutral I don't think that would be normal.

I'll see if I can ask a friend to swap alternators with me and see if the problem persists.

You can NEVER have enough grounds!!!
03-05-2013, 06:47 PM
Civic5lug

Quote:

Originally Posted by USAF EP3

Well considering the engine gets to such a low RPM that it dies when I pull into neutral I don't think that would be normal.

I'll see if I can ask a friend to swap alternators with me and see if the problem persists.

You can NEVER have enough grounds!!!

whoa totally missed that part. Given that you're running two pumps i take it you have Kpro atleast lol. whats your idle set at?
03-05-2013, 06:53 PM
USAF EP3

Quote:

Originally Posted by Civic5lug

whoa totally missed that part. Given that you're running two pumps i take it you have Kpro atleast lol. whats your idle set at?

Idle is set at 900 RPM.

My tuner set it that high instead of the usual 750 because of my cams.

EDIT: One pump is disabled (pulled inline fuse) because I don't need that fuel right now until I'm boosted again.
03-05-2013, 06:58 PM
Jpax

I like an Idle of 900 rpm, usually it smooths things out, sounds like if it's dying off throttle, that its not the voltage . possible that the tune needs some work , and if you were tuned on winter fuel/ conditions your going to need a new one for summer fuel too / conditions.
03-05-2013, 07:01 PM
USAF EP3

It was tuned back in July before I deployed. I remember that day, it was blazing hot inside the building.

It does need a retune, planning a retune date with the tuner soon. Going to have to retune with the headlights on if I don't fix the issue by then LOL!
03-11-2013, 08:09 PM
USAF EP3

So after read through this thread:

http://www.civicforums.com/forums/21...-detector.html

I figured out my "problem".

In a nut shell:

Honda implemented the ELD in USDM model to save gas and kill the alternator to low output to decrease load on the engine whenever the ELD senses lower than 15ampish.

But this doesn't work for those of us that larger injectors, aftermarket stereo systems, etc etc. Because these peripherals require MORE than 12V in the system to operate due to voltage drop at certain areas in the electrical system. If you're stock then obviously you wouldn't notice this alternator "shut off" while driving because they made it to work for stock configuration.

Everywhere else in the world they DO NOT have an ELD and just have a jumper bar inside the fusebox (Canadian models don't have an ELD) and they don't have the voltage drop when there is low or no electrical load on the system and thus don't have this issue and their alternators crank out 13.5-14.4V all the time.

This also makes sense why KPRO has the "Disable ELD" option because everyone that doesn't have a USDM model would throw a code because they don't have an ELD so they would need to check the box option for that.
03-11-2013, 10:53 PM
Jpax

Quote:

Originally Posted by USAF EP3

So after read through this thread:

http://www.civicforums.com/forums/21...-detector.html

I figured out my "problem".

In a nut shell:

Honda implemented the ELD in USDM model to save gas and kill the alternator to low output to decrease load on the engine whenever the ELD senses lower than 15ampish.

But this doesn't work for those of us that larger injectors, aftermarket stereo systems, etc etc. Because these peripherals require MORE than 12V in the system to operate due to voltage drop at certain areas in the electrical system. If you're stock then obviously you wouldn't notice this alternator "shut off" while driving because they made it to work for stock configuration.

Everywhere else in the world they DO NOT have an ELD and just have a jumper bar inside the fusebox (Canadian models don't have an ELD) and they don't have the voltage drop when there is low or no electrical load on the system and thus don't have this issue and their alternators crank out 13.5-14.4V all the time.

This also makes sense why KPRO has the "Disable ELD" option because everyone that doesn't have a USDM model would throw a code because they don't have an ELD so they would need to check the box option for that.

ahh ok, so is everything working good now!? how's she running?
04-26-2013, 12:52 PM
USAF EP3

UPDATE:

So to sum it all up, the voltage drop is NORMAL. Honda made the electrical system this way.

The idle issue was my change in injectors. I previously had Deka/Siemens/Precision 650cc high impedance injectors and I swapped out to ID1000cc's without doing much other than changing the fuel inejctor trim to 1000cc.

Did some researching and reading and found out that the ID1000's are very finicky voltage-wise. Found a voltage compensation table vs. fuel PSI. That's why I was having such shitty idle because in my voltage compensation tables I had a jump from 10V to 13.9V and thus why my car was running just fine at normal voltage.

After inputting these values into Kpro and readjusting all my fuel tables....CAR RUNS LIKE A FUCKIN' CHAMP NOW!
04-26-2013, 10:09 PM
superstocksi

I'm glad that I ran across this post before I actually went through with replacing my ELD. I have had that ELD code for a few years now and never really cared to replace it, but I just started the process of servicing everything after letting the car sit for 6+ months, and this thread just saved me the hassel of fixing it. My voltage has always been pretty rock solid around 14.4v, even with the draw of two reasonably sized amps and a radar detector running. I also never noticed thta I could turn off the ELD in kpro. I'm definately going to do that tomorrow, after I dust off the old laptop that I use for tuning.