Enough is enough..... I still have voltage issues. I have declared WAR.

Current status.
Bat reads 12.6 while the Commander reads 12.4.
I forgot the reading at idle. I believe it is a .2 difference and in the low 14s now that I got the smaller pulley back on the alternator. (Back to a factory size). Not bad at all in my opinion considering I have the batt relocated to the passenger bin.
I was out logging to check how all would go and once again I got low voltage. In a higher boost/rpm cell at one point it recorded a max of 13.4!!!! WTF!!!!! Most of the other cells are 13.7-13.8.
This is what the logs off the pfc say. I am sure if I rechecked the fuel pump it has at least a couple 10ths of a drop from what the Commander reads which should be acceptable....., but this is definitely not cool.

I just got this alternator from IRP. 140 amp.... batt is 12.6 and about 1 year old maybe.

The batt is grounded to a bolt holding the fuel filter and another point up around the starter I believe.. j have to double check.. I am adding one 6 guage from the neg post to the passenger seat track bolt. All will be sanded nice and shiny.
I will start testing every damn ground on the car that I know of I guess.

I will add some 4 or 6 gauge wire to piggy back the wire from batt to starter and fwd. I will replace the grounds or piggy them on the fuse blocks.

What the hell else is there!!!???!!! What am I missing? The only thing I can see that looks questionable is one ground from the big fuse block in the bay.

Anyone else have any ideas how to move fwd with this? I am sorry to keep bring this up!

 

The wire in question...

 

 

 

i checked mine the other day, and i checked voltage at the battery with it running and its low, but if i check the way the FSM says, the alt tests fine, the FSM has a good trouble shooting tree for this

 

Welcome to relocated batteries.

Remember, the RX-7 does not have a body that's made out of ultra-fine copper, it's STEEL, spot welded together with seam sealer goop at the joints. That does not make for a good ground path.

Get good quality large gauge wire and run one from the negative terminal of your battery to the engine block (the center iron has some extra tapped holes that will work) and one to the driver's side shock tower where the factory ground went.

The body of the car was not engineered to have a ground going from a threaded hole in the storage bin.

That may not be the whole problem but it's not helping. There was discussion on the PFC list about this not too long ago.

Also, to be honest, you're doing pretty good if you are seeing 13.4 - that's acceptable. A lot of that is probably that upgraded alternator. Mid-13's is a happy place.

Dale

 

Thx J9fds3. I will check it out.

 

Thanks Dale. I will look on the irons and see what I can tap into.
I am worried for the 13.4 as that means my fuel pump probably has 13.2 and to me that is low enough to drop some pressure and lean out. I will probably still swap out for the walbro.

I am trying to find a link to a diagram where ground and power wires are on the fuse blocks..... they ground to the irons and strut tower also correct? I am getting ready to hammer all this with a vengeance!!!

 

Atkins (I think) gives away a free grounding cable that goes from the block to the chassis by the front strut tower. Of course, one should order something if asking for that. I also ran a 4 gauge cable from the battery negative to that same ground for my battery relocation. Either way, a nice 4AWG, or larger, grounding cable should help.

 

What pulleys are you running? Check your grounds. As mentioned above, a battery relocation with just a single ground going to a threaded hole in the chassis is not sufficient.

 

Pulley that's on is what's on your upgraded alternator.
I have 2 grounds.. one to the threaded bolt on the fuel filter bracket, and I have to see where the other is going. Regardless, I will run an additional up to the engine block as Dale described. Very frustrating for sure. I thought your alternator would have fixed the issue to be honest.

 

The alternator can only do so much when you don't have the right wiring. It's like running a ported engine with a large turbo through a stock Honda Civic exhaust, you are choking it down.

Also that fuel filter bracket is, I believe, on the subframe, which is even worse for a ground.

Just to be more clear, the stock irons have holes already threaded on them on the driver's side that you can use. You don't have to drill/tap or anything weird.

Stock, the negative battery terminal goes to the bracket that is on the driver's side strut tower that holds the fuse block. It grounds to that bracket. Then it continues to a bracket that's bolted to the AC/PS pump bracket. That's part of the reason the grounds even stock aren't great, they are going to these brackets and not the direct engine and chassis.

Pettit Racing is who has additional ground wires they give out free with purchase. This is a VERY old mod, it can help with the 3000 RPM hesitation on the stock ECU, it just goes from the negative terminal of the battery to a threaded hole on the driver strut tower. That helps overcome some of the problem with the stock cable going to that goofy bracket.

Dale

 

Thanks. If I ever get off work I will get it done and report back.


You guys think 6 gauge is enough for these additional grounds or I should go with 4? If I go any bigger then I will tear everything out and put 0 or 2.

 

The numbers you are giving doesn't sound so bad. The electrical system was never very good on old cars like this. You can go ahead and add ground wires, but don't expect some drastic improvement. Even with the higher rated powered alternator, remember that an alternator's output is proportional to its speed.

 

On the log you can see it drop to 13.4 and end there.. I believe thats when I saw it climb a little on the afr. I am sure the pump saw 13.2.
I am sure your aware I was talking about the diodes, but I am so unfamiliar with it and everyone I speak to about it looks at me like I have 2 heads. I am just hoping to keep it all up around 13.7 or higher. I will give the grounds a shot. I will also be changing my injectors to ID 1300 and on a recommendation I will be swapping the denso pump for a walbro.... maybe those to changes will make it a little less susceptible to small changes in voltage....??...

 

On the log you can see it drop to 13.4 and end there.. I believe thats when I saw it climb a little on the afr. I am sure the pump saw 13.2.
I am sure your aware I was talking about the diodes, but I am so unfamiliar with it and everyone I speak to about it looks at me like I have 2 heads. I am just hoping to keep it all up around 13.7 or higher. I will give the grounds a shot. I will also be changing my injectors to ID 1300 and on a recommendation I will be swapping the denso pump for a walbro.... maybe those to changes will make it a little less susceptible to small changes in voltage....??... Supra and EV14 2200s currently

 

I took some time and skimmed over this thread and the other one you had that was related. Like you, I had a very similar scenario with great cold voltage of 14.3 ish and would drop especially when hot. Sometimes to around the 13.2 mark when heat soaked with the fans running. It took me a while to isolate it as well. I installed the stock pulleys, more grounds, new upgraded alt with heavier cabling, and chased it for some time before I solved it. I do have a couple questions first. Can you explain the current wiring method of your relocated battery ( size, routing, ect )? Have you load tested the current battery? In your photo the fuse block is missing the cover. Is the cover missing currently and not being used or been that way for an extended time?


~ GW

 

Hey Dale, have you ran this ground center iron and if so what gauge would you recommend using to be most effective?

 

Thanks for taking the time. The covers are only off for me to inspect the connections. The car stays in the garage with nothing odd to report.

I should know the wire size off hand, but I do not. It is Pettit's relocation kit. I will try to estimate the size when I get back home.

I have not load tested the batt. Probably should have done that before making these threads. I just know it has 12.6 at rest.

I can't recall the 2nd ground, but I will report back with that also. The other as stated goes to the threaded bolt holding the fuel filter.

 

So you have the stock pulleys, you're going to add a bigger ground wire, you've got a higher output alternator. Maybe switch to a lithium ion battery (I know that seems to be a can of worms around here)? I mean really, you've got a 30 year old car designed when a large % of cars on the road still had carburetors. When I bought my FD it had a Miata battery in it (stock location) allegedly to save weight. Well guess what, Miata batteries suck. Pretty much the stock heavy batteries in the stock location have decent output and everything else is a compromise of some sort, but even a good battery doesn't change tiny *** weight-saving 30 year old wires.

If you're worried about fuel pump voltage dropping affecting AFR's, yeah you need to consider the fuel system you chose then.

I doubt these cars ever got more than low-mid 13ish volts to the ECU and the fuel pump from the factory when you consider accessory load in hot weather (A/C, headlights, cooling fans all at the same time). Throw in these small relocated batteries and you're making it harder on the electrical system.

I guess what I'm trying to say here is you need to focus more on the robustness of the systems that depend on the battery voltage than expecting it to run 14+ volts under all conditions.

 

Just makes me wonder how many cars out there have popped motors for the same reason and never even thought about it or figured it out.
Again I don't think many people would noticed this. You make a few pulls, adjust fuel, afr are perfect and you move on..

This is a tiny batt for a "honda". It appears to be the biggest I can fit in the bin.

1. I will figure out what is the most serious batt I can fit.
2. Rewire and/or beef up the current wires from batt to respecting locations.
3. Re clean all existing grounds.

Do Not boost the car at night or with stereo on

 

Arghx do you think the bosch 2200s with the denso would be more affected than say id1300 with a walbro by voltage? Or am I just throwing money around unnecessarily swapping things out?

 

I do agree with raymond most of these cars are lucky to see voltage in the high 13s. They will fluctuate with the load demand placed on the system. My other mostly stock fd with bolt on's with a factory alt ( not upgraded ) sees voltage anywhere from 13.7 ish to 13.3 ish. While I don't necessarily like the numbers, they are in spec and are consistent day to day. I have seen one year old batteries that passed the load test cold but not pass hot. I very much doubt that's the issue you're having though. My other fd that I was having the voltage issue with was actually so bad that it would lean out after driving the car for an hour or two. Like you I also noticed that at the top of a pull the voltage would drop as well ( around the 13.4 13.5 ish mark ). What I found to be the culprit was actually located in the front main fuse block, the one you have the top off of. It was corrosion in the actually copper plate, main fuse, and alt termination of that fuse block. I had previously cleaned the alt termination point at the actual alt and the fuse block thinking that as the heat went up the resistance on the system went up as well causing the voltage to drop from being unable to flow enough electrons. I believed at the time I was just chasing my tail because since I had already done this once before. The reason I decided to recheck my work was because the main fuse size is supposed to be a 120 amp and mine was a 100 amp ( someone must of changed it at some point ). While putting in the correct size fuse I realized at that point the fuse slides UNDER the copper plate and is sandwiched between the plate and the 6mm nut that the bolt holding the termination end on goes thru. I wasn't able to clean the actual point that the electrons flow from the alt to the system on the back side the first time. I took my time and removed the box from the car. I removed all the fuses and de-pinned the actually copper bar from both sides, which is a total pain btw. The back side of my assembly was actually green. I took my time and cleaned the assembly till it was all shinny again. Replaced all the fuses with new ones and used dielectric grease sparingly. After I reassembled the car on a cold start I now see 14.5 ish cold and 14.0 hot. The only time I see anything under that is at idle, hot, heat soaked, fans running, radio on, and ac running which is 13.8 ish to 13.7 ish. ( I am running the irp alt as well on this car )
Having said all that this is my suggestion. I would make sure you have a good full size battery and not a mini battery. Have your power wire not be anything less than 1/0 from the battery to the main fuse block directly. Have two grounds from the battery, one that matches the power size of 1/0 or step down one size that goes to the seat or seatbelt mounting point and the other follow along the power wire and terminate at the body at the front fuse block so you can connect the factory ground and tail a final jumper to the center iron as dale suggested. This size can be smaller but I would use at lease a #6 copper. Make sure the connections are clean. You can throw another ground on there if you want but in my experience its not necessary. Take apart the main fuse block and clean / replace what you need ( I believe at the time of this the fuse blocks are still available new) , I did all the fuses and yes its a total pain to get that assembly apart. Where gloves when cleaning and reassembling it. The oils from your had will have it green again in short order otherwise. Clean the connection at the actual alt as well. I did add another wire in parallel from the alt to the main fuse block to help. This is what I did and now have had zero issues with the system. These cars are broaching the thirty year mark and as time goes on they will continue to deteriorate. Its just nature of the beast. Hopefully this help and you can learn form my hours and hours of troubleshooting, saving yourself the annoyance. These are just my two cents tho. Take it for what its worth.

~ GW

 

you need to tune it so that its ok under that condition
but clean your fuse box first, like gdub says, or at least look at it....

 

I was chasing an endless voltage war on my car as well and ultimately the cause ended up being the main yellow EGI relay. For whatever reason it was dropping voltage under hard load - from 13.5-14v all the way down to the 11s during a pull. The Haltech ECU in my car had data for the injectors and ignition coils at those voltages but it was very obvious that something was off. I ended up replacing the alternator, even ran a dummy light bulb to the exciter wire on the alt in case something was up with the factory dash, converted over to all 1/0 AWG wiring from the rear mounted battery(HUGE improvement in starter speed and worth every penny over 2ga). Ultimately I ended up attempting to bridge the EGI relay with some wire and got the full voltage back. Swapping the relay solved the issue and have had no issues since. Unfortunately I wasn't able to find a suitable non-oem alternative and the OEM relay costs about $80.

Worth a look.