bks84

iTrader: (9)

Im having some weird voltage issues at WOT in my Turbo GSR Civic, on Hondata S300 V2, Hondata COP, CJS Tuck Harness (COP integrated)

Ive swapped alternators twice, second time being to a reman from Advance. I am using an ATI Street damper (which is supposed to use the same size pulley as the OEM balancer). I do have a few OEM pulleys and a spare Fluidampr I can swap on to test out.
Belt is tight
Fuse 15 is good
ELD is disabled
Engine harness does not have ALTC wire, but when using HondataCOP that wire is depinned/cut at the ECU Connector anyhow.

I have 14.28v at the alterntaor
14.28v at the battery
14.28v at the fusebox
13.9v at the A25 on the OBD1 P28

All primary testing done on the original V2 that the car was tuned with. Ive since picked up a S300 V3.

Based on the datalogs, the voltages drops just as I start building boost. It drops to the low 12's.

Basically, at 7400 I was at 12v.

What other diagnostic steps am I missing?
Should I pull the alternator and have it warrantied out?
Are there good alternator options out there? OEM isnt an option anymore.

Aradin

I see this issue frequently with aftermarket alternators and even experienced it myself at one point. The remans are nowhere near the quality of the original OEM unit. Typically the aftermarket unit will run fine under normal circumstances but at high RPM voltage will drop off and cause all sorts of issues. Usually including the battery light illuminating in the cluster. I have had occasions where I had to warranty the part 5+ times to get a decent one. I've seen them test bad right out of the box too.

What I started doing is buying used OEM alternators/starters/other electrical items from junkyards or on eBay with the lowest mileage possible. I have had nothing but success going this route.

It sounds like you have gone through some troubleshooting and ruled a lot of things out. My recommendation would be to try and source a used OEM unit if you can and see if that remedies the issue.

bks84

iTrader: (9)

Looking at my logs, as soon as the car makes 1psi of boost the voltage starts dropping.

I hate that OEM units aren't available. However I did see a denso reman on rockauto... its 140 with core I might give it a shot. Who knows if it's rebuilt with denso stuff or the same **** they use on all rebuilt units

The 1st & 2nd alternators on the car were OEM. I have a 3rd obd1 and an obd2 one I can try.

I did put stock gsr crank pulley on it, nothing changed.

Aradin

That is interesting. Have you gone over your grounds and the actual output wire from the alternator? What gauge wire are you using for those?

bks84

iTrader: (9)

I covered all that in the first post.

Using 4gauge wire for alternator power and the 3 grounds i have (trans to frame, alternator to core support, cylinder head to core support)

I have 14.28v at the alterntaor
14.28v at the battery
14.28v at the fusebox
13.9v at the A25 on the OBD1 P28

The issue here is that S300 (tried two, a V2 and a V3) regardless what I get on the alternator or anywhere else, Smanager sees it varying, from as low as 12v to in the 14s while idling. and of course when at WOT it dances around as well in the datalog.

bks84

iTrader: (9)

Found my fuel pump relay harness had essentially shorted itself and slightly melted.

Replaced it with a deatchworks relay harness.

Even still the voltage in boost, drops into the 12's. Kinda at a loss right now, not sure what the next step might be.

AllMtrRex

Try a different harness. Oem harness if you have one.

bks84

iTrader: (9)

I'm leaning towards doing that... super irritating that you spend a good chunk of $ on **** and it's worse than a 18 year old hacked up harness.

To "try" a different harness I have to find the harness, distributor and wires, ECU jumper. Such a damn headache

motoxxxman

the fuel pump itself is likely the culprit. Especially if it drew enough current to melt the harness. What pump are you running?

bks84

iTrader: (9)

Walbro 450. I replaced the melted harness with a deatchworks universal harness. So we'll see how it goes when I log it again

bks84

iTrader: (9)

Well the pump wasn't the culprit

Ive just about given up on this thing.
Replaced battery (purchased a new one tonight actually)
Pulled alternator brackets, sanded all the matting surfaces
Tried three used OEM alternators (I have as n obd2 alt. but haven't tried it yet) and one reman
Ran new alt charge cable
Ran new grounds
Tried 2 different ecus
Replaced the fuel pump harness
Replaced the fuel pump
Swapped complete fuse checked all fuses
Rewired my wideband power source
Tightened the belt really tight
Tried stock gsr crank pulley (alt pulley on the gsr was slightly bigger than on the ATI street, but not much) I have a b20 pulley which has a larger alternator pulley, should I toss that on for laughs?

As soon as it's in boost it starts showing less than 13v, as low as 12.3 (maybe lower)

Is it worth trying an OEM 99-00 engine harness with a ECU jumper harness and stock distributor? Get rid of the CJS harness and coil on plug kit?

GIZZ - EXV

I know this is an older thread, but it's one of the most recent of this issue. What was the eventual solution? Or does anybody else have any insight on this?

I'm datalogging a drop in voltage at high rpm, fuel pressure gets erratic and it goes lean. I really thought I was overspinning the alternator, rigged up a 4" alternator pulley to get alt speeds under 15000 at the limiter but I still see voltage dropping at 13500 alternator speed, this is with another oe alternator. I'm okay up to 8400 engine rpm, but there is more power to be made. Very frustrating.

bks84

iTrader: (9)

I cant remember if I solved this issue before it blew up or not. Sorry.