[Stefanzoh]

Hey all. Got to do some pulls today and immediately noticed voltage dropping at high rpm’s.
My setup:
2000 civic with k20
Autozone rsx-s alternator
Ktuned ac/ps delete kit (belt is tight)
Hondata kprov4
DIY charge harness
Odyssey p680
Spal fan/deatschwerks dw400 pump/headlights pull lots of load.
Anyone have any guidance? I refuse to believe that my battery/alternator are too small. I have the same pump/fan/battery in the same chassis with Hondata s300 no issues.
I’m thinking of removing the alt-c cable (#b18) or following this step I saw on a forum: “The ELD circuit is pretty easy to fool. Pull the ELD out and use a 600-800 ohm resistor to ground and the ECM thinks the car's current load is high (forcing C to keep the alternator in high mode).”

 

[drtye]

What sort of grounding do you have for the engine?

 

[Brotatochip]

I immediately suspect the Autozone alternator. My only reasoning being I have heard plenty of stories of them being bad right out of the box or going bad quickly after install.

 

[Stefanzoh]

What sort of grounding do you have for the engine?

All short runs of 8 gauge, maybe 6inches or so for each. Tranny to chassis, intake manifold to chassis, engine harness to valvecover stud.

 

[Stefanzoh]

I immediately suspect the Autozone alternator. My only reasoning being I have heard plenty of stories of them being bad right out of the box or going bad quickly after install.

I do too honestly. I’d like to troubleshoot easier/cheaper solutions first though

 

[Lotus]

You can disable ELD in the KPro and cut the wire. You can also disable the the function to lower alternator load at high rpm and WOT.
Most of these aftermarket alternators are chinese knockoffs of questionable quality. I’d not be surprised if it

 

[Stefanzoh]

You can disable ELD in the KPro and cut the wire. You can also disable the the function to lower alternator load at high rpm and WOT.
Most of these aftermarket alternators are chinese knockoffs of questionable quality. I’d not be surprised if it

I was looking in Kmanager for that: " disable the the function to lower alternator load at high rpm and WOT.". Any idea what it's called?
It says I have ELD disabled. I wonder if that Alt-C pin is still active, since I have ELD disabled.

 

[Stefanzoh]

To not leave this thread as a dead end for future readers:
I strongly believe I installed the AC/PS delete kit wrong and/or it is such a bad design which leads to these problems. The top alt. bolt was able to rattle loose and fell out. Either way, I will be ditching this setup and just using the EPS cars' idler pulley like I should've done in the first place.
I will also be ditching the autozone alternator and using the OEM one to rule out any inconsistencies there.

 

[Lotus]

In the Doctronic ECU you can then reuse that analog ELD input for other purposes, e.g. for an external wideband controler signal. In Europe this is common as we mostly got the PRA ECUs, which only use narrow band lambda sensors that are no good for map tuning.

Regarding alternator control, could be that Hondata does not offer that option.

 

[Stefanzoh]

Welp, sad to say that this issue is not fixed.
Though I did find some details on what could be causing this.

I'm now using the OEM alternator and idler pulley. I do have my small battery relocated to the fenderwell. I am using pure and true 8awg wires with solid copper lugs. t1 and t101 are hooked up properly. 3 grounds also hooked up, re-sanded and cleaned last night before this datalog.

Another user, Stern, posted this:

I noticed that the time between me starting the car and the A/F reading to start there was a smoother idle and voltage wasn't fluctuating. This got me thinking so I unplugged my o2 sensor and the voltage fluctuation was basically gone. I was seeing 13.8 to 14.1V with a lot less fluctuation. So I started checking the o2 power supply and what may be causing the voltage issue. I made sure there was good voltage at the battery, alternator, and fuse box with the car off and on (12v+ and 14v+). That was all good so I moved into the car. Voltage at the ECU was 12v+ with the ignition on but was fluctuating with the engine running. I then thought to check my relay which is part of my PNP harness. This relay has pins 30, 87, 86, and 85 (numbers could be wrong :silly and I started inspecting those. Turns out the 30 pin (constant 12V) was getting its voltage from the same wire the ECU was getting its voltage. If my memory serves me correct this is plug C101. Now this relay runs the primary o2 and they are pretty voltage dependent. So I ran a separate power wire from the battery to the 30 pin on the relay and not to my surprise the voltage fluctuation was gone and I still had the o2 sensor connected and reading A/F. Looking over the wiring diagrams posted the RSX o2 relay is wired to the ignition power and not the main relay power/ecu power (pins A2 & A3). It would make sense to me to have the relay powered by on constant 12v as that's generally how they are used."

However, I'm using the Ktuned chassis conversion harness and am not using the o2 sensor relay. I simply have both o2 sensor female and male connectors unplugged. So, unless if the relay coil is still pulling amperage away from the ecu, then I doubt that is causing the issue. But, to rule it out, I'm going to try that now and I will post back any results.

 

[Stefanzoh]

Scratch that. All 3 pins on the alternator match up. 2 pins on the B connector, 1 pin gets ignition power 12v. Alt C is not used for some reason.

 

[Lotus]

The ALT DIAGRAM is on 4-31 and 11-73

C101 is one of the reverse switch contacts:

https://doctronic.at/download/K-Swap%20Harness.pdf

B13 is ALTF: “This signals ECM when alternator field circuit is energized.
ECM compensates for changes in idle speed and low battery voltage which can cause erratic injector pulse width."

= the ECU can control the alternator charging current through this pin. It can increase it at idle with AC on or it could switch the alternator off at WOT to gain more power.

Just search for C101 in the Acura manual

 

[Stefanzoh]

Well, the o2 sensor relay rewiring yielded no results as I expected.
I started playing around with grounds and found that if I added an extra strap from the valvecover to the strut tower the idle changed, and when I check the voltage seemed to smooth a little. Here is the new datalog with the added ground.

I'm not sure if this is normal fluctuation? Still drops to 13v at WOT?
Car seems to drive pretty smooth. However, I'm getting P0336 Intermittent CKP.. going to double check timing, pins at the connector and maybe swap actual sensor. Using k20z3 sensor and ebay harness with k24a.

 

[Bjorn]

Well, the o2 sensor relay rewiring yielded no results as I expected.
I started playing around with grounds and found that if I added an extra strap from the valvecover to the strut tower the idle changed, and when I check the voltage seemed to smooth a little. Here is the new datalog with the added ground.
View attachment 110830
View attachment 110831
View attachment 110832


I'm not sure if this is normal fluctuation? Still drops to 13v at WOT?
Car seems to drive pretty smooth. However, I'm getting P0336 Intermittent CKP.. going to double check timing, pins at the connector and maybe swap actual sensor. Using k20z3 sensor and ebay harness with k24a.

The ecu is likely commanding the alternator to reduce load at full throttle. I wouldn't be concerned about that.