ZCHondaCRX91

Okay, I got a 91 crx. Before the car would idle at around 800-1000rpm, with all the accessories on (headlights, heater, etc...), but I swapped in my new cams and got it all tuned, but now at idle if I turn any accessories on it will not want to idle right and might idle at like 200-300 rpm. I thought it was the ELD, because it was only putting out 0.5 volts at idle and would drop to 0.2 volts with accessories on. It's suppose to be 4.5 to 5 volts with nothing on, and around 2-3 volts with accessories on. I tried 3 other fuse boxes with the same result. The wire from the ecu to ELD is good, there is a good ground and power going to the ELD. No CEL, the alternator FR system checked out and the battery and alternator are newer (newer wiring also). Any help would be appreciated. Thanks.

frankenghia

Check alternator output and check your grounds.

ZCHondaCRX91

Alternator output is 14.5 volts (13.5-14 volts with everything on), and all grounds are clean and new. I also checked resistance to ground and all the wires.

frankenghia

have you tried checking the input voltage at the plug going to the eld?
Any CEL's?

ZCHondaCRX91

Yeah, voltage going to the ELD is 12 volts with the engine off, and 14 volts with the car running (about 0.5 volts difference from it to the battery). The ground wire is also good. So the only voltage coming out is 1.1 volts, with key in start and engine off and maybe 0.5-0.8 volts with engine running, 0.1-0.4 volts with accessories on. There is no CEL, probably because it's getting low voltage as if it has all the accesories on.

PyroProblem

Is the ELD disabled in the tuning software youre using?
Tuners sometimes diable it...

ZCHondaCRX91

I have turboedit, and it doesn't have a place to disable ELD. It also shows 0.00 volts when datalogging, I guess it should show 0.50 or something. Does the ECU determine the voltage output of the ELD at all?

PyroProblem

If I remember correctly, the ELD is an input to the ecu and the ecu will adjust IACV pulsewidth and alternator output accordingly dependant on electrical load on the vehicle...
So to answer your question, I believe the answer is No.

ZCHondaCRX91

So the ELD should be putting out more voltage. Does it decide what a load is by amperage or by the voltage drop?

ZCHondaCRX91

Okay, so I tried testing the RF signal from the alternator and it didn't test good. I did as it said and disconnected it, turn the key to on, and it measured 4.66 volts at the B14 (blue alternator input). Then I tried starting it with it disconnected and it idled fine, and the idle didn't drop at all when I had accessories on, but it wasn't charging. It's suppose to go down in voltage (ECU B14 wire)when accessories are on, but it doesn't move at all. I tried testing it with the alternator connector reconnected and the voltage went from 4.66 volts to 1.5-1.6 volts and still didn't change voltage at all when accessories are turned on. I checked the wire for short to ground, but it was fine.

If anybody reading this has a CRX or Civic that is perfectly fine could you check these voltages for me to compare? I don't know why the voltage would drop just by connecting the alternator plug. Also, does anyone have any idea what the other two wires do on the alternator plugs? They are black/yellow and white/blue, they both have 20ohm of resistance to ground so are they some kind of ground wires? Thanks in advance, I really need to know this.

PyroProblem

According to this...
http://www.civicforums.com/forums/21...-detector.html
The ELD determines load via current draw (amperage) and the more load on the electrical system, the higher the voltage to the ECU. Thats how Im understanding it...
Then the ECU sees this and activates alternator field circuit to supply the battery..

Have you tried voltage drop tests to and from the ELD/battery/ECU?
What if you tapped into a 5 volt pin and introduced it to the ELD input. It should activate the alternator signal wire and everyting should be at full power, right?

ZCHondaCRX91

Yeah, that makes sense. I think it now has to do with the Alternator wiring, because if I disconnect the alternator plug it idles fine, just doesn't charge the system. I have seen a few people with the ELD disconnected and it idled and ran fine so I don't know if that's the main problem. All the wiring tested fine to the ECU. I figured there is (2) 12 volt sources the white/blue and black yellow, to the fuse box and battery light. They seem to be fine, the ecu has 4.66 volts at the blue or yellow wire, but as soon as I plug it in the voltage goes down. I don't know if it's suppose to do that or what? I think it's a combination of the ELD and FR signal not getting to the ecu or wrong voltage, which is causing my idle problems.

ZCHondaCRX91

Voltage at the battery is about 14.2 volts, voltage at fuse box is about 14.16 volts, and the ELD power is about 13.98 volts (tried hooking straight to 14.16 with no difference). I thought about doing the bypass, I read a few threads about that, but those were guys with huge stereos and seems kind of a band-aid fix.

ZCHondaCRX91

Has anyone just used a 1-wire alternator on a Honda? When I remove the connector it idles fine, it just doesn't charge. I think just a basic 1-wire alternator would end all these problems. Could it also idle fine because the alternator isn't charging?

ZCHondaCRX91

I just read on a old thread, where they just used the black/yellow wire and left the other wires off and it work that way. I'm going to try it out.

PyroProblem

I think the better/correct way to measure alternator output is by measuring the amperage output, not necessarily the volts. I forgot exactly why, but it seems like I remember seeing/hearing an alternator can have OK voltage output, but be low on amperage output, and still be bad.
IDK all the theories behind it...

Hopefully some honda electrical gurus can chime in and lend some advice..Good luck either way!

ZCHondaCRX91

Yeah, I might just do that. The alternator is newer, and I guess I can see if it is in high or low amps when the accessories are on. Thanks.

frankenghia

Just out of curiosity..... Whats the voltage output of the alternator before and after you turn on lights or any acc.?

ZCHondaCRX91

If I turn on the headlights, the voltage will be about 13.8 volts and then when the idle drops down to 400-500 rpm it will be around 13 volts. If I have heater, headlights, high beams it goes down to 12 volts and if I rev it up it goes back up to around 14 volts and then when the idle drops again it goes back down to 12 volts. I'll see what an amperage test will show.