I tried fooling the P13 ECU into thinking the ELD was present without success, and gave up, since it doesn't cause limp-mode. Now that the Prelude-powered Mini is running I've been doing test drives and up to now battery charging hasn't been a concern. Recently though, in slow traffic, the electric radiator fan was switched on. It was pretty surprising when the engine acted like it had been kicked in the nuts, similar to letting out the clutch too fast. Apparently the inrush current of the fan caused the alternator to really load down the engine.

Not having an ELD, I'd like to use a two-poll switch for the fan, one side switching the fan, and the other telling the ECU to increase alternator output. I've messed with it some, but haven't figured out what the ECU wants to see as a signal.

Anyone know?

 

I would guess it just measures the voltage drop across a shunt in the fuse box assembly. The helm might have some details, and I have a coule spare assemblies that I could open up if you are really interested. You might try hooking your switch to the A/C input. The ecu will also bump the idle if the A/C is turned on. If you just want the CEL to go off, you can switch to your other ECU and disable it in the ROM.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flyrod &raquo;</TD></TR><TR><TD CLASS="quote">I would guess it just measures the voltage drop across a shunt in the fuse box assembly. The helm might have some details, and I have a coule spare assemblies that I could open up if you are really interested. You might try hooking your switch to the A/C input. The ecu will also bump the idle if the A/C is turned on. If you just want the CEL to go off, you can switch to your other ECU and disable it in the ROM.</TD></TR></TABLE>

Hi Flyrod. Doh! VERY good idea about running it to the A/C input!!! I'll do that. I read somewhere the ELD input into the ECU isn't digital, but an output from a current sense coil. If true (which is why I'm asking) it could make it very difficult to fake it out. However as you point out, that can be gotten around by just using the A/C. The CEL doesn't bother me. Anyhow, cool! I'll give you full credit.

 

yes i believe its just a coil that;s measure the current flow across a wire or something, kind of like a current clamp that you would use on your digital multimeter to measure the current.

i;m surprised that your experiencing that much of a problem. i used an aem ems, which doesnt have any alternator control for like half a year and never experienced charging problems. though i have never tried to see what it would do on a stock ecu w/o the eld plugged in.

 

I don't have any charging problem, it's only when the fan is first turned on. The inrush apparently puts a huge load on the alternator which puts a big instantaneous load on the engine, but just for a second. The idle takes a big hit but recovers in less then a second. It's not a big deal but it would be nice to have it less tramatic to the engine.

 

ah i got ya.

perhaps u can bump up the idle a tad, so when it hits the drop won't be so severe. what are you idling at now?