I like to think I am very knowledgeable in circuits but this one has me stumped!! I hope this doesn't get long, but I'm trying to give as much info as I can...

P28 socketed ecu, boost by gear, running eCtune, Ostrich v1.0 and Tunerview 2.0 datalogger/display. Car will intermittently act up....

Car idling - voltage is 14.15 through eCtune, 14.7 through tunerview. I checked with a multimeter and its 14.2 across battery. I think the tunerview is off slightly (its always done this). With all the lights on its about 14.0v.

Car off - voltage is 12.5 with nothing on. When car is turned on (not running) with all lights (4HIDs), brake lights, stereo, etc voltage drops to 11.7.

Battery is new 2 years ago, and cranks the car fine.

Problem
-it will begin idling high (usually idles 900-1000 with pro1's but goes up to 1400) when this glitch happens.
-TPS when idling, instead of being 0% will stay at 2-3%
-When shut off, IAT fuel compensation will jump to -100% and the car will crank and not start. Then sometimes after 3-4 seconds of cranking, the IATc will go to the normal value (-1 or -2 depending on temp) and then car will start (i watched it do this through the tunerview)....this made me think the ECU was fried..


What I've done:
--TPS is tight, is calibrated perfect at 0.47v, until the glitch happens and it sticks at 2-3% (0.67 volts if I remember).
--I swapped out the ECU's for another known good one, same problem.
--I re-mapped the ostrich from eCtune, same problem.

I notice sometimes after driving and the car is sitting idling, that the voltage will sometimes drop to 13ish from the usual 14.2...the car studders during this time (the idle drops), AFRs go whacky, etc.

I have another moates ostrich, I am going to try swapping them out tonight to rule out that being the issue. I doubt it though, since eCtune verifed the ROM is ok even after the glitch has happened.

I'm more inclined to think something is wrong with pins A16 (Alt control) and D9 (Alt FR)......any thoughts???? Could the alternator somehow be bad?

This is a CDM car, i do not have a ELD.

 

Keep in mind that Hondas charge is two modes, low output and high output. The low output mode will kick in after the car has warmed up and you are either at idle or up to about 45 mph and under low throttle/rpms and you have no acc on. Other than that it will charge at the usual 14.6 or so.

Since you say you do not have eld and you are referencing the FR circuit of the alternator I would start there. The FR is only relevant with regards to eld.

 

^thanks for the explanation. I'm not exactly sure how the FR works with no ELD but I think I have solved the problem.
I will drive the car some more this weekend and see if its solved.

when I scaled my TPS in eCtune I must not have been paying attention to the voltages.

I put the voltmeter on the TPS when it was connected and it was 0.47v closed (this is good) but at WOT it was only going to 0.95v!
So eCtune was setup for 0% at 0.47v and 100% at 0.95volts......damnit!

I swapped the TPS out for a known working one, and the idle seems good, alternator is consistent again, and TPS obviously isnt sticking at 2-3% anymore.
The TPS hanging at 2-3% sure must mess up quite a bit.

The whole -100% IATc - I am still not sure but I think its a glitch in eCtune. The car has been starting fine now, but it still reads -100% until you start cranking, and then it goes to the actual value...weird.