RSX base CEL, limp mode, no codes, datalog problem

[Spunkster]

If voltage is fluctuating you need to resolve that issue first and go from there.

[lammertime]

update:

Tried again and voltages seemed ok.. between 14.3 and 14.5 while on. I left it in to drive around the whole day. Usually I had been plugging in the stock for daily driving as I didn't want to run the car in limp. The bottom red button flashes and the CEL comes on in limp mode but goes away after 7-8 minutes. The kpro will "click" and the light will go from red to green. The engine will do like a mini stutter and then the CEL will turn off and is good to go.

Once the engine is warm, I can restart my engine and the kpro will be good to go. I will try to take a datalog of this tomorrow. I'm guessing that it will be unreadable while in limp but the sensors will start to read after it is warm.

Does this change anything?

[Spunkster]

It sounds like the battery voltage is too low when cranking and that is causing the problem. You either have a weak battery, or there is a problem with the wiring causing the voltage to drop. Use a multimeter to determine where in the wiring the voltage is dropping and there could be corrosion or a loose connection.

[lammertime]

Update:

Has been doing much better lately. I can either start the car with no codes, or it goes away much quicker (1-2 minutes of driving).

The voltage at the ECU should be same as the battery right? It seems to be consistently about .4-5v lower.

Crank at battery is 11.7v. Have not had a chance to check wiring yet, but I feel confident that that will be the problem.

[lammertime]

Update:

Still having problems, but it works much more consistently now. No more DB comm error, but still occasionally does not work properly.

When it's not working, the green LED is not lit and the one below it blinks red. What does this mean? It's not listed in the kmanager troubleshooting page. When it's not working, datalogging/uploading works fine. The red light stays illuminated dimly and blinks brightly when datalogging and the sensors being stuck.

Is the long strip labelled j4 supposed to be plugged into anything? It appears that it has plugs but there's no pins on the ECU to go in there.

Have tried a new battery and does not help.

[Spunkster]

Have you tried the ECU in a different vehicle to see if it has the same voltage drop. It sounds like there may be a wiring issue in your vehicle that is causing this voltage difference.

[lammertime]

No not yet. Hope to do that soon. I run with the stock ECU almost all the time and fiddle with this one when I have spare time..

Question: Is there an acceptable voltage drop? Or should it be exactly the same as the battery? Voltage at the ECU is about .4v lower than the battery which is very healthy.

[Spunkster]

There should be no drop in voltage.