|
It has been a while. The idle revcount behaved itself quite some time, but the high idle state returned eventually. Today I had some time to take out my scope and probe some of the signals, just for fun.
The signal on the IAC at idle:
Loading the engine down by engaging the clutch while I had my other foot firmly on the brake pedal lowered the duty cycle to something like 50%.
Then I jacked up one rear wheel and engaged first gear to measure VSS:
Same thing in 5th:
The speedo showed somewhat over 30 km/h (say 20 mph?).
Then I decided to do the "drag test" on all connector pins of both ECU and EZK.
The bent pin 25 caused a little less drag, so I put a little bit of wire insluation in the slot to increase this a little.
Its signal looked like this, BTW. I forgot to zoom in, but I'm expecting they're just short bursts of data.
Pin 4 on the EZK connector almost felt like there was no drag at all. When there's no knock it should read 7.5 V. I had measured this previously, so I thought it was okay.
But with so little tension on that pin I decided to eliminate this as a possible cause. I soldered a wire on the inside of the EZK to pin 4 and ran it through a hole I drilled next to the connector. I stripped a bit of insulation of the white-brown wire without cutting it and folded the new wire around it. Some solder fixed it in place. This way it bypasses the connector.
This knock enrichment signal is 7.5 V when the engine is running. When knock is detected, the EZK will first retard the ignition timing. If that doesn't cure the knock the EZK drops the voltage on pin 4 (pin 28 ECU-side) and the ECU will respond by enriching the fuel mixture.
I don't know how this possibly bad contact could be the cause of my high idle, but I decided not to assume anything and eliminate it anyway. Now I must be patient again.
|
