Finally got back from sunny California. Managed to buy a static timing light off eBay for under US$40 while there. It's ridiculously cheap for such a decent quality piece of equipment. I can't find anything like this here for under S$100 (approx US$80).
Another friend with a K11 (CG10DE) complained that his engine does not seem to make good power after a distributor replacement at a generalist mechanic, so I invited him over.
We had both K11s (both 4 speed automatic) sitting in my carpark last night and started working on our throttle pos. sensor, base idle speed and ignition timing.
TPS adjustment
Friend's TPS was fine (0.46V fully warmed and closed).
Mine was way off @0.30V after an earlier struggle with the multimeter (see post #7 above). It now reads ~0.45V closed.
I've seen recommendations in this forum to set it at 0.5V closed being the middle point of the range provided by Nissan (0.45V-0.55V), but I think the upper end of the range is for when the waxstat is cold, so the correct setting is to have it at 0.45V when warm (>80 deg C).
For the record, it reads 4.05V wide open when at 0.45V closed. Both our waxstat seems to be working and the screw holding the mechanism with the green spring has seized, so we did not remove/bypass them.
Base idle adjustment
Fired up the laptop + conzult and put the car into base idle adjustment mode.
Both our base idle settings were too low. In fact, my friend's K11 stalled the moment I put the car into base idle adjust mode.
We got both cars idling at around 780-800 rpms (couldn't get it spot on at 750 rpms but I guess that's OK). It's also interesting to note that the radiator fan puts a considerable drag on the alternator and the engine loses ~30 rpms when it kicks in. We set the base idle with no radiator fan and no A/C running.
Timing adjustment
With the car still in base idle adjust mode, we hooked up the timing light.
Here comes the best part. BOTH our cars had our ign. timing retarded by a fair bit. Both were set at ~10 deg BTDC. We set both our timing slightly advanced -- just a tad after the 15 deg BTDC mark since we get generally good fuel quality here.
Note that when advancing timing idle revs also increase, so it is necessary to repeat idle adjustment until you achieve around 750-800 rpms at the desired timing.
Time for a test drive
Right off the line my friend's car (CG10 engine) felt VERY different and also sounded different. It had a more throaty growl when pulling under load and felt much more powerful than it was before.
Mine felt different too (mine is a CG10->CG13 block swapped), but my butt dyno felt it was making less power. It did tend to cruse at lower rpms though.
The smell of rich running exhaust fumes also went away, so I think the retarded ignition timing was causing the lambda sensor to read incorrectly making the engine run rich.
Both cars now idle very nicely, irregardless with A/C off or on, fan off or on. We'll continue to monitor for the remaining tank of fuel and report back.
