As I was monitoring cluster TEST 7.2, the digital tachometer, i have noticed the following:
from the cold start, the car start idling at 900 RPM, going up and down 10-20 RPMs... I have not timed it, but within a few moments of that, the RPMs drop to 700, give or take 10-20 RPMs, and within few more moments, the RPMs drop to "normal" idling speed of 600 RPMs. AC is off.
At 600 RPMs I observe 580 to 640 RPM floatations, which does not concern me... however, as I hear and feel the "hiccup", the digital tach registers DROP in RPMs to 540, once it was 520, and then it rebounds back up to 600 and vicinity... All of that happens at idle speeds, regardless if the gear is not engaged (Park), or if the gear is engaged (Drive or Reverse) and the foot is on brake. If I let the foot off the brake, and the car start moving under the idle of the engine, I feel the light jerking of the car as it propels forward or rearward, coinciding with the drop of the RPMs... The frequency of the "drop" is not ties to anything, it seems to be random but rather annoying...
Two incidents that occured and I have not seen them happen:
1. when going from cold start, idling at 700 RPMs , the engine surged to about 1200 RPMs and then dropped to 600 RPMs with the same symptoms as before
2. while at a traffic light, the idle dipped to about 500 (this is what the digital tach registered for a brif moment) and I saw the D in the gear selector indicator turn off, as if in FAIL SAFE MODE, and then the indicator lit up again - this was very fast, in the blink of an eye, and I saw it as my eyes were glued to the cluster...
I have not performed the flush yet, waiting for the weekend...
Can there be issues with the Throttle butterfly?
Can MAF be defective and I need a new MAF? I spray-cleaned it, to no avail
Can the issue be further into the engine? like coil packs?
What other symptoms should I be on a lookout to further narrow the possible culprit?
Thanks guys - I am somewhat OK with electronics, but get scared over the juicy parts of the engines!!!...
