Engine hesitation when cold below 2000rpm (2 Viewers)

[CharlieS]

I haven't finished my coffee, and don't know a lot here, but wonder if something like a knock sensor failing/failed could cause significant changes to where the ignition fires during the compression stroke as is shown in the data in that last image?

If so, (and someone is kindly going to tell me to go read the FSM) I wonder if there is an easy bench test to verify correct knock sensor function?

 

[Mfb]

I haven't finished my coffee, and don't know a lot here, but wonder if something like a knock sensor failing/failed could cause significant changes to where the ignition fires during the compression stroke as is shown in the data in that last image?

If so, (and someone is kindly going to tell me to go read the FSM) I wonder if there is an easy bench test to verify correct knock sensor function?

Both knock sensors have been replaced. I did notice the connector on the first knock sensor was a little melted, but I would have thought if the problem was the wiring to the knock sensor, it would throw a code?

 

[Mfb]

Hi all,

I've being playing around with the timing, as the advancing the timing seems to make the hesitation less noticeable, as mentioned. I advanced the timing to 10 degrees from TDC, and the car was running fine for a few days but then I noticed the hesitation come back

I tried further testing by advancing the timing again to 12 degrees thinking it might improve as it did with 10 degrees, but it didn't. There is still a very noticeable hesitation during the engine warm up phase, until the car get to complete operating temperature (95oC ECT).

I was reading some threads on mud relating to the harmonic balancer, and how a failing HB can make the car run rough (no mention of hesitation and specifically during warm up)... As I'm running out of things to try, I had a look at my HB and noticed a small wobble which I'm not sure is normal or whether it could be related to the hesitation issue I'm experiencing?

Here is a short video of the HB:
FZJ80 - Google Drive - https://drive.google.com/drive/folders/1Qk15TAAqgGeKs06nXgPRW61PtBhB8x_q?usp=sharing

 

[Irish Reiver]

@Mfb The HB could well be an issue. During the rebuild of my engine and with everything aligned to TDC the timing mark on my HB was nowhere near the corresponding mark on the timing cover. New HB arrived a few days back but yet to fit it.