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Thread: Erratic idle and another erratic idle at the same time

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2020-10-17 18:04:52
Erratic idle and another erratic idle at the same time
I believe this will not be easy to solve. This is after swapping a lot of parts from rust-egg. Powerband got a bit better. It's feels smooth to me but I have no dyno proof.

First youtube, I hope for suggestions, (don't mind the water pump ), also, please don't mind the chain rattle, but in this youtube my Sr20 goes like hmm HRR, hmm, HRR, hmm hrr where the middle HRR is the obvious one in this movie.

What could that be?

Second youtube, my Nx on two jacks (front), this amplifies the issue I have on the end of this youtube you will see my hood shaking on the erratic idle.

What could that be?
Last edited by richardwbb on 2020-10-17 at 18-07-00.
2020-10-18 09:38:19
It might be time to source a FSM if you don't have one already, and go through the idle issue diagnostic steps.
Idle issues can be almost anything, and it can be tough to track them down without a detailed diagnostic plan.

There are digital FSMs linked in The Manifesto that could work in a pinch.

I'll watch the videos later and see what I might come up with.
2020-10-19 13:26:36
FSM I have, I am under the assumption I did follow that but will do again. But if you say it can be a lot of things I will start over. I just figured that if all is good according to FSM, could it be the slack on the chain itself doing this? That in the first movie the ECU just gets erratic CAS signal and does this? And that on the second movie the chain slack makes engine run unbalanced literally by weight distribution? I just made that up but since I am sure I did my best but not sure I did it all, I just made up this chain slack theory being unhindered by any form of knowledge
Last edited by richardwbb on 2020-10-19 at 13-29-07.
2020-10-19 13:48:19
Slack in the timing chain can indeed cause a rough idle.
2020-10-20 15:46:41
Ahh okay, that explains when problem is away under load. I would like to learn from other Sr20 movies how theirs is if possible but another idle check is on my to do list while I am aware it can be a lot of work but I will read that again from FSM.

Chain replacement certainly looks doable after my water pump trip via all the boars on the road I believed I could see (lol) and Ben please give me your opinion just looking at the movies I posted. If you can confirm this is chain or not would be great and I can find the Manifesto, that will be fine.
2020-10-20 17:04:08
Finally got around to watching the videos.

Honestly, I am a bit surprised. The idle doesn't seem bad at all. I know it could be better, but that's some minor shit to complain about IMO.

Maybe a video of the tach while idling would help? Because I just don't think it is doing anything too bad...

I would not go replacing the timing chain and/or tensioner just for that.
2020-10-25 16:31:27
Yes I won't replace it for that but on the other hand this Sr20 does have a slappy chain. It's melted catalyzer figured it was raced hard for a good while. Maybe it is the movie but this sure does hrr worse enough for a layman owner to turn to the dealer, like 20 years ago. I also figurumated that the latter is weight distribution and by emperic evidence only the first is ecu doing that. I forgot to make a movie of the idle but I can Datascan that, it is like 75 - 100 ish. I actually am at the point to look for a not expensive smoke test. For the chain, yes I should do that sometime and I think I can do it after water pump since I eyeballed a nice accessible oil pump and did it on a Ga16 engine out.
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