[02fbody35th]

Originally Posted by RicSimonis

I'm seeing it when the clutch is engaged and slowing, regardless of Rev Match, right around 1100-1200 RPM. I believe this to be a normal condition, I would have expected it at a lower RPM but no concern here. Just trying to help possibly explain it. The engine is approaching its idle RPM and looses the ability to slow the car. Essentially a good point to down shift unless going into 1st.

Just my $2.47 ($.02 adjusted for inflation).

I'm not really worried about it either. I just wanted to see if it was a normal condition. I don't think it's the engine approaching idle speed though, because if it was it would just cut out and that would be it. But rather it feels like it cuts out and then lunges back in. I do believe this to be normal for the car for whatever reason

[clanky]

I only notice it cruising in 5th or 6th gear at roughly 70-80 mph. After I let off the gas for a bit around 8 seconds or so it gives a slight bump and feels like it was taken out of gear.. but when you get back on the gas it's fine. Maybe that is fuel cutoff like someone else said? I'm not too sure and like 02fbody35th i'm not too worried about it either just seems a little strange.

[KenH.]

I've noticed it in probably every gear and it does only happen below 2k rpm that I've noticed though I stopped paying it much attention. It is what it is I don't care to log anymore service time on my car now that I've got it back.

It could be something with rev-match ... I've never noticed it with rev-match off though really besides forgetting to turn it on why would you ever drive with it off?

[clanky]

Originally Posted by KenH.

I've noticed it in probably every gear and it does only happen below 2k rpm that I've noticed though I stopped paying it much attention. It is what it is I don't care to log anymore service time on my car now that I've got it back.

It could be something with rev-match ... I've never noticed it with rev-match off though really besides forgetting to turn it on why would you ever drive with it off?

Ha ya I don't know who would ever drive with it off. Unless I forgot to turn it on, love having it maybe i'm just getting lazy though.

[Ryephile]

It sounds like it could be the decel fuel-cut reengaging to avoid stalling, if it occurs at a repeatable RPM.

Does anyone have a good OBDII datalogger they can use to capture some sensor data while inducing the problem? Seeing the RPM with throttle position, VVT position, spark, and fuel pulsewidth or at least the wideband O2 would go a long way to deciphering what's going on.

[1BlueSS]

A lot of what y'all are describing sounds like every single manual trans car I've ever driven. My bone stock z71 does it, and my 5spd swapped Cutlass does it too.



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[RicSimonis]

Originally Posted by 1BlueSS

A lot of what y'all are describing sounds like every single manual trans car I've ever driven. My bone stock z71 does it, and my 5spd swapped Cutlass does it too.



Sent from my iPhone

Yup, shudda mentioned that my Subaru does it as well. Trying to explain only with words is a little difficult sometimes.
Nothing to worry about.

[TimsZ28]

Boilermaker128 explained it correctly. DFCO is one term for it. It is purposefull to allow better coasting for fuel economy AND cat converter protection. Injectors stop spraying completely in quick de acceleration or coasting situations.