Hesitation-Lunging While Moving Slow and Pressing Pedal @ Zero Throttle

Alright, the title isn't the full details.

So I've had this problem ever since I bought this car about 3 years ago. If I start from a stop it's fine, when moving at a decent speed at higher rpm it's fine. However in traffic if the RPMs drop too far and I do not have any throttle input then press the pedal there is this slight bog in response and then the engine will start to actually increase throttle. sometimes it'll kinda lunge back and forth if I'm still trying to drive slow and I have to push the clutch in. However if I'm in say 4th gear and I let the car slow down enough and let the RPMs drop and push the throttle in it appears to be fine. The car does not misfire at all that I can feel or hear.

Now, it's very hard to tell if it's mechanical or electronic. However at this point I'm beginning to think it's ignition related:

- At a stop sometimes the idle will drop below 500rpm or low enough that you can hear it begin to compensate and the engine shake a little. It doesn't happen a lot but just sometimes it raises an eyebrow
- At idle it doesn't hunt a lot and the RPMs are stable enough to pass smog is no issues (not that means much in this case
- If I'm driving slow and purposely let the rpms/speed drop in first or second gear and pin the throttle there might be a slight shake from the engine and then bog (which a little is to be expected)

I did plugs and wires when I got the car as well as the fuel filter. However I do not think I did any sort of resistance tests on the coil packs.



Mechanically:
- replaced lower a-arms
- new front and rear motor mounts
- new shocks
- new sway bar end links



The car runs fine other than this.

Educated thoughts and wisdom?


Thanks!

perhaps you aren't explaining it very well? Can you define "low RPM" and "bogs"? Maybe a short video would be better?

From your description, sounds to me like a typical 4 cylinder manual transmission being out of its power band. This is why you are able to select a different gear... if you're in 3rd or 4th gear at anything under about 2000RPM you can expect it to bog, feel gutless, and have no response. ANd if low enough it may buck and jerk because you're dumping in fuel and causing it to misfire.

02 sensor and PCV valve are the 1st 2 things I'd change. Cheap and famous for making your car do just what you're describing.

Seems to me like an AFR issue. Is the car stock or does it have an aftermarket intake and/or exhaust?

PCV valve and and O2 have both been replaced. Forgot to mention that. Yes the car is completely stock.

I assume when you say AFR you are saying Air fuel ratio?

Natey said:

02 sensor and PCV valve are the 1st 2 things I'd change. Cheap and famous for making your car do just what you're describing.

Seems to me like an AFR issue. Is the car stock or does it have an aftermarket intake and/or exhaust?

Click to expand...

MaydayDown_Joey said:

.. However in traffic if the RPMs drop too far and I do not have any throttle input then press the pedal there is this slight bog in response and then the engine will start to actually increase throttle.

Click to expand...

I'm almost positive my car does that too...

I don't let my car do it... I pick a lower gear or it will start to buck..

Or I push in the clutch, spin up the rpms then reengage the clutch slowly.

It's just the nature of the beast but I will sober up and try it tomorrow for verifications sake.

Ok, maybe I need to rewrite what I wrote. This isn't "normal" by any means, I realize the car will bog down if the rpms are too low. This is different.

I'll try to get a more accurate RPM range when I leave work today, when moving the RPMs aren't dropping down to idle, the car should perform fine at the range I'm thinking of.

Try to get a video clip with sound.

This might help...