2G Car stutters and shakes, no acceleration under half to wide open throttle

[Shiggy]

Hi all,

Last week I had replaced my O2 sensors and then took the car out on a drive (everything was fine). However, later that night I filled up my tank and was on the highway, and as I tried to pass someone, my car begin shaking and stuttering, no acceleration while it was happening. It was almost like hitting a rev limiter at 3500. After a few more test drives, I found that this only happens when giving the car half and above throttle, and under boost. The car isles just fine, and the shaking stops as soon as I let off the gas. The car hasn’t thrown a CEL or anything, and the problem seems to have come totally out of the blue.

So far I’ve:
- Double checked my timing
- Cleaned maf
- Boost Leak Test (no leaks)

On a side note:
- I got a P0420 engine code like four weeks back that hasn’t come back since clearing.

For reference, I’m on stock boost on the stock turbo, only performance mods I’ve done are a HKS cat back and Injen cone filter.

If anyone has any idea as to what could be going on, I’d really appreciate it! Been losing my mind trying to figure it out. And if there’s any more information/details I can give, just let me know, thanks!

 

[motomattx]

It could be knocking, do you have a way to datalog the car to check knock sensor activity? could be bad spark plug wires and or bad spark plugs also.

 

[Shiggy]

It could be knocking, do you have a way to datalog the car to check knock sensor activity? could be bad spark plug wires and or bad spark plugs also.

Ah right! Should’ve added, I inspected the plugs (gapping/wear) and wires and didn’t find see any damage.

In terms of knock sensor activity, I’ll have to look into that, thank you!

 

[motomattx]

Wires you really cant tell by looking at them, and as boost goes up it gets harder for the ignition to deliver spark through them if they are breaking down, if you dont know how old they are it would be general good measure to replace them anyway.

 

[JeffwithaG]

I had a similar issue on my GSX a couple years ago. Eventually traced it down to my EGR valve. It had a ton of buildup. Picked up a new one and it solved my issue.

It's annoying to diagnose sometimes because varying problems have the same symptoms, at least that has been my experience with this platform.

 

[Shiggy]

Wires you really cant tell by looking at them, and as boost goes up it gets harder for the ignition to deliver spark through them if they are breaking down, if you dont know how old they are it would be general good measure to replace them anyway.

For sure, thanks for the tip!

 

[Shiggy]

I had a similar issue on my GSX a couple years ago. Eventually traced it down to my EGR valve. It had a ton of buildup. Picked up a new one and it solved my issue.

It's annoying to diagnose sometimes because varying problems have the same symptoms, at least that has been my experience with this platform.

I’ll be sure to check that out tomorrow. Hadn’t considered giving that a look over yet, thanks!

 

[JeffwithaG]

Did you get this issue figured out? Or still happening?

 

[Shiggy]

Did you get this issue figured out? Or still happening?

Still no luck, egr valve looks fine (forgot to mention I had replaced it a few years ago)

 

[JeffwithaG]

Still no luck, egr valve looks fine (forgot to mention I had replaced it a few years ago)

Ah okay, sorry! Definitely post it once you do find out. I've read a bunch of threads on here while researching, just to get to an end with no resolution. It's always so frustrating haha.

 

[Shiggy]

Ah okay, sorry! Definitely post it once you do find out. I've read a bunch of threads on here while researching, just to get to an end with no resolution. It's always so frustrating haha.

No worries at all, I appreciate you trying to help out! I’ll definitely keep you guys posted And update this thread when I get this fixed

 

[jed344]

When is the last time the fuel system has been checked out? Normally even if knock sensor is pulling a ton of timing the car will be slow but still pull clean. Could it possibly be going lean from plugged fuel filter ect? Could check the fuel pressure.