While I drive my Si, it kinda jerks at certain speed (or maybe related to RPM). I know it's not because of my bad shifting.

So what I mean is when I put into gears, my car does not jerk, but after few seconds, it would jerk for a short time... like a half-second. so for example, I would feel the jerk when I am accelerating on the first gear, around 10MPH... and on 5th gear when running around 43MPH...


On 1st gear when it goes 10 MPH
On 2nd gear when it goes on 18MPH
On 4th gear when it goes around 37MPH
On 5th gear when it goes around 43MPH


anyone have anything like this??? i am thinking that it might be some kind of air leak...and might have to do with the engine light it is throwing in...btw it throws a code of P0172 - too little air sucking with too much fuel consumption.

 

It's running rich. Did you check your plugs? I bet one is carbon fouled (black, non-oily buildup). Check it out and let us know.

 

i went and changed all the four sparkplugs...and cleaned out map censor...nothing happened
do you think the jerking has to do with the engine running rich?

 

maybe you can list your mods. are you running an aftermarket ecu?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by aznvietboi87 &raquo;</TD></TR><TR><TD CLASS="quote">maybe you can list your mods. are you running an aftermarket ecu?</TD></TR></TABLE>

This would be helpful to know, OP

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by simonEp3 &raquo;</TD></TR><TR><TD CLASS="quote">

This would be helpful to know, OP </TD></TR></TABLE>
Completely uncalled for.

Changing the plugs will not resolve the problem if your car is running rich. Check the plugs and tell me what they look like. I bet at least one will be black.

 

dunno if this would be helpful...but i have a aem cai, aftermarket exhaust, and just a denso 02 censor...
i was worried about the CEL, but now i worry more about the jerk for some reason

 

and thanks to whiteonrice..you've tried to help me alot anytime i had similar questions like this....i appreciate it!!!
and btw, how do i check my plugs???

 

Remove them all. They should look pretty much how they did when new. If the node and ground strap is covered in black, non-oily material, the engine is running rich in that cylinder.

 

i c...imma try doing this sometime at the end of this week..

 

I'd do it today. Just go to Autozone and use their tools if you don't have any.

 

okayy so i took my car to my technition and he told me that they will go through a compression test on the car
do you think the compression test will pinpoint out the problem?? what are they gonna do and what are they gonna find out throughout the test???

 

check the plugs and tell us what they look like and save you money with the comp test.

 

^What he said. A cheap compression test kit can be had for $12.

Compression is one of the last things you need to check (checks for major internal problems). Just check the plugs and other components (coils and injectors).