Doomtor

I noticed recently that my car kind of jerks sometimes, and it did it quite a lot recently. Yesterday was the worst ever so far, and it was raining, dunno if it has anything do with it though. Car has about 81 000 KMs as we speak.

Like I am cruising on the HW at roughly 70 MPH, and sometimes I'll feel the car jerk, and I'll also see my boost gauge goes from like -1, -2 PSI (just below boosting) drop a few PSI as it jerks and go back to normal. It's been just sometimes here and there but yesterday was kinda rough and even at wot I felt it jerk hard once or twice at some point. I'm really wondering what it might be. I have just bought 4 new OEM spark plugs which I was planning to install soon, hoping it would solve the problem. I have also bought a forge motorsport bypass valve which I should receive very soon, as I think it may have something to do with the stock valve. I also have a CEL P2261 on.

Mods to the car are for now are K&N Drop in air filter, Hahn catless downpipe (been on for a year without issue) and I got HP Tuned about 6-8 weeks ago (had GMS1 before for about a year). Other then that car is completely stock.

Any help or input would be appreciated. This is really getting annoying and I don't want to harm the car as I drive it, but I need to solve this problem!

Awaiting your helpful comments!

Thanks!

Dominic

black67

iTrader: (1)

Have you replaced the purge valve yet?

This might help with some of the jerking that you are seeing. It is on the front of the intake manifold. My care was jerking lightly in first and second, replaced this valve and that cured it. The turbo cars appear to have some problems with this valve.

The new plugs might help too. They should be checked every few oil changes. They do change out quite easily.

RooTBeeR

iTrader: (4)

that cel is

P2261 Turbo/Super Charger Bypass Valve - Mechanical

Doomtor

When you say purge valve do you mean the blow off / bypass valve? In any case, this has never been changed.

RooTBeeR

iTrader: (4)

no, the Evap purge valve

http://www.amazon.com/ACDelco-214-2142/dp/B002AMEUR0

Doomtor

As I explained, I'm a little worried about harming my car. Could a bad tune cause this? I do trust my tuner he's tuned a ton os SS/SCs and a few TC's, but still. Could a bad air/fuel cause that? Bad tune?

I'm planning on getting a gauge to have my air/fuel monitored. Would a normal cheap gauge be fine or should I pay 200$ for a wideband?

DerekDTP!

im experiencing this too.. read something about that evap purge valve.. read something about you can disconnect it?

RooTBeeR

iTrader: (4)

i think a lot of LNFs are having a prob with this


#5



Link

GMPartsDirect.com - Find a Item

Doomtor

Should I be getting the whole vapor canister? Or just the purge valve? Or just the vent valve itself?

And anyone know if I can harm the car driving it as it is for a few more days / weeks?

nutty21

iTrader: (1)

Bump.

Been having the same Prob.

nutty21

iTrader: (1)

Really would like some more input on this.

My TC has been dong this always in second gear. It's in gear and I give he some gas then she starts jerking or back firing. Just mid way through second gear. Give it gas, going along for a sec then she bucks and jerks, or back fires. Not fun.

any other thoughts Ideas?

Engine light blinked at me today when it did it. Just blinked for a min then went away.

Can't be good for the car at all. Bucking like that...

Happens at about 2400 RPM

Dart_SI

iTrader: (1)

Id try cleaning your maf before u do anything to eliminate that as a possibility.

Chevrolet Cust Svc

I recently called a dealership in regards to a vehicle was brought in for a diagnosis on a bucking concern, and the dealership cited the possibility of a modified cold-air intake interfering with proper air/fuel mixture. The recommendation in that case was for the vehicle to be brought back to stock.

I don't know if this is occurring in these particular situations, and this isn't an official GM diagnosis, but it's worth consideration I suppose.

Best,
Sarah
GM Customer Service

Dart_SI

iTrader: (1)

I highly doubt the intake is throwing off his a/f, especially being a k&n.

RooTBeeR

iTrader: (4)

any changes(including the k&n drop in filter) skew the maf on the lnf more than youd want

nutty21

iTrader: (1)

I just put it in the new intake about 2 months ago. Looked clean as could be then, but guess it only takes a sec to have a second look to make sure.

nutty21

iTrader: (1)

So what about this?

mikej

dude its your k and n filter...they are garbage....when it rains and gets colder the oil from your filter is being sucked into the motor and all over your sensors....it will feel like a power surge or a misfire...use a non oiled filter

nutty21

iTrader: (1)

I've also been getting flutter EVERY time I shift from first to second and some second to third.
Soon as you left off the gas.

Any ideas?

Been reading through the form, but seems like it could be a lot of different things.

nutty21

iTrader: (1)

I have an oil catch can and ran guard for the filter.

mikej

let me guess u have a k and n filter too....the blinking light is for alot of things but most likely fuel \air mixture is off causing a jerking and sometimes a misfire...ive had this in my truck and its from the oil in the k and n filters getting on your maf sensors and sometimes all the way into the intake....open the air box and rub your hand on your filter and see if its extra oily from all the moisture in the air....the enigine will suck that in....GET RID OF THE CRAPPY K&N....a wix will work better

nutty21

iTrader: (1)

I have a K&N Typhoon intake.

mikej

best thing to do is recharge the k&N filter but do not over oil...then clean the maf sensors with carburator cleaner...just spray them down good and let them air dry...remeber the turbo cars have 2 fo these sensors....when they are dry you can re install or even test them with a volt meter....check with manufacuter for the proper ohms range....if they fall outside the ohms range then they are bad and must replace

nutty21

iTrader: (1)

The intake is brand new two months ago, and the sensors were clean then.
I have an oil catch can.

RooTBeeR

iTrader: (4)