bucking after EGR unplug

[sam_cotter]

Hi all, 2001 with 180,000 and change, no service records, have had for just over a year, car always had some bucking sometimes excessive, I unpluged the egr valve, bucking is almost gone but occasionally still get some bucking. I plan to replace egr valve, but what could be causing continued bucking?

Bucking occurs at low load rolling onto throttle.

thanks for any help

Sam

[eq1]

I had some 'bucking' when I first bought my car. After I did only a few things it stopped, though I'm not sure which was responsible for what part of the bucking. EGR valve repair and plate cleaning seemed to do the most, probably to the low rpm moderate throttle hesitation. Other than that it was ground strap repair and new spark plugs. I think each of these was responsible for other types of hesitation and bucking. My plugs were worn, tips were rounded and gaps were big. Main ground strap between transmission area and side of engine bay was disconnected...

[Eli]

Most likely ignition related then, so plugs/coil packs.

[madmanmostafa]

Mine bucked under the same conditions when it was cold. Once the car warmed up, all the bucking went away. Turned out it was my O2 sensor. Though, I would exhaust all other options before replacing that thing, since it can get Very expensive. I got lucky and scored an open box for half the price, but that doesn't happen often.

I was talking to Eli about in car testing to see if your O2 is kicking the bucket. If you look at your AFR on the OBD2C&C gauge and it's constantly changing between 13.9-14.5 under the same throttle, it's probably bad. My new O2 is a solid 14.5 when I give it gas, even when I give it heavy throttle it doesn't change. Only when I completely let off does it drop to 13.9, but under throttle, it's right back at 14.5 Before it was all over the place. Then again, to do this test, you have to have the proper equipment.

[sam_cotter]

Originally Posted by madmanmostafa

Mine bucked under the same conditions when it was cold. Once the car warmed up, all the bucking went away. Turned out it was my O2 sensor. Though, I would exhaust all other options before replacing that thing, since it can get Very expensive. I got lucky and scored an open box for half the price, but that doesn't happen often.

I was talking to Eli about in car testing to see if your O2 is kicking the bucket. If you look at your AFR on the OBD2C&C gauge and it's constantly changing between 13.9-14.5 under the same throttle, it's probably bad. My new O2 is a solid 14.5 when I give it gas, even when I give it heavy throttle it doesn't change. Only when I completely let off does it drop to 13.9, but under throttle, it's right back at 14.5 Before it was all over the place. Then again, to do this test, you have to have the proper equipment.

madmanmostafa, my car is definitely up to temp when the bucking occurs. Yes I would like to exhaust all trouble shooting before changing parts, that was part of my thought when I unplugged the egr. I do like you idea of monitoring the afr when the bucking is occurring. My car is stock with no mods. What would I need to monitor the afr? I have installed a innovate wide band O2 sensor in another car I have, but that was using a megasquirt fuel injection computer. How easy is it to interface with the insight from a plug and play stand point?

thanks for the help

Sam

[markw]

Sam, where are you located? Someone close by might have an OBD2C&C gauge that you could use.