View Full Version : weird sputtering on interstate?

11-07-2005, 02:02 PM
I have a red top with minor modifications, and on interstate the car is jerking me forward with a weird sputtering around 70 mph. I have already checked the timing, and the CAS seems to be ok i.e no visual damage to the unit. I have a megan racing O2 housing and my turbo blows some oil. Could this problem be caused by oil on my O2, because I replaced the O2 and it seemed to go away but came right back. The car also has a walbro 255 fuel pump. Does anyone know the average life for one of these pumps. Also, the sputtering goes away at full throttle, and then the car backfires when it is de-reving. I've had a couple people look at it and we cannot narrow it down, if anyone could help me out i would really appreciate it.

Thanks in advance.

11-07-2005, 03:36 PM
the 02 sensor is definently part of your problem, if not all. are you setting a code? if you've got an a/f meter, what is it saying? (and if not, go get one, you need it).

full throttle is most likely okay because the sensor isn't doing the voltage sweep crap that it does at part throttle; decel is bucking because it can't lean out the cylinders (i.e., it's not seeing lean when the injectors shut off).

fix the oil blowby, and replace the 02 sensor. check for vaccuum leaks too. should help out.

walbro's last a pretty long time, at least for me- there are guys running dual walbros on 500 hp ka's here, and i know most of them seem to hold up. deal with the sensor, it's probably not your fuel pump.