sputtering like out of gas when O2 wire plugged in, runs fine when not plugged in??


New member
Hi, I'm new to this forum, I have a 1986 westy and I was getting poor gas milage (12.5 avg.) because of a bad O2 and cat. (O2 also unplugged), so I decided to replace my blown out cat and replace oxygen sensor with new Bosch replacement direct from "cost plus 10 program at GoWesty" Installed both and now the van runs like a clamp is placed on the fuel line in the first couple thousand RPMs of all gears. Its worst when cold and gets slightly better when at temprature, but not acceptable for a daily driver, I crawl from traffic signals. When I unplug the O2 sensor It runs fine in all conditions? Any suggestions? Thanks.


New member
Hey Jeff1974, did you get an answer to this? Have you checked The Samba? I do not know active this site is anymore. Though it is a great mine of knowledge that I constantly refer too. The Samba is very active. I have the same problem with my 1986 Westy.


New member
If your issue is only apparent when the O2 sensor is plugged in then you have a mixture issue. The O2 responds to oxygen content in the exhaust and the ECM uses it to adjust the amount of fuel injected in the intake. The amount of air is (usually) constant so the fuel is regulated to provide the correct mixture for combustion and power. If your 'issue' is only apparent when the O2 sensor is plugged in then we must assume that the amount of oxygen in the exhaust is causing the ECM to lean out the mixture so that suggests you have an air leak in the intake or in the exhaust. But, the ECM does 'assume' some constants and one of them is fuel pressure so I would make sure your fuel pressure is good before proceeding.