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Discussion Starter · #1 ·
The efi (single point carb looking thingy) small block in my trusty Chevy Van has been running progressively rougher for a fair while now. Its fine under load and also idles fine but under light load and just off idle it runs real rough and if you keep it there it will stall. I know it's well over due plugs, leads etc. but someone a while back mentioned the O2 sensor could be the cause?

Has anyone had similar problems or have any ideas what would cause this?

Thanks
Dave
 

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Before you do anything change the plugs & leads if you know they are bad. Fuel contains oxygen & if your not burning it the O2 sensor will read it & add more fuel thinking your running lean when in fact the opposite is happening. O2 sensors work right if everything else is i.e. complete as possible combustion. At idle your using too little to be of much consequence & under load it's probably just running rough but the engine speed is fast enough to hide it. At cruise your inj' system may be flooding the cylinders making it run rough.

If it's still running rough check the O2 sensor (to be honest for what they cost replace that too) & your air flow meter connections. Check all earths too as these can often be the culprit of wierd signals.
 

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Discussion Starter · #3 ·
Thanks for the input Adam. I will give it full service stuff seeing as it needs it anyway and take it from there. I'll let you know how I get on.
Dave
 
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