Hi Greg,

If the O2 sensor is feeding back bad data to the engine it's going to  
mess things up pretty bad. In my case I can tell from the fuel  
pressure readings that for some reason the ECU does not fire the  
injectors as much as the engine comes off idle. This may be an AFM  
issue or throttle position sensor or elsewhere. I think the O2 sensor  
was reporting a rich condition and the ECU was leaning it out.

Frank realigned my throttle position sensor a few weeks back, so I  
don't think it's a mechanical problem in my case. In your case I'd  
start there.  I get the same response with 2 different AFMs and ECUs  
as well, so (in my case) I don't think they are at fault either. At  
this point I am leaning to a fault in the O2 sensor wiring or the  
throttle position sensor wiring. When I get a chance I will inspect  
the TPS wiring and see what happens.

It's nice to get the performance back, now I just need to work on  
getting more than 200 miles per tank of fuel. The last motor gave me  
more than 250.

Greg

Quoting Greg S <sorkilmo@GMAIL.COM>:

> Wow. I just unplugged my O2 sensor and have had the same transformation.
> Wish I had figured this out months ago - but better late than never (thanks
> Greg).This still leaves me wondering something about the O2 sensor though. I
> understand that when the engine is cold the sensor should be in open loop,
> effectively disabling any input from the O2 sensor. Why then would my engine
> run poorly (laggy performance under 2500rpm) when it was cold (as well as
> after warming up)?
>
> Cheers,
> Greg S.
> 87' Hardtop Wolfsberg
> Ottawa ON
>
> On Sun, Oct 18, 2009 at 8:17 PM, Greg Potts <greg@pottsfamily.ca> wrote:
>
>> Hi Chris,
>>
>>
>> Then I tried unplugging the O2 sensor; It was like I bought a whole new
>> engine.
>>
>