I've always battled getting my MPFI system on my 90 suburban to produce a nice sine like O2 swing. (EBL Flash + Port Mod)

I've got a 5 wire O2 sensor installed going to my EBL flash. The signal quality is great with full swings so I'm happy with its operation.

However my cruising (15/25 mph up a small hill) O2 outputs are very low frequency switching with a high frequency component super imposed.

I don't feel any surging but I can see the integrator chasing the O2 signal.



PRP O2 Swing

15MPH Data above.
(Red line is integrator) (Blue is O2 sensor in mv)

I'm currently using the PRP tables and values copied from F_2010.bin file which is appropriate for my truck year.

Any suggestions on where to start here would be great.

-Eric

 

So if the INT is oscillating to maintain the O2 swings, try increasing the Prop Gain at that air flow.

Although now seeing the scale for the INT, ITS NOT THAT BAD. tweak the prop gain a bit and see what happens. I did the same and lowered the Prop Gains quite a bit but then saw the INT making up for it. increased the Prop Gain and now the INT and so the BLMs are much steadier.