o2 reading is choppy, not smooth

[lov4godgst]

My car has ran fine since the 6 bolt swap 5k+ miles ago, when used 550cc injectors were also installed. At that time, onward, I noticed my o2 values were reading normal in open loop or WOT, but really choppy/jagged as they displayed, instead of smooth lines. Has anyone seen that before?! We were thinking the injectors were junk and causing the choppy reading, but now that my car won't start, which isn't what I want to discuss, I'm wondering if the injector resistor pack was going bad?
Andrew
Oh, and I'm using DSMLink v2

 

[blcknspo0ln]

Wait, you're logging Front o2 voltage readings? If so, they're supposed to oscillate from ~.01V to ~1.1V. -or- are you saying that at WOT you are getting an inconsistent front o2 reading?

 

[GORBS88]

Your post is unclear, are you sayin that in OPEN loop (WOT) they are choppy?? Or in closed loop?
They should go rich-lean-rich-lean only in closed loop, NOT wot.

 

[lov4godgst]

Sorry, I'll try to clarify. In WOT, its accurate and tuned fine at around .92 for the front o2. The open loop is oscillating normally as well. Its just when I'm sittin there idling, and I've attatched two pics of the log. You can see me slow down and idle and gets all choppy. In the 2nd, I slowly accelerate and it stays in open loop, but its smoother.

 

[kscott]

My theory on this is that you have injectors that aren't balanced, so some cylinders are richer/leaner than others. At idle, the exhaust is passing by the O2 sensor slowly enough that it can pick up the difference in mixture from each exhaust pulse.

On my first Laser, my earliest datalogs had a zigzag appearance (TMO logger), although not nearly to the extent that your DSMlink ones show. A while later the problem went away, probably due to having the injectors cleaned/balanced. I don't have the logs from that long ago any more.

On my second Laser, it looks to have much the same problem (completely stock). Some datalogs are here; scroll down to the 3rd-from-last plot.

Yours seem to show a lot more jagginess, but maybe it's just the difference between the two dataloggers.