Strange running problem after plx install, please help

[Josh8596]

Wondering if anyone could help me out. K20/k24 dc3.2 setup stock block, running on my previous tune for k24 long block oem k20 cams but with vtc and vtec disabled and 5k rev limit, just been cruising around on that to put some miles on clutch/engine while I save for tuning.

Car has been running my old tune on open loop just like I always used to have it with the old setup, perfect then and perfect on this car too for around 800 miles until I wired my Plx wideband in.

Wired into an0, ground with an8 and spliced into a2 ignition, I was running closed loop at first no problem, all good 14.7afr, then when logging I noticed even when on the throttle the afr would freeze at 29.40 and then to 10s for a second and then back to 29.40,with that came very bad running, very lumpy idle like vtec killer cams, spluttering, alot of over fueling.

So I put it back on open loop but with the plx still wired in, all was perfect again, fueling wasn't ideal but was running good, I then tried closed loop again a couple days later, was good for a couple of days then same problem, back to open loop.

All was well again until my idle started getting a little lumpy, not like it was with the closed loop but noticeable, along with some spluttering etc while driving, checked afr and is in the 9s idling and 9s/10s when driving :/

So now I have the same problem in open loop as I did when in closed loop when it was freezing at 29.40afr

So far I have checked the all the wiring for plx to ecu
Changed spark plugs because unsurprisingly needed changing due to fueling issues
Checked injectors and double checked they are genuine Honda rdx which they are
Fuel pressure is good
All sensors showing good in kpro

Tomorrow I will change the injectors just to rule them out, I have ran this tune and injectors on my old setup for 8k miles daily driving no issues

Any help/ ideas greatly appreciated
Thanks
Josh

[Spunkster]

Try grounding to A4 instead.

It also sounds like you may need some additional tuning if it is running that poorly in closed loop. Look at the fuel trims in closed loop.