RH cylinder bank running richer..

[vsslpr]

is it normal to see one bank of cylinders running richer than the other? my rh ltft is always negative and seems to be running richer than left side..

[The1]

by what are you determining this? just from narrowband o2 fuel trims? narrowbands are not highly calibrated devices, could be faulty o2, if they are fine and it's out by 10% or more then could be leaking injector.

[vsslpr]

yep just looking at LTFT for both RH and LH sides and O2 millivolts, when TPS is 0% RH LTFT is around (-ve)9-10 BLM% but drops off when throttle is opened up again. I need to change my plugs soon so ill have a look at them and see if I can spot a rich cylinder.
As far as narrowband o2 sensors go they're brand new!

Cheers

[The1]

Are they getting good crosscounts? Say more than 5 under some throttle.

ive seen heaps of brand new ones fail out of the box in the last couple of years, manufacturing seems to have gone downhill. Delphi is the only brand so far i havn't had fail out of the box and gives good response.

[vsslpr]

yep they're getting around 5-8 under throttle and the o2 millivolts swing either side of 450mV- RH LTFT usually gets its highest coming off throttle and then sitting at 0% TPS

I think I have a small rocker cover gasket leak on drivers side but I really dont see how that would effect afr..

Here's a trace of a recent log

o2-mV trace.JPG (104.04 KiB) Viewed 4365 times

[The1]

Right hand side doesn't seem to like going lean as much as left does and when it does looking on the right side of the graph it's only for a small period of time. Not that it's anything out of the ordinary but it does fit your issue.

perhaps swap the o2's over and see if it follows and is a bank issue or o2 issue.

[vsslpr]

i didnt think of doing that- good idea. that would be interesting.. ill give it a shot this weekend and take a log; if its the same bank of cylinders then most likely an injector leak right? I'll have a look at my plugs too to see if that shows any clues

thanks for the suggestons

[The1]

process of elimination sometimes.

[vsslpr]

just thinking about this- despite a bank of cylinders "apparently" running richer my wideband reading still tends to be on the lean side more than rich- just trying to explain that.. lets say my RH o2 is out and actually reading richer than it should be in this case LTFT for RH bank will say take away fuel in actual fact bringing the afr leaner than that which is commanded- lets say 14.7 assuming its in closed loop mode so this would cause my wideband to read probably in the 15's.. does that sound logical?

Btw my old oxygen sensors had a white residue on them (both sides) which I would have thought would be lean? looking through some old logs before new o2 sensors both LTFTs were quite high around (-ve)9-10% so these were probably reading richer also? to me that makes sense.. as they get older and more coated in crap they would probably read rich since the coating will make it harder to "sense" the presence of oxygen?

[The1]

white residue assuming your not burning coolant or an adative in the fuel having caused it would be lean. Not loosing any coolant? as this could be why your seeing rich at the first o2 sensors, then later on wideband see's lean when coolant is somewhat dissipated more. Though i doubt would be the issue. i would still do the o2 swap giving you confidence it's in that bank.