Injector Duty Cycle ?

[DrX]

Seem to be noticing more instances where Inj Duty Cycle is different on banks 1 and 2(see attached screenshots). Normally it is only a small variation but on throttle transitions it can be large. I can't see any reason why they shouldn't be identical at all times while in OL/SD if the PCM/INJ Drivers are functioning properly. Any ideas? Pretty scary when the pcm treats both banks differently when the O2s aren't even plugged in.

During these WOT blasts it also started to break up badly as if spark was being cut off and switched back on(possible misfire). Didn't log misfire this time. Haven't seen any abnormal misfire levels on previous logs. No SES. Seems pretty repeatable if I am rolling about 60km/hr(40mph) and stomp on it. Kicks down into 1st, starts to scream for a second, then cuts out(nowhere near rev limiter), and then kicks in again and will rev to the shift point OK. But it has also happened in the middle of a run. The sudden TP drop may just me backing off when it starts acting up.

BTW. My wideband is now on bank 1 so who knows what the AFR was at on bank 2 when InjDC was at 70% on bank1 and 54% on bank2!:Eyecrazy:

[Tordne]

I see you are running Custom OS V3. If you are commanding 14.63:1 then you could/will be actually running Semi-open Loop in which case the banks will be different because trimming is occurring. Just a possibility?

[DrX]

I see you are running Custom OS V3. If you are commanding 14.63:1 then you could/will be actually running Semi-open Loop in which case the banks will be different because trimming is occurring. Just a possibility?

I am commanding 14.62 in the lower part of B3647 ramped up to 11.80 as I go into boost. But the scan log shows commanded as 14.68 where it is 14.62 in the table and 11.84 where the table shows 11.80? I think we tried to figure that one out before and gave up. O2 sensors aren't even connected.

[Delco]

Given that it is only happening on backoff or large transitions I would suspect you are logging lots of data and seeing some lag effects rather than the true data

[DrX]

Given that it is only happening on backoff or large transitions I would suspect you are logging lots of data and seeing some lag effects rather than the true data

I hope so. I see it through the entire log but where TP is steady the variation is only 0-2%. Will try reducing PIDs logged.

[redhardsupra]

when i see inconsistencies between banks, i tell people to retorque their headers and check all the exhaust clamps. more often than not it's a leak somewhere. do you have any wot logs where you log your narrowbands? that's the quickest way to see a leak.

[DrX]

InjDCs are identical again(as they should be) now that I have reduced the number of PIDs being logged to 21. Seems 24 was a little too much.

Looks like it is the PCM that is pulling throttle and fuel on me as I tried a few logs without lifting my foot when it cut out. The TP and INJDC plots still have the sharp drop off at 4800-5000 RPM before it kicks in again and the RPMs continue to climb. What could cause this besides the Rev Limiter? It occurs after a kickdown into 1st.

[joecar]

Is your logging mode set to "Stream-Fast"...?

This handles 24 "channels" in one frame (a pid may occupy one or mode channels), so you won't get data skew.

Check how many channels your 24 pids occupied, and how many channels your 21 pids occupy.

[DrX]

Is your logging mode set to "Stream-Fast"...?

This handles 24 "channels" in one frame (a pid may occupy one or mode channels), so you won't get data skew.

Check how many channels your 24 pids occupied, and how many channels your 21 pids occupy.

Stream-Fast= Yes

With 21 PIDs I am now at exactly 24 channels! I think I had it right initially, switched some PIDs for others and forgot to keep track of channels.:doh:

Now I just have to determine out what is cutting the throttle on me.

[Chuck L.]

Stream-Fast= Yes

With 21 PIDs I am now at exactly 24 channels! I think I had it right initially, switched some PIDs for others and forgot to keep track of channels.:doh:

Now I just have to determine out what is cutting the throttle on me.
Trans downshifts, acceleration goes way up, the fuel pump "sucks wind". Once the accel falls off, the pump picks up, and by then the accel rate is down far enough, the pump stays primed??? [Engine rpms are hi enough, that you are on the "downslope" of the torque curve.]:nixweiss:

Have you monitored FP when this happens?

[DrX]

Immediately after kickdown the PCM knocks the throttle back down to 20% then lets it go back to 100%. All of this takes place within 1-2 seconds. It must be responding to input from some sensors to trigger this. As it is in OL/SD(no O2s or MAF) it must be related to RPM, MAP or something to do with the trans, right?

FP is steady since I installed the returnless system and the PCM has no input as to what the FP or AFR is anyway. Although AFR does rise during the sudden throttle transition. Misfire logs all show 0 counts.

[DrX]

Is the rev limiter anticipatory? Could it be responding to the rapid rise in RPM on the downshift? I will have to try disabling it completely.

[DrX]

Well I set the ETC Rev Limiter to disable and just in case that didn't work, changed the engine overspeed allowed time to 1 sec from 0 so the PCM wouldn't make any hasty decisions.

Problem solved! So something must be triggering the Rev Limiter early.

[DrX]

Thought it was safe to plug the narrow bands back in now. But as soon as I did that I am seeing constant INJDC variation between the banks again even though it is still in Open Loop/SD! Only 22 channels being logged. This the reason I unplugged them in the first place. It was the only way I could get the expected congruent INJDCs in Open Loop/SD. Something happens when the PCM sees input from the O2s even though trimming is disabled.:nixweiss: