Tuning the Z...

[Superdave]

Well, i installed a GM 4 wire o2 on the rear bank, the GM sensors are a bit slower so the values don't bounce around nearly as much wich is really nice.

Of course there is a damn exhaust leak at the collector gasket right next to the o2 so the BLM's shoot up into the 160's. Once that's fixed i'll see what it does. For now just disabling open loop fixed the stalling issue.

[Joseph Upson]

Well, i installed a GM 4 wire o2 on the rear bank, the GM sensors are a bit slower so the values don't bounce around nearly as much wich is really nice.

Of course there is a damn exhaust leak at the collector gasket right next to the o2 so the BLM's shoot up into the 160's. Once that's fixed i'll see what it does. For now just disabling open loop fixed the stalling issue.

Are you certain it's the O2 swap that's responsible for the swing rate of the O2 sensor signal?

My idle problems have pretty much disappeared and here's where the adjustments made the most difference for me; the Base VE table with one column of rpm vs VE, I had to pull a significant amount of fuel here because the other two VE tables showed little change during idle on the WBO2 read after changes were made. I'm also using a late model GM 4 wire O2 sensor.

I switched to using TunercatRT for adjustments and it has a base pulse constant independent of the BPC vs EGR constant that TunerproRT does not have. It is located under the constants section of Tunercat and it is also proving very effective at toning down the remaining rich condition. It's a big help now that I know the Gal/hr and single inject flow parameters in Tunerpro do not work towards tuning.

To avoid missing the point, changes I made in the above areas resulted in my O2 signal swinging much more rapidly as could be observed on my AFR gauge, I don't believe a slow O2 sensor offers a positive benefit by being late at telling you that your fuel mix is too rich or too lean.

The sluggish result could very well be representative of your AFR being off more in one direction or the other and a varying time at which it takes the ecm to pull or add enough fuel to correct the matter if it's as fara off as mine was, along with what may ultimately be a better overall sensor giving a more accurate reading.

Just a thought, hope you get it ironed out soon and take it to the dyno and impress again.
I'm almost done installing the smaller turbine housings so that I can go on another test drive to rate the effect of the last spark timing increase above stock TGP code.

[Superdave]

Once i get the leak fixed i'll get a datalog and graph it.

I might see about modifying the bin to use a spare input so i can log both narrow band signals. That should be an adventure.

[OldSkoolGP]

If you're running a 4 wire O2 does that mean you hooked up the heater wires? And if you did, where did you ground the heater to? I just got an Innovate LC-1 WB O2 and the directons talk at great length about how everything should be grounded to the same post for the most accurate reading, including all sensors and major engine grounds. I'm not sure how a 4 wire has its heater grounded, but you may want to try to copy that. It may give you a more stable reading.

[Joseph Upson]

If you're running a 4 wire O2 does that mean you hooked up the heater wires? And if you did, where did you ground the heater to? I just got an Innovate LC-1 WB O2 and the directons talk at great length about how everything should be grounded to the same post for the most accurate reading, including all sensors and major engine grounds. I'm not sure how a 4 wire has its heater grounded, but you may want to try to copy that. It may give you a more stable reading.

That's a very good point because no matter how unlikely it seems that the stock grounds aren't good enough, you can't be too sure. My engine is solid mounted, yet when I connected my electric fuel pressure gauge it did not register a reading with the gauge grounded inside the car, I ran a ground wire directly to the sending unit and it functioned properly which revealed that my current ground situation was not good enough.

[ForcedFirebird]

If you're running a 4 wire O2 does that mean you hooked up the heater wires? And if you did, where did you ground the heater to? I just got an Innovate LC-1 WB O2 and the directons talk at great length about how everything should be grounded to the same post for the most accurate reading, including all sensors and major engine grounds. I'm not sure how a 4 wire has its heater grounded, but you may want to try to copy that. It may give you a more stable reading.

The LC-1 actually says NOT to ground all the wires on the same lug. I seperated mine and it worked good, whereas others had problems until they moved the signal ground away.

They DO recommend that you ground the signal to the same lug as your ECM.

I don't like the LC1 because it is so sensitive to issues, even if your charging system is low, it creates problems. I know people who have reverse-engineered the algorithms and said they were quite satifactory, but the hardware components could use help. -- But that's what I got and I'll continue using it until another is in the budget.

[Superdave]

both grounds on the GM o2 are tied together and bolted to a clean spot on the chassis. The only problem i'm having is that the donut gasket at the header collector leaks a little so the o2 reads lean. For now i disconnected it and am running off the wideband controller again.

Open loop is still disabled and it starts up every time and runs great.


I took 2 datalogs of it idling earlier, one with the 4 wire and one with the wideband's NB output hooked up.. then combined the o2 readings into a graph just to show the ammount of swing.



the 4 wire is stock from my 3500, maybe it's a little different because GM has one on each bank... either way, much smoother output.

[OldSkoolGP]

The LC-1 actually says NOT to ground all the wires on the same lug. I seperated mine and it worked good, whereas others had problems until they moved the signal ground away.

They DO recommend that you ground the signal to the same lug as your ECM.

This is taken directly from the Innovate LC-1 Manual:

Since it is not always practical to ground every device to the exact same location, here are some
tips on grounding:
1. The BEST grounding scheme is all grounds (i.e., ECU, Gauges, LC1 heater, LC1
system, etc.) SOLDERED into a single lug and bolted to the engine block.
2. The next best is all grounds attached to the same source, as close as possible, but on
separate lugs. This is because even the corrosion between lugs can create ground
offset and noise. Incidentally, this is why many ECUs have separate ground wires for
injectors vs. ECU system ground- separating high voltages and low voltages reduces
noise.
3. Grounding to the engine block is usually better than grounding to the frame.
4. Grounding a gauge to the radio is usually bad- ground offset can vary with volume.
5. Grounding to an ECU housing is generally not optimal- housings are strapped to the
frame for shielding, but not necessarily grounded.
6. One of the WORST things to do is to ground most of your electronics to one place (i.e.
the engine block), but ground one device somewhere else (i.e., the frame). Not only can
this result in ground offsets, it can also create a “path of least resistance” for high
currents THROUGH a low-current device. This can result in melted wires and vaporized
diodes, when, for example, starter currents flow through gauges.

So it would seem grounding to one place is a bad idea if you can't ground everything to the same thing like the engine block.

[Superdave]

Ok ladies and Gentelmen.. Lets move on to the newest batch of issues and discoveries.


This part was all done with Open Loop Disabled*


Problem #1 Starting it sucked, it flooded every time

Solution: Drastically reduce the Crank Fuel PW VS. Coolant Temp table

Now the startup BPW is in the .2 range most of the time..

The weird part:

7/10 times the startup BPW is in the .2-.4 range (good)
3/10 times the startup BPW rockets up to between 100 and 218.. Of course it won't start like this, but just turning the key off for a sec then re-trying gets the BPC back to normal and it fires right up. wtf is with that? lol


Now onto the open loop problems:

All my adjustments to the crank fuel deffenetly helped the open loop start.. all 3 closed loop timers were set at 15 sec for this part...

Problem #2 Open loop starts are rich as hell, car floods and dies

Semi-Solution: Since open loop relies on tables to calculate fueling and it was rich i decided to change the open loop AFR VS Coolant Temp VS MAP table to command a 16:1 AFR.. that helped alot, still rich and won't idle though..



Still a problem: (see the attached log).. too hard to put into words.. lol

I just don't get why the PW rockets up like that.. :/

[IsaacHayes]

MS it... :P

[Superdave]

well, i broke down and dropped my BPC from 129 to 102 and then bumped up my VE tables. I'll do some more datalogging tomorrow and see if the global changes help..

[sprucegagt]

So it would seem grounding to one place is a bad idea if you can't ground everything to the same thing like the engine block.

I remember going through all of this when installing my LC-1. Basically what the instructions are trying to tell you is to use 2 ground lugs on the same piece of metal. This is to prevent noise feedback on the heater ground from interfering with the controller ground. Do not under any circumstance split these two ground points (i.e. engine block and chassis). This can cause a ground loop feedback and damage the LC-1.