Return to Closed Loop?

[DPS]

Hey guys,

I'm just wrapping up a tune on a '97 Z28 with the EFI Connections COP and 0411 swap. The car is running pretty good. The MAF in the car was descreened so I decided to run SD.

I attempted to put it into CLSD when I was finished but it continues to stay in OL. This creates a couple of questions:

1. What's the risk associated with leaving it in OLSD? (FYI...it doesn't have a WBO2)

2. What could I be doing wrong that is keeping the car in OL?


The car is currently a dedicated road course car. The owner did express some interest however in putting it back on the street.

Any thoughts are welcome.

-Brad

[mr.prick]

Are there any DTCs?
Post the .tun

[WeathermanShawn]

What could I be doing wrong that is keeping the car in OL? The owner did express some interest however in putting it back on the street.-Brad

Brad, open-loop is going to need a really good VE Table. Biggest problem on the street (open-loop) is heat soak. You go to Home Depot..turn off your car..IAT may now be 160F around the IAT sensor. Without a custom OS..chances are your car starts very lean (if it will start).

CLSD or a custom OS allows trimming to stoich. Not a bad deal. Whether for road course racing one is superior to the other..perhaps others can comment.

Good luck..

[DPS]

DTCs:

P0102
P0103
P0463


I followed SSpdDmon's notes on setting up OLSD found here:
http://forum.efilive.com/showthread.php?p=105577#post105577

I imagine that the problem resides in the processing enablers since I wanted to fail the MAF without tripping an emissions code which would result in a failed inspection if he were to put the car on the road.

Go easy on the .tun fellas. I know that the VE is "peaky" and I'm very sensitive :bawl: :hihi:

There is definately some smoothing to be done.

Many thanks,
Brad

[WeathermanShawn]

I attempted to put it into CLSD when I was finished but it continues to stay in OL. 2. What could I be doing wrong that is keeping the car in OL?Brad

Brad, if you wanting to go CLSD you just need to change B3801 to Enable (if you want LTFTS) and change B4205 back to stock values..I.E. 34C..(Seems to be a mislabel on the EFILive Labels..IAT?).

That should put you back into CLSD. If you are getting DTC's for the MAF..then you should be SD..

Is that what you wanted to do..go back to CLSD?

[DPS]

Thanks Shawn.

I had initialy intended to put it into CLSD. Once I started to struggle with it I contemplated OLSD.

Either way, it looks like the car will get more of my attention before I consider it done.

On a side note. I hate opti-spark ignitions. This car has 29,000 miles on it. It arrived with a bad upper RPM misfire with a new opti installed. Opti #3 was installed and still had the same problem. We had an o-scope hooked to everything you could imagine. After many nights of scratching our heads, the car received the 0411 and LS COP conversion. Results are attached.

-Brad

PS - I hate opti-sparks :ranting:

[WeathermanShawn]

Wow, thats a pretty big improvement. Congratulations..that is impressive.

I think I understand on the tune. You are keeping it OLSD. A few others are more expert on the MAF DTC's. I know the Processing Enablers get tricky..the 'Non-Emissions' one always got me confused. But if you are getting a DTC code on the MAF..you should be all SD.

If you ever want a sanity check..you can always change the Low-Octane by .5 -1 degree. If the MAF is failed, you will be running off the Low-Octane.

So it looks like you are utilizing PE Mode as your Commanded AFR vs B3605. Probably not a bad way to do a road course car.

Good luck..and good work..:cheers:

[5.7ute]

One thing to note Brad is you will have to do some serious work on that VE table over 4000 RPM. Even though you rarely hit these areas you should hand fill them somewhere in the ballpark. Hint: Edit the table in 2d view to see the trends clearer.

[DPS]

It's on my "to do list."

Thank you! :cheers:

[joecar]

...

I imagine that the problem resides in the processing enablers since I wanted to fail the MAF without tripping an emissions code which would result in a failed inspection if he were to put the car on the road.

...Brad,

To run SD the PCM must see a failed MAF dtc... i.e. the MAF dtc's must not be set to Not-Reported or Non-Emissions... set them to 1-Trip.


I don't think anyone has yet found a way of running SD without failing the MAF (i.e. triggering a MAF dtc).

[joecar]

BTW(unrelated): set B3609 to all zeros.

How much was the initial bump up of the VE table...?


This is an LT1...? How big is the motor and cam...? What other mods...?

:)

[5.7ute]

There is a bit of a trap involved in just raising the whole table in some OS's.(like this one appears to be). Since over 4000RPM is usually uncalibrated due to the maf taking over at this point. The 4000 RPM band gets jacked up during AutoVE due to interpolation with the lower 4400 RPM band.

[DPS]

BTW(unrelated): set B3609 to all zeros.

How much was the initial bump up of the VE table...?


This is an LT1...? How big is the motor and cam...? What other mods...?

:)

I started with a 15% increase of the VE and went from there.

Mods include:

Hotcam - 218/228, 525/525, 112 .....unsure about rocker ratio

Mildly home ported stock heads

Longtubes

Moroso/K&N CAI ?

Edelbrock TB

No cats into a bullet style muffler

Those are the highlights. It makes decent torque. I rather like it.


Yes. It's a stock bottom end LT1

[DPS]

There is a bit of a trap involved in just raising the whole table in some OS's.(like this one appears to be). Since over 4000RPM is usually uncalibrated due to the maf taking over at this point. The 4000 RPM band gets jacked up during AutoVE due to interpolation with the lower 4400 RPM band.

Is hand smoothing the 80kPa and below values to trend more like the 85kPa and up values beyond 4000rpm the proper way to fix this?

Thanks for the tips guys!

-Brad

[5.7ute]

Is hand smoothing the 80kPa and below values to trend more like the 85kPa and up values beyond 4000rpm the proper way to fix this?

Thanks for the tips guys!

-Brad

Pretty much. Your 4000 RPM values appear to be jacked up due to the low 4400 RPM row. But this will clean itself up once you do another tuning run.
Another tip is to try & hit the centre of the cells, especially with the rpm bands. For instance I will set cruise control to 2000 RPM & use the terrain to vary the map cells to do this band on road. Not as good as a dyno, but it gets you there fairly quickly.

[joecar]

Brad, can you post some very recent log files... :)

[DPS]

Here is a log file based on the 0015.tun that I posted previously.

I've also attached 0016.tun that has the changes implemented that were suggested by you guys.

Please take a look and tell me if it's worth flashing 0016.tun to the car before it leaves. I will not get a chance to log or re-tune anything before it goes.

Thanks again guys! :cheers:

-Brad

[WeathermanShawn]

Something still looks amiss..at least on my Scan Tool.

I see you want it to go to closed-loop, but your Scan says it stays open-loop the whole time? Also, it looks like one or both your O2 sensors are not working. H02S11 stays flat-lined. Furthermore there are no LTFT or STFT's..

But I see in your tune you have those enabled.

So, it still looks like SD-Open Loop..I am confused also...:confused:

[DPS]

What you just described has been the problem right along. I wanted to put it into CL but for some reason it wouldn't switch over. Perhaps it is the O2 issue that you discovered.

I was going to give the car a final flash tonight before it leaves in the morning as a last ditch effort to put it into CL. Since I have little confidence that it will work, I've been massaging the VE Table (97 Z28 0016.tun) per 5.7Ute's advice. That way if it stays in OL I will have a little more confidence in it.

-Brad

[mr.prick]

Clear the DTCs you have and try again.

[WeathermanShawn]

Brad:

My brain is working again. I recall a similar problem on my 2002 Z-28. I had closed-loop enabled, but an O2 sensor read bad (too high) and by default it went into open-loop.

The difference was I got a DTC. I also have the front O2's set to 2 trips, Emissions-Related on all the Engine DTC Processing Enablers. In other words, all my C6001 Enablers are still stock.

I bet you are not getting a code since a lot of yours are set to 'Not-Reported'. I am 99% sure that a bad O2 will put you into Open-Loop Fault..

Anybody else have any ideas?

[DPS]

I was just reading through C6001 and stumbled across P0170 and P0173 (Fuel Trim System Banks 1 and 2) set as Not Reported.

Is that normal? Seems like this could be a problem. :doh2:

The entire C6001 section might be effed for all I know. The initial tune wasn't based on a stock file. It's tough to find a stock tune for an LT1 car with a 0411 PCM. :hihi:

-Brad

[WeathermanShawn]

I was just reading through C6001 and stumbled across P0170 and P0173 (Fuel Trim System Banks 1 and 2) set as Not Reported.

Is that normal? Seems like this could be a problem. :doh2:

The entire C6001 section might be effed for all I know. The initial tune wasn't based on a stock file. It's tough to find a stock tune for an LT1 car with a 0411 PCM. :hihi:

-Brad

Thats probably why there are no LTFT's plotted...

Seems like you have 2-3 options.

1. Keep it in SD Open-Loop. Reset B4205 to Max Temp (140C).
Set B3801 to Disable..

2. Keep it SD Closed-loop. Replace 1 or both Front O2 sensors..We could easily configure C6001 to operate normally..(I.E. my C6001 Tune would probably work..)..

Personally if this car will see some street, I would pick Option (2). Since your Table B3605 is already primarily set to stoich (14.63)..it would be an easy option.

I am sure with Joecar and crew, C6001 could be straightened out. It still looks like from your Log that the O2 sensors are not acting 'normal'. I assume that is mechanically-related and not because of the Tune (C6001). I think that just made the DTC not appear.

I would wait to see if you get some more reader/tuner feedback. Its an educated guess on why it won't go to closed-loop..but like I said I am pretty sure it involves C6001 and the O2 sensors..

We will get you some more feedback..:cheers:

[DPS]

Thanks for the help.

Since the owner is picking it up today I've decided on Option 1. I'll just have to inform him that if he wants to drive it on the street he'll need to get a new O2 and an unmolested MAF and bring the car back.

Assuming he decides to do this, have you guys had any luck doing a MAF tune with a Granatelli or a stock descreened MAF? I ask this in case the owner hesitates at buying a new MAF.

-Brad

[WeathermanShawn]

Brad:

I have found the good ole stock GM MAF produces a fairly consistent and reliable frequency vs airflow (g/s).

You can get into massive Internet debates over 'de-screened' and "ported' MAF's. Some have big time problems, others seem to avoid them. I have tried all 3. I am back to the stock MAF. I just find it easier to tune for my application.

I will let others comment, but so far I have not found the stock MAF limiting my HP goals..:grin:..

Good luck..

[mr.prick]

I've got a milled out stocker and have no problems.
I'm not sure what problems one would get from a non stock MAF,
you can always make adjustments to the MAF scale. ;)