Dfco help vy v8

[LS1GU]

I am looking for some help with regards to DFCO after a mafless tune in a vy Calais LS1 after cam fitment.

I have a vy Calais that has had an exhaust, OTR and mafless tune for about a year now and has been running fine, I have recently had a camshaft fitted 220/220 and since fitting have been noticing what feels like a reduction in engine braking when backing off the gas.
I have spoken with my tuner and he has told me that he has had to disable the "DFCO" function in the tune via maxing out kph as it is not possible to have this operational after fitting a camshaft as the program keeps "disabling" the function even know all parameters are set correctly.

So can DFCO be made to work with a camshaft fitted in an auto?
Is there something in the tune elsewhere that overrides any DFCO parameters?

I have been in the vehicle with my tuner and looked at the data while driving, and it seems what he is saying is correct, you can move numbers around in DFCO setting and they don't seems to have any effect, as if some other setting overrides these settings.

I asked him to enable DFCO by lowering KPH and setting all other settings as should be, we then went for a drive and when DFCO is engaged it "hunts" it feels like in back off the throttle gets "blaped" and on the graph it looks like a heart beat, wont stay in DFCO mode.
I don't understand if all parameters are set, TPS, MAP, SPEED, RPM,ect and all stay within settings how it wont stay there?

My wife now doesn't like driving this car (her daily driver) as she is used to de-cell felling that the DFCO offers especially on slight down hill runs.

Please help as I don't want to sell this car, and if it cant be fixed I will take the cam out and go back to where it was before.

Cheers

[joecar]

Post:
- a log file.
- a screenshot of your DFCO parameters.

Is you transmission the M6 or the A4...?

[limited cv8r]

yes you can still run DFCO with a cam and auto. I ran a 218/224 in an auto no problem. You often don't get much DFCO / engine braking in 4th, but if you drop it down to third you can usually feel it working. I'm going to assume the Calais has instant fuel usage in the dash display,this is an easy thing to watch to see if DFCO is activating.

[swingtan]

Again, DFCO is possible, but it depends more on the transmission than the cam. Manuals are easy to do, as the clutch is always locked, auto's can have issues with the engine RPM causing the DFCO to cycle on / off.

This is due to the TCC releasing during DFCO which results in the engine RPM falling below the DFCO exit setting and turning off DFCO. When this occurs, the RPM rises again and the PCM re-enters DFCO mode. It's not just DFCO settings that need to be adjusted, but also the transmission settings.

My massive ( really massive ) assumption is that you have been given a "generic" tune that causes the DFCO cycle problem. This is my car with a 220/224 cam, but it's a manual. Watch the "AFR" gauge as I crest the hill and you'll see it goes into DFCO and stays there. (Actually, I just noticed the thumbnail shows DFCO on....) I've done a few other LS1's with cams and not had massive issues with DFCO, the only ones I normally disable it on are cars with big stalls.

[IJ.]

Another for DFCO+Cam+Auto, no dramas here.

[warlock007]

why does the numbers jump that high when it goes into it?

I am new to all this and try to learn a little at a time.

Thanks ahead of time.

[joecar]

why does the numbers jump that high when it goes into it?

I am new to all this and try to learn a little at a time.

Thanks ahead of time.

You mean "why does AFR jump high when DCFO enables...?"...?

It cuts fuel on decel throttle close, so wideband shows lean.