Car will not follow commanded AFR

Discussion of tuning specific to MAZDASPEED6/MAZDASPEED Atenza/Mazda 6 MPS vehicles

Car will not follow commanded AFR

by mfinlay04 » January 31st, 2016, 2:21 pm

This has been an ongoing issue ever since I can remember. This issue occurred when I used to have my Cobb AP, so it's not something that is VT specific.

I target Lambda 1.14 @ low load cruising RPMs, yet the car does not seem to follow them. Typically the AFR is off by a margin of 0.04 lambda. I log my AFR as 1.10 lambda but the desired is 1.14. All of my Fueling tables match up OL, CL, & WOT...

I've uploaded my tune, and I'll grab a log here shortly and upload it as well.

I'm wondering if there is a fueling table that perhaps we don't have access to that is affecting over all AFR. My STFT and LTFT are typically -/+ 5 when this occurs so it's not a MAF cal issue.

Any insight would be appreciated
Attachments
Base Tune v1.04 v2.00.zip
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Re: Car will not follow commanded AFR

by mfinlay04 » January 31st, 2016, 7:05 pm

Alright, so here is a log of me today on the freeway.

The tune has the Lambda set at 1.14 for 2k-3.5k and 0-0.69 load. As you can see in the log, the ECU sets the desired lambda at 1.11 instead if the 1.14 commanded in my tune.

Anyone else experience this? Or am I the only crazy one running this lean?
Attachments
VersaTuner Logs.zip
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Re: Car will not follow commanded AFR

by mituc » February 2nd, 2016, 9:04 am

It looks to me like you took this log right after you flashed the map. Was the car warm at least? The cold ECT fuel enrichment may work against you on this. Otherwise the desired and actual lambda is pretty much spot on, and the STFTs show very little compensation so your MAF cal is indeed spot on, but with those STFTs in place I'd expect to see some LTFT values as well.

Probably using some 3D interpolation to smooth the edges of that patch of 1.14lambda there may help as well, because if you don't do it the ECU logic will do it for you and it's possible that you're looking at the result of that.

By the way, what mods do you have? Did you disable any PIDs to be able to run leaner AFRs?
2008 Cosmic Blue Mazda 3MPS
Build engine + WMI + GTX3071, ~476WHP @31-32PSI
2008 Icy Blue Mazda CX7
Stock engine, intake and exhaust (YES!!), GTX2867 gen2 + Autotech HPFP, self-tuned to 320-ish BHP
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Re: Car will not follow commanded AFR

by mfinlay04 » February 2nd, 2016, 10:02 pm

The actual vs desired is spot on. The issue is it doesn't match what I've commanded in my tune. Ive dialed in 1.14 lambda and the ECU is commanding 1.11
 
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Joined: February 13th, 2015, 3:27 am

Re: Car will not follow commanded AFR

by mituc » February 3rd, 2016, 4:43 am

mituc wrote:Probably using some 3D interpolation to smooth the edges of that patch of 1.14lambda there may help as well, because if you don't do it the ECU logic will do it for you and it's possible that you're looking at the result of that.


^^This!
2008 Cosmic Blue Mazda 3MPS
Build engine + WMI + GTX3071, ~476WHP @31-32PSI
2008 Icy Blue Mazda CX7
Stock engine, intake and exhaust (YES!!), GTX2867 gen2 + Autotech HPFP, self-tuned to 320-ish BHP
VersaTuner guru
 
Posts: 881
Joined: December 17th, 2011, 2:47 pm
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Re: Car will not follow commanded AFR

by ShakesReaper » August 23rd, 2016, 1:10 am

Hi

I am also dipping my feet in the high AFR @ cruising pond.

I am now commanding 1.021 while cruising, but my desired logged values are 0.992. that is quite a way off. what will be the reason for this?
Logs were taken while cruising on the highway, so my engine was nice and up to operating temp.

Sorry to hijack the thread, but I think this might be the same issue.
 
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Re: Car will not follow commanded AFR

by mituc » August 23rd, 2016, 12:40 pm

Can be a lot of things starting with the MAF cal. I had a tune commanding 1.035 and that was exactly what I was hitting under the load/engine speed circumstances I was commanding it.
Post a log and eventually your tune (make sure it's not a tune from an e-tuner but some tune you made).
2008 Cosmic Blue Mazda 3MPS
Build engine + WMI + GTX3071, ~476WHP @31-32PSI
2008 Icy Blue Mazda CX7
Stock engine, intake and exhaust (YES!!), GTX2867 gen2 + Autotech HPFP, self-tuned to 320-ish BHP
VersaTuner guru
 
Posts: 881
Joined: December 17th, 2011, 2:47 pm
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Re: Car will not follow commanded AFR

by ShakesReaper » August 24th, 2016, 1:44 pm

If you could have a look that will be great.

I have attached a zip file with my tune as well as 2 logs while cruizing on the highway in 6th.
the highway stretch I drive daily has a lot of uphills and downhills, that is the reason for the loads going up and down.

I do have a BT build with stock engine. Meth spraying from 0.7 bar, 3.25" intake, 3" catless exhaust, HPFP and 2 steps colder plugs.

Thank you in advance.
Attachments
Logs & Tune.zip
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Re: Car will not follow commanded AFR

by mituc » August 25th, 2016, 2:15 am

But that happens all the time or you just found these sections where it doesn't follow the AFRs in the tune? The AFRs match the commanded ones though, but unless these logs are in the middle of some transition or recovering from a small KR event it's hard to tell why the commanded AFRs don't follow the ones in the tune.
2008 Cosmic Blue Mazda 3MPS
Build engine + WMI + GTX3071, ~476WHP @31-32PSI
2008 Icy Blue Mazda CX7
Stock engine, intake and exhaust (YES!!), GTX2867 gen2 + Autotech HPFP, self-tuned to 320-ish BHP
VersaTuner guru
 
Posts: 881
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: Car will not follow commanded AFR

by ShakesReaper » August 26th, 2016, 1:31 am

This happens all the time as far as I know.

My drive home is about 30min, of witch 15min is city driving and 15min on the highway. I can post a log of the entire trip if you like. from cold start till I switch off at home.

The logs I attached were not after a detonation event, but if that is the case, how long will the ecu remain in the KR Present AFR tables before reverting back to the normal AFR tables?

I would really like to sort this out, because if my car cannot follow the parameters I set in the tune, how can I ever really trust the ecu to do what I want it to do?
 
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