rich lamda before fuel-cut-off

Tuning discussion for all second generation Mazda 2.3 MZR DISI Turbo powered vehicles
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Andi_RC36
Posts: 8
Joined: December 30th, 2016, 4:07 pm

rich lamda before fuel-cut-off

Post by Andi_RC36 »

Hey Guys I have the following issue:

Each time I change from part throttle into fuel-cut-off my lambda is going pretty rich (~0,7-0,8) before it goes to 2.
What could be the reason for this and how can I fix that?

Best regards
Andi
mituc
VersaTuner guru
Posts: 1323
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: rich lamda before fuel-cut-off

Post by mituc »

Lambda 2 means that there is actually no fuel in the exhaust to be measured. It is a sign of fuel cut, even if it's for protection (some parameter value was exceeded) or you're engine braking.

Post a log with that problem occurring and we will be able to help you more.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Andi_RC36
Posts: 8
Joined: December 30th, 2016, 4:07 pm

Re: rich lamda before fuel-cut-off

Post by Andi_RC36 »

Hi mituc,

yes I'm talking from engine braking.
When I drive with part load (Lambda 1) and then lift the gas pedal the engine doesn't go directly to Lambda 2.
Instead Lambda gets really rich before fuel cut off

I can post a log at the weekend.
mituc
VersaTuner guru
Posts: 1323
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: rich lamda before fuel-cut-off

Post by mituc »

Post a log.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Andi_RC36
Posts: 8
Joined: December 30th, 2016, 4:07 pm

Re: rich lamda before fuel-cut-off

Post by Andi_RC36 »

Here's a screenshot.
the complete log follows later, I'm in a hurry right now.

Second 203 and 231 is what I'm talking about.
Anfetten vor Schub.JPG
Anfetten vor Schub.JPG (156.49 KiB) Viewed 9324 times
mituc
VersaTuner guru
Posts: 1323
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: rich lamda before fuel-cut-off

Post by mituc »

Man, post a log. You can see nothing from a screen shot!
Nobody forces you to post at a specific moment, just take your time and post when you're not in a hurry.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Andi_RC36
Posts: 8
Joined: December 30th, 2016, 4:07 pm

Re: rich lamda before fuel-cut-off

Post by Andi_RC36 »

Okay, here is the log.
Attachments
VersaTuner Logs.zip
(612.27 KiB) Downloaded 338 times
mituc
VersaTuner guru
Posts: 1323
Joined: December 17th, 2011, 2:47 pm
Location: Iasi/Romania

Re: rich lamda before fuel-cut-off

Post by mituc »

The Long therm fuel trims are not learning, so it looks like you may have a problem with an injector (slow reacting, stuck open, whatever).
I reckon your tail pipes are black like a North Pole night.

What tune are you running? Are you running any sort of aux fuelling?
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
Andi_RC36
Posts: 8
Joined: December 30th, 2016, 4:07 pm

Re: rich lamda before fuel-cut-off

Post by Andi_RC36 »

Hi mituc,

the fuel trims are not learned yet. I just flashed the tune a few kilometers before.
Yes the tail pipes are quite black, but the last time I was driving a lot short distances.
The tune is self made.

No aux fueling.
I hav an aquamist HFS-4 Kit installesd but not activated yet.

I have the following setup:
FMIC, 3" Intake, Upgrade Turbo, Manifold, HPFP upgrade, Downpipe und the Aquamist.

How can I check the injectors?
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