M35 Vq25det Safc Ii

[danwatt]

Hi Guys, Has anyone installed an SAFC II on the M35 Stagea VQ25DET engine ?

Does it work well and would you reccomend the modification ?

[crisis]

The guys at Unique Autosports tried to fit one to my ARX with no success.

They had previously installed on on my 300zxtt with very positive results.

I'm currently investigating having the chip reprogrammed by Silverwater Automotive Services.

[danwatt]

The guys at Unique Autosports tried to fit one to my ARX with no success.

They had previously installed on on my 300zxtt with very positive results.

I'm currently investigating having the chip reprogrammed by Silverwater Automotive Services.

Do you know whta the problem is with the SAFCII ? Does the standard computer try to over right the settings and take control?

[crisis]

Do you know whta the problem is with the SAFCII ? Does the standard computer try to over right the settings and take control?

Exactly

Runs incredible rich and boost drops off in the higher rev range

[danwatt]

Cheers, Let me know how you get on with the re-programming of the ECU.

Even if they can modify the standard program to stop it taking control would be good

[KiwiRS4T]

The guys at Unique Autosports tried to fit one to my ARX with no success.

They had previously installed on on my 300zxtt with very positive results.

I'm currently investigating having the chip reprogrammed by Silverwater Automotive Services.

Did the guys at Unique motorsports say what the problem was? The ecu can't really "override the settings" because all the SAFC does is to modify the signal from the AFM thus creating a new reality for the ecu. One downside can be that it alters your timing so they should really be fitted together with an Apexi SITC so that your timing can be fine tuned. I will be fitting both over the weekend together with a wideband sensor and afr meter (LM2) so I can start tuning - although this is on an RB25DET. I don't know how the V6 is different but think the SAFC/SITC should work OK too.

p.s some tuning tips from SK which may or may not be useful to your particular car/engine:

Recently a few guys have been asking me about how to get around the DFA (SAFC) compromise of leaner A/F ratios at high boost and higher rpm and richer A/F ratios during (and sometimes just after) boost build. The problem is if you increase the AFM voltage at higher rpm (to get richer A/F ratios) the standard ECU sees this as increased airflow, which may push it into R&R mapping. Which results in power dips and a lack of response. Sometimes this doesn't show up on the dyno but raises it ugly head when you drive in variable conditions on the road or track.

To fix this “R&R versus too lean at higher boost” problem you have to increase the fuel pressure (via an adjustable fuel pressure regulator). The trick is to increase the fuel pressure just enough to get the A/F ratios to the target (say 12 to 1) in the rpm range that it is currently running too lean (usually above 4,500 rpm).

For adjustable FPR I use the Nismo bolt on style, ~$150 from Nengun.

Set the FPR to give 45psi above boost when boost has stabilised (anything above c3000 rev/min).

Once you get the higher rpm A/F ratios in the range that you want them, you use the DFA (SAFC) to lean it out in the other rpm ranges where it will then be too rich. This (reduced AFM voltage) also helps with preventing the ECU going to R&R, as it uses lower airflow map load points. So you get 2 benefits.

In order to lean out the A/F ratios, the DFA settings are used to reduce the AFM voltage (that the ECU sees), which usually advances the ignition timing. So the SITC is used to retard the ignition timing. This retarding is mostly required at revs over 4,500 rpm. Most times under 4,000 rpm you can sneak in a bit more advance, which improves the response considerably.

If you are using a suitable turbo (eg; GCG ball bearing high flow) the adj FPR, DFA and SITC you should be able to get the boost up to 1 bar, maybe 1.1 bar. That will give you another 30 to 40 kW over the 12 psi that you may well be restricted to if you don’t use the adj FPR to cure the high rpm leanness first. It does require some fiddling around, but no more than trying to achieve the same results with a Power FC on a manual. It’s just a matter of tuning the right bit first.

Hope that was of some help to fellow auto owners.

[danwatt]

Did the guys at Unique motorsports say what the problem was? The ecu can't really "override the settings" because all the SAFC does is to modify the signal from the AFM thus creating a new reality for the ecu. One downside can be that it alters your timing so they should really be fitted together with an Apexi SITC so that your timing can be fine tuned. I will be fitting both over the weekend together with a wideband sensor and afr meter (LM2) so I can start tuning - although this is on an RB25DET. I don't know how the V6 is different but think the SAFC/SITC should work OK too.

p.s some tuning tips from SK which may or may not be useful to your particular car/engine:

Recently a few guys have been asking me about how to get around the DFA (SAFC) compromise of leaner A/F ratios at high boost and higher rpm and richer A/F ratios during (and sometimes just after) boost build. The problem is if you increase the AFM voltage at higher rpm (to get richer A/F ratios) the standard ECU sees this as increased airflow, which may push it into R&R mapping. Which results in power dips and a lack of response. Sometimes this doesn't show up on the dyno but raises it ugly head when you drive in variable conditions on the road or track.

To fix this “R&R versus too lean at higher boost” problem you have to increase the fuel pressure (via an adjustable fuel pressure regulator). The trick is to increase the fuel pressure just enough to get the A/F ratios to the target (say 12 to 1) in the rpm range that it is currently running too lean (usually above 4,500 rpm).

For adjustable FPR I use the Nismo bolt on style, ~$150 from Nengun.

Set the FPR to give 45psi above boost when boost has stabilised (anything above c3000 rev/min).

Once you get the higher rpm A/F ratios in the range that you want them, you use the DFA (SAFC) to lean it out in the other rpm ranges where it will then be too rich. This (reduced AFM voltage) also helps with preventing the ECU going to R&R, as it uses lower airflow map load points. So you get 2 benefits.

In order to lean out the A/F ratios, the DFA settings are used to reduce the AFM voltage (that the ECU sees), which usually advances the ignition timing. So the SITC is used to retard the ignition timing. This retarding is mostly required at revs over 4,500 rpm. Most times under 4,000 rpm you can sneak in a bit more advance, which improves the response considerably.

If you are using a suitable turbo (eg; GCG ball bearing high flow) the adj FPR, DFA and SITC you should be able to get the boost up to 1 bar, maybe 1.1 bar. That will give you another 30 to 40 kW over the 12 psi that you may well be restricted to if you don’t use the adj FPR to cure the high rpm leanness first. It does require some fiddling around, but no more than trying to achieve the same results with a Power FC on a manual. It’s just a matter of tuning the right bit first.

Hope that was of some help to fellow auto owners.

Thanks for the advise, Since I dont know much about tuning but have an understanding of what you are talking about, would it be fair to say that when you talk about using a FPR to increase the fuel pressure above say 4000 rpm to get the A/F ratios correct at high boost would it fair to say that you could achieve this also by installing slightly larger injectors then using the SAFCII to adjust the A/F ratios under other operating boost pressures and conditions.

Would this be a better option if you have or are about to install a bigger / higher flowing turbo?

[KiwiRS4T]

Thanks for the advise, Since I dont know much about tuning but have an understanding of what you are talking about, would it be fair to say that when you talk about using a FPR to increase the fuel pressure above say 4000 rpm to get the A/F ratios correct at high boost would it fair to say that you could achieve this also by installing slightly larger injectors then using the SAFCII to adjust the A/F ratios under other operating boost pressures and conditions.

Would this be a better option if you have or are about to install a bigger / higher flowing turbo?

Disclosure: I used to be a mechanic back in the last century but my hands on experience with RBs is pretty much limited to my S1 Stagea. Whether bigger injectors are indicated for now or later would depend on the duty cycle now - if they are running at only 60- 70% now they should not require replacing. And even if they do or maybe especially if they do you still need to ensure an adequate fuel supply from your fuel pump and fuel pressure regulator. Increased boost will require increased fuel pressure to get the fuel out of the injectors at the required rate.

[danwatt]

Disclosure: I used to be a mechanic back in the last century but my hands on experience with RBs is pretty much limited to my S1 Stagea. Whether bigger injectors are indicated for now or later would depend on the duty cycle now - if they are running at only 60- 70% now they should not require replacing. And even if they do or maybe especially if they do you still need to ensure an adequate fuel supply from your fuel pump and fuel pressure regulator. Increased boost will require increased fuel pressure to get the fuel out of the injectors at the required rate.

Cheers, Sounds like the fue pressur regulator is the way to go, Install the SAFC2 and see what the tuner can do.

WIll keep you updated on the progress.

[BoostdR]

http://www.apexi-usa.com/content/pdf5486.pdf

Apexi AFC NEO lists the M35 VQ25DET Stagea.

I'm sure the SAFCII also works.

[BoostdR]

http://www.apexi-usa.com/content/pdf5486.pdf

Apexi AFC NEO lists the M35 VQ25DET Stagea.

I'm sure the SAFCII also works.

I agree if your engine is lean to raise the Fuel pressure then uses your AFC to lean it out...Will keep it away from boost cut as well ....unless the boost sensor stops the party...in that case put the boost sensor on the wastegate side of you boost controller and it will see less than actual boost.

[scotty nm35]

I put a standard air regulator on my boost sensor so it sees 8psi, I don't know if it helped, but I run 20psi now, no dramas.

The stock ecu does a fine job of keeping the burn stoich, I don't like the idea of just modifying the airflow signal, I much prefer the voltage clamp p1ggyback units use as the low end mapping isn't changed much.

[bbenny]

Yeah cant see why one wouldnt work on a VQ.

I used one on my old RB and had great results, I actually have an SAFC II in my cupboard waiting to be fitted to the M35 when things need a little fine tuning.

[scotty nm35]

I can, for a start the engine is a 30 year newer design, and ecu's have come a long way.

Tuning by only bending the airflow signal is not a smart option in my opinion.