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Discussion Starter #1
I spoke to my neighbor who has slew of HP cars about my lean issues after the tune. He suggested since I have no vacuum leak, I may need a bigger injectors to compensate for lean issues with current brenspeed 93 octane tune. He said 47lb injectors should be good on my Roush with M90. U experts please chime in, new tune needed?
 

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If you get new injectors then yes you ll need a new tune. After see you havinh tune issues woth brenspeed already i would be moving on and get a true custom tune or getting a custom tune using datalogs not the tune that is a modified out of the box type.
 

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Discussion Starter #3
If you get new injectors then yes you ll need a new tune. After see you havinh tune issues woth brenspeed already i would be moving on and get a true custom tune or getting a custom tune using datalogs not the tune that is a modified out of the box type.
Actually, dyno tune will be my next tune as many from this forum recommends. It's little frustrating to pay for something and not working right with tune I got.

Off topic a bit, my sct tuner fuel pump duty cycle at idle is around 24%. Is this actually 48% as some suggest to multiply by two. I don't even know what is normal FPDC percentage range is for the fuel pump.
 

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Fuel pump duty cycle should never exceed 80% to be safe. I know folks that run 90% without issue. There is no normal range as it varies from build to build. And different pump set ups have different capacities. That is why we refer to duty cycle.

Changing injector size requires tuning. The same injector pulse on different size injectors will flow different amounts of fuel. Whether you need bigger injectors should be based on capacity or duty cycle. I'm pushing the envelope but I run 32#'s at 480 rwhp.

Have you added any fuel to your current tune to see if you can get it closer to stoich? I believe you can add fuel across the board or just to certain rpm ranges. It's been a while since I had my SCT hooked up so my memory is a little foggy.
 

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The guys above hit it right on the head. Have a look at the injector duty cycle if you are able to datalog. Also check out your fuel pressure drop across the injector. If its much lower than 39 psi, a fuel pump should be the first thing you buy. Since you are running an SCT tuner, you can add fuel across the board, assuming the FP can handle it. What size injectors are you running now? Any idea what power level you are at? I run the 47# injectors at 430 whp with room to spare. Do you lean out only at WOT? That could be an indicator that bigger injectors may be a good idea. If you are leaning out at partial throttle but not WOT, common sense tells you that your tune may need some attention.
 

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He may also need a pump. I know my car was pushing 468rwhp on about a 100shot and it was running out pump at 5k+. Shooting for nitrous and blower id be doing injectors and pump.
He said fuel pump was at less than 50%. I think it just needs to be properly tuned.
 

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Discussion Starter #9
Fuel pump duty cycle should never exceed 80% to be safe. I know folks that run 90% without issue. There is no normal range as it varies from build to build. And different pump set ups have different capacities. That is why we refer to duty cycle.

Changing injector size requires tuning. The same injector pulse on different size injectors will flow different amounts of fuel. Whether you need bigger injectors should be based on capacity or duty cycle. I'm pushing the envelope but I run 32#'s at 480 rwhp.

Have you added any fuel to your current tune to see if you can get it closer to stoich? I believe you can add fuel across the board or just to certain rpm ranges. It's been a while since I had my SCT hooked up so my memory is a little foggy.
I checked with Roush. My injectors are 34 pounders and will definitely need tune with 47 pounders.

My SCTx4 was sent by Brenspeed. It is so locked, I can't do anything but watch gauges, upload tune, clear DTC's. There is no options for programming on the tuner. Is there anyway I can unlock the tuner?

---------- Post added at 05:26 PM ---------- Previous post was at 05:21 PM ----------

Also check out your fuel pressure drop across the injector. If its much lower than 39 psi, a fuel pump should be the first thing you buy. Since you are running an SCT tuner, you can add fuel across the board, assuming the FP can handle it. What size injectors are you running now? .
It's around 40 to 45 depending on what rpms. As I wrote above reply to Boss, can't do anything programming except load tune, gauges and dtc with the SCTx4 I purchased from Brenspeed.
 

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I checked with Roush. My injectors are 34 pounders and will definitely need tune with 47 pounders.

My SCTx4 was sent by Brenspeed. It is so locked, I can't do anything but watch gauges, upload tune, clear DTC's. There is no options for programming on the tuner. Is there anyway I can unlock the tuner?

---------- Post added at 05:26 PM ---------- Previous post was at 05:21 PM ----------



It's around 40 to 45 depending on what rpms. As I wrote above reply to Boss, can't do anything programming except load tune, gauges and dtc with the SCTx4 I purchased from Brenspeed.
I didn't think about that. Tuners can lock out many of the few tuning parameters that we have options for. They do this to protect themselves from anyone adjusting it and then claiming the tune from so and so blew up my motor. Normally you would be able to adjust all sorts of things including simple things like gear ratios, or tire revs per mile. My Shelby tune has all of that stuff locked but my Lund tune doesn't.
 
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