Fuel Delivery Lag
09-17-2015, 05:38 PM
#77
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I'm not 100% sure what you are getting at.... my aftermarket AFR gauge doesn't dip below 11.0 afr (I'll see it periodically hit 10.8 for half a second or so) but it is capable of reading down to 10.0..... Brett can comment more on this because he is the tuner but I believe the target AFR's at this stage in the tune is probably aimed to be right around that 11.0-11.1 mark.
And no I have not dyno'd the car yet; want it to be running perfectly again before I get on there.
Last edited by RotaryMachineRx; 09-17-2015 at 05:41 PM.
09-17-2015, 05:52 PM
#78
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Gotcha, I'm just wondering if you are not running pig rich in those areas and getting spark blow out. But if you are certain the AEM is not dropping below 10.8 then that is probably not the issue.
09-17-2015, 06:34 PM
#79
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Ah IC, no I don't believe this to be the case. I've had bogging due to rich conditions before in the past; this is definitely different. When that lean spike happened it was a lurching forward motion it slowed me down so much; almost immediately followed by a good backfire from the exhaust, then when afr's dropped again it was full power back on again all the way to redline. I will have to do some more testing but I believe this only happens with the EBC on, when I run with the Actuator only (about 7psi max) I don't notice this, at least not to this extent. When it happens it is always almost immediately right after I reach full spool....
09-20-2015, 04:19 PM
#82
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Have you checked duty cycle of injectors at tip in? They may be getting maxed out here for a moment, causing the lean condition. Also may be worth getting the injectors swapped/cleaned/flow tested to rule them out.
With the fuel pump replaced the dipping fuel pressure symptom may not be the root cause. Mine sits on about 59psi and drops about 3 points when I nail it before the pump kicks into high power mode to bring the pressure back up to 59..
With the fuel pump replaced the dipping fuel pressure symptom may not be the root cause. Mine sits on about 59psi and drops about 3 points when I nail it before the pump kicks into high power mode to bring the pressure back up to 59..
09-20-2015, 06:24 PM
#83
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Have you checked duty cycle of injectors at tip in? They may be getting maxed out here for a moment, causing the lean condition. Also may be worth getting the injectors swapped/cleaned/flow tested to rule them out.
With the fuel pump replaced the dipping fuel pressure symptom may not be the root cause. Mine sits on about 59psi and drops about 3 points when I nail it before the pump kicks into high power mode to bring the pressure back up to 59..
With the fuel pump replaced the dipping fuel pressure symptom may not be the root cause. Mine sits on about 59psi and drops about 3 points when I nail it before the pump kicks into high power mode to bring the pressure back up to 59..
No I will definitely have a look at duty cycle when I log next; currently I don't have it included in my logs as it shouldn't be an issue on a stock GReddy.... but if you look at my last log the lean spot is not happening at throttle tip in, hence why I will be testing my coils and wires to check for misfiring.
I am seeing exactly what you have just described with my fuel pressure also; with two different pumps now.... replacing the fuel pump seems to have resolved the original tip in "lean delay" I was seeing when I started this thread.
Last edited by RotaryMachineRx; 09-20-2015 at 06:42 PM.
09-20-2015, 06:40 PM
#84
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Not as nice as Brett's but you can see what's going on. 1st Gear WOT..... I have only noticed this in 1st gear.
You can see that my AFR's are dropping at much more reasonable loads with the new fuel pump. (Brett's graphs are with the old fuel pump; both DW200's)
Edit: Added rpm to graph; I have also attached the excel file with the log and graph if people want to look at more parameters or see things more specifically.
Last edited by RotaryMachineRx; 09-20-2015 at 07:15 PM.
09-20-2015, 07:09 PM
#85
09-28-2015, 11:39 AM
#87
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Tested all coils as per Teams thread. All showed strong spark. When I jump the fuel speed relay I am seeing a pressure drop when I floor it from 62.5psi down to 54psi. Thinking I now want to eliminate the fuel pump assembly as a factor.... So anyone have a fuel pump assembly for sale??
09-28-2015, 02:15 PM
#89
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Yeah I priced a new one at dealership and it was $400 so that's why I was looking on here, I'll talk to Charles too. But I'm not even sure if it's an issue, just want to eliminate it as a possibility...... The assembly I have is only 2 years old but I guess there is a chance that there is a defect
09-28-2015, 02:28 PM
#90
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Well if you tested the pump and the related electrical components then the last part of the equation is the pump assembly and you can't really test the pressure regulator.
Fuel line pressure
375-450 kPa {3.83-4.58 kgf/cm2, 54.4-65.2 psi}
375-450 kPa {3.83-4.58 kgf/cm2, 54.4-65.2 psi}
09-28-2015, 04:05 PM
#91
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I am falling just below that 54psi, so fingers crossed that the low fuel pressure is also the cause of that lean spike. The other thing to test I guess would be my fuel pressure sensor...
10-01-2015, 08:48 PM
#92
My bet is that you just need to tune for it. There is no reason to need anything above 45 psig, which is the standard EFI pressure for most systems at WOT and injectors sized accordingly.
I'll go ahead and drop a bombshell here in advance of posting the Deatschwerks test results on the S2 fuel pump assembly; the Mazda S2 fuel pump module pressure relief valve starts blowing off before hitting 50 psig!!!! The only way to achieve pressures higher than this is to be blowing off so much flow through the relief valve that it causes backpressure against the fuel pump outlet. At that point a high flow aftermarket fuel pump isn't flowing that much more than the OE pump to the fuel injectors. And that's a fact, Jack ...
I'll go ahead and drop a bombshell here in advance of posting the Deatschwerks test results on the S2 fuel pump assembly; the Mazda S2 fuel pump module pressure relief valve starts blowing off before hitting 50 psig!!!! The only way to achieve pressures higher than this is to be blowing off so much flow through the relief valve that it causes backpressure against the fuel pump outlet. At that point a high flow aftermarket fuel pump isn't flowing that much more than the OE pump to the fuel injectors. And that's a fact, Jack ...
10-02-2015, 11:06 AM
#93
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^^ Hmm interesting, well I do have another used S1 pump assembly on the way that I will swap in just to see if this changes anything....... Other than that I'll have to chat with Brett about what he thinks he can do tuning wise, maybe I need to play around with EBC settings some more too; thought I had them nailed down pretty good but this issue is only happening when I have it on so... 
God damned winter is just around the corner up here though too....
God damned winter is just around the corner up here though too....
Last edited by RotaryMachineRx; 10-02-2015 at 05:46 PM.
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