[88mustanggt]

2014_Dec_16_08-33-34.csv

a few pulls

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not sure if its in the tune or mechanical issue. if someone could please look it over and give me some ideas. ive been beating my head against the wall trying to figure it out. it feels like a rev limiter . put a fuel pressure gauge on it and it, was at 50psi till it hit the wall and dropped to 40psi at 5k as it fell on its face.

[Paulie]

What are your plugs gapped at? Could be spark blowout.

[88mustanggt]

Wouldn't it go rich instead of lean with spark blow out? And it's been along time sense they were put in I'm not 100% sure , guess I should pull a plug and check. Dam p heads..

[cgrey8]

Wouldn't it go rich instead of lean with spark blow out? And it's been along time sense they were put in I'm not 100% sure , guess I should pull a plug and check...

Any time you have a misfire of any kind where the fuel didn't get combusted correctly or at all, the sensors will see that as a lean condition purely due to the presence of unburned oxygen in the exhaust despite what the actual AFR was in the cylinder.

I doubt this is it, but looking in your tune, FN367 is misconfigured. Top value is 15.0. It should be absolute max value. Put in say 100 and BE will adjust the value to the max possible value.

I didn't see anything else doing a VERY quick once-over of the tune. My guess is going to be fuel pump, fuel lines, or injectors not able to keep up. I didn't have time to look at the datalog.

[88mustanggt]

pulled a plug it was at .30 any suggestions? I was leaning to fuel injectors but don't want to blindly start buying parts.

[cgrey8]

Confirm your injectors aren't maxing out. You can do that from the datalog. Just see if the Injector Duty Cycle is anywhere near 100%. If they are, then there's one problem. If they are going 100% right as you are going lean, that's most likely the problem.

If injector PWs don't look suspect, then check fuel pressure. Setup a pressure gauge so you can see it while driving. Then take it out and make it happen. See if fuel pressure is holding steady as the cutout begins. If you see it dropping at or just before the loss of power, then the fuel pump/fuel lines are not up to the task.

If it's neither of those, then you can at least eliminate them as possible suspects.

[2Shaker]

Is he pegging the MAF?

[88mustanggt]

they arnt to 100 % but they have been in the mid 80% I did post a datalog.

I did set up a pressure gauge as per 1st post. and fuel pressure drops from 50 to 40 as the issue happens.

I have a 255lph in take, and stock everything else beside fpr and injectors (42lbs) . I would find it hard to believe that I am taxing the rest of the fuel system?

should I try around .025 gap ? is the factory ignition system going to be an issue at any point?

[decipha]

fuel pressure drops from 50 to 40 as the issue happens.

I didnt bother to look over the logs or the rest of the thread for that matter but based on this alone you have a fuel supply issue

also, with an injector duty cycle of 80% or more you should really consider larger injectors

[cgrey8]

I didnt bother to look over the logs or the rest of the thread for that matter but based on this alone you have a fuel supply issue

also, with an injector duty cycle of 80% or more you should really consider larger injectors

Ditto...

[88mustanggt]

would It be injectors and pump? or is this where new lines come into play as well? I didn't think I was that close to the limit of the stock system with a 255 in tank

[Paulie]

The highest injector duty cycle I see in your log is 85%. While you don't have much reserve left, the injectors are probably not the problem. If your fuel pressure is dropping from 50psi to 40psi when this is happening you could have a fuel pump issue. But if you are losing boost at the same point that could also cause the drop in fuel pressure.

[88mustanggt]

boost wasn't dropping, just fuel pressure. shouldn't a 255 be enough for my combo? any recommendations

[Paulie]

boost wasn't dropping, just fuel pressure. shouldn't a 255 be enough for my combo? any recommendations

Not necessarily. How old is the fuel filter? How old is the pump? What brand? Is it a genuine Walbro? Its possible you have a voltage drop and the pump doesn't have enough voltage to work properly. The hose between the pump and the hanger could be leaking. A 255lph may not be enough, every combo is different.

[decipha]

255*2.8=714 rwhp N/A and *0.8= 571rwhp boosted

all from the pre tune info

http://info.efidynotuning.com/pre.htm

[cgrey8]

Perhaps you explain this further in your link but what you posted up for a formula doesn't take into account the drop in flowrate of a fuel pump as the fuel pressure goes up. At 40PSI, a fuel pump rated for 255lph might deliver somewhere around that. But under boosted conditions and/or applications where an adjustable FPR has the fuel pressure raised above stock, the actual flowrate of the pump will likely be less than rated assuming the rated value is accurate. Here's an example Walbro in-line 255lph pump flow curve.

The chart is in gph, not lph, but you can do the conversion easy enough. However just save people a little time, here's some conversions:
255 lph = 67.4 gph
240 lph = 63.4 gph
220 lph = 58.1 gph

I don't know if this is the problem he's having...just something I thought worth mentioning since it's an easy thing to overlook if really high boost pressures are involved.

[jchambers]

In ten years of doing dyno tuning I have never seen a single 255lph pump even come close to 571RWHP in a boosted application. I establish expectations for a 255lph pump application to 380RWHP in a mildly boosted application, 420 RWHP if a boost-a-pump is used. I know what the math says, but real world environment has way more variables in play. LIke cgrey had shown, pressure and voltage alone have a tremendous impact on the pump output.

[88mustanggt]

thanks for the help, I did change spark plus and reduced the gap a little, it will go above 5k now, however I now know that I have a fuel issue up top even if it wasn't causing my issue. so time to figure out what to shove in the tank.

[decipha]

In ten years of doing dyno tuning I have never seen a single 255lph pump even come close to 571RWHP in a boosted application. I establish expectations for a 255lph pump application to 380RWHP in a mildly boosted application, 420 RWHP if a boost-a-pump is used. I know what the math says, but real world environment has way more variables in play. LIke cgrey had shown, pressure and voltage alone have a tremendous impact on the pump output.

that sounds about right for returnless pumps, Ive taken a single in tank 255 return style pump to 550rwhp boosted before, I usually upgrade at that point but have done so numerous times with no probs

[EDS50]

Leave the 255 in the tank and install an inline pump such as a t-rex or gs392 and problem solved; As long as its tuned properly and your not pegging your meter or experiencing some other mechanically or electrically related issue.

[88mustanggt]

sounds good, cause I think I have one on the shelf!!

[EDS50]

sounds good, cause I think I have one on the shelf!!

Awesome. Let us know how it works out.