Fuel system problems - injector and fuel pump duty cycle

[HPLouis]

Hi,
For the back story, I bought this car in June 2018. I'm the third owner. The original owner had the car from 1/2004 through 4/2015 and it was garaged in NJ. From 2004 through 2010, they put 5,400 miles on it. The second owner bought it in 2015 with 10K miles on it. From 2015 through 2018, the second owner (also in NJ) put an additional 4.5K miles on it during his 3 years of ownership. This is also when the mods started. The second owner put on a Mac Prochamber, upgraded radio headunit, amp and speakers, Borla ATAK catback, Billetflow 2.76 pulley with LFP Aux idler and pullies, NGK TR6's gapped at .028, JLT Ram Air Intake, LED headlights and foglights, Varroensteon 18 inch rims and tires and mail order SCT tune from JDM out in NJ. He also put on a NMB WOT Box but removed that before sale.
I bought the car in June 2018 with 14.5K miles on it. I replaced the Mac Prochamber with a MRT catted H and the ATAKs with S-Types. I put the stock headlamps, foglamps, Ford Mach radio headunit, amp and speakers back on. I tried to put the car back to stock since he gave me the stock parts and I like to start from stock when it comes to mods so I could know what's going on with the car. I got the base tune from JDM so I could use it with my Pro Racer Package. I didn’t do much with the tune besides turning on the rear O2 sensors and adding 2 more degrees of timing up top.

 

[HPLouis]

Using the Livelink software, I started datalogging the car:

These numbers are from August of 2018:
For the stock pulley, I was at
Fuel Pump Duty Cycle = 86
Injector Duty Cycle = 81

For a 3.1 pulley, I was at
Fuel Pump Duty Cycle = 90
Injector Duty Cycle = 91

For a 2.93 pulley, I was at
Fuel Pump Duty Cycle = 90
Injector Duty Cycle = 98

For a 2.76 pulley, I was at
Fuel Pump Duty Cycle = 92
Injector Duty Cycle = 100

This is the thread: https://www.svtperformance.com/thre...what-fpdc-and-inj-dc-are-you-running.1163173/

I was alarmed a little at the injector and fuel pump duty cycle for the 2.93 and 2.76 pulles but after reading how some guys needed a BAP with even a 2.93 pulley, I relaxed a little bit and just drove the car around.

 

[HPLouis]

I went to the dyno in June of last year. Here's the thread: https://www.svtperformance.com/threads/not-happy-at-dyno.1161444/

Another thread with my issues: https://www.svtperformance.com/threads/maxed-out-with-2-76-pulley.1161560/

Dyno graph:
View attachment 1496612

Datalog:
View attachment 1496613

Mods at the time:
Billetflow 2.76 pulley
NGK TR-6 plugs
MRT Catted H-Pipe
Borla ATAK catback
Varrstoen ES7 rims with 265/35/18's in the front and 315/30/18's in the rear
Mail order tune from JDM (they were the original tuner)
I have the Pro Racer Package and looked over tune. Car still has stock MAF transfer function.

It still has the stock airbox and paper filter.

Fuel pump DC was 92 and injectors maxed out at 100. Car only made 406 rwhp.

Now I’m frustrated. The car only made 406 rwhp but tons of torque! Why? The timing was at 18 and I know I had the stock air box, filter and silencer but still, it should have made more. The A/F was decent too. It should have made more power.

 

[HPLouis]

Now I just came back from the dyno a couple of weeks ago: https://www.svtperformance.com/thre...no-with-questions-about-my-a-f-ratio.1175083/

This time, I have the 3.1 pulley. It only made 403 rwhp and it's still pegging the injectors and pump. Now, it still had the stock air box and silencer but 20 degrees of timing and it made 11.76lbs of boost. The torque was right there at 433 but no power and I read that for the Terminators, torque is usually within 6-10% of the range of power.

I've been reading, searching on here and the FB forums and I see people getting up to 450rwhp on the stock fuel system and 2.93 pullies. I'm guessing that there's something wrong with my fuel system. I should be making more power and I shouldn't be maxing out the injectors and the fuel pump. I changed the fuel filter and there are no codes. The car idles and drives well. I can't figure it out and I wanted to ask the group here before I take it to a shop and have them diagnose it. Thanks

 

[HPLouis]

My datalogs from last night with a 3.1 pulley, JLT RAI, MRT catted H and Borla S type catback. This is from a second gear pull to redline on the highway.

As you can see, where I was maxing out with the 2.76, now it's happening with the 3.1. The injectors are at 100% and the fuel pump is at 98%. I don't know if the fuel pumps are getting tired and old, or if there's something else going on but over the past year, the duty cycle has climbed up as I've lowered the boost. I don't get any check engine lights or anything and the fuel pressure across the injectors are staying steady. I also put a new, rebuilt, Ford alternator (bought from the Dealer) in the car because I thought the old one was going out but this new one still puts out the same volts as the old one.

Does anyone have any advice or experience with this? Thanks

 

[HPLouis]

What bothers me now is that from last year to this year, nothing's really changed and the injector and fuel pump duty cycle has climbed up. It's maxing out even more with the 3.1 pulley now than it was with the 2.76 last year. There's something going on. I don't know if it's the fuel pump on its way out, bad injector somewhere, some electrical issue, or something. My tuner said to check the fuel pump drivers and that the fuel pump should be good until 500rwhp. With the 3.1, I shouldn't be anywhere close to maxing anything out but here I am.

 

[wkornf]

fuel pump and injectors don't make horsepower. what's your air fuel ratio throughout the pull? if your still ideal air fuel ratio at Max load the pump isn't holding you back.

also what's your boost throughout the pull? does the belt slip?

peak horsepower is just ideal airfuel + timing.

Good luck!


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[HPLouis]

fuel pump and injectors don't make horsepower. what's your air fuel ratio throughout the pull? if your still ideal air fuel ratio at Max load the pump isn't holding you back.

also what's your boost throughout the pull? does the belt slip?

peak horsepower is just ideal airfuel + timing.

Good luck!


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The A/F ratio was in the 11.0-11.5 range. Then I added fuel and it went down in the 10.8-11.2 ratio throughout the pull. The dyno operator was wondering how accurate the data logging software was since, even though it showed maxed out, the A/F ratio never went lean and even richened out when we added more fuel.

The dyno operator said the fuel system can support the power the car is making but it still bothers me to see 98-100 percent duty cycle on the data logs.


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[01yellercobra]

The best thing to remember is every car is different. What works for one doesn't necessarily work for another. I had fuel system on my last Cobra that should've supported 600. It maxed out at 500. No one could figure out why. Just how the car was.

As for power being down was the car babied? I've noticed cars that are babied when broken in tend to be a little lower on power in the long run.

 

[HPLouis]

The best thing to remember is every car is different. What works for one doesn't necessarily work for another. I had fuel system on my last Cobra that should've supported 600. It maxed out at 500. No one could figure out why. Just how the car was.

As for power being down was the car babied? I've noticed cars that are babied when broken in tend to be a little lower on power in the long run.

The tuner and I are thinking that the low power was due to the stock airbox and silencer. I'm gonna re-dyno with the JLT intake and see what happens. I'm more worried about the fuel system.

 

[me32]

Did you ever get the boost a pump and wiring upgrade?

Also ever do a compression check?

 

[HPLouis]

Did you ever get the boost a pump and wiring upgrade?

Also ever do a compression check?

I made an appointment for those. Compression + leakdown first. Then a check of the fuel system and electrical. Depending on what they find, it can be an alternator upgrade, wiring upgrade, BAP or injectors. If we do the wiring, BAP, injectors, etc. then I'll just finish it off with a tune, SCT MAF and a 2.76 pulley.

 

[me32]

I made an appointment for those. Compression + leakdown first. Then a check of the fuel system and electrical. Depending on what they find, it can be an alternator upgrade, wiring upgrade, BAP or injectors. If we do the wiring, BAP, injectors, etc. then I'll just finish it off with a tune, SCT MAF and a 2.76 pulley.

Keep us updated on the test

As for the fuel system
You definitely need a bap looking at the info provided. Also the bap wiring upgrade is always recommended. Other option is bigger injectors but with and upper pulley only the bap works great.

Definitely have the alt tested. Also what battery are you using? How old is the battery?

If you do go with an aftermarket alt its always recommended to do the big 3 wiring upgrade. Even on the stock alt is never a bad idea.

 

[HPLouis]

Keep us updated on the test

As for the fuel system
You definitely need a bap looking at the info provided. Also the bap wiring upgrade is always recommended. Other option is bigger injectors but with and upper pulley only the bap works great.

Definitely have the alt tested. Also what battery are you using? How old is the battery?

If you do go with an aftermarket alt its always recommended to do the big 3 wiring upgrade. Even on the stock alt is never a bad idea.

The battery is an Optima Yellow Top and the date on it is 3/15. The old alternator was tested and passed and since I already bought the new one, I kept the old one to have rebuilt and installed the new one.

Spoke again to the tuner and he said when I bring it in, he’ll test it with Ford’s IDS. He said that even though he’s a SCT dealer, he said that the LiveLink software isn’t that accurate and he uses IDS. He said that if I was really maxing everything out, I would run lean at high rpm and the car holds onto 10.4 A/F ratio past 6600 rpms. He also said the low power reading was due to the silencer and stock airbox and he could tell because it was the same power with both the 2.76 and 3.1.

He sounds like he’ll be able to fix me right up.


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[me32]

The battery is an Optima Yellow Top and the date on it is 3/15. The old alternator was tested and passed and since I already bought the new one, I kept the old one to have rebuilt and installed the new one.

Spoke again to the tuner and he said when I bring it in, he’ll test it with Ford’s IDS. He said that even though he’s a SCT dealer, he said that the LiveLink software isn’t that accurate and he uses IDS. He said that if I was really maxing everything out, I would run lean at high rpm and the car holds onto 10.4 A/F ratio past 6600 rpms. He also said the low power reading was due to the silencer and stock airbox and he could tell because it was the same power with both the 2.76 and 3.1.

He sounds like he’ll be able to fix me right up.


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With a jlt you will start leaning out.

Its not uncommon with your mods to max out the fuel system. The stock setup did not leave alot of extra room on the terminators.

 

[HPLouis]

With a jlt you will start leaning out.

Its not uncommon with your mods to max out the fuel system. The stock setup did not leave alot of extra room on the terminators.

That’s good. The car is rich already so it could use a little leaning out. I’ll see what the dyno says.

I’m thinking the same thing you’re thinking. It looks like, for this car, I don’t have a lot of room to play with.


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[me32]

Keep us posted

 

[HPLouis]

Did you ever get the boost a pump and wiring upgrade?

Also ever do a compression check?

I just bought the tool and did the compression test myself

It looks like the motor is fine. The car is sitting in the garage and it's hot so I'm going to wait for cooler temps before I hit the dyno to check the A/F ratio.