Tuning Help Need, Dyno Results Inside

[Formula51]

Just got back from the dyno and my car is falling flat on its face after 6,000rpm. My tuner was a little stumped so hopefully yall can help give some suggestions or things to check.

Details:
2003 Cobra with 57,000 miles, daily driven for past several years and in excellent condition
2.3L Whipple with 3.25" pulley
Ford GT fuel pumps and 60# injectors
Single modified FPDM
BA2400 MAF
Stock manifolds and stock catted h-pipe with Magnaflow catback
Steeda cold air with K&N filter, stock intake tube and throttle body
NGK TR6 plugs gaped at 0.027, fresh plugs and we checked them after the pull and they were all clean

From the dyno pull:
Timing at 17 degrees
Made between 15 and 15.5 pounds of boost throughout the pull
Air/fuel stayed steady at 11:1 all the way until we shut it down
Fuel duty did max out at about 5,600rpm (flat lined at 0.499 on data logger) but A/F stayed solid at 11:1 and fuel pressure stayed pretty consistent
Engine is smooth and makes no unusual noises or valve train noise of any kind

Here is the graph:


Unfortunately, the SCT tuner the previous owner gave me is locked to another car so we were unable to make any changes (I will mail it in and get it unlocked for the next tuning session). Regardless, my tuner was a little stumped since everything checked out pretty good on the data logger. He did not suspect a fuel issue because of the A/F readings or spark blowout because it never got choppy. Everything looks nice and clean until it just falls flat on its face past 6,000rpm. One thought he had was that possibly the cats are melted/broken and chocking off the car up top, but he wasn't real convinced of that. I do have an off-road X-pipe in the garage I can put on to rule that out though.

I would appreciate your thoughts on what to check, change or look for when I go back.

Regards,
Eddie

 

[Weather Man]

Get your fuel supply issue fixed.

 

[Formula51]

Is it an issue? Tuner says it is not since the A/F is steady at 11:1 all the way to shutdown.

 

[Weather Man]

If you are maxed at 5,600 rpm, it is an issue.

Talk to another tuner, can't believe he would say that. Think about it, a/f stayed even with power taking a dump.

 

[Formula51]

If you were starved of fuel, wouldn't the A/F go lean?

 

[Weather Man]

If you were starved of fuel, wouldn't the A/F go lean?

Not if the power produced dropped.

 

[racebronco2]

I am not tuner but i have read once the pumps are maxed out the ecu lowers the base fuel pressure to help save the engine from going lean. Did the tuner datalog fuel pressure?

 

[Weather Man]

Some guys, if the fuel maxes a couple hundred rpm before set redline and a/f stays good, will run that way. You are a long way from a couple hundred rpm.

 

[Formula51]

Some guys, if the fuel maxes a couple hundred rpm before set redline and a/f stays good, will run that way. You are a long way from a couple hundred rpm.

Yes, it started dipping a little around 5600rpm for a few hundred rpm and then came back up to normal levels the rest of the way.

Would it be normal to need a BAP along with the Ford GT fuel pumps with my relatively mild setup?

 

[Formula51]

Since I wasn't able to see the tune in the car due to the wrong handheld, is it possible the tune has a spark or fuel cutoff set at 6000rpm as a safety measure? Would that explain the results?

 

[Weather Man]

Spending a little money to consult with one of the remote tuners on here would be a wise investment. Cheaper than a engine by a long shot.

 

[01yellercobra]

When the pumps are maxed out the ECU will keep the injectors open longer to make up for it. So then you start maxing out your injectors. Not a place you want to be. You need to fix your fuel system. I ran the GT pumps up to around 600hp with just a wire upgrade. But that was with a centri set up. I'd log fuel pressure drop across the injectors and see what it's doing.

 

[Brutal Metal]

If you were starved of fuel, wouldn't the A/F go lean?

Actually no because you can manipulate the injector to keep that steady A/F while the fuel pump duty cycle is maxed, ask me how I know? Once you approach the 550 range your on the ragged edge with the Twin GT pumps without a Bap. Op I'd do a wire upgrade from the battery back to the trunk and a 40 amp BAP ALSO did you replace your stock fpdm with a single modded? If not the stocker could be going in and out of thermal shutdown and through time will burn out from the increased current of the GT pumps versus oem's..

 

[Formula51]

This is all great stuff guys, thank you.

Actually no because you can manipulate the injector to keep that steady A/F while the fuel pump duty cycle is maxed, ask me how I know? Once you approach the 550 range your on the ragged edge with the Twin GT pumps without a Bap. Op I'd do a wire upgrade from the battery back to the trunk and a 40 amp BAP ALSO did you replace your stock fpdm with a single modded? If not the stocker could be going in and out of thermal shutdown and through time will burn out from the increased current of the GT pumps versus oem's..

I bought the car the way it is currently, so I have some questions.

1. Can you provide some details of the wire upgrade you mentioned? I may already have it, but I need to know what I am looking for.

2. The wiring is there for the BAP (I found the wire with two pig tails in the engine bay but they were not connected to anything, where do they go?). I also found the other end of the wires in the trunk, with the end taped with electrical tape. I did not physically put my eyes on the BAP itself, but I will take a look and confirm it is there. I am ASSUMING the previous owner was running a BAP before the Twin GT pumps were installed and did not hook up the BAP back up after the install. It sounds like I need to hook it up.

3. How can I check if the fpdm was replaced with a single modded one? *edit* All I can find on a search is that the heat sink will be visually bigger. Anyone have a picture of what the bigger heat sink looks like compared to the stock one? Also, if the FPDM was going in and out of thermal shutdown, I would think the dyno graph would have been choppy, which it was not.

I will do some searches on the forums, but any help is appreciated.

 

[Nightmare302]

A wire upgrade would be a large typically 8 ga wire that runs from the fuse box back to the trunk to the FPDM.

 

[Formula51]

Another thought. The previous owner thinks the car may have the rev limiter set at 6,000rpm to be safe. Would that explain the dyno results? During the pull, I never heard the traditional "bap, bap, bap" sound I am used to when a car hits a rev limiter.

 

[Nightmare302]

You need to data log rather than guess. I'd log MAF counts to check to see if the engine is ingesting more air or not and I would log cycle duty on my pump, injectors along with pressure drop and fuel pressure. That will give you a good indication of what is going on. It sounds to me like it's a fueling issue but the only way to know for sure is to get some data.

 

[Formula51]

The tuner did log data. The fpdc maxed out (flat lined) starting at about 5600rpm. Now I need to figure out why. Fuel pressure dipped some (nothing dangerous according to tuner) for a few hundred rpm starting at the same 5600rpm but then came back up and was choppy, even spiked once to max. I did not see MAF counts (he may have looked at them without me). Honestly, I am not even sure what MAF is on the car. Sounds like I have lots of things to check. I will take a look and report what I find. I will also see if I can get the log file.

 

[Posi]

OP I ran your fuel system up to 660hp and still had some room left…of course with a BA2400 mass air meter and a single modified FPDM along with it.

Twin GT pumps in a modified stock hat with 60lb injectors, stock rails, and lines too.

 

[Brutal Metal]

OP I ran your fuel system up to 660hp and still had some room left…of course with a BA2400 mass air meter and a single modified FPDM along with it.

Twin GT pumps in a modified stock hat with 60lb injectors, stock rails, and lines too.

Brian one thing to consider if his stock hat still has the pprv supporting 660 will be very difficult, yours was removed right? The fuel has to go through that pinhole..