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post #1 of 10 Old May 15th, 2019, 11:04 AM Thread Starter
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Stutter between shifts

Good morning everyone, I've had my 2004 Cobra for a few years and and finally started to decide to dig into her. I just put on a 2.7 upper, Accufab throttle body and inlet body, AFCO heat exchanger with dual fans, 80lb fuel injectors, dyno'd and tuned. The stock Eaton is not ported. She is putting out around 480 490 hp and 500lb torque. The issue I'm having is the car stutters as if it's not getting enough fuel between shifts. It's super annoying and I'm totally regretting messing with her. So I'm not sure if this is an issue with the tune, if I'm requiring a BAP with this setup or what the issue is. I have looked around some forums with people having similar issues stating that it may be the PPRV or that I need to upgrade the fuel lines. Any thoughts?
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post #2 of 10 Old May 15th, 2019, 11:52 AM
Hans Sprungfeld
 
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The PPRV delete is a pretty common mod to try and remedy this. I'm running it myself, but I didn't notice a big hesitation during shifts to begin with.
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post #3 of 10 Old May 15th, 2019, 02:14 PM Thread Starter
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Are you running with similar mods?
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post #4 of 10 Old May 15th, 2019, 02:59 PM
Hans Sprungfeld
 
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I was. Ported Eaton, 2.76 upper, FR500 cams, 60lb/hr injectors. I went to the PPRV delete pretty early on.
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post #5 of 10 Old May 15th, 2019, 04:27 PM Thread Starter
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So maybe going with the 80lb fuel injectors is what's causing the issue. Now I'm having issues with the car overheating. Wish I never would have started modding the car.

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post #6 of 10 Old May 15th, 2019, 08:22 PM
Hans Sprungfeld
 
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I highly doubt that it's the injectors. If anything I would think the PPRV would be a very possible cause. A quick search will turn up tons of results.

If you go the PPRV delete route I'll key you in on a little trick I saw and used; use a stainless U-bend fitting in the hose to prevent it from kinking.

The overheating could possibly an air pocket. Those engines are a bitch to deaerate with their cooling setup. It's another thing I improved and have been thoroughly pleased with.
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post #7 of 10 Old May 15th, 2019, 09:41 PM Thread Starter
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Thanks for the tip!! Any cooling system upgrade in particular? I burped the car earlier today so hopefully I wont have any more issues until I get something new in.

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post #8 of 10 Old May 20th, 2019, 08:14 AM
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Update to the hesitation suggestion. I was reading through the LaSota tuning book and noticed a section on Cobra hesitation. He recommended two things before doing the PPRV delete:
1.) Change maximum MAP counts to 1023.
2.) Change the maximum fuel pressure clip to base pressure + maximum boost + margin. If you're running a 2.76 pulley/15psi, that would be 39+15+10 = 64psi.

On to the cooling section. I changed a lot of routing, ensured I had properly routed vent hoses, a downflow radiator helped a lot, relocated the thermostat, and did the correct fill procedure. I also welded a large nut to the crossover plug to make it easier to open, because it can be a bitch with that 1/4" square drive to get enough torque.

For the most part, it comes down to fill procedure. Do as the Ford manual says. Park it with the nose slightly up. Open both the crossover and surge tank. Fill from the crossover nice and slow until you get to the full line on the surge tank. Close the surge tank. Continue filling until it comes up to the crossover.

Now here's where I deviate. The manual says to stick a long funnel in the crossover and keep some liquid in there for when it drops. I've tried that and you know what happens? As soon as it warms up, the pressure is too high and the coolant rises. You could make it work if you had a column of coolant that was tall enough and a funnel that was wide enough to slow it down. Mine deaerates so well I just close the crossover, run it until it gets warm (heater on full blast), shut it off, let it cool down, and then top it off, and I'm good to go. With the stock configuration that may take a few times. If you've got the stock setup, get one of those big ass fill/dearation funnels and give it a try that way.

With the thermostat my biggest gripe was that it didn't open when it should because it was located down low. The engine was getting up around 225 deg F before it was cracking open. Low mount thermostats are better for a steady coolant in temperature, especially for aluminum blocks, but it doesn't control temperature as well based on coolant outlet. But that's another discussion altogether.
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post #9 of 10 Old May 23rd, 2019, 08:39 PM Thread Starter
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Alright i'll give it a try and let you know what comes of it. Thanks

2013 Fusion SE
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1999 Mustang "Project Judgement Day"
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post #10 of 10 Old May 31st, 2019, 10:13 AM Thread Starter
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Alright so it turns out the issue shifting was the Throttle position system. The issue with the coolant was simply the cap. Replaced the cap and havent had any issues. Now, onto the next mod 😁😁. Thanks for the help

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