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Fuel Line Extension / Stumble Fix Mod
Fuel Line Extension / Stumble Fix Mod
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Old 02-22-13, 01:17 PM   #1
tweeked
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Default Fuel Line Extension / Stumble Fix Mod

Disclaimer: I will not be held liable for any damage that you do to your car while working on it. You do this mod at your own risk.

Original Thread is here:
Parts needed for installing longer fuel line from stock FPR to hard line?

But I decided to consolidate it all into a nice DIY.

After I did this mod, I noticed that my car ran smoother. For some people, its a night and day difference, others, maybe a bit less.

See End for Tune Modification recommended instructions

Time: 15-20 min
Tools Needed
-Flat head
-Phillips head
-Fuse Puller
-2 Large zipties, or cut one into two pieces
-Blow dryer

Parts Needed (cost me $3 for everything)
-a couple zipties
-2 5/16" Fuel INJECTOR Hose Clamps
-3ft 5/16" Fuel INJECTOR Hose (must be multi-fuel compatible and handle at least 200psi)




STEPS
1. Locate the fuse box under the hood and pull the Fuel Pump Fuse.





2. Crank the Car to use up fuel in the lines. (car may start and then eventually die, crank it a bit more to be safe)

3. Using the Philips, unscrew the clamp by the Fuel Pressure Regulator (FPR). and pull the hose off.
note: BE PREPARED FOR FUEL TO SPEW OUT for a few seconds. keep face away.




4. Using the 2 zip ties, find the two tabs (180degrees apart) on the inside of yellow/green quick connector, and push the flat part of the zip ties in to raise the tabs.
5. Pull the hose + quick connector out (yellow/green slides out with it)

tabs shown here


Ziptie tie configuration shown here


5. Make sure there's no foreign debris in the new hose.
6. Using the blow dryer to heat up the hose, push the New 5/16" hose tube over the bump (PITA)
note: caution not to damage the hard line.
7. Slide and tighten one clamp over the hump, and one right before the hump as shown here:




8. Route and ziptie the hose however you want and use the OEM clamp to tighten the other end to the FPR side. (you can use a new clamp if you really want)




9. Put the fuel pump fuse back in.
10. Apply the modified tune (preferable), or just reset the ECU. (won't reap the full benefits)
11. Turn Key, Let the car prime. And start the engine.
note: check for leaks while priming and after engine is on.


Drive cautiously and log at first to see how your car handles the change.


Tune Modification (thanks endrswrd and Heide264)
Adjust your Engine Load Compensation Cruise (MP) and Non-Cruise (MP) tables.
1. Change every value to 20% (multiply by 0.20)
2. Zero out all the values besides the “stumble areas” (keep them at their 20% value)
3. You can smooth transitions out more if you want.
note: Cobb AP users / ATR users- the tables you will mod are slightly different. They have two less rows at the top, and they start @ 1k rpms vs 650 for the romraider tables. But the mod can be done in a similar fashion
4. If your tuner put any "holes" in the ignition table to help eliminate knock during your protune, you can smooth them back out now after the fuel line mod.

Last edited by tweeked; 01-06-15 at 11:10 AM.
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Old 02-23-13, 10:22 AM   #2
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Default Re: Fuel Line Extension / Stumble Fix Mod

Thanks for making the DIY from the other thread!
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Old 02-27-13, 09:43 AM   #3
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Default Re: Fuel Line Extension / Stumble Fix Mod

Could I do this on a bone stock car that has the stumble?
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Old 02-27-13, 09:53 AM   #4
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Default Re: Fuel Line Extension / Stumble Fix Mod

Yes you can, but the most benefit comes from modifying two tables in the tune.
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Old 02-27-13, 09:54 AM   #5
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Default Re: Fuel Line Extension / Stumble Fix Mod

Yea you could, but I'd probably at least get an Accessport and Email cobb for a modified OTS tune. Email them first asking if they'd do that for you.


Quote:
Originally Posted by endrswrd View Post
Yes you can, but the most benefit comes from modifying two tables in the tune.
you talking about timing and Load compensation tables?
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Old 02-27-13, 10:07 AM   #6
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Default Re: Fuel Line Extension / Stumble Fix Mod

Not timing, its just mods to the Load compensation tables.



This shows what you should change.

You cut the entire table to 20% its original value, and then zero out the areas around the two little islands.

Some tuners out there may be protecting this info, but, this is what it looks like. Timing tables have nothing to do with it, at least, in the 3 GRs I have tuned that have the fuel line mod timing wasnt touched(for the fuel line mod).

Also, you could probably smooth things out, but with these numbers being so small the amount of correction applied from these maps is much smaller then in its oem form.

Please also note that Cobb AP users / ATR users the tables you will mod are slightly different. They have two less rows at the top, they start @ 1k rpms vs 650 for the romraider tables. But the mod can be done in a similar fashion.

Last edited by endrswrd; 02-27-13 at 10:16 AM.
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Old 02-27-13, 10:44 AM   #7
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Default Re: Fuel Line Extension / Stumble Fix Mod

Quote:
Originally Posted by endrswrd View Post
Not timing, its just mods to the Load compensation tables.

Image Link


This shows what you should change.

You cut the entire table to 20% its original value, and then zero out the areas around the two little islands.

Some tuners out there may be protecting this info, but, this is what it looks like. Timing tables have nothing to do with it, at least, in the 3 GRs I have tuned that have the fuel line mod timing wasnt touched(for the fuel line mod).

Also, you could probably smooth things out, but with these numbers being so small the amount of correction applied from these maps is much smaller then in its oem form.

Please also note that Cobb AP users / ATR users the tables you will mod are slightly different. They have two less rows at the top, they start @ 1k rpms vs 650 for the romraider tables. But the mod can be done in a similar fashion.

Thanks ^very straightforward the way you explain it.
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Old 02-28-13, 08:22 AM   #8
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Default Re: Fuel Line Extension / Stumble Fix Mod

Just out of curiosity why do you have to tune for this. It looks like a simple hose replacement?
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Old 02-28-13, 08:25 AM   #9
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Default Re: Fuel Line Extension / Stumble Fix Mod

Quote:
Originally Posted by myblusti View Post
Just out of curiosity why do you have to tune for this. It looks like a simple hose replacement?
With the stumble gone the LC tables will cause the car to inject more fuel than is needed. The LC tables are there to try and compensate for the stumble.
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Old 02-28-13, 08:51 AM   #10
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Default Re: Fuel Line Extension / Stumble Fix Mod

Quote:
Originally Posted by Sabrewings View Post
With the stumble gone the LC tables will cause the car to inject more fuel than is needed. The LC tables are there to try and compensate for the stumble.

Bingo!
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