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Discussion Starter #1 (Edited)
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:
http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/250449-parts-needed-installing-longer-fuel-line-stock-fpr-hard-line.html

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.
 

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Discussion Starter #5
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.


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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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.
 

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Discussion Starter #7
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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Not timing, its just mods to the Load compensation tables.

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).
Timing tables may need to be modified afterwards.

Having a large load compensation (eg 20%) will cause the car to act such that it has a 20% higher load than it does for a given MAF. This not only changes fueling, but ignition as well. If you tuned your ignition map properly, with a 20% load compensation in some areas, you will need to add that 20% ignition advance back in to get the equivalent ignition timing you had before the fix.

I don't think it is critical, but it is something to consider. I doubt most people have their ignition map tuned to that level, and most may not even notice a 20% reduction in ignition timing in those areas. I'd personally advise adding some in there, however, considering how much load compensation you are removing.

I don't think any tuners are 'protecting' this info personally. I do, however, believe that most tuners would be hesitant about removing it and not touching up their tune afterwards. If you are on an open source ROM, then you are good to go.

Keep in mind, some of these values, especially if tweaked further than stock (the original fix for the GR stumbles) are quite high.

Mine are zero'd out currently. They could use some tweaking though. The resonance is still there, but its much smaller and a bit higher in the RPM range.
 

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I actually have tried what you outline here on the same theory.

Timing can definitely be added back in here, but the drivability isn't the same. Plus some people have issues with pesky FLK in this area anyways, So adding timing isnt always the best!

The reason for the huge bump in timing is to compensate for the fuel the ECU usually would be dumping in this area to compensate for the resonance issue. Once you pull the load tables back, a lot less fuel is getting injected, so the need for the timing goes with it.

From what I have experienced, the need to go back and smooth timing out in this area is on specific cars. Cars that have noisy low ends to begin with. I have worked with cars that are pretty much knock free(much like my own) and others that have annoying FLK @ 1.0 load x 2.5-3k rpms. It gets a lot better after the fuel line mod, but further smoothing is needed to get rid 98% of it.

I wasnt calling out any tuners in particular, just that I have yet to see anybody post anything about the map changes. I had limited success with the previous GR stumble fix. It worked, but not nearly as well as what we have accomplished with this mod.
 

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Timing can definitely be added back in here, but the drivability isn't the same. Plus some people have issues with pesky FLK in this area anyways, So adding timing isnt always the best!

The reason for the huge bump in timing is to compensate for the fuel the ECU usually would be dumping in this area to compensate for the resonance issue. Once you pull the load tables back, a lot less fuel is getting injected, so the need for the timing goes with it.

From what I have experienced, the need to go back and smooth timing out in this area is on specific cars.
There are two factors at play with the ignition changes (I was impacted by both, personally):
1.) The actual ignition timing change due to the calculated load difference when applying large load compensations vs none
2.) Filling in the "holes" that have been created by attempting to remove the knock due to the fueling resonance


1.) The reason for the huge bump in timing is NOT to compensate for the fuel the ECU normally dumps in. Actually, the load comp tables would traditionally PULL timing advance, since it is using a higher load calculation for a given (lower) air flow, depending on the direction of your compensation. The need for added (or reduced) timing is due to the change in CALCULATED LOAD. Adding additional fuel to a given amount of air should have minimal changes to MBT, but moving up the load spectrum by 20% will change MBT dramatically.

Considering most cars have had their ignition tables tweaked to run with +/-20% load compensation, it artificially moves the ignition table a column or two to the right. Removing that 20% load compensation will most definitely change the effective ignition timing per MAFV (actual air flow).


2.)To make it worse, most people will pull timing in a zone to attempt to correct the "pesky knock" you were speaking of with the fueling issue. If it was as my experience, you had to reduce timing a LOT (well under MBT) to get the pesky "knock" to go away. When the resonance is corrected, most of that knock is removed in my experience, and you can run proper timing. I believe if anything, this would cause your drive ability issues more so than anything.

It's like a gopher going through a golf course... gotta fill in the tunnels afterwards =P


In the end, it's worth noting that this is all part of the cruising area of the map. If anything, you want your timing to be spot on MBT in that region. Without really spending some time getting MBT in that area, you'll be down on responsiveness, you'll be cruising at a higher throttle/load area, and you'll lose a good chunk of whatever mpg our cars have. Just my $0.02 that have taken me a substantial effort to learn.
 

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I guess there really are more then two things going on here. Because they are some cars that like you said, when you fix the fueling issue, the low load knock goes away completely. But with others there is still some of it that needs to be smoothed out.

For a small portion of the cruise map, the load bump does increase timing ( much lower rpms) but in the higher rpms 2.5k-3.2k there is like you said the timing being pulled. Now in between the two islands of the LC maps, you can get into a weird grey area(switching between negatives and positives). I have had the most issue with OL transition.

But what I was referencing in my post was a car that the fuel line mod certainly reduced low load knocking by a quantifiable amount. Timing still was needed to be reduced in certain areas for CL/OL transition areas. Like you said, because the mod is done and LC tables are reduced, the car is now running more timing, for a given lower load but at a higher cruising RPM. For the most part we are talking 1.0ish load in higher rpms then I would normally cruise in. 2.8-3.5k. I however, wouldnt be running MBT in these areas for smoothness purposes(I dont have a dyno so I couldnt actually verify MBT in these regions anyways).

You are right that I did get the LC part mixed up(in terms of reducing timing). To be honest I was mixing up info related with DAVCS and the Load compensation stuff. As I have had a fun time making it all work together!

Back to the original point though, What i was trying to reference, is that not all cars will need their timing looked at. Any tuner should be doing good logging after this mod to make sure no additional work is needed. On my car, non was needed. On 1 of my customers cars it was, on the other it wasnt.

I always speculated that the LC tables caused the ecu to go OL more, which increased fueling, but like you said in some areas its reducing timing, and it others its adding it. By drivability issues, I more meant in terms of smoothness. When I tried to run more of the low load cruise areas closer to MBT the car felt peppy(er), but didnt feel any where near as smooth. Its all a balancing act!
 

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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.




you talking about timing and Load compensation tables?
I don't plan to get an AP until next year. What are the drawbacks from running the mod without modifying those tables, other than running a bit rich?
 

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Just to be 100% clear, every cell in both tables is .2 of it's value?
i.e. the -3.5 becomes a -.7 applied on every cell?
Yeah, it sounds scary and looks crazy while you are changing the table, but you are correct.

Also, I found that taking a cheap pen cap and cutting off the closed end and cutting it open lengthwise made the perfect connecter removal tool.
 

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Yeah, it sounds scary and looks crazy while you are changing the table, but you are correct.
I'm fine with changing the table, just like to be 100% on what the result is supposed to be. :)
Going to try this, see how it works. I've had the stumble since day 1 and none of the previous solutions seemed to be 100% so I never bothered replacing FPR, dampener etc.
 
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