I thought i'd start a fresh thread about this in the hopes it will become a point of reference for new members instead of burying it in my rotated kit build thread. For those of you experiencing the fuel related lean / stumble between 2000 & 3000rpm's what have you done to solve the issue? Option 1: Add 20-30cm of fuel line to the FPR return to add "cushion" for the pulses and resonant pressure waves that occur. Option 2: Replace stock FPR with 07 and older one that doesn't have built in dampeners. Most also add some extra fuel line as well for further cushioning. Option 3: Replace stock fuel rails AND stock FPR and convert routing to parallel from series. There is a kit for replacing the stock FPR with the older ones: http://www.iaperformance.com/product_info.php?products_id=3155 However this method has not worked for everyone, and just like the "add some hose" method, when jumping to bigger then stock injectors and a larger fuel pump you end up seeing the issue resurface. Option 3 seems to be the obvious fix, and to anyone running big power or exotic fuels this is the standard choice anyway. However, not all fuel rail kits are configured to run in parallel. The Perrin rails are an example of ones that ARE setup for parallel. What would be a good solution for someone in my case who is jumping to a rotated setup, installing Bosch 1000cc injectors and a 340lph fuel pump (also converting to speed density)? Should I replace my rails & FPR, or is that overkill? I currently have the stumble REALLY bad on stage 2 with the stock fuel system. I can't imagine this getting magnified any further and it being safe.
I felt this the other day and was thinking I bet it was a result of the stock tune. So this "stumble" is a result of physical design and not the tune? Interesting...
http://www.vividracing.com/catalog/...t=62651&ph=1&gclid=CPa1jOWYv7sCFUyu4godmgYAFw Any difference besides 345$?
1. I would never buy ANYTHING from vivid racing. THey screwed over a bunch of customers in the past and has a really bad rep in the subaru world. 2. That setup looks like the stock FPR bolts onto the distribution block? WTH?
Agency Power stuff SUCKS. I personally watched a AP fuel rail leak in the middle of the line and it was new. JUNK! Yeah you are going to regret this build down the road. I've seen too many people fall into it....myself included.
Ok first of all this thread (like all my threads) is intended to help others who might be searching our forum. Second, enough with all the negativity and pessimism! If you don't have anything good to say, don't say nuthin! So you spent a lot of money at one point and regret it, we all have regrets, that's what reddit is for. Anyway I wonder if this would just be suffice? Didn't doug use stock rails and stuff for his two STI's that made good power? http://www.iaperformance.com/product_info.php?products_id=3155
I wasnt trying to be negative...I was just letting you know that Vivid is not a company you should deal with....I believe the AP brand is their in-house brand. I dont think anyone is being negative....just giving you our experiences. Take for what it is....we are trying to help others learn from our mistakes.
http://www.iwsti.com/forums/ecu-tun...lution-gr-stumble-2400-3000-rpm-using-ap.html Some guys just use exorbitant tuning strategies to "fix" this problem using compensation values. This is how Subaru handles it in the stock tune as well.
Yeah Vivid / Agency Power is out for sure at this point. By being negative, I meant trying to tell someone they are going to regret building their car. I would equate that to the "I just got my brand new STI!!!" threads where the first 5 posts are folks saying "good luck with those ringlands" or "hope you don't need to use the warranty" etc etc.... it's just depressing is all. I'm pumped, about the challenges, the successes, the POWER, all of it. I don't tend to use the word regret in my vocabulary, EVERYTHING happens for a reason and offers tremendous benefit in some way or another, if not for you, for someone else who was watching / listening or reading. BACK OT: 200$ seems like a lot for a replacement FPR and some lines... it would be tough to justify that if it wasn't a big improvement.
Not to mention they've repeatedly ripped off products from reputable vendors such as Nameless and Kartboy.
lol that's good stuff, explains the cheap price too. the MSI kit looks solid I have just never heard anyone mention it before in a build or speak any feedback on it. Uses the stock FPR as well.
I know the stock rails can handle plenty of flow, so I wouldn't replace them just for the heck of it, and you can configure the stock rails to flow in parallel versus series, it's just that some report issues even after replacing the FPR and also switching the flow method. Their only solution was upgrading the rails at that point to resolve it.
I think James is right here. We should have posts like this and they should be civil. Nothing was really "negative" in my opinion, but a couple of the posts were definitely unneccessary.
Honestly none of these kits are magical by any means. They are just rails, fuel lines, distribution block, fittings, and adapters. I thought I could make a kit myself for cheaper than a kit but in the end, I spent just as much piecing one together than what a kit would of cost me.
Yeah I only plan to run 93octane in my car, so I doubt I really need any of this but the point of this thread really is to try and narrow down some sort of a solution for the stumble problem. Honestly it drives me crazy on the highway in 6th right now @ stage 2. I'm patiently waiting for all my parts to this build to come together so I can install and re-tune to see where we shake out. If I have to go further I will. I might get the http://www.iaperformance.com/product_info.php?products_id=3155 as a start.
Some good information from IWSTI that was compiled on the subject: http://www.iwsti.com/forums/ecu-tun...lution-gr-stumble-2400-3000-rpm-using-ap.html
Not to jack my own thread, but it's somewhat related: http://www.ultimate-racing.com/xcart/product.php?productid=217&cat=122&page=1 Is the walboro 255 enough? I just like it because the fuel basket is pre-modified and by a CNC machining process not me with a dremel.
I ended up getting the IAPerformance fuel lines which eliminate both dampeners and replace the FPR with the old style 07 FPR. This and zero'd out compensation values should give me what I want.