oncesir

Thats a great way to describe it. I'm extremely picky about the running condition of my cars and the stumble is like having an unresolved problem. Aside from that I love the car. Its fun, handles decently and has never left me. Its had its usual 4th gen issues but thats more just repairs based on age. I will say that after adding the 3 ft of inlet hose to the fuel line that the stumble is still relatively minimal. It comes and goes but is definitely less than it was before. Maybe Ill add a fuel pressure gauge on the inlet side and see if that helps. Before this is all said and done Ill have 50 different fuel dampers, gauges and other BS in that 3 ft of hose just to remedy this one issue.

I posted several pages back about my fuel setup on my etuned stg2 LGT. Sti FPR, BOV reference line for FPR and slightly longer fuel hoses. Ive had the stumble for quite awhile since I last posted. None of the above took care of it completely. Im at the point where Im looking for answers and found this on one of the romraider forums. http://www.romraider.com/forum/viewtopic.php?f=15&t=4911&hilit=stumble&start=285 Recently I added more hose (3ft) to the inlet side of the fuel rail fitting and reset the ecu. It was much smoother after the reset but I can tell its relearning the stumble again after only a few miles. I know M Sprank talked about blocking out the learning capabilities of the ecu for that area of the tune. Has anyone ran a t-style fitting on the inlet hose to stop the water hammer effect? Am I understanding the cause of the stumble correctly??? TIA One other question. Im not sure if this is just me or what but I also feel that different brand fuels cause the stumble to be more or less pronounced. Am I crazy? Lol

Installed the Sti FPR and reset the ecu about a week ago. Ive been driving around hoping that the stumble didnt return and so far so good. Sending logs to Dave @ Cryotune shortly and will report back. Overall the car feels so much smoother at the usual stumble rpm of 2500-3000. I did notice that the Sti FPR is a bit noisey on startup for some reason. It goes away once the engine is revved fwiw. Not concerned about a bit of noise for smooth driveability though. One thing I noticed and experimented with was that after I installed the Sti FPR I didnt reset the ecu. The stumble was still noticeable. After resetting everything the car has actually gotten smoother as I have put miles on it. Granted, there is a small stumble from time to time but this is a Subaru after all... Overall I'm happy with things. A huge thanks to all those involved in this thread.

Nope. Stumble is still there. Gonna try the Sti FPR and see how it does. Ill update shortly.

The car was etuned by Cryotune last yr. I decided I'm going to put some miles on the reset Ecu and see what happens. I'll report back shortly. Thanks guys.

Took your advice and ran a plenum source for the fpr. I didn't reset the Ecu and went for a drive. Immediately I noticed less of the stumble. How do you stop the Ecu from relearning the stumble? I have the sti fpr right next to me and it's tempting to install just for simplicity sake. TIA

After installing the lines and resetting the ecu the car ran much smoother. Unfortunately the stumble came back after a few months of driving. I ordered an STi FPR and will report back my results.

Honestly I'm not sure. I extended the top hose on the manifold. I planned to experiment first to see what worked and then trim my 3ft of hose. Lol

I extended the supply line about 3 ft and the hesitation is almost completely gone. I'll add length to the return next and see what the results are. I have not changed the regulator setup. Total spent so far is less than $25.

I'm in the process of tuning with cryotune and have this same stumble. How long do you make the new fuel lines? Do you extend both of the lines that connect to the manifold or just the supply hose? I also read that if you use a bigger size hose you won't need to use a longer hose? Any truth to that? TIA Sent from my LG-D850 using Tapatalk

Interested in H&R Springs for a 4th Gen. Message me if you have some for sale.

WTB: LGT wagon/sedan mufflers. Need asap to pass inspection. Text 6185312151. Can pick up or will pay to ship if necessary.

Willards, MD 98 Legacy GT 5spd Black w/ 05 WRX wheels