kompressorgolf

Hello All, new member long time lurker, i got my b5 s4 about 7 months ago, got it super cheap as the 1-2 shift collar was gone so i rebuilt the trans myself with JHM's carbon synchro kit. been bomb proof ever since.

So after a few months, the car began taking a long time to start, excessive cranking, than would begin to catch and splutter into life, once running its totally fine. has just hit 120k. Car had no CEL whatsoever, when scanned anyways still showed 0 engine faults.
have vagcom but its unregistered. i replaced all the cheaper things associated, as it probably would need them sooner than later, replaced was the coolant temp sensor, engine speed sensor, fuel pump with a walbro 255, and a fuel filter. the only mods to the car are fully gutted downpipes with CELiminators. never had an 02 code from them, and the walbro. long story short it was a bad fuel pressure regulator. boom fires up great.

now it has a new issue that i cant find anything about. I fueled up to go on a road trip, about 350 miles round trip. while cruising 75 the car has a hesitation, it feels like i turned the key off and back on, the guages stay lit and working, so i dont think its ignition switch. but it literally feels like the engine stops then a second later comes back and is fine, i tried to swap out my spare set of power output stages to no avail. sometimes it does it once in a while but on the trips first leg it hiccuped badly for a while then seemed to stop, on the way home it had one small hesitation then never did it again. still no CEL whatsoever.

Once home i did a fuel pressure test, and i was running 80 psi with the vacuum pulled, and 75 with it connected, stayed perfectly it does have a walbro 255 in the tank. i believe its supposed to run in the 60 PSI range as its a 4 bar regulator. mileage seemed decent, was a hilly trip and got about 27 28MPG

One thing i noticed while doing a fuel pressure test, was one time it had a little dribble of fuel come out when i removed the line, after just pulling it in, and the other time it seemed like there was alot of air pressure excaping from the line with not much fuel spray?

Sorry it was so long, and i hope for some good replies, and thanks in advance fellas!

kompressorgolf

Edit* im thinking i may be getting spats of raw fuel from a pluged N80 valve or the tank is either pressurizing and cranking up my fuel pressure, or it may be pulling vacuum and the fuel pump is sucking air causing it to stall for a second? if thats even possible, there are no fuel smells at all, nothing out of the ordinary, i have also extensivly boost tested the system all the way up to 25 PSI with no leaks, also maybe the maf is crappin out, it is a bosch maf after all, wish i had the hitachi, when i drop the F21's on it and go stage 3 then ill have my hitachi i also forgot to mention i have twin forge 008 diverter valves on it with blue springs installed.

Also if been trying to find a vac leak, i have the PODI mechanical boost guage brand new, and it shows im only holding about 15hg vacuum, and 8PSI boost pressure, when i gutted the DP's the turbos were super tight literally zero play up down in and out. the vac seems about 6 hg low, and i thought it ran 10psi stock, but never had an issue with it. the hesistation leaves me worried about being stranded on a baron highway in montana's 30 below winter.
on my trip they closed the road with me on it, and was plowing 8-10 inches of snow for 80 miles and busting drifts, Quattro baby! the highway patrol gave me a funny look when i pulled around the barricade in my lowered german luxury car on the other side of the closed highway

kompressorgolf

well today it threw a MAF code erased it and it came right back, so instead of replacing the bosch maf, im converting from Abox to an Mbox with a Giac stage 1 and Hitachi Maf, maybe it was an erratic maf the whole time?