SimBa

My gas tank has been hard to fill for a while now. I don't get pressure building up (at least it's not pressurized when I remove the cap), but I can't get gas to flow in properly.
I always assumed this was because of the lack of evap, and I doubt that helps, but I'm starting to think that's not the case. My roommate has his NB setup similarly and has never had issues.

I realized the other day that none of the evap stuff would be running when the cars off and your filling it up anyway. All of the fuel tank pressure sensors/solenoids would be inactive. Presumably my issue is something more static.
My guess is that it's the rollover valve being stuck, not allowing fumes to vent back to the filler neck. I've looked at some diagrams and this seemed like an obvious answer.

Well, I pulled the fuel tank cover yesterday and I couldn't find the valve. This is what I was greeted with. I expected the valve to be right on top, but I'm guessing that's the NA setup.


I'm guessing that the sensor there is the fuel pressure sensor, as it intercepts that hose that's next to it. I believe the sensor on top of the hanger is the fuel pump power.

I still need to read into the larger hose. I'm guessing that's where I need to look for the valve/vent. It seems to me like I have an NB2 style gas tank. This doesn't line up with the NB1 diagrams I've looked at.

I'm guessing that something in here has a clog.

There's a hard piece in this hose, but it doesn't seem to be a valve, just some reinforcement.


I checked the lines in the trunk again (I've checked these before) and didn't see anything concerning. The NB1's were supposed to have a plastic flapper valve that sometimes would get stuck. I've looked for this before and couldn't find it.
The mystery continues. I will probably open this back up and try to dig into some of the other hoses on top of the gas tank. I figured since what I saw didn't match up with my research that I'd read up a bit more and see if anyone had any ideas.

I have issues filling up even when the cars isn't up to temp and it's cold outside, so I really don't think it's an issue with fumes. The gas backs up the filler neck pretty quickly, which requires me to hold the pump super lightly and trickle the gas in.
Now that I said that, I should double check that the large filler neck isn't plugged again. I know I've done it before, but that seems like the most obvious solution. I only checked the smaller hose in the trunk yesterday.
EDIT : Actually I just rememberd I stuck a bit of tubing down the filler neck yesterday and it made it down to the rubber section, so maybe I'll check the rubber section into the tank next.

douginjenison

iTrader: (1)

My NA6 had a large ball (1”) check valve/rollover valve in the larger fill hose. Make sure that one is free.

SimBa

Thanks for the pointer. I know the NB's had one but when I took the hose off previously I didn't see it where I expected it to be. I'm thinking it was removed by a PO or I looked in the wrong place.

SimBa

Exciting development. I heard a new noise right at 2K RPM today when driving around. Nothing too concerning, but noticeable.

I'm still not sure what it is/was, but when I was doing some checks before the weekend I pulled off my intake and noticed some shaft play in the turbo. Nothing extreme, but definitely noticeable front to bad. I fired the car up later and couldn't replicate the noise, so I kinda doubt it was the turbo. I drove the car around today without issue. The turbo still spooled like normal and nothing sounded strange.

No idea what information you'll get from this generic photo of my turbo, but posts feel empty without photos.

I'd been throwing around the idea of grabbing a backup turbo, as the exhaust housing on mine looks like a boat anchor. I figured I'd wait a bit since I just spent some good money on the exhaust but it looks like fate had other ideas.

I haven't done as much research as I'd like, but I'm currently looking at going for a 2860, either a Garret or PSR. There's a lightly used Garrett on marketplace for ~$500, or I could get the new Pulsar for ~$615. I sent a message to the guy in Utah to confirm if it's a GT or a GTX. He's got it listed as a GT, but I'm assuming it's actually a GTX.

If anyone more knowledgeable is reading let me know what you would do. I don't have plans to swap transmissions at this point, but I am shooting for around 300 WHP. I'd look at another 2560 but from the little research I've done it seems like a modern 2860 should spool about as quick as my old 2560 and not be as strung out trying to make 300 HP. For the rest of the season I'll try to be closer to 225-250 if possible.

I'm still planning to run this failing turbo for the time being. I've got events the next couple weekends that are local, but I do want to have something sorted before we head to Winnemucca. That's a ~4 hour road trip each way coupled with 2 days of autocross on a bigger course and I don't want to do that with a failing turbo. Pulsar's lead time means I'd need to order within the next week to have any shot at getting it here, installed and retuned before the event.

All the car guy drama I've seen over the years on YouTube is finally making sense. I guess it's finally my time to be that guy.
EDIT : I don't have to be that guy. On eBay they have ~3 week shipping. Pulsar's website looks like it could be here in a week so I've got a bit of time to figure this out.

redursidae

Maybe it’s the angle of the picture but the tank seems different than my NB1. In my NB the rollover valve is right on top as per the manual and the pressure sensor is on the opposite side to yours. The sensor with JE96 in your picture is the fuel tank pressure sensor, and on the other side should be the CDCV. I could snap a picture tonight to show you the differences.

I don’t have a picture to point you straight to it, but look for the drain cut valve and the CDCV and make sure neither of those is seized shut. There is also an air filter after the cdcv that could be clogged. My understanding is that if those are clogged or shut, the air can’t escape from the tank when you’re refueling.

SimBa

Last weekends autocross was a success. I ran the car at 6 PSI to start and after seeing that coolant temps were reasonable I bumped that up to ~10 PSI.
On the runs I datalogged I saw temps stop rising right around 100 C. I got some videos as well, I'll try to get those posted up soon.

I took 1st in class on Saturday and 3rd on Sunday. The main competitors are a 2.5 swapped NC and a ~270 WHP Turbo NA, both driven by super cool people.

I'm still trying to figure out what to do as far as the turbo's concerned. I'm not sure if I'm overreacting or if the shaft play is something I need to address ASAP. I can get a Pulsar 2860 here in a bit over a week for ~$600, but I'd rather not throw more money at the car for a bit. I'd also like to have the car not blow a turbo.

Regardless, I'm really happy to see that the temps were manageable this weekend. I'm not sure what played the biggest role, but the ducting, bleeding and fan switching points all seem to have done something. I suspect cooling will be an ongoing battle as the summer comes.

Home Depot magnetic vent covers are easy to cut and work pretty well for AutoX magnets. Less than $10 for enough to make a full set.

The next event for the car is with the Porsche club on Saturday.

The exhaust got here yesterday, but that'll get it's own post.

Z_WAAAAAZ

The magnetic vent covers are pure brilliance. Congrats on the results this weekend and glad to hear the car ran well! Your car’s punching pretty damn hard against that competition at 10psi.

What were ambient temps like? I’m not too familiar with general AutoX temps but 212 coolant temp on a tight course with an undertray only seems reasonable. I guess it depends on the course length.

SimBa

Saturday was the warmer of the 2 days and it was mid 70s and sunny. Not brutal conditions by any means, but not cold. I did spray down the Intercooler and rad between runs to be extra safe, but when I rolled back into the pits I was usually seeing temps around 85 C (185 F).

I just ran out and did some pulls with the boost turned up. These were just shorter pulls, but around 15-17 PSI the car peaked around 98 C. The temps seem to be a bit less spiky than before. I'm not going to write the issue off, but it's not at the top of my list for now.

SlowTeg

Very nice! Sounds like the car's running well! Also props on the HD magnetic vent covers idea.. I will definitely pick some up on my regular weekly trip to HD.

SimBa

Thanks, but I can't take credit for that one. I learned it from a buddy who was tipped off by someone else. 1 pack of them made me enough magnets to get the numbers 1,6 and class letters cut out IIRC. I have lost one or two before, so I usually cut out an extra set as a backup/template in case I need to make more. Now I just make sure that they're clean and not bent up before throwing them on the car and don't seem to have issues..

SimBa

The exhaust finally showed up on Monday. I wasted no time and dropped the old exhaust during lunch. Soapy water in a spray bottle and some exhaust pliers made it a simple ordeal.

I'm no expert but the welds look really nice. The whole system seems really well constructed. One gripe was that the plastic wrap on the resonator and muffler seems to have been folded into some of the overlap, IE you can't really get it all out.
I removed as much as I could. I haven't noticed any melting/smoking sounds outside of the usual stuff.


Even got my name embossed on the muffler and resonator. Now everyone will know who it belongs to.


Yikes. The old exhaust was pretty haggard. It worked/sounded decent for what it was. If the cat hadn't been hacked in I probably would've kept using this setup.

Yeah, I think the exhaust was leaking out of that slip joint a bit.

As far as I'm aware, that's leftover welding wire.


The subframe brace had to come off obviously. I have no idea if this is a DIY unit, or if it's an old aftermarket setup. If anyone has ideas let me know.



I discovered that the FM downpipe had a smaller pipe inside the flange, presumably to center the exhaust? To me this looked like a restriction, especially considering the DP is 2.5".
I'm not sure if it was the right decision, but I decided to remove that, which turned into a bit of a project.

With a handful of dremel cutoff wheels and some bending/crushing the pipe I was able to get it free. The pipe was flared, so it was a bit more involved than just cutting the welds.





My neck wasn't super happy after that ordeal.

Drilled some holes in the new hangers as they weren't drilled out. After that I started fitting the new exhaust. Soapy water was sprayed into all of the rubber isolators and they slid on no problem.
Overall it fit up pretty well. I think it could use ~5mm more length, as the whole system seemed to need to be pulled towards the front of the car to meet up with the downpipe.
I'm wondering if I should pull some of it back off and try to bend the hangers to make things align better.




Unfortunately I wasn't able to get the subframe brace to fit without hitting the exhaust. I will revisit that later though, as the car is pretty shaky on the highway now.

Removes bracing and installs 3" exhaust.
Car is loud and suffers in the NVH department



Sound
For how quiet I expected this setup to be I'm wondering if I have a leak somewhere. I actually went back out and sealed the downpipe flange today with some high temp gasket maker to see if that helps.
Around 1300-1500 RPM it's quite boomy, which isn't ideal when warming up the car in the neighborhood, although I'm a bit overly worried about pissing off the neighbors.
I'm actually surprised that it doesn't sound extremely different than my old exhaust.

I don't find it raspy by any means. Maybe a bit of highway drone, but I want more time in the car before saying anything definitive on that.

Performance

The fuel table didn't require too much changing. A bit more fuel up top, but I was able to get it adjusted pretty quickly with some autotuning.

The new setup is 40 LBs. The old setup was 28 LBs and the subframe brace is 12. If I leave the subframe brace off it's a wash, but that's not my plan.

I don't have much concrete data here. I was fairly surprised to see that virtual dyno is still reporting ~170 HP, even with the boost turned up to 15 PSI.
I will see what temps look like this weekend at the Porsche club event. They seem to be slightly less spiky than before, but that could be placebo.






Overall I'm pretty happy with the exhaust. I expect I'll do a bit more adjusting of the hangers and figure out how to get that subframe brace mounted without interfering.
I'll try to get some clips of it this weekend.

Z_WAAAAAZ

Looks good, man! Much prettier than the old system haha.

I gotta imagine you picked up more power and spool that what VD suggests. Does the ol' butt dyno say differently?

SimBa

It does feel faster, but I have been running less boost previously, so I'd expect that.

I've got a fitting to do a boost leak test, so I'll probably try that in the next week to see if I'm still losing air somewhere.
The tune could be playing a part as well, but I'm running numbers that are pretty similar to yours, so I doubt that would be causing a 100 HP difference from what I'd expect to see with this setup.

I wouldn't be surprised if it's a mixture of things. There are still at least a handful of questionable links in the chain.

virtulent

Hey SimBa
I been eyeing the exhaust too, if you have or could get any sound clips I would be appreciative of it, most posts ive read said it is pretty quiet so hearing its loud is surprising.
Do you think the rear brace did not fit because it isn't an OEM one or it just is way too close to the exhaust? The construction of it looks like an autoexe brace, but I cant find a photo of the rear one.

curly

iTrader: (25)

I'm looking at your previous graph vs. the new graph, and you're actually hitting 14psi about 300-400rpm sooner, that and maintaining pressure to redline are the main benefits to the exhaust. As to why you're hitting the same psi but making less power according to VD, unsure.

that cone you cut out of FM's downpipe is in fact to help restrict over-boost issues.

I've seen that rear subframe brace before, but I forget who made it. I'm not surprised it doesn't fit with the aftermarket exhaust. Get a stock one and I bet it'll fit much better, without any sacrifice to perceived ride quality.

SimBa

@virtulent I actually went out this morning and pulled off the 2 bolt flange where the exhaust is connected to the downpipe. I saw some condensation drip out of that joint after I first installed it but decided to give it a test anyway.

It was pretty obviously leaking so I added some red RTV to the gasket and bolted it back up. This afternoon I took the car out and it was much quieter. While I was under there I tightened some of the V bands a bit further, so I'm not exactly what fixed it.



I will hopefully have some sound clips from this weekend, although those would be from a garbage GoPro mic. I can probably grab some with my phone as well.

SimBa

Thanks for the info Curly. I'm not worried about cutting that bit out then, No sense spending the money on a bigger exhaust to unnecessarily handicap the flow before it even gets there.

I'm going to try to bolt up that subframe brace again and get another look at it. I was pretty anxious to get the car back on the ground so I figured I'd leave it be.
The stock one might be in order if this one doesn't work. I've removed a couple different braces and am now learning that, yes, they actually do something. Performance wise I can't say for sure, but definitely for NVH.

I'm still curious why the HP and Torque drop off like that. I'm pretty new to building/tuning vehicles, but the curve seems to drop off pretty quickly to me. Could be the scaling on the graph playing a part as well.

virtulent

Thanks for following up, glad to hear you found something that made a change.
If you were able to get a clip this weekend I still would be appreciative of it.

Did you have to also retune your car now you’ve had it a couple more days?

SimBa

Not after the initial tuning. The fuel map just needed some small initial tweaks.

Z_WAAAAAZ

Patiently awaiting for an update on how the Porsche club event went this weekend