Here is my setup. Just got done break in, with 2000 miles, Rotary aviation seals.

Series five turbo two, completely stock other than
Streetport
TID/conefilter
Aftermarket rad
oil cooler lines
FCD.

Above 5000rpm the car hits a wall and hesitates, boost starts to die off, and it won't go past 6k rpm it seems like if I try to push it past that, it just fouls the plugs. They have black soot on them (i'll take pictures tonight. I just replaced the plugs.) I failed emissions earlier that day because I was running a hair rich, I think that's due to the fouled plugs or some other, as of yet, unidentified issue.

Is an S-afc going to be a bandaid to this issue?

Is a stock downpipe/exhaust going to restrict the street port to the point that the engine performance degrades? (i.e. more air going in then can get out?)

Could it just be a bad O2 sensor? I plan on replacing this tonight, because I ran this 02 sensor on the blown motor prior to the rebuild so I'd imagine it's pretty dirty.

 

What boost numbers you running?

 

Stock. 8lbs.

 

If it's fouling the plugs then it's running too rich, which doesn't really make sense at all. Check your injectors to make sure they're working properly, might check grounds and such.

 

Well my goal is to pass emissions, then tear down the intake manifold, remove airpump, send the injectors to be cleaned, then put on a 3 inch RB turbo back exhaust on and a tuned s5 ECU and run 11lbs of boost, and be done with it.

 

No fuel pump upgrade? Really not needed at 8 lbs though.
When you say stock dp/exhaust.....Both cats in place?

 

Ah yes, There is a walbro pump there, forgot to mention that.

There are two cats? I have a down pipe, midpipe, cat, then the stock cat-back, just one catalytic converter. I assumed it was stock (looks stock anyway). I've never had an s5 t2 before so I have no idea what should be stock on the exhaust. Generally in my experience if it looks old, rusted, cast, has heat shields on it, It's probably stock.

 

I would say that a S-AFC wuuld help. If you get a S-AFC dont max out your injectors, you dont wanna exceed about 80% duty cycle. You should probably go on and get a fuel pump, walbro 255's are good.

 

FYI-The factory exhaust has a precat in the dp, and the factory main cat covers almost the entire length from the midpipe to the "Y". Just checking to see if the cat could be semi clogged, and not allowing the exhaust to flow properly.
Also, there is probably somthing causing the car to run rich, and the O2 sensor just monitors the condition.

 

Is a vac leak going to make the car run rich?

 

Probably not, but i'm not certain.
I think Turbonut is probably heading the right direction about the clogged cat. That could cause a rich condition.

Do you have still have the Airpump installed?

 

Vac leaks make you run lean, because there's unmetered air getting into the engine. Probably not your problem. When was the last time the plugs were changed? Sure your FCD is working properly and not set a little incorrectly so that you're hitting fuel cut (I'd imagine your setup would creep a hair bit, so it's possible). Sometimes you have to adjust them.

 

It's a Racing Beat FCD, I have all stock emissions equipment (including the air pump) in place, but I assume I've got an aftermarket catalytic converter. I didn't do the exhaust work, the guy before me had it all done.

The last time they were changed was at the rebuild.

 

You need to check and see if the Airpipe that goes from the ACV to the cat is still connected. If it's not then your cat is probably clogged.

 

I'll take a look at it. It's a real head scratcher. I can't figure it out. When we first got the car back on the road after the rebuild a purge valve of some sort was bleeding off boost at 4krpm. It wasn't enough to cause a vacuum leak. It was right behind the oil filler neck.

 

what temp and model spark plugs are you using?

 

NGK's

BUR7EQ
BUR9EQ

 

Hmmm, I was expecting both trailing and leading to be '9EQ. I have seen simular fouling on people using '9EQs as leading plugs, and using too big of secondaries.

 

I'm being very conservative with my setup right now.

Kids + houses do that to you

 

do u see black smoke or anything when underload?

will it rev to redline in neuatral?

 

I don't rev it to redline out of gear. And right now, being so cold, it's hard to tell if it's smoke or not, I would assume not.

When I smell the exhaust It's very obvious that there is a high fuel mixture in it.

 

do u have an aftermarket boost gauge?

how many lb's of boost are u at when u "hit" the wall?

Do u hit the "wall" when doin WOT runs?

can u go till redline in gear at partial throttle?

 

Yes, in my earlier post, i'm running a stock 8.6lbs of boost, when I hit the wall at 5000 rpm boost dips down to 6psi and stops building while it slowly bleeds off.

It happens under full or partial throttle.

I think it's totally possible that it's a clogged catalytic converter.

 

U can try opening the exhaust temporarily and hanging it off to one side, and try a run with "open exhaust" to see if it helps


I had a similar problem in my skyline GTR... it was driving me crazy, I changed the plugs, I changed the fuel filter, I had the injectors prof. cleaned, cleaned the maf's, opened and refitted all teh IC pipes...hell I even changed the fuel pump to a MKIV supra's... none of it helped...

it turned out to be the coil packs in the end

u can try swapping with a buddy of yours to see if that helps...

 

I've got a racing beat downpipe, presilencer and apex'i n1 just... laying around... ya know

I'm putting that on tommorow. I cleaned it up and an re-painted and heat wrapped it today. I'll let you know how it works out.