P0455/P0456 - Will go into limp mode
 

So within the last couple of weeks I've received a P0456 code for a small evap leak. Didn't think too much of it since it ran fine, but was going to have it addressed.
2 days ago, on my way from work, the car suddenly went into limp mode and ran like crap. I pulled over and the car completely stalled out. Tried starting it and it would start, but immediately stall. I could keep it running if I gave it throttle, but would shut off as soon as I let off the gas. I checked the codes and now there was a P0455 code for a large evap leak.
Decided to troop it home slowly, but within not even 2 miles, the car immediately went back to normal...
Today the same thing happened, but this time I didn't pull over and would assume it would go back to normal. Sure enough it did.

About my car:
-Kraftwerks supercharged
-550cc Bosch injectors
-Crawford AOS


(Things that were recently done)
-DW300c Fuel pump
-High Boost pulley

The newer mods have been on and tuned and were running fine for the last 2 months. All other mods have been on for at least a year.
Also have addressed the hoses underneath the intake manifold as well.

Found a possible problem. Fuel is leaking from the tank, most likely the lock ring on top.
Will be tackling it tomorrow.

Update: EVAP codes disappeared because fuel pump canister lock ring was not on tight/correct.
However, the stalling and running in a limp mode was still happening.
Found out through my tuner that my skunk2 4bar map sensor has malfunctioned.
Sure enough, bought a new one and all is working fantastic.
So if you ever have starting issues or your car run likes crap for a few minutes
and you're boosted, change your map sensor.

Kojiro did you do that work yourself for the lock ring? Is it easy to get to the fuel pump canister? I'm having what I think is the same problem. I've had the p0455/p0456 code for a year now, had it inspected at the dealership at least 3 times with smoke tests (at their expense not mine) with no luck. Then recently I developed a small fuel leak that follows fillups and gas. And I have an inspection of this scheduled for this weekend.

It's fairly easy. Unbolt the rear driver's side seat cushion, lift it. There you'll see the "door" to the fuel pump assembly. Get gloves because the sticky gasket they use will stick everywhere. There is a big lock ring that you will need to probably hammer out carefully. Once that lock ring is out, you will have access to the tank black rubber gasket. Replace it and now be careful to sit it properly in the mouth of the tank. Carefully replace lock ring, hammer it is carefully, replace gas tank "door", replace seat cushion, bolt in and you're done.

Thanks for the help, let's see if this is finally my fix!

I did it myself yes. It's easy, but you gotta be slow and careful and make sure you don't mess up both the lock ring and seal for the canister.
My CEL and problem was actually from my MAP sensor.

with rubber type gaskets and O-rings I use a small amount of silicone lube on the gaskets and fittings, so the o-ring or gasket doesn't catch and tear/move while your tightening up the lock ring or fitting.

Update
 

I was still under warranty, took my car in, told them what I thought was the problem, within 3 hours had the car back, they said the lock ring was loose, tightened it. I've now put 2000 miles on the car and obviously a ton of starts, the light hasn't come back! After a year of battling that thing, it's fixed! Thanks for the thread y'all

I have had the CEL come on ever since getting the Sprintex supercharger installed. I found out it was a gas leak from the top seals as I have read about. When the gas leak was fixed I unplugged the battery to remove the code, but it has since come back after 3 or 4 startups. ProECU reads DTC P0456
Do I need to reset the ECU again?

I don't understand gas leak from top seals. Gas as in gasoline? Seals on what top? Injectors?

If you're talking about the fuel pump seal, did you ever open that in the past? Those things don't just go bad.

From the ring at the top of the gas tank. This has been fixed, but I still have the CEL

Ok. I edited my previous. Those seals don't just go bad but there are other places where the evap system can leak. Which code did you get, the fast leak, or the slow leak?

There's no point to resetting the ecu. As long as the fault condition exists it will throw the cel.

ProECU reads DTC P0456 (slow leak)
I have upgraded fuel pump and injectors. Could this have anything to do with catless header?