APR Stage 1 Flat Spot

[Cumulonimbus]

2008 FSI - Running 94 Oct on the 93 map - stock except for a chip engine wise.

Have a flat spot around 4700-5300 (varrying) in higher gears, mainly 5th, sometimes 4th.

Does not feel like a fuel cut, almost like power has been reduced by about 20whp for half a second, then continues.

RPM changes but it is usually in the low 5000s, and only under high load.

Did some searching and saw a few other people had a similar issue, am I just running out of fuel or what?

I do not have VAGCOM or know anybody with it.

Hoping APR will chime in here, I know this is not an issue with the software and an issue with my car, but perhaps they can shed some light on what is happening.

 

[langer]

Sounds like you'd probably be chasing your tail unless you do some logs. Which would require you to find someone with vcds. Try one of the local forums on vortex.

 

[07bunny]

Had the same issue, I actually did some logs with the local apr dealer and found that boost was cutting out in these rpm's, really didn't know why, but I ended up buying a dp and going stg 2, that fixed my problem for that

 

[Cumulonimbus]

Had the same issue, I actually did some logs with the local apr dealer and found that boost was cutting out in these rpm's, really didn't know why, but I ended up buying a dp and going stg 2, that fixed my problem for that

Feels exactly like dumping boost, sounds like we had the same issue.

Glad to know Stage 2 makes the issue go away, was concerned it would get worse.

Curious why the boost cut occurs, anyone have any insite?

 

[GTi R Enigma]

lack of a downpipe, increade back pressure at those rpms..thats my guess. stg too gets a dp that is wider, allows more flow, less back pressure..

 

[BurgerGuy]

Could be the "safety parameters" in the tune. I've heard APR speaking of something like this in the past. Someone had dyno'd their car and inquired about a strange drop in curve at higher RPMs and I believe someone from APR explained what it was there for. The non-technical explanation was something along the lines of "to keep your turbo from exploding."

I just tried to find the thread, but couldn't turn up any results. Was maybe 2 years ago.

lack of a downpipe, increade back pressure at those rpms..thats my guess. stg too gets a dp that is wider, allows more flow, less back pressure..

You're on the right track, though I believe it has more to do with EGTs than back pressure.

 

[Cumulonimbus]

Makes sense to me, restrictive DP plus the high loads / increased timing on the 93 program.

I would imaging the EGT gets pretty high, especially with the cold *20F weather I was doing the pulls in.

Nice to know APR has these safeties built into the software.

 

[KingEgi]

the flat spot will still be there on stage 2 as well, just wont be as noticeable. You should log like others have said to be sure but if its not boost leaks then its probably fueling. I couldn't solve that "flat spot" issue until I went stage2+ with hpfp and then upgraded to the higher limit fuel return valve. After doing that, power is smooth until shift and fuel is always there, every time.

 

[07bunny]

It was demanding less boost from what I saw, it won't cut it out completely when you go stage 2, it will just drop from 20psi to 15-17 in the higher rpm's because of the turbo being small

 

[KingEgi]

Ofcourse, no matter the tune pressure will drop on a k03 nearing redline but the if you are wondering why their is a soft spot at 4500-5k its more than likely fuel. I'm on Revo which allows me to slightly tweak my requested boost (Boost setting - 8) and I have a few extra bars of fuel up top to deal with timing pull at peak requested boost to keep from hitting a dead spot. Stock fuel valve can crack prematurely, Rs4 valve will not. Still, fuel logs will tell the complete story. (i.e fuel requested and actual)

 

[BurgerGuy]

How much is that valve, KingEgi?

 

[KingEgi]

How much is that valve, KingEgi?

$85