Awful throttle cuts...

[USAFVMI08]

So I've noticed as the temperature has dropped, my car is getting more and more extremely violent throttle cuts as I'm accelerating with my foot at or near WOT in any gear past 3. I know that it's not a fuel issue as I have an upgraded fuel pump and my fuel pressure is still good. I have a feeling that with the colder air, my boost has increased (as my datalog will show, I'm hitting around 21psi in 3rd gear, not spiking). I'm currently tuned to stage 2+ TMIC +Cobb SRI and TIP and I'm desperately in need of a custom tune. Until then, I'm babying the car.

The datalog was taken back at the end of September when the temps were warmer when I was merging on to the highway, but I can imagine that it's probably looking about the same. The cut was noticed right at or just below 5000rpms and have occurred at that moment every time.

What do you all think?

 

[Blendercloud]

Do another datalog, but exclude vehicle speed and wastegate duty this time. The event logging is too slow and choppy to really tell what's going on.

 

[8.5MS3]

your afr is jumping all over the place. in that pull you go from 11.3 to 12.9....
boost cut is slated for 22.5psi, you may be hitting that, as blender said its very choppy and probably happening between log points.

I wouldnt do any more wot pulls with logs looking like this, your leaning out a bit too much imo

EDIT: WTF is up with your wastegate? its 0'd out........

that means the wastegate is wide open, and your still building 20psi??????? something is def not right with this log

 

[USAFVMI08]

I was under the impression that that means it's closed... At least that's what I've been told.

I'll try and get another datalog but I'm scared to because I'm really worried something bad is going to happen. Plus, whiplash from getting thrown forward in my seat sucks...

 

[USAFVMI08]

Nevermind...you're right. That concerns me. I'll try and get another log tonight after I get off work.

 

[USAFVMI08]

Here we go...OAT was around 18*F. This was from a roll in 3rd gear merging on to the highway. When I shifted up to 4th and planted my foot on the floor, that's when I saw the boost cut. Just at or under 5000 rpm.


Check out the boost... O.O

 

[8.5MS3]

ya your def hitting boost cut. need a custom tune. dont do WOT pulls anymore until you get it resolved

 

[tunersteve]

Cold weather boost cut. I had a similar issue last year before the AP. All of their maps have the 'cold weather fix' built in them, and you won't have that problem.

 

[USAFVMI08]

My current tune is off of mzdspd.com. I'm guessing those don't have the cold weather fix?

I'm really not too keen on running that high of boost, seeing as how these turbos don't like anything THAT high...

 

[tunersteve]

My current tune is off of mzdspd.com. I'm guessing those don't have the cold weather fix?

I'm really not too keen on running that high of boost, seeing as how these turbos don't like anything THAT high...

That's where my map is from, never had an issue. I need to look at your logs again, make sure your fuel pressure is good.

 

[USAFVMI08]

Weird. I'm also guessing you're seeing temperatures that are colder than the ones I'm seeing too.

Maybe I should try and reflash my ECU with the current tune? I have v103a, which is the latest version...

 

[Blendercloud]

Try reflashing with the standard Stage 2 map.

I think the more unique they've tried to make those OTS maps, the more adversely some cars are affected by them.

 

[tunersteve]

I'm actually still running a v1.01 map. They may not have included the cold weather fix in the newer maps.

 

[USAFVMI08]

I'll try that. But what about the really high amount of boost that I'm seeing? Isn't 21-22psi a little too much for this turbo?

 

[tunersteve]

I'll try that. But what about the really high amount of boost that I'm seeing? Isn't 21-22psi a little too much for this turbo?

If it's spiking, that's not a big deal, just don't be holding that. I'm spiking to 22-23, then holding at 18psi no problem.

 

[Blendercloud]

I'll try that. But what about the really high amount of boost that I'm seeing? Isn't 21-22psi a little too much for this turbo?

I spike 22.2 and hold 21.6 without issue. Have for more than six months. The turbo's efficiency is a bit grim post-21psi. You will make a little more power from 20-22psi, but not terribly much more. I would probably like to be down around 20.5-21.0, but I've been lazy/busy and haven't gotten a custom tune yet.

 

[8.5MS3]

I'll try that. But what about the really high amount of boost that I'm seeing? Isn't 21-22psi a little too much for this turbo?

yes it is, 20 is pretty much the limit, and even then life expectancy is drastically reduced

 

[USAFVMI08]

See that's what I thought. It's not spiking, it's creeping up to it... That's what concerns me.

 

[8.5MS3]

wasnt there something wrong with corksports initial design of the downpipe. i remember reading something about how it prevented the wastegate from fully opening and it was causing creep. I could be wrong tho...

 

[Blendercloud]

wasnt there something wrong with corksports initial design of the downpipe. i remember reading something about how it prevented the wastegate from fully opening and it was causing creep. I could be wrong tho...

I don't think I was around for that, but hell... advice is free. It never hurts to give Derrick and Jason a call at Corksport and ask them for some help.