Boost question?

[FeebleBiscuit]

Okay I have a 1.8t Aeb with a frankenturbo setup. C2 tune with 550cc injectors and a 044 in tank pump.

This is a newb question but I just want to make sure that I'm understanding this properly. I have been running 20psi all summer. The car at full boost goes to 10:1 a/f. I keep trashing plugs and it's getting old. Well today I started playing with the boost and notice at 25psi it leans out to 13:1 at 4k to 5k and at 6500 it's about 11.5:1.

My question is will more boost lean out your car? I just want to make sure I understand this correctly.

[salz2135]

Yes. Is the C2 software written specifically for the hardware that you're running? I don't think adjusting boost levels is the best method of achieving a target AFR.

[FeebleBiscuit]

Yes, the tune is for my hardware and supporting mods. It probably not the best way to get there but it runs good at 25psi. I would rather not do another out of the box tune. I was thinking about getting it dyno tuned. But this will work for now. But what your saying is that I am right boost will change my a/f

[salz2135]

In theory yes. If you increase boost without making fuel changes as well, the mixture will lean out.

[pbcrazy]

Most AFR gauges only go down to 10 AFR, so there is the possibilty you are below that. Get an AFPR and tune your pressure down to ~11.5ish AFR at WOT

[SynapticA4TQM]

Okay let's set something straight first... The higher the number the more lean it is... 10:1 afr is kind of rich but is a very safe afr ... 11.5:1 is of course less rich... 12.7 is an ideal afr, so 13:1 is pretty safe. If you were getting down to say 8:1 or 9:1 air-fuel ratio you might be needing to start digging into your system to figure out what's happening.

It's typically recommended that the injectors selected for a tune are chosen by their max at 85% flow. So if c2 has followed those norms and they trying to be crazy aggressive, you should have another 15% of flow above what boost level the tune is supposedly for. If they were covering their butts and went pretty safe, you may have even more over head. That being said, the system should dynamically follow the amount of boost being made as long as the injectors/fuel system can keep up. Once you start pushing the boost higher than the injectors can keep up with, you WILL lean out.

What I wonder is how you're logging your air:fuel ratio or are you just following a gauge? I would want to be extreme sure of your mixture before feelings age about pushing things much further. Tuners pick 85% as a safe duty cycle to give themselves some variance to accommodate the changing temps during the year... Turning up the boost may be eating all of the buffer/safety zone up... You admit to being a newb about things... I would be sure to get educated before you start pushing things to a place that requires a lot of diligence to keep things safe.

What I'm saying is, you're not quite in danger at 13:1... But, with more heat soak, with hotter temps outside, all this is assuming you don't have any boost spikes... Which is another problem with pushing your boost higher than the tune is designed for... Maybe I should say, pushing the power beyond what the engine is built for. If your pushing the power up towards 300crank hp, you can start taxing the rods, if you don't have forged rods or at least something stronger than stock. Especially if you get a boost spike, you could find yourself in trouble... All because you found out you could turn up the boost a bit...


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[FeebleBiscuit]

Well first of thanks for the replys. Sorry about the delay in response sometimes life has to take priority over car stuff.

The tune is set up for 20-22psi. But it is very sluggish. I'm getting these reading from a gauge. I'm just taking note at WOT. And as I increase rpm it still get richer. As I stated above. Maybe I should just get software to log it and send the tune back. When I say it feels sluggish. It's really sluggish. It feels like I'm spoiling up a GT35. I'm waiting for a significant about of time.

[FeebleBiscuit]

I have a vag com, can I log with it?

[vrmm]

Yes you can use it to log.
What's happening to your plugs? Gap? Brand?
There is nothing wrong with adding boost to make up for your car running rich as long as you aren't pulling too much timing or anything like that. It may be that you are actually running too little boost for your tune. At 25psi though you are too lean though. Maybe try 23psi. I would NEVER drive my car @wot with 13:1afr. Ever. Never ever. It's possible it's not actually bad, but I have never once heard that's an ok afr to have. With that dinky turbo you should be well into boost at that point, so i'll say it again, 13:1 is not okay. It doesn't make much sense that it's richest up top unless your turbo actually flows less at higher rpm's. A rrfpr isn't a bad idea.

When do you get full spool? My turbo that can churn out up to 500whp'ish has full spool at 4200. Have you compared to others who have the same turbo?

[FeebleBiscuit]

The plugs are ngk 4091.
.025 gap. I had them at .028 but it kept cutting out. I'm going to log this when I get home.