My 6 port turbo is overboosting in 2nd gear and higher. 1st gear is dead on at 6psi and 2nd it creeps to 9psi and hits fuel cut. I have hit it probably 4 times now, how bad is it for the engine? As soon as I would feel the hesitation/brick wall I let off.

Car is a stock S5 NA boosted with the following mods:

Stock intakes
550cc x4
Stock TII ECU, MAP, AFM
S4 turbo, ported WG
FD fuel pump
Open 2.5" downpipe
1.75 to 2.5" IC piping to TII TMIC TO FMIC
2" TID

Thanks in advance.

 

i hit it couple times and so far my car hasn't broken but mine is a turbo II...what exhaust manifold did you use?

 

I used the stock TII manifold with a spacer.

 

So are you running the n/a intake manifold or TII manifold?

 

NA intake manifolds.

 

fuel cut cuts fuel to the rear rotor only. So, at 9 psi boost, is running lean on one rotor good? No. I suggest getting either an RTek so you can make sure you are tuned for boost that high, or at least get a FCD and a wideband, make sure that the ECU is fuelling enough for that kind of boost w/ high compression rotors.

 

What he said ^ Running a high comp engine on a TII map just doesn't seem like a good idea, even it you weren't hitting fuel cut from boost. You really need to do it right before blow something.

 

have you ported the wastegate since your using a stock turbo and manifold? This would help your boost creep issues.

 

Boom Shackah Lackah!

 

The WG is ported but I didn't measure how much...it did have a larger door welded on the flapper, probably the size of a golden dollar or quarter. I think the boost creep will go away when I finish the exhaust (2.5" Y to RB stock replacement mufflers).

My reasoning for it was that the stock TII maps are conservative and reputable members claimed to have run much more aggressive maps on EMS's and had no issues. Also the engine is putting out 90psi per rotor, I don't think the compression is still 9.7:1. The AFRs while being less then ideal are probably on the rich side because of the FD fuel pump and no O2 for the cruise. If I avoid high load/high throttle situations I think it'll be good assuming that I don't hit fuel cut.

I replaced the TID with 2" PVC from the original 2.5" and it seems to have helped. Still waiting on my big check for the RTEK and wideband. I guess I will stay out of 3rd until I get it, I want to top this bitch out already.

 

The compression ratio is still the same. If the engine is worn, then you are experiencing the rotary equivelent of cylinder leakdown. You test the compression at 250 rpm, but what happens when you are running at 4000 or 6000 rpm? When you are at speed, the seals don't have as much time to leak down. You still have a high compression core in your engine. It will pop!

Do this stuff in the right order. The fuel cut saved you from your boost creep, just like the Mazda engineers planned. If you had a FCD, you would have boost creeped till it popped.

Get your exhaust finished. Stay out of boost till then, as much as possible. Then, if you still have boost creep, deal with it first, more, larger wastegate porting may be in order. Then add some fuel with an safc, an rtec or even just larger secondary injectors.

You don't want to be this guy: