FC_DRIFTER

I recently purchased a S4 TII...I just have a few questions.

1. What is stock boost on a s4 turbo?
2. What is the maximum safe boost to run on stock?
3. What could be causing a rough idle? It sounds like it is pulsating. Would it be the TPS? MAF?
4. What is the proper way to do a compression test? Which spark plugs holes....leading or trailing? What is a ideal compression on a 100k S4 TII motor?

CyborgRyu

iTrader: (8)

1.) 6psi
2.) I want to say 8ish, you'll probably hit fuel cut.
3.) I don't have a clue.
4.) I'll leave that for the experts

FC_DRIFTER

Anyone else?

FC_DRIFTER

Does anyone know if the seals are able to with stable a constant 10 psi?

CyborgRyu

iTrader: (8)

yea, mine hit 12. How long do you mean constant? I've done a few high pulls and drags, no problems so far.

FC_DRIFTER

Daily driving on 10psi? i want to know how well the seals will hold up if the boost is set at 10psi for awhile (previous owner had it set at 10)...need to know whether or not the seals will give out ne time soon.

JoeHawk

There are people running well over 10 p.s.i. daily. But, when you get up there, you're getting close to maxing out the stock IC, and turbo. I believe the top mount loses efficiency at around 11 p.s.i.(not too sure), and the stock turbo at around 13. I could be wrong, but, I think this is what I've been told. You can run 10 p.s.i., but you're going to want to make sure you have enough fuel, and get an FCD first.

CyborgRyu

iTrader: (8)

i don't understand why you would want to daily drive that high, you'll soon notice spend about $100 on gas weekly.

rotaryrudy

iTrader: (2)

you should get a boost controller like the profec B that has two settings, high and low. Then for daily driving you can set it stock. Then if you want to race someone you can just turn the boost up with the flip of a switch

eriksseven

iTrader: (6)

Ya, to run anything more than 8 or 8.5 psi, you've got to get a 'fuel cut defenser'. And 'turning up the boost' on a boost controller wont really do much unless you have a free(er) flowing exhaust/intake system.

I'd recommend searching on the compression question. I do know you have to use a modified conventional tester so that it's allowed to jump around as the engine pulses. You'll want to see #"s of around 100psi on all six rotor faces.. There's a little more to it, but I'm not 100% confident on my info. You've got to pull the EGI fuse (pretty sure that's the one) to make sure you're not dumping fuel into the motor when you test it.

GregSL-SE

he's right

I'm pretty sure you check compression in the leading holes with a fully charged battery