Too much boost, need help

[Second Shadow]

93 240sx, sr20det (s13 blacktop)intake, BoV+hotpipe, dump pipe, downpipe, aftermarket cat.

So I get my sr swap done about a month ago, and this weekend, finally got all the parts and got my boost meter installed. Went out and checked what is was making, and it peeked out at 18 psi. This is on the stock turbo, stock head gasket, stock (KA) fuel system, stock (SR) ignition system. so...yeah, problem. I haven't touched the boost in this thing, so I can only assume what ever dumbass in Japan was driving it was, well, a dumbass.

I've boosted it up to that about a dozen times so far just driving around, quick shots nothing sustained(although in my head I knew better, my foot got the better of me).

I think some damage may have already come from this, just hoping its nothing too severe. Its still running okay, although my idle has gotten just a hair unsteady, and when I start it there is a feint raw gas smell comming from somewhere. On the freeway this morning I noticed that trying to accelarate from 70 to 80 it seemed to kind of stall out, as if I had a boost leak or something. Haven't herd anything like pinging yet, and water temp is steady.

If my research is correct I should be okay if I can keep it under 10 psi, but I'd like to adjust the boost down so this doesn't happen anymore, and for all my effort, I havn't found how to do that.

Also, based on what I've wrote here, can anyone give any advise/commentary on what might be damaged, needs looked at, precautions that need to be taken, and repairs/mods that need to be made imeadiately before what is still a strong running engine is killed?

[Hijacker]

The stock T25 can start to melt the turbine wheel if it boosts over 18 psi sustained. Also, at that point the fuel system is pretty much maxed (it maxes closer to 15 psi really), so it's possible that a lean situation has occured, which on an SR tends to lead to a melted piston.

For sound of mind, run a compression check. It will give you an idea if a piston is damaged, or if the headgasket has blown out.

For turning the boost down, it helps to know what kind of boost controller you're using. The stock wastegate actuator is set at 7 psi (or 10 if you're using the stock vac lines with the restrictor). Most times, an HKS adjustable actuator is used as a cheap controller (very effective IMO and doesn't creep/leak from my experience).

[Second Shadow]

so worst case senario, pistons, head gasket, turbo(compresser, but if its bad I might as well just get the DP like I planned).

I'll get the compression check, but is there anything else I can look at in the mean time? Like is there a way the spark plugs will look if theres piston damage? I won't be able to get a comp check till like tomarrow or the next day and I hate to not know whats going on.

I have no idea how the wastegate is being controlled. Based on the mods the engine had when I got it I figured it would have been stock, but I guess I was wrong. Thank god I didn't run sustained high boost. Most of the quick shots were just getting on the freeway.

[Second Shadow]

Okay, just checked compression. Bought a checker because I didn't feel like waiting till friday for an "apointment". Never done this before but it seemed pretty strait foward on the instructions. Engine was warm, (not really "hot", but you wouldn't want to open the radiator cap). Engine has about 60-70k miles on it.from front to back(firewall), this is what I got

152146149152

Plugs(new) also looked fine, clean threads, tips (where actually in the combustion chamber) had a little carbon on them, electodes clean. no oil, no scorching. Also, I don't see any milkshake effect in my oil or water, they both look fine.

However, this morning when I started the car to warm it up, it still had the feint gas smell, and there was smoke comming from the tail pipe. Not much, in fact I almost mistook it for steam. When I stuck my hand behind it, after a sec there were little dark brown spots on it. I know this can be gas mixed with carbon in the exhaust, or oil from the turbo, I can't tell exactly what its comming from though.

The engine isn't running poorly, and I still have boost. Most people would prob look at it and say its fine, but it doesn't feel right to me. Its not sputtering but I feels like it wants to, and it just doesn't sound right.

I'm thinking what happend is I overspun the turbo, and blew the seals. However, I'm really new to turbo maintaince and what not and I really don't know anything for sure. Anyone have anymore thoughts?
Modified by Second Shadow at 9:36 AM 7/1/2008

[Second Shadow]

I found what ever it is thats supposed to control my boost, has lines going to the ...... that was a pause as I just realized I think I know what's wrong. one line goes to the waste gate actuator, the other goes to the intake pipe, after the air filter but before the turbo. so if thats supposed to read manifold pressure, and its only reading vacuum from the intake, the waste gate would never open. Can anyone confirm this? I don't want to change anything till I'm sure.



Also, this is the spot where I want to relocate my oil filter to, so will getting that HKS controller or another mechanical one allow me to remove this?(I'd like the boost controller to be on the other side of the bay, where theres room, and were the turbo is).

PS: car is still driving fine, and I did notice when I did my compression test that the plugs wern't in there all that tight. makes me wonder if any slight disturbances in engine performance might have been due to that.