boost spiking to 23psi

rideyama

Member
:
'08 MS3
SO....I had a little incident and now I have a fresh long block. The motor is not broke in yet, but the few times I have punched it the boost shoots up over 22, then backs its self down to about 16, then it spikes back up and down. This is all in 5th or 6th gear. Mods on this right now are: turbosmart Dual port BOV, corksport SRI and turbo inlet, Turboxs dp and rp HKS catback
I have been taking it easy for the most part on the new motor, but my last one didn't spike like this. I bent the tiny aluminum tit on the new turbo inlet when I installed it, I didn't kink it, but it is bent could this have something to do with it? Is the computer still learning? Should I just bring it back to the dealer and have them deal with it since the new motor is covered, or is this normal.
Thanks for any input....
 
Yeah, it just never went that high with the old engine. I'll try to keep my foot out of it for a while....like that will happen
Thanks again
 
I have similar mods to you, Rideyama. I was seeing those spikes due to high flow on the intake side and the TuboXS catless dp/rp on the exhaust side. They were very quick and transitory and then immediately settled to about 17-18, as reflected on a good manual boost gauge. I felt they were safe, since they were so quick. Others here disagreed. We never came to a clear conclusion, although I never saw anything in monitoring to suggest a real problem.

I do want to say that the Hypertech tune has eliminated the spikes. I realize that Anm6 is still getting the spikes after the same tune, so I guess every one of these cars responds a little differently to the same mods.

With your open exhaust, including an even more free flowing CBE behind the very open catless dp/rp, you should be seeing more than 16 psi as a "hold" target, at least up to about 5,500 rpm, after which it should fall like a rock on stock tune. I was seeing 17-18, as indicated above. In cold weather I was hitting load cut.

I'm not trying to sell the HT tune. It's not right for everyone. But I have found that it does take that sharp spike away for me, and that because of its slightly higher target boost tune and its moderate lifting of the load cap, I'm typically holding at 18-19 psi now with a slow taper down to 17 at 5,500 rpm, which is where I shift, and so far, I have not seen and boost, fuel or load cut at 18-19 psi.

I am at sea level, if that makes any difference.
 
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I haven't held the throttle on it long enough to really see where it settles at. I wanna say the last motor settled at 17 on my gauge, honestly I cannot remember though, It took the dealer in Pensacola more than 2 months to get my car back to me.
Like I said, I'm still trying to take it easy till I get some more miles on the new block. I have been tossing around getting that tuner...Right now I'm torn between it and high compression pistons for my bike. Too many toys I guess
Thanks for the info
 
what kind of tune are you running or is it stock tune?
and msms3 in your opinion is hypertech really that much better or is the ap a good choice too? ive been wanting one, there are a lot of people that are completely against it. are there curtain dp/tune combos that work together better or is it just buy some stuff and go have fun lol. my goal is to go full turbo back exhaust with a tune whats my cheapist option?
 
msms3 in your opinion is hypertech really that much better or is the ap a good choice too? ive been wanting one, there are a lot of people that are completely against it. are there curtain dp/tune combos that work together better or is it just buy some stuff and go have fun lol. my goal is to go full turbo back exhaust with a tune whats my cheapist option?

I can't tell you if Hypertech is "better" than AP. I've never had or used the AP tune. Ultimately it's probably a matter of what your goals are and where you want to end up in your mods. This varies widely from one user to another. You have to decide what you want, both short term and long term and carefully choose compatable mods. This requires a lot of thought and, I respectfully suggest, a lot of reading of threads here and on other forums. There is no single, "best" solution for everyone.

Let me take a stab at this from my own prespective. This is my daily driver, not a race car. If I wanted a drag car, I'd have purchased a completely different rear wheel drive platform. If I was going to track the car for road racing and trailer the car to and from the track, I'd probably look elsewhere. If I was trying to build a street racer with the engine life of a hand grenade and had the willingness to keep rebuilding the engine and replacing expensive drive train parts every time it goes boom, then I'd probably either look at a different car or give much different advice that I give here.

My goals are for a nice bump up in power for an otherwise stock daily driver, with reliability, predictability in performance and a minimum of bling or "look at me" racer/ricer boy cop magnet appeal. So keep this in mind.

1. I'm still on the stock rear motor mount. I think this was a mistake, even though I've gotten 42,000 miles out of it, with a LOT of hard launches. It's now pretty much shot. So, I intend to fix this next. Probably should have been #1, since it probably accounts for part of my really terrible 60 foot times at the dragstrip. I'll put in an SU mount when they come off of back order.

2. I assume you have a good intake. If not, get one. Either CAI or SRI. It's pretty much a toss up on power. I prefer CAI, but others I respect differ. Either way, you pick up about 20 whp just by that mod alone. If warranty matters, consider the MSCAI. If you are interested in the Hypertech tune, make sure your intake is on their tune list, as the program has built in MAF calibration specific maps for most of the more common intakes.

3. IMHO, it is a mistake, I repeat, a mistake to go full turbo back exhaust on this engine unless you are going to go with a big turbo at some point. It is hugely beneficial to go with a big downpipe and racepipe. That is where the restrictions are. The CBE is extremely free flowing up to and beyond the maximum flow of the stock K04 turbo. So go with a good catted or catless dp/rp combo and save your money on the CBE part of a turbo back, because it ain't gonna get you any meaningful power. It's just a huge cash layout for a change in sound. DP/RP, hell yes. turboback, no.

4. Regarding tune, this really depends on your objectives. You can go with a catless dp/rp and a good intake and run stock tune. I did for over 30,000 miles. But before you go with a dp/rp combo or any aftermarket tune, you absolutely must be able to monitor engine metrics, especially boost and AFR's. You do not want sustained boost much above 18-19 psi on the stock turbo, and do not want much over about 15-16 psi above 6,000 rpm. The tiny turbo just turns into a furnace at high boost levels when rpm exceeds 6,000 rpm with the engine under load.

I like the HT tune because it is MAF calibration specific and appears to tune off of the relationship between boost, timing and exhaust gas temperatures, rather thant focusing mostly on AFR's as with other tuning options. By keeping tuning parameters to try to maximize boost and advance timing without knock, while keeping exhaust gas temperatures at or below 1500 degrees, you get a nice increase in power, without creating harmful engine operating conditions.

It is true that you can develop more absolute power with AP, especially with custom tuning, or with Standback. You can also get in trouble with those tuning options, either by making tuning mistakes yourself, or by having a tuner that does not understand these cars and the conditions that are unsafe for this particular engine taking into consideration its displacement, direct fuel injection system (including the fuel pump limitations), intake, cylinder and exhaust flow characteristics, compression ratio and bottom end strength. You cannot take a cookie cutter approach to building safe, reliable power on this engine.

I want to be able to get over 100.000 miles on this engine.


The HT tune is very mod friendly. It works well with all mod levels, but has its limitations as mod levels reach maximum bolt on level. I'm just about fully bolted except for not having a larger intercooler. At my mod level, I am seeing a slight increase in power, mostly all at the top end of the power curve. What the HT tune brings me that I did not have before is soothness. The power delvery is nice and linear. The removal of the 0-60 mph restriction on the stock tune makes the car a lot more lively and fun to drive around town. All the safety features of the stock ECU are still in place, with the sole exception of a reasonable raising of the power load limits for load cut. The stock ECU will cut power at about 17.5 psi of boost in the higher gears, regardless of rpm, especially in cold weather. The moderate raising of load limits will let you run 18-19 psi without hitting the abrupt cut.

If you are looking to go big turbo, or want more extensive mods such as high flow manifolds, custom cylinder head work, forged internals, modifying compression, messing with camshaft lobe profiles and all that stuff, then HT is not the right choice for you.

I can say that with modest investment -- a good CAI, and a good designed catless DP/RP, the HT tune and some colder plugs, all for under $1,500 dollars, I have knocked over two full seconds off of my 60-100 mph times compared to stock. The difference between 8.1 seconds stock and 6.1 (sometimes as low as 5.8 to 5.9 seconds in cool weather) now.

I could probably knock off another tenth or two with AP or Standback. I could also run the risk of zoom, zoom, boom trying to gain that little extra bit of power.
 
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most likely the DP/TP combo. When I monitored the car with a dashhawk, my mods were catless TP, CBE, CAI, and Turbo Inlet. I would see boost spikes of almost 21 PSI with no tune on the stock DP. As soon as I took the TP off, my boost consistently held 16 psi, no spiking. What happens, is this: the increase in airflow (decrease in back pressure) causes the wastegate to throw incorrect readings, therefore compensating and providing extra boost essentially.
 
Wow thanks! That was a lot of good info msms3. I wasn't really crazy about buying a catback exhaust anyway, all I really want is the dp/rp that's where people net the most gains apparently.
All I have at the moment is a mscai, and all I plan on adding on the intack side is a turbo inlet, I don't want to change turbos, all I'm looking for is something faster than stock without sacrificing reliability. And it's my DD, I got this car as a compromise, I live in Michigan so I need something that I can drive year round but still be fun, obviously it's not a racecar.
I did want an ap because you can monitor engine parameters and tune with it. Figured I could kill two birds with one stone. But if it's dangerous then I'll pass on it.
Ive owned the car for a year and a half and checked the forums off and on so I know a little about the car and I have a background in cars so none of this is new to me but just want to check with people that have done it before ya know. I guess my question is with the mods I'm talking about here what tune would be best for me?
Sorry to the op for jacking your thread lol.

So what is a hypertech tune? Is it a flash tuner like the ap? Are there different levels for different mods?
 
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