diagnosis for excess boost in warmer weather - AP, intake, Forge DV, stock exhaust

[08_ms3_gt]

first off, my mods:
1) HKS SRI
2) Forge BPV w/ blue spring, zero shims
3) AP with 1.03 Stage 1 MSCAI2 map - confirmed to work w/ the intake via logs

i installed and have run the AP in colder temperatures thus far. the most KR i saw was a peak of 1.0 at WOT, which didn't seem of concern b/c i've read that 2.0 is where i should worry. i also get part-throttle KR every once in awhile.

the temperatures are now higher, however - coming up to 60*; hot as hell lol.

i hooked up my new dashhawk (thanks wassup) and went for a spin this AM. i hit KR of 2.1 on the first run. tried again, hit 2.1 again. WTF?!??!?!

next, i tried a long/hard 4th gear pull, and what i found is that the boost was creeping significantly. it settled in in the 17's then went to 18's, 19's, then KR 2.1 2.3 2.5.

i'm guessing it's the Forge valve. advice, por favor? swap to yellow spring?

[SSinstaller]

Your BOV has nothing to do with boost rising. It's just the warmer weather. You might want to try a different tune..

[rodrigo]

first off have u tried the stage 1 sri map??? I know u say mscai map works but dont quit there. As far as boost being higher in the heat, I have experienced this as well.....one would assume its called "thinner air"...........you need meth!!! you can get the advice from 200 guys here, to lower your tune , to add this or take that away.....simple fact here son, you need meth!!! its $330 bucks or so and 1-2 hours max to install and maybe $15 a month usage of meth, but........... the reward........its always winter with it........KR drops to nothing and you dont have to worry about what you are experiencing.....as far as any other solution......stock tune man thats it......in the heat you will knock. Let me say it agin in case you didnt hear me...get meth. (devils own stage 2 kit) dead serious on this!!!

[08_ms3_gt]

i'll try the SRI map. i guess i figured it was the Forge valve b/c the map is configured to hit 18psi and the valve closes more tightly than the stock unit. i might try the SRI map with the stock BPV.

i've DEFINITELY given consideration to meth, but i'm avoiding significant modding for the time being. i want to throw an exhaust, FMIC, and w/m at the car, but it's more involved than i want to be.

i'm under the impression that you have to drill a hole b/w the TMIC and intake manifold for the w/m nozzle, aka the install cannot be undone for a dealership visit. is this correct?

[rodrigo]

well there are 3 ways u can do meth.

a) drill and tap a hole in your stock tmic coldpipe (when u take it to dealers you can put a plug in it.
b)get a fmic and drill a hole in coldpipe
c) get a ptp freeze plug type nozzle

most people think meth is involved , as did I before getting it but from never having dealt with the stuff before to know I can install a kit in under an hours time with my eyes closed, it is a simpler mod than getting a fmic..seriously!!!!! the stage 2 devils own kit is by far the simplest to hook up and has the least amount of mechanical parts in it (pump..thats it) not a large percentage here deal with meth but honestly, and this is not an insult, is out of ignorance. Once they try meth they all understand what they were missing. Dont take my word for it, ask the owner of this forum.

[08_ms3_gt]

i'll take w/m under consideration. i do like the idea but think it's too difficult to swap out. the freeze plug would make it possible, however.

for now, i've installed the CobbSRI map instead of MSCAI2 and also swapped in the stock BPV. once the ECU studies hard and learns its shit, i'll see how the boost/KR are looking. hopefully all will be well, after which point i might try the Forge valve again to determine if the issue was the map or the valve.

[Doc]

lenny has hit the nail...

M...E...T...H

[SSinstaller]

Originally Posted by 08_ms3_gt i'll take w/m under consideration. i do like the idea but think it's too difficult to swap out. the freeze plug would make it possible, however. for now, i've installed the CobbSRI map instead of MSCAI2 and also swapped in the stock BPV. once the ECU studies hard and learns its shit, i'll see how the boost/KR are looking. hopefully all will be well, after which point i might try the Forge valve again to determine if the issue was the map or the valve.

Glad you changed the map, but there was no need to remove the BOV. It is physically impossible for your BOV to raise the boost pressure in any way... You may see less boost withe the OEM valve, but that is because it leaks..

[08_ms3_gt]

thanks for the help guys. we'll see how the map pans out. i realize w/m is a more-or-less foolproof solution to the KR problem, so i'll view that as a last resort for now.

and Doc, your avatar is awesome

[smakdown61]

This is what I understand to be the reason you see higher boost in warm weather:

The ecu itself doesn't give a rats ass about boost. The ecu seeks a specific torque target. It adjusts boost based on this torque target. In the winter, you generally see less boost b/c the cold dense air allows more fuel so better combustion. Car doesn't need to make as high boost to reach its torque target.

In the hot weather, the VE goes down b/c the air is hotter and less dense so the car needs to raise boost to hit the same torque target. Also, with the car pulling timing once the IAT's get high enough, that would be another reason for it to try and raise boost a bit.

I could be completely wrong tho...

[Hectik1]

Originally Posted by smakdown61 This is what I understand to be the reason you see higher boost in warm weather: The ecu itself doesn't give a rats ass about boost. The ecu seeks a specific torque target. It adjusts boost based on this torque target. In the winter, you generally see less boost b/c the cold dense air allows more fuel so better combustion. Car doesn't need to make as high boost to reach its torque target. In the hot weather, the VE goes down b/c the air is hotter and less dense so the car needs to raise boost to hit the same torque target. Also, with the car pulling timing once the IAT's get high enough, that would be another reason for it to try and raise boost a bit. I could be completely wrong tho...

This is what I have read before and agree with...

[08_ms3_gt]

Originally Posted by smakdown61 This is what I understand to be the reason you see higher boost in warm weather: The ecu itself doesn't give a rats ass about boost. The ecu seeks a specific torque target. It adjusts boost based on this torque target. In the winter, you generally see less boost b/c the cold dense air allows more fuel so better combustion. Car doesn't need to make as high boost to reach its torque target. In the hot weather, the VE goes down b/c the air is hotter and less dense so the car needs to raise boost to hit the same torque target. Also, with the car pulling timing once the IAT's get high enough, that would be another reason for it to try and raise boost a bit. I could be completely wrong tho...

i'm on board with your theory, but unfortunately it just makes my situation suck more. the Cobb map 'targets' 18psi +or-1.5psi, so perhaps the +or-1.5 is for hot/cold operation. before my KR started up, the boost was climbing towards 20psi or more.

even if w/m would eliminate my KR, i still want to keep the boost controlled. i'm coming up on 50miles on the map 'learning', so hopefully in the next day or 2 i'll be able to do a log or something.

perhaps i need a custom tune or get the 'right' intake. i've noticed ppl talk of KR when it's warmer, but not overboosting..?

just to clarify - this couldn't have anything to do with tubing/loose clamps, right? i figure that if there's too much boost then everything must be tight.

would an MBC be a potential solution? idk if MBC's are compatible with Cobb maps.

[08_ms3_gt]

UPDATE

i switched to the SRI map and stock BPV.. didn't like the stock BPV so i put the Forge back in.

with the SRI map and Forge BPV, i was getting 'typical' knock values most of the time. maybe KR spikes of 0.7 in 3rd, 1.0 in 4th, and 1.4 in 5th. boost is a bit low, generally around 16.5 or so PSI.

i've found however, that every once in awhile i still get BIG KR like w/ my original post. KR climbs into the 2's, maybe 2.8, before i cut throttle. it appears to coincide with loading up the engine around 3k as opposed to closer to 4.

it just happened tonight. i was going WOT, short-shifted 2nd, and as boost peaked in third i got up to 2.8 KR before i cut the throttle. FWIW my boost normally peaks around 20 or 21 PSI.



anyone have insights on this? why it is happening? should i worry about it or just monitor the KR when going WOT? it's very sporadic and thus i haven't been able to log it.

[twisted99]

Don't load your engine below 3500rpms. Turbo motors do not like that. way too much pressure with out the engine spinning fast enough to deal with it leads to knock and eventually boom

[08_ms3_gt]

Originally Posted by twisted99 Don't load your engine below 3500rpms. Turbo motors do not like that. way too much pressure with out the engine spinning fast enough to deal with it leads to knock and eventually boom

i'll have to get this thing logged. i'm not 100% sure of what RPM's it occurs at. i also wonder if it's a fueling/AFR issue. the DH alarms at KR above 2 so i can't see other variables, but i don't want to change it b/c it helps me to kill power before any damage is done.

it definitely seems possible that it's a load issue at lower RPM's. the Forge valve may increase the problem because it causes a faster turbo spool-up than the stock valve (in my experience).

weird thing is, i can't get the problem to occur just by loading the car below 3.5k - i actually tried to. it only seems to happen after short shifting on a WOT run... FML.