Overboosting conditions?
 

Hi all,

Just a quick question:

Here are my mods...

COBB Accessport V3
COBB 3" downpipe
COBB RMM
COBB TIP
CPE TMIC
CPE Manifold
Autotech HPFP internals
COBB SF AIRBOX
COBB SRI
3" mandrel bend from dump to custom magnaflow muffler
Resonator delete
FORGE V1 BPV

I got all of my mods put on at once except for the BPV and the CBE (got the place to put a 3" flange from dump and run all the way 3" to magnaflow instead of reusing piping. I also got custom tuned in summer heat in Australia @ 20 psi. It is now winter down south here (av 46f here or 8c)

Thought I might see if I wacked anything out so I got a 5 minute run on the dyno just to double check. Dyno run threw a CEL of overboost conditions and we had to stop as was 5pm and time to go home. Booked it in for next week to retune.

As I am learning about this as I go, could the combo of BPV, exhaust increase and temperature drop have caused overboost? I am seeing boost increase to about 22.7psi when WOT in 4th. I did notice first increase when put on BPV, but it never got tuned so I ignored it...was only a psi or so (could old bpv be leaky?).

What do you guys think? Thanks :)

I have ordered a corksport bolt on turbo upgrade, but on back order so I thought I better tune it in the meantime and not leave it until then...was going to just do turbo and tune :/

Seeing 22.7psi just means you are maxing out the 2.5BAR MAP sensor and you are likely getting more boost than that. The cold weather could definitely be the cause of the overboost, especially if the tune doesn't have the necessary compensations for colder weather.

Also important to mention that the K04 inherently temp-overboosts when you punch it around the peak powerband (4K-4.5K) due to the wastegate control system. Lots of things can cause overboost but BPV likely isn't one. The ECM is somewhat tolerant of this temp overboost situation. You should have a summer and winter tune ideally. Even more ideally, you should learn to tune yourself and redo it everytime you notice a hiccup or fueling trims/boost curve start to wander. The "better" tune is always one you understand and can make changes to suit your vehicle and driving preferences. That or be prepared to shell out a few hundred bucks to the skilled e-tuners on the forum.

I agree with @Mike@Stratified; I was seeing 22.7 psi on my K04, went with the 3 bar map sensor and it was actually reading ~25psi.

I guess I don't understand the compensation for temperature comments. If your tune is capable of hitting X boost in hot weather, can't you set up the error compensation to hold that in the cold?

The real answer is probably to load tune?

THIS^

A tune can be made to run well in all conditions

You are on the right track, you can use load and several other compensation tables to keep boost in check during differing temperatures and elevations

What tuners are you looking at?

A full custom Freektune can be had for $200.

They're OTS+ map is even cheaper.

Thanks guys for the replies. I am starting to thing the drop in temperature has a major part in this. My original tune as I said was probably done at 90f and now its 42f (I had to convert from c lol). Yesterday I went out during the day and it was fairly mild. The boost held at about 19.5 after WOT in 3rd and didn't budge. Went out that night and it shot up to 21.5 (not off the MAP, but close!) with the same effort applied. Funny, I gave it hell in 4th and it stuck at 19.5, where as 3rd really overboosted..

Could me changing the exhaust from 3" COBB to stock piping and muffler TO 3"COBB to straight through 3" piping to magnaflow??? Straw that broke the camels back?

Thanks :)

Might have helped. But the temperature change was probably the key. Like said above, a good tune should control that

Like I said before. The way these crappy turbos are, the faster the boost comes on, the more they overboost which is why I always used 4th for logging. The overboosting when you punch it in the middle of the power band won't go away. Non-emission-section exhaust upgrades do practically nothing functional. Reading your last sentence was hard so I'm assuming that's the only thing you said you changed. You could also get ATR and go in there and change your boost targets, WGDC, and IAT vs boost tables like everybody else does if it bothers you that bad.

I was seeing some overboost as well, especially when up shifting at higher RPM's with like 2.10 calc load. Contact a tuner for best results. I went with Nishan he does a bang up job! Smoothed my spikes out right away...

Also look at the Guardian Angel by Stratified. Saves your motor from going boom.

I have ordered the guardian angel through edge, but hasn't shipped yet as might be on back order. Overboosting might not go away as such, but overboosting past your MAP sensor can read is not good! Thanks for advice.

Also changed from stock BPV to forge V1 and well the massive change in temperature from boiling to cold.

Get it tuned by a real Protuner that know how to use Load /Hybrid Tuning before the thing ties the rods in knots during cold weather.

Hey fellow aussie! Getting retuned tomorrow and will discuss this with tuner. I go easy on my car, never even hit redline unless its spinning. Never seen a race, I just enjoy the pull. My tuner owns an MPS6 with many MPS tuned to good effect. Only time its ever overboosted was on dyno anyway...which was once.

Summer dyno attached..