Boost creep/overboost due to Test Pipe?

[Parkeway]

After doing a fair bit of Googling, I discovered that the turbo manufacturers all point to more "more restrictive exhaust" as a remedy for creep/overboost (well that and wastegate porting).

With my recent boost spikes of 22.7 using the AP Stage 1 map, I wondered if my innocuous little SU test pipe had something to do with it?

In other words, should I get a custom tune for the current setup (Nano, Inlet, Test Pipe) or replace the test pipe with the OEM midpipe?

Would that be a safer bet?

(/puts the work gloves on awaiting a reply....)

 

[Circle9]

Why don't you just put your OEM midpipe on and see if you still have any boost creep?

 

[Sport6]

Yeah do the cheap (free) stuff first to figure out if its the problem.

 

[OJ Bartley]

How do you like that combo (Nano, Inlet, Test Pipe) aside from the boost creep? I think that's what I'll probably end up with, and possibly replaced TMIC... but I'd love to hear your impressions of the car before and after.

 

[MSMS3]

There is a big difference between short term boost spikes and long term boost creep. The former is a temporary spike in boost during the initial "on boost" application of load to the engine. The latter is a situation that occurs after the initial load to the engine and the hitting of the targetted boost level. With boost creep, the boost continues to gradually rise and hold at a point considerably above the target.

It sounds like you are getting some boost spikes at 22 with a settling down to the boost selected by AP for your particular tuning map.

Check with AP.

Garrett has probably the most comprehensive web site for troubleshooting turbo issues and the clearest "Turbo 101, Turbo 102, Turbo 103" and "Turbo Optimization" turorials.

http://www.turbobygarrett.com/turbobygarrett/tech_center/tech_center.html

I could not find anything there suggesting that restricting the exhaust would be beneficial for either creep or spike. In fact, porting of the internal wastegate, or going with a larger external wastegate (the only two suggestions by Garrett to address boost creep), would require more exhaust flow, rather than less.

Boost spike can be addressed in your tune and AP should be able to help with this.

Serious MS3 power junkies here are saying that short term boost spikes much higher than 22 lbs are common with their tunes and mods and that the ECU will engage boost cut or fuel cut to protect against anything that is truely harmful to the engine tune. I do not run AP, but understand that while it has raised some of those limits in some of its tunes, the "safety net" is still there. Check with AP.

 

[Parkeway]

MSMS3

Thanks for the head's up! I'm from a world of roots-type superchargers and boost levels that were not under ECU control, but rather under pulley control!

After dropping back to the stock map, I'm sure you are correct, as the log still shows spikes in the 20psi range. This is with only a Nano, Inlet and Test Pipe. I can live with that, but like anything, I want to maximize the efficiency and safety in the setup. I applaud COBB for leaving the "fail safes" in the ECU, as I have hit some pretty extreme levels on just some of the more basic maps.

OJ

As for these mods, I love them. I am all about making the path cleaner. I have also noticed that even with a Nano, heat soak is pretty much a moot point at any speed. I am in the process of compiling a few runs with the camera rolling to document how quickly the temps shoot down after a stop: This is BEFORE my ETS TMIC arrived!

Still, I think the best money I've spent so far is the MM. Man that thing changes this car's behavior dramatically!!!

Thanks all for all of the input here - will be going custom tune-dyno this week.

 

[ericrapp]

i look forward to the your tuning with the ETS installed. Is it the 3.25? I would think you will have some more compressed airflow to match up with some fuel adjustments. And find some more power! Please let us know and good luck

 

[Speed3Rookie]

MSMS3

Thanks for the head's up! I'm from a world of roots-type superchargers and boost levels that were not under ECU control, but rather under pulley control!

After dropping back to the stock map, I'm sure you are correct, as the log still shows spikes in the 20psi range. This is with only a Nano, Inlet and Test Pipe. I can live with that, but like anything, I want to maximize the efficiency and safety in the setup. I applaud COBB for leaving the "fail safes" in the ECU, as I have hit some pretty extreme levels on just some of the more basic maps.

OJ

As for these mods, I love them. I am all about making the path cleaner. I have also noticed that even with a Nano, heat soak is pretty much a moot point at any speed. I am in the process of compiling a few runs with the camera rolling to document how quickly the temps shoot down after a stop: This is BEFORE my ETS TMIC arrived!

Still, I think the best money I've spent so far is the MM. Man that thing changes this car's behavior dramatically!!!

Thanks all for all of the input here - will be going custom tune-dyno this week.

any updates?

 

[ymic]

The boost spikes are because of the AP tune, which is why I sold mine and went to the CP-e standback. I'm catless, DP/Test Pipe and no longer have spiking problems...

 

[matsuda]

I could not find anything there suggesting that restricting the exhaust would be beneficial for either creep or spike.

The boost control system of the MS3 cannot factor in faster spool-up (resulting from a less restrictive exhaust) unless it is reprogrammed.

It is a closed loop system and the spool-up time is essentially a constant in the algorithm.