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Good morning everyone, I have a quick question that I'm trying to figure out. I recently switched to a Torque Performance stage 3 tune.

2011 WRX Mods:
Process West TMIC
Forge BPV
Cobb Catted DP
DW65C fuel pump
Grimmspeed EBCS
NGK 1 step colder spark plugs
Grimmspeed AOS
AEM Intake

I'm using a tactrix cable and rom raider to tune my car. The tune that I have on the car now has the boost set to 20psi. My car only sees a max of 18.72 psi according to manifold relative pressure in logs (I would upload them and post but I'm at work and google docs is blocked , I'll post later). I'm also running slightly rich. My question is about boost set in romraider and actual boost seen. When I was just with a Cobb DP, AEM intake and a tune I saw 19.3 psi according to manifold relative pressure (Tune set at 19psi).

This is just for learning purposes, I'm testing for boost leaks tomorrow and getting the map revised once my wideband comes in. What I'm thinking is the reason why I'm not seeing the 20+ psi that the map I have on the car now is set at is because of pressure drop from the larger TMIC? The car pulls great, I get no knock. According to my MAF I'm actually pulling in 20g/s more air at peak rpm than my stage 2 so I've probably gained about 15-20whp over just my DP and intake tune with the stock TMIC. Either that or I'm completely wrong and I do have a boost leak but my car holds that 18.72 psi consistantly at WOT leading me to believe there must be something more because wouldn't the car adjust to get to that 20psi even if I had a very minor leak? I've even driven at partal throttle to see if it holds low amounts of boost consistantly and it seems to. Again just trying to learn. The issue will get solved. I'm bored at work and curious and couldn't find anything on the internet/nasioc.

What is being used to indicate your pressure reading, gauge or ECU value? You mention pressure drop differences across the IC, this should be meaningless if you are taking your pressure reading somewhere past the IC outlet. If taken before the IC, then that could definitely be the cause of measurement difference.
If the lower pressure differential in the IC is not the cause, I would check your EBC logs. When comparing your before and after boost readings, did you have the EBCS rate in both? If the duty cycle is the same in the before and after, then I would say there is cause to think there is a boost leak.

ECU value. I have no idea where the pressure reading is taken from. I've just read a few places that say you have boost set to 20psi. If you introduce a larger amount of area to charge it can lead to a drop in boost, especially when using a stock sized turbo. My intercooler doesnt have specs on pressure drop and I don't know what the pressure drop is on the stock tmic either. I'm not really sure I understand the EBC logging part. I log what my tuner tells me to log and I send it back to him via email.

Make sure you are logging "Manifold Relative Pressure (Corrected)". Some of the other values will not go past 18.5ish PSI. As Zak said, the larger TMIC shouldn't really affect the boost your running. What is your Wastegate Duty Cycle like? Your Stg 3 tune might need some tuning, lol.

I can think of a couple of things:
Your new TMIC could be causing a slight pressure drop vs the stock if that is what you are measuring against. I would't expect this to be the case though.
Are the logs in the same gear? Max boost in 3rd will not likely be the same as max boost in 4th.
Does the ECU adjust the boost due to intake temp charge? I don't recall the older ECUs doing so, but the newer might. Logging in 70 degrees will likely yield different results than in 30 degrees.
A boost leak before the intake manifold is usually apparent. A hole in an hose or intercooler will usually make a good deal of noise.

drwrx wrote:Does the ECU adjust the boost due to intake temp charge? I don't recall the older ECUs doing so, but the newer might. Logging in 70 degrees will likely yield different results than in 30 degrees.

It doesn't take intake temperature in to account, but it has a PID controller built in that will sense boost error (I should be at 20, I'm at 18, I need to go up some) and correct it. Sometimes for larger turbo's like mine, you end up adjusting these, but that isn't the case here.

It is manifold relative pressure corrected. I hit a max with this new stuff of 18.72 psi and tapers after about 4700rpm. With my previous setup up of just a downpipe and intake I would easily hit 19.3psi. I do 3rd and 4th gear WOT logs from 2k-6/7k. Checking my romraider ecu editor the boost is set at 19.99psi. I think I'm leading towards a boost leak being the problem. I guess I'll be finding out tomorrow lol.

https://docs.google.com/file/d/0B14AxKV ... sp=sharing
https://docs.google.com/file/d/0B14AxKV ... sp=sharing
https://docs.google.com/file/d/0B14AxKV ... sp=sharing
https://docs.google.com/file/d/0B14AxKV ... sp=sharing
https://docs.google.com/file/d/0B14AxKV ... sp=sharing

LOGS!! I made sure to zip tie everything and to re tighten the intercooler piping clamps and I think that might have done it. If it weren't raining I'd go do some logs but I guess it'll have to wait until tomorrow.

I think I figured it out. I wasn't running a powerful enough spring in my BPV. I think it was opening while at WOT. It make sense. I'm going to do some logs tomorrow.

I usually don't see problems with the stock spring until 21 or so PSI. After that, you can either replace the BOV or do the dent trick

It would not be entirely, unheard of. My 02 WRX wagon had a boost fluctuation issue right around 17.5 lbs. that was caused by a week spring on the BOV.
The adjustable AVO unit solved the problem.

Also have you guys ever heard of the ecu limiting/ lowering boost because of cold weather? I had someone tell me that I'm not hitting all the boost I should be because of lower intake temps and the way the map works to lower boost because of it. I can't use the stock bpv since it has a diamond gasket and my process west requires a circle gasket.

It might be a new thing with the 08's, but I can tell you the 04-05's don't have that. There speed limiter (stock is reduce boost by 6% till 30ish MPH), but temperature compensation is all handled by the PID controller.

VERY basic way boost control works: For a given requested load, start at initial wastegate duty, add (actually subtract, but that's a different discussion) duty cycle until you hit the requested boost. From initial wastegate duty on, the PID controls how fast boost comes on, controls over boost, and boost corrections. This is why you don't set your initial wastegate duty at the same duty cycle that you would make your target boost at; It would essentially cut out the PID controller and not allow it to control your boost. Normally you set your wastegate duty at half of what your target WG duty is so that it has enough room to do its work and adjust for temp's, altitude, etc.

Update

Boost is fixed, I never got tested but I replaced my spring in my bpv and it seemed to fix it and my tuner didn't have a problem

Now for what I'm experiencing now.

I can't seem to figure out why I'm getting knock in 4th gear and not in 3rd. I have a 2011 wrx with a TP stage 3 tune. The load is the same, every parameter is the same at each rpm of both 3rd and 4th and I'm getting small instances of -1.4 degrees of timing being pulled. Also everytime I reset the map, i wont get knock at all the first time I do a 4th gear pull but every time after that I do. Any ideas?

https://docs.google.com/file/d/0B14AxKV ... sp=sharing
https://docs.google.com/file/d/0B14AxKV ... sp=sharing
https://docs.google.com/file/d/0B14AxKV ... sp=sharing

I had eric tweak the map again and I got even worse knock after that so I went back to this map. I only knock in 4th gear at WOT and it happens off and on. I thought it might be shit gas but I tried a different place and the knock both times between sunoco and gas that is sold on andrews afb yielded the same results so obviously it is the tune.

It is harder to push the car in 4th. The pistons won't accelerate as fast because of the higher load.
I bet if you took the car to a proper environment for a 5th gear run, would be worse.

zaxrex wrote:It is harder to push the car in 4th. The pistons won't accelerate as fast because of the higher load.
I bet if you took the car to a proper environment for a 5th gear run, would be worse.

So is this normal? I don't want to see any knock but from what I've read around 1 degree of knock and timing pulled is the norm

Here is why it's happening

As you move up in gears, you're at a specific load for longer, and as Zak pointed out, the piston doesn't accelerate as fast. Because of this, heat builds up in the cylinder, which causes the gas to ignite before the spark plug goes off (because of all the extra heat and pressure), causes knock. 4th gear pulls will be worse for knock than 3rd, 5th worse than 4th etc because of this.

The reason your tune is fine when you initially reset the ECU is because your IAM is probably less than 1 (stock is .5), so your not getting the full timing of the map. Slowly, the car starts increasing IAM to get to 1, meaning full timing in the map, and that is when you start seeing knock. It will then use the fine correction to correct the knock in that area of the map that you are knocking in. Your tuner should start your IAM at 1 so you're seeing full timing at reset.

Most tuners will tune a person for 1-4th, but not really 5th (and 6th in STI's) because they will never reach those gears in high boost for long periods of time. Track cars will usually run lower timing, but higher boost to prevent that problem. The lower timing helps with the knock, and the higher boost helps with power. The problem is, higher boost also makes the engine not last as long, which is why "street" tunes use timing to get better numbers. This isn't good for when you are doing long 5/6th gear runs though.

Example: With my car, I run 13-15 degrees at peak torque now. For the street, this is great Give me tons of power down low and with relatively little boost (22-23psi). Back with my big turbo, built motor, and racing map, I ran 11-12 degrees at peak torque, but at 25-28psi.

Hope that helps

Sabre wrote:Here is why it's happening

As you move up in gears, you're at a specific load for longer, and as Zak pointed out, the piston doesn't accelerate as fast. Because of this, heat builds up in the cylinder, which causes the gas to ignite before the spark plug goes off (because of all the extra heat and pressure), which is knock. 4th gear pulls will be worse for knock than 3rd, 5th worse than 4th etc because of this.

The reason your tune is fine when you initially reset the ECU is because your IAM is probably less than 1 (stock is .5), so your not getting the full timing of the map. Slowly, the car starts increasing IAM to get to 1, meaning full timing in the map, and that is when you start seeing knock. It will then use the fine correction to correct the knock in that area of the map that you are knocking in. Your tuner should start your IAM at 1 so you're seeing full timing at reset.

Most tuners will tune a person for 1-4th, but not really 5th (and 6th in STI's) because they will never reach those gears in high boost for long periods of time. Track cars will usually run lower timing, but higher boost to prevent that problem. The lower timing helps with the knock, and the higher boost helps with power. The problem is, higher boost also makes the engine not last as long, which is why "street" tunes use timing to get better numbers. This isn't good for when you are doing long 5/6th gear runs though.

Example: With my car, I run 13-15 degrees at peak torque now. For the street, this is great Give me tons of power down low and with relatively little boost (22-23psi). Back with my big turbo, built motor, and racing map, I ran 11-12 degrees at peak torque, but at 25-28psi.

Hope that helps

awesome thanks julian, that makes perfect sense! I guess now I'm wondering if it's ok or safe since I get timing pulled i 4th. I'm looking into getting protuned by element tuning but I dont know if I need it if this is common and will always happen.

Phil is an amazing tuner. He knows how to work around it and will definitely give you a safe tune.

It's safe, don't worry. The stock ECU will pull timing quickly, so no harm will come to your motor unless you don't fix it for 10 years, lol.

Lol you guys are awesome. People on nasioc are all like me and don't really know much about cars other than stuff that's regergitated and probably is wrong. It's nice to hear about the underlying reason behind why things happen in my car.

Happy to help!

Every once in awhile I go on there to help, then get shot down for being wrong... and then something blows up, and they PM me for help.

Julian is a pretty smart guy, just don't confuse pre-ignition with knock/detonation or ask him about the difference between rotary and radial engines.
In his scenario above, the fuel is igniting before the spark, timing is irrlevant. This is pre-ignition and is violent.

lol, oops. Zak is correct. Pre-ignition is when the mixture ignites before the spark. Knock is when multiple ignitions happen in the cylinder uncontrolled, causing spikes in pressure.

Brought my laptop but only had enough time/ room to do a quick 2nd - 3rd gear pull. -1.5 fine learn knock in both 2nd and 3rd. How bad is this? https://docs.google.com/file/d/0B14AxKV ... sp=sharing

it doesn't matter anymore I dropped the money to get protuned at agile automotive tomorrow. Phil wont touch the car because he thinks its damaged.... lol