[atlharry]

Originally Posted by phil_

I'm monitoring boost and the high is reading as 17.2?

91 octane map 1.1

Have you done a datalog? Can you post it?

[Clap135]

Originally Posted by phil_

I'm monitoring boost and the high is reading as 17.2?

91 octane map 1.1

What you are seeing is a boost spike once you get off the throttle.

[phil_]

Originally Posted by atlharry

Have you done a datalog? Can you post it?

I reset the monitor and did a 2nd gear pull to about 6500rpm and the high read 16.3. It's currently -12C here shouldn't I be boosting less?

I don't mind data logging but isn't this a dangerous zone for 91 octane?

[atlharry]

Originally Posted by phil_

I reset the monitor and did a 2nd gear pull to about 6500rpm and the high read 16.3. It's currently -12C here shouldn't I be boosting less?

I don't mind data logging but isn't this a dangerous zone for 91 octane?

Like clap said, it's most likely the boost spike seen when you get off the throttle. Since our boost sensors are pre-throttle, you're gonna see a spike every time you get off the throttle (it's also misleading because it doesn't represent manifold pressure in that situation). Better way is to datalog vs recalling high boost on the gauge so you can see sustained readings.

[mithiral67]

Yea, look at your logs, odds are you didnt sustain boost higher than 14 for more than 1/4 a second.

[phil_]

You guys are right it is a boost spike. I'm new at this

Attached is the log. Lines 3649 to 3989 is a rolling start 1st gear to 3rd gear. I stopped at around 6300rpm in third.

What's wrong with the A/F ratio?

[Clap135]

Nothing is wrong with your af. Your throttle is fine, your boost is only 11.x psi throughout most of 3rd gear. I am wondering if you are looking at the right things?

[themyst]

Since the Cobb is targeting load, it doesn't surprise me one bit that certain cars are boosting less than others, case in point, Clap135's boost levels compared to say, Alans.

[Clap135]

phils boost is low, but also his car is targetting a different load value as well. He is only hitting 150ish, I see almost 180, holds 170 for a while, then mostly 160s falling to 130-140 by redline.

[Gimlet]

91 vs 93 octane? RWD vs AWD? Just throwing ideas out there -

[Charleston335]

Question: So do you guys think a Cobb 335 stage 1 tune with DCI will be able to take a 2009 stock M3??

[Clap135]

probably not

[atlharry]

Originally Posted by Gimlet

91 vs 93 octane? RWD vs AWD? Just throwing ideas out there -

Yeah, he stated that he was on the 91 map.

Here's a graph of one of Phil's WOT runs for those that like em.

[Alan l.]

all of my logs were done on the 93 octane map. I've seen shift spikes as high as 20psi on my car

[atlharry]

Originally Posted by Alan l.

all of my logs were done on the 93 octane map. I've seen shift spikes as high as 20psi on my car

overboost spikes or throttle lift-off spikes?

[Charleston335]

Originally Posted by Clap135

probably not

But I've seen a JB3 on Map 5 beat a new M3 and doesn't the Cobb dyno more than a JB3 Map 5?

[Clap135]

Originally Posted by Charleston335

But I've seen a JB3 on Map 5 beat a new M3 and doesn't the Cobb dyno more than a JB3 Map 5?

Ive seen a stock 135 beat a stock e9x m3, doesnt mean anything. Properly driven, a m3 is capable of 114ish traps, no 12-13psi is touching that.

[Clap135]

Originally Posted by atlharry

overboost spikes or throttle lift-off spikes?

throttle lift off spikes...every tune has these

[atlharry]

Originally Posted by Clap135

throttle lift off spikes...every tune has these

I understand, but since he mentioned it, I just wanted to make sure that's what he meant.

[MDORPHN]

Originally Posted by Clap135

throttle lift off spikes...every tune has these

Yes, I also log them on my twin screw supercharged Z3 M Coupe.

Can you -- or anyone else -- explain to me why they occur?

Thanks.

Neil

[atlharry]

Man, that 91 map is definitely conservative... looks like it starts dropping load targets at around 5800 RPM...

[Clap135]

Originally Posted by MDORPHN

Yes, I also log them on my twin screw supercharged Z3 M Coupe.

Can you -- or anyone else -- explain to me why they occur?

Thanks.

Neil

Don't know about your car but on this car the map sensor is located before the throttle body. throttle body shuts closed, air is blocked from going into the engine. That air is now pressurized btwn the turbos and the throttle body untill the bov goes off. Being that the map sensor is btwn the turbo and throttle body, you get the idea.