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Old 03-19-2006, 07:06 PM   #1
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theory on boxster bolt on problem

First off, hello to all. Now to the theory:

This may or may not apply to the Boxster S (we own an 02)- but the symptoms and setup are the same.
I sell Nissans. The 350Z, one of which I own, was having the same issues with headers, exhaust, intake, and chips not adding much power, or worse, creating a net loss. The problem in the Z's anyways, was the knock sensor. As you increased airflow, the ECU sensed a leaner mix. Since the engine is set up out of the box to control emissions first, protect the engine second, and develop power last, the ECU would retard the engine, instead of dumping more fuel. The more stuff you did, the more it would pull it back. Even bigger injectors won't help. as the feul flow is control by the central ECU - same prob with new fuel maps. Sure the curve would call for more fuel - then old knock sensor pulls it right back.
The solution for the Z was to reflash the ECU disabling the knock sensor and the fail safe mode activator command, as well as a dummy plug that gave the MAF a constant intake temp reading of forty below.
I know that we are talking about two very different cars here - but both have vairable valve timing, MAF's, and knock sensors. These items work the same no matter what car they are in.
What do you guys think?
Has anyone tried this on a Boxster?
PS
had to repost - somehow or another I posted twice......then deleted the reply. sorry bout that.

Last edited by turtle; 03-19-2006 at 07:11 PM.
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Old 03-19-2006, 07:10 PM   #2
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from kiasattampabay

"have a Boxster-S and upgraded the intake with EVO, by-pass cats, and sport muffler from Dansk along with GIAC ECU remapping. I have noticed a real difference in power from the start all the way through the RPM. In fact I just came across another post on Pete's Boxster page from Andy in Oregon that done the EVO and ECU but with headers and sports cats and dyno the car before and after and he is getting 35+ HP at the rear wheels.

The GIAC engineers feel that the ECU re-mapping gives more gain on the 2.5 and 2.7 than the 3.2 (they feel Porsche tuned the S more from factory than non S).

I know there are lots of postings that say no gain, but you have to do combination of things together. Just putting EVO without re-mapping will not give you that, or installing the header without the more air-flow and ECU.

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Old 03-19-2006, 07:21 PM   #3
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ok - I can see that. But on the other hand, many accounts claim otherwise...just as many,such as yours, do.
I have had a few cars, and modded them all. I ran across this prob with my Z, and many of my friends with modern natural induction cars have had the same issue.
HOWEVER - to say that each car is the same is crap. We have a dyno at work (no emissions control in Tennesee makes for a lot of fast cars :P) and I have seen a 20RWHP difference on the same vehicle from baseline.
What I am getting at is I would like to see a consenus. It would be good for us all.
As for dyno inaccuracies - for me, it is the difference in the controls - that is to say, is it the same tank of gas? Is it the same humidity? How about the temp?
Has anyone mapped ECU response in these cars with a CONSULT piggyback?
If not, who sells the software for the diagnostics? I will graph it out if I can find it.
It would be interesting to see timing and injection volume graphs.
PS
I am not a mechanic, but have acess to bunches. Any tips would be welcome, and I will share all charts and findings after. I am really interested in ECU fuel response ratios.
Thanks,
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Old 03-20-2006, 08:51 AM   #4
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the limits in the boxster motors are likely designed into the valve train. there's only so fast air can enter a cylinder through a given sized hole.

as for the knock sensor issue, GIAC and others have been tweaking these settings for years (i.e. optimizing for 93 octane, 100 octane, etc.)
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Old 03-20-2006, 08:55 AM   #5
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Will GIAC do a custom ECU tune like you are suggesting?
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Old 03-20-2006, 09:24 AM   #6
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Quote:
Originally Posted by turtle
The solution for the Z was to reflash the ECU disabling the knock sensor and the fail safe mode activator command, as well as a dummy plug that gave the MAF a constant intake temp reading of forty below.
Hmm.. That's pretty nuts. So you completely fake out the computer on IAT and it never can do any sort of compensation based off it.... that's not as bad as disabling the knock sensor though! Did you have some other form of auxiliary knock control or are you just waiting until the car coughs up a piston?

Yeah, there is a bit of a "buffer" in what Nissan thinks is safe and what the average tuner thinks is safe, but still... completely disabling one or the other of those two sensors is a recipe for disaster.
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Old 03-20-2006, 09:38 AM   #7
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"Yeah, there is a bit of a "buffer" in what Nissan thinks is safe and what the average tuner thinks is safe, but still... completely disabling one or the other of those two sensors is a recipe for disaster."
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I can see how you would think that.
BUT notice that the MAF reading is set to factory default failure code - forty below. Colder the air, the denser the air, less particles can be suspended in it - so the the ECU compensation by running the richest it's program will allow. After that, just make sure your mapping is right so that you don't run too rich.
As a matter of fact, fouling plugs has been our only problem. We haven't had a single lean out in about 20 cars over the last 3 years, and at 52k miles my Z is just fine.
As for GIAC..I don't know. That is why I am posting, to gather info. It's always just a matter of electronics these days. If someone knows where I can buy Porsche diagnostics for out CONSULT station here at the dealership our Techs could figure a lot out.
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Old 03-20-2006, 09:55 AM   #8
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Ahhh.. I see, yeah that is rather cold, and sounds really vehicle-specific to me--every car has its own tricks and I guess that's a Z thing as I've never seen anyone do that before. I used to tune and install AEM EMS systems on Eclipses and so I'm pretty "textbook" when it comes to tuning--trickery like you described makes me nervous.
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Old 03-20-2006, 10:14 AM   #9
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ECU Tuning

What GIAC and Revo need to due is a custom on-site tune such as HarmonMotive does for the WRX and EVO. http://www.harmanmotive.com/

You should put on the headers, intake, exhaust, etc. then take it to them for a custom tune on the DYNO.

HarmanMotive takes advantages of all your bolt-on's so all the peramiters are maximized for HP gains and running solid with no hick-ups or CEL's.

My friend had a 2004 WRX with intake exhaust, larger intercooler, larger turbo, etc. it ran so rich he would shoot sparks out of the exhaust (Converter was removed too) and it ran really crappy. After his tune with them, his car gained like 20 hp and it ran just like stock NEVER any problems after the tune.


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Old 03-20-2006, 11:44 AM   #10
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Quote:
Originally Posted by Porschekid
Will GIAC do a custom ECU tune like you are suggesting?
not POSITIVE, but i believe yes. there are some others (can't remember all off hand) that will let you choose a map that is optimized to 91, 93, or 100 octane. don't know if anyone has dual map firmware yet.
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Old 03-20-2006, 02:57 PM   #11
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OK, after reading the posts I went back and asked one of my techs that builds our upgrade jobs about leaning, knock sensors, and the role played in an engine set up with variable timing. REMEMBER I am not a tech, so if I cross something up, I apologize -
He described the knock sensor's role these days as an effeciency device - keeps the engine running at peak gas milage. I asked him about leaning out and detonation and he said more or less as follows:
The process of leaning out is a cycle, I think he called it a spiral, and happens over several cycles. Evidently sensors in the exhaust loop can pick this up, and correct it in the place of the knock sensor. You will still get pinging, at idle, but this can be corrected by an elevated idle setting.
This whole knock sensor thing came to me by way of Carlos Alvarez, who works for the Service side of Nissan USA, and HE got the tip when he pulled the cats off his M3 (not sure of the year). Said the car was running like crap, and retarded so far it was stumbilng under hard acceleration. So it worked on a Bimmer, works on the Z's...
Is GIAC the premier chip proger for the Boxster? I will ask them...

And eslai:

It made us nervous too...we waited till someone came in with enough money and balls to try it. I sure as hell wasn't the test case.
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Old 03-21-2006, 08:38 AM   #12
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i've emailed giac and waiting for a response - will you guys know.
also - all acounts here say that when the MAF fails, you foul plugs. SO - it runs rich with a failed MAF=low temp reading is factory failure default. this is the first peice of the puzzle - how to get the ECU to run rich so that airflow mods such as intake and exhausts don't lean out the mixture.....
now to see what GIAC comes up with in regards to the knock sensor
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Old 03-21-2006, 11:12 AM   #13
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GIAC does not disable the knock sensor, or any other sensor. This is what seperates the leaders in the industry from the local laptop tuner.
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Old 03-21-2006, 01:49 PM   #14
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for clarity, i didn't mean to imply that GIAC would DISABLE the knock sensor.

what i believe they can do is to optimize firmware for a specific grade of fuel (i.e. 93 octane if you live on the east coast, or 100 octane if you race) by programming the ecu to allow spark advance appropriate for those fuels.
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Old 03-21-2006, 03:44 PM   #15
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Quote:
Originally Posted by PorscheDoc
GIAC does not disable the knock sensor, or any other sensor. This is what seperates the leaders in the industry from the local laptop tuner.
Seems to me that when you bypass cats and fool around with the exhaust in a big way you'd better disable something(cancelling the code effectively eliminates the sensor) or you'll be driving around with the check engine light on, and god knows what happening from the ECU to compensate for the readings on the exhaust sensors. So it's not an unusual thing.
If an industry leader has such a solution I am all for it.
But for every person that reports good gains from indusrtry leaders, there is another that doesn;t get squat, often listing the same mods. As I read through the archives, it's been beaten to death on these boards, with seemingly more folks not getting gains.
And while I understand we are talking about two different cars, I have seen the same issues before - and not from "laptop tuners". I would like to avoid that is all.
Anyways, I will hopefully hear from GIAC themselves shortly.

Last edited by turtle; 03-21-2006 at 03:53 PM.
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Old 03-21-2006, 04:16 PM   #16
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Quote:
Originally Posted by turtle
Seems to me that when you bypass cats and fool around with the exhaust in a big way you'd better disable something(cancelling the code effectively eliminates the sensor) or you'll be driving around with the check engine light on, and god knows what happening from the ECU to compensate for the readings on the exhaust sensors. So it's not an unusual thing.
If an industry leader has such a solution I am all for it.
But for every person that reports good gains from indusrtry leaders, there is another that doesn;t get squat, often listing the same mods. As I read through the archives, it's been beaten to death on these boards, with seemingly more folks not getting gains.
And while I understand we are talking about two different cars, I have seen the same issues before - and not from "laptop tuners". I would like to avoid that is all.
Anyways, I will hopefully hear from GIAC themselves shortly.
Yes, disabling the knock sensor is a great way to keep a CEL from coming on, which is why most hack programmers will do it. Proper programming eliminates the need to disable the knock sensor and will optimize the maps in the ECU to keep the CEL from coming on...properly. Don't get me wrong, I am not a programmer, but we work closely with GIAC on our tuning (our boxster supercharger kits are tuned through GIAC, in fact we will be tuning the 3.2 kit hopefully this week), and I know what you can expect from people who know how to properly tune engines, and what to expect from people that don't. We just went through a huge battle with EIP on a VW turbo kit, and after seeing their "tuning" and "ecu chip soldering" abilities, I am leary of a lot of lower level tuners.
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Old 03-21-2006, 05:25 PM   #17
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What do you think of the role of knock sensors when tuning?
And do you think that there is difficulty in getting good power gains from items such as chip and air flow components?
I don't want to go the route of forced induction. And I don't need 400 HP. Just enough to get me into the low 300's.
As for who is doing the mods, I will get the best I can afford...it seems you have an opinion on that subject....who would you recommend?
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Old 03-21-2006, 07:28 PM   #18
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Knock sensors in the 5.2, 7.1, 7.2 and 7.8 cars is not for fuel economy. Your four 02 sensors are for that. They determine fuel economy as well as low throttle drivability.

Knock sensors are a very valuable tool to tune with. Why? Because they pick up a frequency that is just on the cuff of damage. To properly tune a car you watch these sensor and see what they are doing. Any knock count is a problem. Ideally you would steady state a car on the dyno and bring the timing up and watch the TQ. As the TQ nears it peak and the knock sensor counts at all you back off the timing and you have achieved max timing for that mark as well as max HP. Each cell (100RPM) is tuned in this fashion through the whole kPa map. Knock sensors are not a tool for anything other than protection. We use them in tuning and in fact will be installing them on all of our older CIS to EFI conversions.


We do not shut off any sensor. Not now not ever. If one has to tune in a fashion that causes the CEL to come on then he doesn't know what he is doing or has done something incorrect. A cars tuning is either safe and correct or it is not. Not running cats these days is a poor excuse for a light. The new style cats do not restrict flow and certainly retains drivability since the aft 02 actually control this map.

Tuning 7.2 is not easy...there are over 18 maps that switch based on a 3D overview of several components. Instead of just pulling timing it switches whole maps. The TT for example has 2700 maps in total. The original programming takes another piece of software to write just to fire up the motor. Man can not interpret all the maps and how they cross relate. It then takes 100K hours, yes that is correct to dyno the car.

Rarely will you find anyone who has GIAC and has issue. In fact in the last year we have removed over 70 other "tuners" ecu mods and placed ours in there. We have proudly tuned more cars and introduced things such as switching and flashloading that shows a learning curve and understanding of the programs second to no one.

Can gains be made without FI. Sure. What happens is Porsche writes the maps to deal with the worst of owners. People that would run 85 Octane if they could find it. What we do is go back in and look at all these maps. We then retune the system for 91 octane and level the maps not to deal with trying to run on 85 but nothing less than 91. So we are able to increase timing, offset and increase the VE table as well as the injector PW. The end result is a real world gain. The down side…you have to run 91 at minimum. Then again you should be doing this anyway..

My apologizes in advance if there are grammatical errors. It has been a long day and I am rather beat and headed off to bed!
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Old 03-22-2006, 05:35 AM   #19
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Quote:
Originally Posted by turtle
"Yeah, there is a bit of a "buffer" in what Nissan thinks is safe and what the average tuner thinks is safe, but still... completely disabling one or the other of those two sensors is a recipe for disaster."
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I can see how you would think that.
BUT notice that the MAF reading is set to factory default failure code - forty below. Colder the air, the denser the air, less particles can be suspended in it - so the the ECU compensation by running the richest it's program will allow. After that, just make sure your mapping is right so that you don't run too rich.
As a matter of fact, fouling plugs has been our only problem. We haven't had a single lean out in about 20 cars over the last 3 years, and at 52k miles my Z is just fine.
As for GIAC..I don't know. That is why I am posting, to gather info. It's always just a matter of electronics these days. If someone knows where I can buy Porsche diagnostics for out CONSULT station here at the dealership our Techs could figure a lot out.
I hear what your saying about the 350z. My father and I are bulding a 3.5L 95 Maxima for drag racing and were doing the same thing. The knock sensor on the VQ35DE is totally a drag and is best eliminated, but this is rare and only applies to that motor. I would never do this to any other car. It just seems that the stock programming in the VQ computer is designed the say way as others are saying. For retards that put water in the tank, they have to make the car still run. We are getting around the stock computer with an emanage ultimate and some time on the dyno. I wouldn't see this as even an option on a Porsche.

On that application yes it works, but I would never apply that logic to another platform.
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Old 03-22-2006, 07:05 AM   #20
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What a great thread. I have nothing to contribute beyond a THANK YOU for all this back and forth knowledge about tuning, etc. I'm learning a lot!
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