theory on boxster bolt on problem - 986 Forum - The Community for Porsche Boxster & Cayman Owners

turtle · 03-19-2006, 07:06 PM

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.

turtle · 03-19-2006, 07:10 PM

"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.

Regards,"

turtle · 03-19-2006, 07:21 PM

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,
Turtle

insite · 03-20-2006, 08:51 AM

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.)

Porschekid · 03-20-2006, 08:55 AM

Will GIAC do a custom ECU tune like you are suggesting?

insite · 03-20-2006, 11:44 AM

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.

turtle · 03-20-2006, 02:57 PM

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.

eslai · 03-20-2006, 09:24 AM

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.

turtle · 03-20-2006, 09:38 AM

"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."
__________________________________________________ _______________

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.

eslai · 03-20-2006, 09:55 AM

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.

KRZTACO · 03-20-2006, 10:14 AM

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.

KRZ

986Jim · 03-22-2006, 05:35 AM

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."
__________________________________________________ _______________

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.

RandallNeighbour · 03-22-2006, 07:05 AM

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! :dance:

turtle · 03-22-2006, 08:35 AM

PorscheDoc - if you are some way offended I apologize, or perhaps I am reading too much into it. The way you describe a knock sensor is only half the job for the VQ45 sensor. Intake air volume and temperature play a big part for it as well. All the chips were modding exactly as you specified - but as soon as more air started coming in, it would jump all over the ignition curve - even with new maps from such suppliers as Technosquare and Stillen. In this case, with all the extra fuel flow, it would be hard to see knocking unless you are in a high boost FI application.

We are a dealership that has been in business over 30 years, and we have been in tuning ever since previous owners son bought a new 260...tens of thousands of hours of performance work has been performed here, and all the techs that do it are master certified, and many of them race, track or strip, and sometimes both.
The mods to the knock sensor and the MAF have always been performed on cars that have already been remapped and have had extensive airflow work done on it. Perhaps you thought I was advocating it as a mod in and of itself. Not the case.
986Jim - good to see someone who has actually done it. I thought that it may be VQ45 specific. We recorded an increase of around 10% over the modded baseline on all of the Nissans we have done it to.
We only work on Nissans and Fords though, so the reason I posted here is to see if anyones has used it on a Porche.

It may or may not work, but untill someone tries,we won't know. I am waiting for LNS Motorsports, who seems to be the Porchse builders around here, to comment. I will let you guys know what goes on.
Cheers,
Turtle