996 RaceCar 3.6L Dyno, 267rwhp/217rwtq, (Sub 10.0 AFR) Super Rich Condition

Setup is as follows: 2002 Porsche 996 3.6L Naturally Aspirated K&N intake Equal length headers, short center exit exhaust Stock DME/Ecu I feel like there is a Major issue going on here. The air/fuels are pegged at 10.0 on the dyno which could mean they are actually lower. Any suggestions will help i have not gone through every wire on this car yet but i will if i have to lol. Just a background this car was built from a bare shell. I will answer any questions to the best of my ability as this is new for me. Video and pics 10/16/13 2002 Porsche 996 RaceCar 3.6L dyno, 267whp/217/wtq SAE, I/H/E/Stock ECU - YouTube Porsche codes - YouTube YouTube

What is that 1 fault in the DME?

If it is a track car only, I would either flash the ECU or go stand alone. Once the AFR is correct (Closer to Stoich) you should see very fair gains in power.

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i was not able to access. the scanner stated "Can timed out" when we attempted to access the code

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i understand that however if there is an intermittent electrical issue a tune would not solve much. I did not build this car so my knowledge in that aspect is limited. There may be a break in the wiring i cannot see. I am slowly going to chek the continuity with my volt meter as time goes on. I just want to get feedback from neone. Sometimes you never know someone may have had a similar issue and can help you solve quicker. Right now im basically trying to learn what wire/sensor/malfunction would cause the Ecu to peg it rich.

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The fastest way will be to hook up Durametric or even a generic OBDII scanner to the OBDII port, assuming there's one. Duramteric will tell you all the parameters (e.g., MAF reading, coolant temp, fuel trim, etc.) you need to diagnose this.

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Stupid question, but is the ECU from that exact engine?

i do not have a scanner i just got lucky at the dyno. also i am not 100% sure about the Ecu being for the engine.

Make sure the ECU is for that exact engine. For example; The automatics and manuals will be different.

When these engines see upgrades they typically richen up, not lean out. The power you are making is what I consider "stock" for a 3.5 on my dynojet from an engine that has nothing done to it. What are the fuel trim values in TRA and FRA?

check maf and o2's for a fault. check to make sure there isn't a leak somewhere on the intake manifold. check fuel pump performance bench flow injectors can you data log or see the map? Does the computer have a stock tune or was it designed for a different set up?

Well today seemed to be a good day. After much research and diligence last night we came across this thread from Renntech. http://www.renntech.org/forums/topic...l-air-mixture/ We learned of someone that had a similar problem with super rich mixtures and what a few suggestions were to remedy them. The one in particular that stood out for us was the addition of a Resistor of a certain OHM that could essentially trick the computer into running lean. This resistor would be added in between the #5 signal wire on the MAF plug (White/Dark blue color). There is no way anyone would believe that a simple $.05 cent resistor could make such a dramatic difference. Well we decided to take the plunge today and purchase these miracle resistors and give it a try. WE installed a 560 ohm 1/4 watt resistor. I dont have pictures at the moment. I will get them ASAP. The difference is unexplainable.... lost for words is more like it. Our car would not even idle prior to this "mod" if you wanna call it that. Prior to the resistor, the fuel smell was so so concentrated that it would saturate the air and your clothes. Prior to the resistor, the dyno was the proof that we had a severe fuel dumping issue. As of today it was what i would call a "miracle mod". The engine immediately started with barely one crank. The idle was incredibly stable. The revs were much smoother. The smell of fuel was almost completely gone. Smells like a usual de-catted car. Unbelievable more like it... I dont expect to take any recognition for this i am just happy and truely humbled by this experience. We had an amazing team effort up to this point and never ever would we have thought a frikin $.05 cent resistor would be the answer. Wow.... Just as a precaution we did however schedule an immediate Dyno session and we purchased a large assortment of various OHM resistors to "fine tune" the A/F ratios to a safe range. I will get the results and all the info and share it as soon as i can. I am not crying victory here just yet however the overall difference today is good enough to call this a victory.

No offense, but it seems to me that you just put a band aid on it not solved the real issue.

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I agree but if it's really just a race car and it works consistently and reliably, then it's really your call. I don't know if I wanna be gambling on an engine replacement down the line if something were to happen though...

Is think that the fuel trim was adding fuel (FRA) for a reason. The resistor might have worked, but an underlying condition is something I'd be concerned about. What were the fuel trim values before and after the resistor?

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i do not hav any tools to data log, we are a young team in regards to Porsche experience and fuel injection all together. But make no mistake we are problem solvers. This is the second time in a year this car has hit the track and less than a month ago this car was in pieces after being dissassembled a year ago from an engine failure. We run in a local club at a modest budget so spending thousands right now is not an option. I cannot disagree with anyone because like i said my experience with Porsches is only days old. Also i am well aware there could b a deeper issue we are not seeing because there are so many frikin codes on its like Christmas on that dash. As i understand it the K&N air intake system has an inside diameter of ~3 inches and a perfect cylindrical shape where the MAF sits. Also the MAF is located right after the air filter and the overall intake length is much much shorter than the stock box. As opposed to the stock airbox that is a larger unit, the MAF housing is ~3.5 inches and an oval shape. What the K&N intake is doing is speeding up the velocity of the air in such a way that the MAF is getting a voltage reading that is off the charts and therefore telling the Ecu to dump fuel as opposed to the design of the stock airbox that moderates the velocity of the air passing through the MAF giving a more balanced fuel trim. So what we are testing at this point is using a .05 cent resistor to manipulate the signal since we do not hav an airbox nor any larger MAF housings. We also decided we could make the test more effective with a potentiometer instead of changing out resistors on the dyno.

Also wanted to share some images of how we installed the resistor. The potentiometer is the little blue box thing with a gold screw that varies the resistance from 0-1000 OHMS of resistance by turning the screw.

You got something else going on. +1 for this being a band aid. The resistor trick is an old one, the tuner crowd loves it because its cheap but its a false sense of security. The engine now thinks it is getting less air than it really does. If you dyno it now and looks good and then the air gets thicker (colder) then what?

It doesn't cost thousands to get fuel trim data. It's the proper diagnostic method to gain an understanding of why the engine is doing certain things. Most any intuitive scan tool will offer this and even a durametric does.

Why not put a stock intake on the engine and see what happens...?

It is a bad idea to use k&n intake on a track car. You will be sucking in hot air from engine bay on a track. It is quite bad. I bet you have problems with maf sensor, probably oil is on it from this intake so it mixes up everything and you adding up resistor to alter maf sensor signal proves that. Put back stock intake box and try to wash or replace maf sensor. If you want better intake than stock one - get a dual port intake box from x51 kit.

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K&N filter was washed thoroughly and any oily residue was eliminated. Also a new MAF was installed and is only days old. I could not agree with you more. The K&N intake is great in terms of the lack of heat soak due to the plastic tubing. However, we need to design a more efficient cold air design.

Dyno vids are coming but here are a few dyno graph screenshots with the "band aid" . These are direct comparisons from Weds night dynos. In case there is question, yes at ~3200 RPM that is an approximate 75 lb/ft torque gain...

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thank you for the suggestion, i just learned we do hav a stock airbox so we would like to a direct dyno comparison with it as well.

You said you are new to EFI, what about the others in your team?

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I personally have more experience in EFI than the others. I hav never however until last weekend driven or ever turned a bolt on a Porsche until i did my first club race ever last Sunday lol.

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Porsche or not, it doesn't matter. Basic EFI experience should tell you why the resistor to the MAF is not a good idea. I get the feeling that somehow you don't get this.

It's not just EFI, it's engine management. What you probably also don't realize is that you may have ignition issues too... Safety retardation can be impacting the engine and your resistor may not make up for that. You'll learn.

I understand your opinions are well founded thank you. But my question is if i had an engine problem would it not show up on a dyno reading?

Is your dyno guy monitoring knock in any way? Also in regards to basic obd diagnosis, you could even do one step better and get a Piwis cable from overseas for under $30. This isn't popular with everyone but certainly another option.

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If the K&N does not have oil on it, it most likely will not filter the air properly. Just say'n.

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No it would not. Dyno tells you power output and AFR if it is hooked up, that is about it. This is why everyone is telling you to be careful Go get a laptop and download some software. (I am sure someone here can suggest great software) It will give you more information than you could imagine. Then take that info to a pro (There are many here) and let them tell you what it means. Laptop - $600 Software - $200 (Or less) Improving your engine output and not blowing your engine - Priceless

Id have your ECU programed back to stock with the Piwis. Make sure the correct file is in place on that DME

ok i c we need data acquisition that would b a good place to start

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Yes. Data logging software can be found fairly cheap. Most come with OBDII adapters too. They give you everything, Any sensor the car has will be at your fingertips. Once this data is gathered it will give you a much better picture of what is going on with the engine and allow you to diagnose problems much more accurately.

Too many things that are expelled by the OBDII port are calculated values. For data logging you must gain raw values.

Dyno video of comparison runs we were able to do a quick header swap to the X51 headers for the last test of the day You Tube

As a side note. we did install the stock airbox to test the drivability and it runs very well with no in line resistors etc... we still need to dyno the stock airbox to learn what the effect is on power.

The factory airbox is not a restriction.

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understood. no harm in dynoing though.

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Please do, I don't think there has been too many independent tests done.

Isn't a dyno super sensitive to conditions?

Going stand alone is not a bad idea. I did on my GTS 3 car and it was far easier to tune the car. You can have different files for various fuels if you want. The data from a stand alone is far more meaningful than what you can get from the OBDII. On the newer cars the CAN has more data.

Are the secondary o2 sensors still in the exhaust, not just hanging open air? It's my understanding they still need to be sniffing something even if it's triggering a CEL because they don't like the value they are seeing. Long shot but nobody's asked about it yet.

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that is a great point. we do NOT hav them in the exhaust flow. i feel the same as you they should be detecting exhaust. As of today we are still preparing the chassis for a track day this Saturday so we dont hav much time to hit exhaust shops or dynos.

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I suppose you could use some of the resistors you have for the o2 as a temporary option.

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The EPA bankrupted the company that used to make/sell the O2 simulator a few years ago. The easiest way to fool ECM is to get a spark plug spacer and remove the downstream O2 sensor from the exhaust path. Since less O2 passes through the sensor, the ECM will think all is well. These spaces can be foudn at any parts store and they are about $10 each.

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Based on the video of OP showing custom exhaust, I'm not sure if that would be an option but sort of hard to tell from the vid.

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ye we dont hav the secondary 02 sensors in the exhaust path at all. We need to redesign the tubing location to weld in new bungs because there is just no room right now

No room anywhere in the entire system?

I just tested the K&N intake on our dyno and it caused the same issue you are having - too rich. A/F's were down to 12:1 and the car was not making good power. Bolted on the stock airbox, and the power came up significantly. This is due to the fact that the K&N intake does not have the same cross sectional area as the factory MAF housing - this is causing incorrect airflow readings in the ECU. The ECU thinks there is more airflow than there acutally is, and so adds more fuel. Here is the dyno graph to show the difference. We dyno the cars with the decklid closed and a fan blowing on the decklid. On K&N's website they show a 996 on the dyno with the decklid open - no wonder there are HP gains. We have been guilty of this in the past. There is no aftermarket standard for dyno testing components, and this is the problem - it is exacerbated on 911's, which have the engine in the back.

Playing with intakes on the flow bench with pitot tubes around the MAF area proved this with hard data for me. It doesn't stop with the K&N system in regard to aftermarket arrangements. We've been seeing this characteristic for about a decade now with these engines.. I have seen some intakes so bad that the engine would literally shut off due to immeasurable turbulence around the MAF The other interesting data is gathered when air inlet temps are measured at 5 points within the intake system from the inlet to the plenum. That's when you see that a cold air intake is really a hot air intake. I love data.

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So are there any CAIs on the market that actually deliver better performance than the stock air box? My indy stated that stock air box is the way to go on the 996 as he sees a lot of issues with CELs from aftermarket CAIs.

If you read up on intake design, one of the fundamentals of a good design is to have the least amount of bends as to not have any adverse flow characteristics, especially when MAF and NA combo are involved. I'm a bit surprised that some basic thought hasn't gone into the K&N system. I don't know of any aftermarket systems that snake around like that with those radical bends.

After watching the dyno video, I have some additional comments: Why are the dyno runs so short (what gear were they using? 3rd?) If running in 3rd, the car is still down on power. You should be up in the 260 ft. lb range running headers and without cats, if the exhaust is built right. Especially if dyno'ing in a gear lower than 5th. The fan in front is extremely insufficient. It would be better if you had 2 snail fans and had them directly in each front grill. Proper cooling while on the dyno translates to more accurate dyno results. If the shop has the OBDII data-link setup, post up some graphs that show what the ECT's are and what the MAF is reading. On a race car like this, I would build a ram-air box based around the stock airbox and use something like a Fabspeed cold air kit, which allows you to remove the internal resonators out of the stock airbox which increases it's volume. Wrap the whole box in gold foil and block off the holes on the bottom of the airbox that allow hot air in. The car will run consistently well.

If the source of the air is cold, the speed that the air moves through the intake will not have time to warm up. Therefore, insulating the airbox isn't needed.

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Agreed but plugging the holes on the bottom of the OEM box does make a difference. FWIW, I run the Orange CAI with a stock box and a BMC filter element. No MAF issue for 3-4 years. I run straight pipes from 3.8 manifolds, secondary 02 sensors tied to rear fame, and I dyno in the 305-310 range on a Dynojet, 12.5-13 A/F ratios. Oh and I'm a 3.6 bottom end with 3.4 heads, cams, TB, and 5.2 ECU (GIAC street flash)....

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You confirmed my suspicion. My air filter is dirtiest where it's close to those bottom holes. The air intake temp is definitely quite a bit higher than ambient. I think a lot of hot air get sucked it from those small holes. However, plugging those holes also means rain water ingested by the snorkel has nowhere to go?

thanks to everyone for the positive feedback. We did install the stock airbox for the last track day and the car ran great. Probably not with the most possible power but dramatically better than our initial dyno with the K&N.

amazing how the stock air box is the best way to go... everytime people check my engine bay at the track they ask me why did I , at least , change the air filter box... I am glad to hear that I was right...All the parts are design to work together and all is there for a reason. Change one bit and you have to do it all.