Actually the a/f is only adjusted in part throttle parts, at WOT (open loop ) the computer doesn't listen to the O2's at all, it simply looks at some preset tables for its data. The EEC does have what ya call 'adaptive' tables which change frequently at cruise and part throttle, and these after time will affect the open loop tables. That is why its important when you go to make a pass or dyno that you drop the battery, it resets teh adaptive tables soo you actually get wahts on the chip. Given enough time the computer will actually learn around whats on the chip...


Hope that helps
Brandon

 

Exactly that is why a 2lb pulley works for some, the computer is already soo right and conservative that it can do it, the 4lb is a tad too much. Anyone that wants to test the durability of the rods over a 300$ chip go ahead, but why not maximize the parts your putting on, and safely go race it, rahter than hope the stock computer can accomodate with it, which it cant. The biggest problem is the lower rpms near the torq peak. once detonation stops it doesn't just go away, ya gotta let out of it.

Brandon

 

Determining load is the tricky part. RPM is typically used.

The stock computer is fine as long as you end up within the boards of its tables. Where the bounds are and how far you can push it has never been (to my knowledge) scientifically tested (sure plenty of people saying 4lb seems OK, but no dynos/loads tests etc).

Where I get my information:

I've had to develop a whole chip program (no base tables) for my Saturn race car. Because of that, I did a whole lot of research into what into them there computer bits...

Coldie

 

i want to hear a tuners take on this whole topic...

 

I have dynoed my 01 with a five pounde pulley and the a/f ratio is 10.8 from 3000 to redline. The mass air sensor is used at wot. You will hear the tunners talk aboyt our 90mm starting to max on high hp setups. I beleve that 5volts is max but I could be wrong on this point. You must run cooler than stoc plugs, i have tr6s.

5lb daily driver and no chip.

I would like to know at what boost levels the tuners start to take out timing. For the no chip guy the point that max advance on pump gas is = to stock settings would seem to be the max pulley.

Has anyone seen bad a/f ratrios on a no chip setup?

 

stock pcm
- for all the info why doesn't anyone talk about the sort/long term fuel trims? - the factory pcm does compensate, it will actually change the long term to match the short - say a 10% short term will show an adjustment on the long term side - the long term side will evenutaly match the 10% and then become 0% long term fuel trim - aswell as the sort term will go to 0% - the wot fuel calculations are based off of the long term fuel trims so one would think if a person increased boost on non chiped truck they would be better off to drive the truck easy until the stock pcm relearend and the fuel trims adjusted.

Also a maf sensor controls timing/load/fuel calculations , so would the higher maf readings cause the stock pcm to take timing away?

One thing I've always wondered is if aftermarket chips bypass the lean codes? If a stock pcm cant adjusted the fuel trim by the max of 25% it will set a lean or rich code. Also does a chiped pcm still learn in the same way as a non chiped truck and can they compensate for different altitudes as that will affect timing and fuel trims.

There is a lot of opinions on here but i'm just curious about how many of them are right. (mine included)

 

IMHO the biggest reason for the chip is to maximize H.P. gains and minimize risks of detonation. It just doesn't make sense to me to save a few hundred bucks after spending 30k plus on a truck.



Rocks

 

I think you have that backwards. AFAIK, aftermarket chips are typically leaner and with more spark advance than stock. That hardly qualifies as "minimizing the risks of detonation."

So, for me, it just doesn't make sense for me to risk blowing my engine (and certainly voiding the engine warranty) on my $30K truck by using an aftermarket chip.

One day (probably when the warranty is up), I will have a dyno shop install a custom chip. But this chip will be MORE conservative than stock.

 

A few points have been lost in this discussion. The o2 sensors feed a signal back to the computer continuously, as does the Intake Air Temperature and Mass Air flow Sensor. With three signals, the computer can calculate what the current air density is that the truck is driving in. If the computer determines that it takes say a 5% correction to the base A/F tables to get a 14.7 A/F ratio then it saves that temporary correction the short-term table. If after a few starts the correction is still valid, then it then saves that correction to the long-term table. If that correction is more than say 10% from what the computer would considers normal for the IAT, the computer will light the Check Engine Light. Any time you get on the gas hard, the motor goes into what’s known as Open Loop and no longer looks at the o2 sensors and goes to base calculation load tables times the percent correction that it is using today to get the new tables.

From the factory the stock motor is designed to run what is known as Butt Rich at WOT say 10% too rich. If you go to a 2# pulley and start pushing say 9% more air, everything is close enough that the o2 sensors and computer will compensate for the air of the day and when you go to open loop, everything is close enough to not light the CEL. The larger the pulley the closer you will get to critical mass. If your tuner has pushed the issue ever farther by increasing the timing you may be even closer to critical mass.

Go to a 100 degrees and 28 in of mg day and the air density goes to 86.7%. At 10 degrees and 30.5 in of mercury and you get 112.5% air. A blower is just an huge air compressor that messes with these numbers in a big way. Change the pulley and change the percent air from what the motor is expecting to see. Use a really big pulley and you max out the Mass Air Flow sensor and things even get worse. Below is an Excel calculator for air density. The go-kart, snowmobile and dirt bike guys live by these calcs. Computers and the demise of the carburetor have produced an entire generation of hotrodders that have missed these basics.

Lots of problems can arise when you get to the limits of the operating range without enough room for error. Remember that there is always error. Hopefully you will never get to critical mass and break a rod with detonation or burn thru a piston.

See http://www.ncs-stl.com/Files/airdensity3.xls

And http://www.ncs-stl.com/Files/BlowerRPM.xls

Hope this helps


AW

 

Quite a few posts in this interesting thread, but no input from the big name tuners yet. I would think they would want to chime in with reasons why we should use chips with aftermarket mods.

 

Tuners make a lot of money on selling and reburning chips.
Do you really think they are going to say something that may decrease the number of chips they sell?

Also I agree 100% with Tim Skelton. My decision not to get a chip right now has nothing to do with trying to a few hundred bucks. It's about trying to save a few thousand in repairs down the road.

Black F150, I am thinking the same way you are about driving the truck easy until the PCM has had time to adjust the "long term" fuel/timing tables. Wonder how long that will take?

Also like Crazyone said, it is a good idea to disconnect the battery on a chipped truck before a dyno pull or race to erase the adjustments the PCM has learned. But for someone running a pulley without a chip, this would NOT be the thing to do since you would probably want to wait for the tables to relearn before getting on it hard.

Come on tuners, enlighten us! This should be the stuff you guys know inside and out...

 

I have been here a long time and am glad to see us get back to our roots.

Great post GUYS, I am learning alot and no one is bitching or backbiting. This is what we are all about -- learning and sharing information without fighting with those that disagree. That's what knives are for, not web boards.

GREAT JOB AND KEEP IT GOING WITH THIS PAGE!
Alvin

 

I also DONT think anybody who is rinning a pully without a chip is trying to save anything but their warranty.I see more and more people using pully's without chips and with NO problems.I see more and more people with chips having problems with detonation.Its also very convienent that NO tuner will talk on this subject and tell us what they use for timimg tables and air fuel.I think there is NO reason for this because all the major tuners already have their programs and there is no time for stealing info like their might have been a couple of years back.....Its not about the $300 chip.its about the $2k tranny or $4K motor if a plug decides to launch or a clutchpack lets go.Ford is doing EVERYTHING they can not to honor warranty on these trucks.Sometimes they have every right due to serious mods but there are times when you have an aftermarket air filter and they wanna void your warranty.I dont know about computers compensating or anything but I have driven Lightnings with pully's and without chips and with chips.The chipped pullied truck DO have much more power than just a pullied truck but probally are not as safe.Ive come to one conclusion.

LEAN makes power so:
If you are running a pully without a chip and are getting good performance fine.

If you are running a pully with a chip and have better power then the a/f is probally leaner to creative more power along with some timimg curves being different.Its very simple.The truck without the chip is OBVIOUSLY running richer due to the power difference.This is common sense to a point.This is probally why you dont hear tuners on here.

The chip /pullied truck is probally running a leaner program WITH pully than the pullied truck runs without chip.

 

Lol tim

 

Money is definatly not the issue for most people, saving money by not buying a chip,I have a mail order $400 flip chip sitting next to computer as i write this, I'm using it as a paper weight. I have every mod back on my truck and then some as i did when it vented EXCEPT the chip. I feel safer whithout a chip, transmission at correct pressure,shift points at 5200 rpm, no pinging at all, plugs have black soot at bottom of threads and porcelin tan color if it was lean they wouldn't look like that , and i run it hard most of time driving it. Look on NLOC board search under " pulley revisited" and theres a good discusion and findings there. No tuners responded to those threads either except JJ of JJ's svt, and when the tracks open he is going to post info running with and without a chip