Im seriously considering doing a LE2 H/C project on my 96' Z28.

My question is:

How do I go about tuning my PCM for this new cam and supporting mods and bolt ons?

I know that a dyno tune is best and will get the most power out of your car, but is a mail order tune needed for the break in process of a freshly rebuilt engine? You obviously can not strap a fresh-never-been-run engine to a dyno to beat the crap out of it and test and tune it.

How would I do this? Get a mail order tune at first, break in the engine, and then take it to a dyno shop to fine tune it?

Thanks

 

i think your on the right track there, at least thats what i plan to do. i am using a pcmforless tune right now and i am very happy with it, eventually i will have bryan put it on the dyno to fine tune it.

 

That's what I'm gonna do too.

Same company too.

 

Actually current thinking is it is best to use a fresh motor hard to seat the rings. Dyno tuning is NOT best unless you have a tuner who knows the difference between a track tune and a dyno tune.

 

Would you still suggest breaking it in (hard, or whatever method of doing it) before dyno tuning it?

Also, to get a decent mail order tune, I suspect you would want to give the company who is doing it, the cam specs. Does anyone know if Lloyd Elliot gives out his famous LE2 cam's specs?

 

Once you pay for it, he will tell you the specs

 

not only that but most "major" tuners know all of his specs already so you just tell them what heads and cam you got from him and they know the rest

 

Break it in hard.

On a side note, my pcmforless tune is doing the trick for me, but my car is setup well.

 

Will going with a mail order tune, and sticking with it in the long run, hurt the car at all? Obviously not getting a dyno will result in not getting every horsepower it has, but will not tuning it exactly right hurt anything at all? I mean, as long as there isnt any preignition or detonation and the car is performing and running like a car should, is there much else to worry about?

 

Just need to have a scan tool minimally. If modding any EFI car, a scan tool should be your first purchase. Make sure its not getting any knock and that the BLMs are within reason and its not pegged at one side or the other like washing your cylinder walls dry from too much fuel and you should be ok.

 

Mail order is Sooooooo close to being right that most dyno tunes net maybe 20RWHP,. But if ya need 20HP the dyno is the place to get it.

 

Forgive my ignorance... but what is a BLM? I assume something feul related. Can you adjust this with a scan tool? Or does the mail order tune company/dyno shop need to do that?

I do have multiple types of scan tools accessable to me.

 

Thats the Block Learn Multiplier that either removes or adds fuel based on the current BLM# and the O2 reading while in non-WOT mode. A perfect AF ratio is when the BLM is 128...if its say at 110, then the O2s are telling the PCM that the AF is very rich and the BLM number drops until the O2s are telling the PCM the AF is right. The BLM helps detemrine fueling by this method for the example given.. 110/128 = 0.859 therefore the PCM multiplies the current fueling rate as calculated by the Air flow to be 86% of what is programmed in it for the current airflow.
Once the BLM number is down to 108, it can no longer control the fueling as 108 is as low as it can go.

In order to "tune" it, the PCM tune has to correct it by manipulating the MAF Sensor calculation tables so that the base program for calculating the fuel is reducing the fuel in this case which will in turn bring back up the BLM number into a normal controlling operating range. This is something a dyno tuner would do by reflashing your PCM with new parms/values in the MAF tables.

The scan tool only tells you the values of all the sensors and the current BLMs, also known as Long Term mutlipliers / counts.

 

Ok. So when I get the mail order tune I should check the BLM and make sure it is close to 128? How close is safe, and not washing the oil off the cylinder walls?

 

As long as its not bottomed out at 108 or whatever the tuner sets the min amount to..but you'll know its bottom out when the Long Term and Short Term Integrators are the same at 108 in this case. LT being the BLM I'm referring to.

The way it works is the Short term int drops..once it hits the minimum, the long term decreases by 1 and the short term goes back to 128..and the process repeats until the AF as measured by the O2 is at the perfect mix or both the LT and ST integrators/BLMs are bottomed out.


When tuning, I try to keep the BLMs between 124 and 134...I generally like to have them above 128 so that when you go into WOT mode its adding some fuel...there's a whole other writeup that could be made about how that works