sn95 PCM consistency and PIA factor. Why are the inconsistently a PAIN?

Pokageek

Pokageek

Active Member
Jun 10, 2005
2,767
0
46
MA, USA
#1
So we have many proponents of the "TM40" over the A9L. That's fine and there are a lot of good reasons, like the speed of the processor and such..but to me, the puter appears to be much harder or dam near impossible for some folks to tune consistently depending on their combo. :rolleyes: COULD it be the stupid adaptive strategy? :notnice: Does anyone know?

Why are they such a pain? :shrug: I have had my car to 3 tuners including usage of tweecer, sct and PMS and it still isnt quite right..mainly the buck/pop@2000-2500RPM that doesn't start until I've been driving the car for 3 days...adaptive?

For reference, you see many folks posting stuff like this (this was my experience too):

"A9L in a 95 GT
.."wondering if the A9L or the A9T would work in a 95 mustang with an after market tuner?"

"I would rather stick with the T4MO but for some reason my brain box will not except tuner chips. I've tried Tweecer RT, and after a couple times tryin to tune it, i figured out that it wasn't doin anything as far as the ecu reading the chip. So i went to a Sniper chip it ran fine about about a month, and this is doin the same thing, so i figured if i got an A9L that i would better results as far as the tuner ACTUALLY working. "

Then u see responses like this:
"Find the problem and solve it, don't solve it with another problem. Take it to a reputable tuner, ..blah..blah.. the usual"

Then "well, to me that sounds like the 94-95 cpu is being a little picky or hard to tune wouldnt u say? oh, and btw, i never said the 94-95 cpu was bad,A9L us just easier to tune. so much easier that companies have made retro-fit kits. and this isnt something i think, its something i know"

or ...

"The 94-95 have a really ****ty stock tune...ongoing argument is the 94-95 computer is garbage, after some debate its not the computer that sucks, its the program. they are really ticky and have to be adjusted perfectly or it will not run as it should....my 95 is no different."


or ..

"whats the deal with changing 94-95 mustangs to the 89-93 computers. Some peolpe say dont do it because the 95 computer is faster and better then the earlier mustang computer. but i dont see how because i know if u put a cam in a 94-95 u will have tuning problems. i had a 91 mustang i put every up grade u could do to it and never had one problem running stock computer with no tune. i now have a 95 because i like the body stlye better. but every upgrade i do i have ide sruge problems and i know the car isnt running the best it could. i tuned many mustangs and i know everything i can set manually is right "

or

"i have had mine tuned about 5 times and he can seem to get it right. it sucks. "
 

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#5
I've tuned tons of 94-95's and actually prefer tuning them over Fox bodies - more control. And, as a matter of fact, you can tune any SN95 PCM to act just like a Fox PCM if you like, no problem.

Our own SN95 have been through several 'lives' from HCI, to a Kenne Bell SC to now a 357 with a PT88 turbo and 700 RWHP through a C4 and it drives like stock. Same as my own turbo Gen 1 Lightning, which we converted to mass air and chose a SN95 PCM to run it - we did this because they are so easy to tune.

All the PCMs, even Foxes have adaptive control - can be shut off, but no real reason to. BTW - Processor speed is the same.

I will say that the idle and part throttle are the most difficult parts of tuning a car

(any year) - most tuners can do WOT just fine - I can teach my grandson to do this in probably 10 minutes. Bucking and hesitation means it still needs some tuning help - or more likely, it has some undiscovered mechanical issue. Can't tell you the number of cars that were supposedly mechanically 'perfect' and difficult to tune, until we looked them over and found things like vacuum leaks, bad sensors, wiring/grounding issues, unplugged injectors and in one case, 7-19# injectors and 1-24# injector...

Don
 
#6
My car runs fine with a mail order chip. It has some bucking, but certainly no worse than a fox. The guy who built the engine said it just wouldn't be streetable with an automatic. The guy who burned the chip confirmed it. It doesn't get any worse the more I drive it. It has a little mid throttle ping on hot days, but I'm sure I could fix that if I had a moates or something, just to back off the timing a little at mid throttle.

Kurt
 
#9
Hello Keith

Both of us are long time members here so I know you have had
issues with the 94-95 pcm :bang:

I would say I can echo what Don said :nice:

Don needs nothing I might add :nono:
to give him any more credibility than he already has :Word:

He has been an invaluable source to me in my self tuning efforts
over the past years :hail2:

Now ... Don is a Pro and I am just a guy that tinkered around with
things until I got the results I desired :)

However ... My efforts and the efforts of more than a handful of peeps
in the self tuning community I believe had a basic understanding of how
the pcm goes about doing its business has shown me a thing or two.

I wanted like to give my perspective using the questions you ask here.

Pokageek said:
So we have many proponents of the "TM40" over the A9L. That's fine and there are a lot of good reasons, like the speed of the processor and such..but to me, the puter appears to be much harder or dam near impossible for some folks to tune consistently depending on their combo. :rolleyes: COULD it be the stupid adaptive strategy? :notnice: Does anyone know?

Why are they such a pain? :shrug: I have had my car to 3 tuners including usage of tweecer, sct and PMS and it still isnt quite right..mainly the buck/pop@2000-2500RPM that doesn't start until I've been driving the car for 3 days...adaptive?
Click to expand...

One word can sum it all up here ... KNOWLEDGE ;)

Fact: The pcm controls the behavior of the car based upon input sent
to it by the various sensors

Problem: We put hot rod parts on the car and the values in the pcm
are no longer valid because the sensors are sending info that is seen
by the pcm as out of bounds

Solution: Change the values in the pcm to match hot rod parts

Fact: Everybody wants to tune :banana:
but
Nobody wants to learn about how the pcm works :bang: :Word:

Work Around Solution: Find a more user friendly method to tune :nice:
but
You still have the basic problem :notnice:
Different efforts based upon no understanding of what is needed :fuss:

Now ... All the above applies to the Self Tuner :D
however
Would you not say this ... It applies to the Pro Tuner as well :eek:

The 94-95 pcm has always got bad press simply because it is different

Yes ... Fox pcm will deal with hot rod parts better than the 94-95

UP TO A CERTAIN POINT or LEVEL OF SERIOUSNESS WITH THE COMBO

You go beyond a simple bolt on combo (300 or more rwhp)with the
Almighty A9L in a Fox Body
and
You'll find yourself tuning it for drivability/max hp

True ... Our cars (pcm's) were only a two year run :shrug:

True ... More peeps who tune ... Including Pro Tuners ...
Are more familiar with the Fox Body pcm

BUT ... Knowledge is Knowledge

Most threads like this are based upon someone trying to tune a 94-95
who doesn't have an understanding of how it works

Now ... I know the above statement is not gonna be well received
but my years of dealing with our pcm's tell me that is how it is :)

Lets be open minded here and ask a simple basic question here :D

How would one improve on something
if
They don't understand how it works in the first palce :scratch:

I can say ... Don can make em work

I can say ... I made mine work

I can say ... I know quite a few other self tuners that made theirs work

For reference, you see many folks posting stuff like this (this was my experience too):

"A9L in a 95 GT
.."wondering if the A9L or the A9T would work in a 95 mustang with an after market tuner?"

"I would rather stick with the T4MO but for some reason my brain box will not except tuner chips. I've tried Tweecer RT, and after a couple times tryin to tune it, i figured out that it wasn't doin anything as far as the ecu reading the chip. So i went to a Sniper chip it ran fine about about a month, and this is doin the same thing, so i figured if i got an A9L that i would better results as far as the tuner ACTUALLY working. "

Then u see responses like this:
"Find the problem and solve it, don't solve it with another problem. Take it to a reputable tuner, ..blah..blah.. the usual"

Then "well, to me that sounds like the 94-95 cpu is being a little picky or hard to tune wouldnt u say? oh, and btw, i never said the 94-95 cpu was bad,A9L us just easier to tune. so much easier that companies have made retro-fit kits. and this isnt something i think, its something i know"

or ...

"The 94-95 have a really ****ty stock tune...ongoing argument is the 94-95 computer is garbage, after some debate its not the computer that sucks, its the program. they are really ticky and have to be adjusted perfectly or it will not run as it should....my 95 is no different."


or ..

"whats the deal with changing 94-95 mustangs to the 89-93 computers. Some peolpe say dont do it because the 95 computer is faster and better then the earlier mustang computer. but i dont see how because i know if u put a cam in a 94-95 u will have tuning problems. i had a 91 mustang i put every up grade u could do to it and never had one problem running stock computer with no tune. i now have a 95 because i like the body stlye better. but every upgrade i do i have ide sruge problems and i know the car isnt running the best it could. i tuned many mustangs and i know everything i can set manually is right "

or

"i have had mine tuned about 5 times and he can seem to get it right. it sucks. "
Click to expand...

I have a feeling you have had the unfortunate experience of tuners who
don't have a grasp of how the 94-95 pcm works

Several years ago I was very involved in the self tuning community.

I was always getting PM's from peeps who could not get any positive
results and after talking to them ... Like Don said ... you found they
had stuff like v leaks, frayed wiring, fluid leaks, ... You Know ...

Shoddy Work and NO ATTENTION paid to the details :nono:

I encouraged them to clean up all that mess :spot:
and
A lot of the time, they got back to me reporting things then started
working with their tuning efforts :)

Please ... Please ... Don't think I am bragging here :nono:

I just can't stand it when I see so many peeps believe the internet
hype seen spread all over these Stang sites :chair:

Yeah ... Yeah ... Yeah ... I've heard it all before :crazy:

You got that other site where they say ........

"If you got a 94-95 DON'T use a narrow lsa cam"

Well ... Mine is at 109 ... Is that narrow enough for you :shrug:

Except for cam lope ... Mine drives in every way like a little stocker :banana:

True ... a wider lsa helps with things
but
The truth ... THE WHOLE TRUTH IS .................

Tuning by one who knows how the 94-95 pcm works can make most
street car combos drive stock-like

Like Don said ... tuning for WOT is not all that difficult
but
Tuning for other conditions you deal with is where knowledge is needed :Word:

Heck Fire ... I bet a Dolphin could tune for WOT :nice:
but
His flippers won't work the keyboard :notnice:

Here is another myth we all saw for years :)

"94-95 pcm's are junk and the Cobra is the worst of the bunch"

The foundation I based my tune on is that very worst of the bunch :eek:
the J4J1 found in the 94-95 Cobra :rlaugh:

You just can't always believe what you hear :nono:
and
I'm just trying to show ... Some have DONE IT successfully ;)

NO :nono: bucking ... surging ... stalling ... yada yada yada

If you want something done right ... You gotta do it yourself :D
or
You run the risk of another trying to pull the wool over your eyes :(

SOME say 94-95 pcm's can't do this or that :nono:

That Just Ain't True :Word:

True ... MOST tuners are not as knowledgeable on the 94-95
but
SOME tuners can tune em ;)

I think a different Pro Tuner is needed ...

One who has ... satisfied ... 94-95 customers

Grady
 
#11
Good replies. I dont want to be so selfish as to make this thread about me :notnice: but while we're here: Me personally? My injectors have been changed out so it know its not those. The cam has been changed out to a more friendly cam so I know its not that, .. vacuum leak? Possible. I know the build quality of the engine is excellent because it drove fine before the Long tubes.

But lets go back to the theory of what changed before you had trouble..Well, here it is, the drive-ability was excellent UNTIL the long tube headers and 42# injectors. Now, I dialed back on the injectors and its a little better BUT the car is acting nearly the same way. So its either the LT's OR a mechanical thing of some sort. I am having someone look into it now.
 
#12
talk to don lasota (username Don95Vert, the guy who posted earlier). he has a 94/95, knows his stuff, has been doing this for a long time, and he will without a doubt be able to get you the best tune you can get.

but being remote, if there is a mechanical issue, he won't be able to fix it for you.

you already have a wideband, don't you?
 
#14
I'll taka a stab at an answer here :)

The bucking or surge issues you experience are most likely due to the
large inj size

You most likely are at a low load or cruise condition and the pulsewidth
needs to be dialed back a bit at that condition

Some of the time peeps have reported relief from bucking and surge by
dialing back a bit of spark at low load driving conditions

Again ... Just a shot or two in the dark :shrug:
but
If you got datalogging :nice:
you can look at the hard data to see what is going on ;)

Grady
 
#15
My personal Experience.

I converted my Lincoln Mark vii to Mass Air A9L and dropped in the 383 thats now in my mustang. It ran like a RAPED Ape!!!! I was shifting at 7000 in my built AOD. Until i went sideways on a dark road and totalled the car.

Lets fast forward to My current mustang.
Dropped the 383 from the lincoln in a 95 stang....same trans....Heck i even went all out this time and built a fuel system . This car is SLOW.....Doesn't feel like the same motor. On the A9L the Revs were Snappy!!! Now it drags.

I may be getting a harness and a a9l computer and calling it a day. Either that or Carb. I really Really don't wanna go carb.

Pokageek~
Are you using the Auto or Manual computer? Speed shop i used couldn't get the "buck pop" out. Then i read somewhere on the net that the 5speed computer was better. So i got one off Ebay....The "Buck pop" stopped.


But i digress.....the "tuned t4m0" runs crappier on my 383 than the untuned a9l. Same motor.....2 different cars.

Chris
 
#16
Grady, Thanks - you are too kind!!! You could easily be a pro too, if you decided to go that route. I'm sure. You already have more knowledge than 90% of the 'pro' tuners I have seen...

I might add, the 95-95 PCMs are NOTHING compared to the '05 and up PCMs with the returnless fuel systems and drive by wire. The drive by wire is a NIGHTMARE to tune in some cases - it's all torque demand based and can give ANY tuner fits sometimes. And with Ford going to all mechanical returnless systems and direct injection, it just gets worse...

Don
 
#17
The PMS cant tune HEGO delay to my knowledge , might be one reason the longtubes are giving you a fit , CBAZA cars give guys headaches because of the load based parameters, 9 out of 10 people that have issues are dealing with idle or low load conditions and running a calibrated MAF

Calibrated MAFs skew the load readings and if you want it to run PERFECT then thats the first thing you should get away from , yes they will work with 24 and sometimes even 30lbs injectors , is this ideal , not if you are looking for a car to run and drive like stock .....anything over 30lbs injectors will likely give you issues especially on a 94-95 computer.

The reason guys run the A9L is because you can unhook half the dam sensors on the car and they will still run , but trust me if this guy was working on a airplane you were getting ready to fly you probably wouldnt want him to touch the dam thing so with this in mind. Hes probably the guy that runs around with a roll of duct tape in back pocket.

Here are the reasons why the uneducated and less experienced tuners love them so much , the A9L PCM will not adapt as easy to fuel pressure adjustments etc. , and the WOT timing is a function that is dependent only on RPM , this makes it possible for anybody with a screw driver for the adjustable fuel pressure regulator and a timing light for the distributor to get halfway decent results out of one , is this ideal certainly not.
 
#18
No I dont have a wideband. and from my understanding, the hego tables only matter if the car has trouble idling, which it doesn't. I have problem at say.. 2000-2500 rpm and I put a serious load on it in a gear that drags it out like..4th. And it loses power and lets out an embarassing bang/pop and then takes off at after it reached like..2600. Does that make more sense guys? Now its not the injectors cuz they are 30#r's. Its got to be something with the long-tubes/02's? Would that create the issue I have?
 
#19
Pokageek said:
No I dont have a wideband. and from my understanding, the hego tables only matter if the car has trouble idling, which it doesn't. I have problem at say.. 2000-2500 rpm and I put a serious load on it in a gear that drags it out like..4th. And it loses power and lets out an embarassing bang/pop and then takes off at after it reached like..2600. Does that make more sense guys? Now its not the injectors cuz they are 30#r's. Its got to be something with the long-tubes/02's? Would that create the issue I have?
Click to expand...

What MAF is it ?

You need a wideband ASAP
 
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