Jason Short

Well, I thought that I had things figured out on how high you can rev with the factory PCM....apparently not My post here is prompted by Drag Bear's post in the Drag racing section.

I know this has been hashed out in the past, but I am confused with my own personal experiences with the factory PCM. I have a solid roller motor that shuts down almost EVERYTIME i am near 7000rpms. Now, people are saying that they can go over 7000rpms, they do go over 7000,etc...Now I am hearing that it could be mph dependant (auto cars). ????

I know the factory tach is off on some cars, which may be part of my problem. Shut down ususally happens when my tach is reading ~6800rpms. But, it is not hitting the rev limiter (see a few lines below).

Not sure if this is just my pcm or what?

Its to the point where I am thinking about setting the limiter at 6800-6900 since having the car shut down on you at 100mph is not the really something that I like.

BTW, this is not hitting the rev limiter either since I have that set ~7100 with a 7000rpm pill in my MSD 6AL.

My car is an M6 and has shut down in 1st, 2nd, and 3rd gear numerous times.

I am confused as to what is going on here.

Thanks for any help/insight
Jason

Dr.Mudge

Jason, maybe you can log a run and look at the MPH and figure out if your getting cut off at the correct RPM? Correct meaning 7k or beyond, I have heard that some people could pull 7,200 RPM but with the tach being off who knows where this info is coming from. I think 6375 RPM is the end of the line as far as PCM logging RPM right?

With that in mind I'd look at the MPH.

OneFlyn95z28

Jason what gears are you running? You are at the top of third at 7,000K?

I also know the tach laggs behind on very fast RPM Increases. This would make 6,800 easly be 7k or more. If you can bowwow a Ttattle tale tach from some one. mount it temperary under the hood and make a run. when you get back to the pits check it to see where it logged your highest RPM.

Drag bear is the first and only car in known history to screem past the 7-7,200 beriar. We had a solid roller 396 we thought was one time But After going and checking the dyno sheets it would apper we were mistaken for a 7,100ish cut out.

Good luck man!

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Ellis
Team Captain
Team North West F-Body
www.teamnwfbody.org

Jason Short

Thanks for the info guys

There may be a little confusion here....probably me not being more specific on my end. My car is an M6 (not an auto), so I dont know if you can look at it from the mph side of things (as DrMudge said). Although, I could be wrong....I dont know enough about tuning to decifer that.

Also, my car has not shut down in the 1/4 (since I havnt had it there yet), only on street/highway. It has happened in in 1st, 2nd, and 3rd gear. Last year with my solid roller 355, it shut down a couple times in 1st and 3rd (same exact way).

Here is a little more info on my car (nothing out of the ordinary):

-M6
-93 car (I converted it to 94-95 OBD1)
-has all the 95+ updated things (opti, etc..)
-396ci
-solid roller (cam motions 247/250 .658/.659 112) custom grind
-93 M6 tranny with 3.73s
-AFRs

I dont see what else it could be besides the computer, as all my scan readings are normal up until the point of shut down.

I really dont care about reving past 7000, I just dont want my car to shut down while driving/racing.

Thanks again
Jason

OneFlyn95z28

well i think the key is to first identify if it is shutting down at a certain RPM and go from there. May be as easy as adding a Shift light

Good luck man!

BTW got any more motors for sale

------------------
Ellis
Team Captain
Team North West F-Body
www.teamnwfbody.org

rskrause

Jason: the stock PCM will not rev past 7000rpm (or something close to it, it's some hex number converted back). I am under the impression that it has to do with the size of the data registers the PCM uses. Anyway, there is no way around this. You need to set your rev limiter below the point where the PCM shuts down, even though it may be less than 7K on your tach (which will not keep up with your high revving monster motor).

That guy who was claiming a 1.22 60' with the rear wheels and revving to 8K on a stock PCM is on crack or something.

Rich Krause

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'95 Z-28 383 with Vortech, nitrous, etc.
"1FASTZ28"

[This message has been edited by rskrause (edited July 06, 2002).]

Jason Short

Hey Rich, I just sent you an email...

I know that it wont go past 7000, I am just trying to figure out why my car shuts down at this point where as others dont. Also, I have the 7000rpm pill in my MSD 6AL, and it *seems* like the car is not even hitting a rev limiter before it shuts down.

Not trying to rev past 7000, since I am only cammed for 6900-7000, just trying to figure this shut down thing out

Thanks again for the help!
Jason

OneFlyn95z28

hehehehe I am with Rich on that one

------------------
Ellis
Team Captain
Team North West F-Body
www.teamnwfbody.org

chevyguy3

do you have a shift light? try some 6800, 6900, 7000 pills and see if it lights before the motor cuts out.

i havent done any testing on where my PCM shuts down (i will this year), but at the last race i went to last year i set the rev limiter on my ignition box to 7250, and bounced the motor off that when i launched on all 20 or so passes without any problems. i hope im lucky enough to rev it that high in gear this year? probably not. fwiw its a 95 6 speed PCM

aggiez28

did you get it figured out Jason?

streetbad

Daughter through away the cover for the CD with the Vin./password info on it.
Jason will you please help me out?