gm 847 woes
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Registered User
Joined: Jan 2004
Posts: 451
From: Bradenton Fl
gm 847 woes
I installed a gm 847 last week and a fresh tune to match,also installed a t-350 at the same time.Problem is when settling down to idle after driving it wants to stall untill completly stopped,then a blip of the throttle cleans it up and it idles fine.It has a 3500 stall converter in it and also had the tranny programmed out so that shouldnt be it ,any ideas? It worked fine with my cc305 and 4l60e before the swap.Also forgot to mention exhaust is rubbing crossmember and will be fixed tommorow could this be a cause ?
Registered User
Joined: Oct 1998
Posts: 3,144
From: Jackstandican
Did you get it dyno tuned or a mail order tune?
It's possible the PCM will just have to relearn. When I had my LPE 211/219 cam after I installed Hooker LT's and would disconnect the PCM I would have the same problem. It took about a weeks worth of start cycles for the PCM to finally learn where the idle was.
It's possible the PCM will just have to relearn. When I had my LPE 211/219 cam after I installed Hooker LT's and would disconnect the PCM I would have the same problem. It took about a weeks worth of start cycles for the PCM to finally learn where the idle was.
Registered User
Joined: Jun 2002
Posts: 2,456
From: sarasota, fl
glad to see you got it in already bob..............its definetly the tuning.....the 847 is too big, and too different than you old cam for the same tuning to work........you really need to set her up for some dyno tuning time.........not only will it fix the idle problem, but it youll gain quite a bit of power.
our local shop/club just off of adamo drive in tampa http://www.revxtreme.com/forums/ just got a brand new dynojet, so you can get tuned there.
our local shop/club just off of adamo drive in tampa http://www.revxtreme.com/forums/ just got a brand new dynojet, so you can get tuned there.
Registered User
Joined: May 2000
Posts: 2,889
From: Peachtree City, GA
Originally posted by got_hp?
glad to see you got it in already bob..............its definetly the tuning.....the 847 is too big, and too different than you old cam for the same tuning to work........you really need to set her up for some dyno tuning time.........not only will it fix the idle problem, but it youll gain quite a bit of power.
our local shop/club just off of adamo drive in tampa http://www.revxtreme.com/forums/ just got a brand new dynojet, so you can get tuned there.
glad to see you got it in already bob..............its definetly the tuning.....the 847 is too big, and too different than you old cam for the same tuning to work........you really need to set her up for some dyno tuning time.........not only will it fix the idle problem, but it youll gain quite a bit of power.
our local shop/club just off of adamo drive in tampa http://www.revxtreme.com/forums/ just got a brand new dynojet, so you can get tuned there.
how do u people think a dyno tune will improve anything with driving the car on the street? As far as i am concerned DYNO tune is for tuning WOT not part throttle
The problem you are describing happens too all of us with big cams. It will go away once the PCM learns to deal with it. It usualy takes about a day of driving. Also as weird as this may sound your alternator might be going out. If your problem doesnt go away by iteslf after driving around for a while, you might want to get your alternator checked out.
Marcin
Registered User
Joined: Nov 2002
Posts: 1,831
From: Middle Tennessee
Originally posted by xxsaint69x
how do u people think a dyno tune will improve anything with driving the car on the street? As far as i am concerned DYNO tune is for tuning WOT not part throttle
The problem you are describing happens too all of us with big cams. It will go away once the PCM learns to deal with it. It usualy takes about a day of driving. Also as weird as this may sound your alternator might be going out. If your problem doesnt go away by iteslf after driving around for a while, you might want to get your alternator checked out.
Marcin
how do u people think a dyno tune will improve anything with driving the car on the street? As far as i am concerned DYNO tune is for tuning WOT not part throttle
The problem you are describing happens too all of us with big cams. It will go away once the PCM learns to deal with it. It usualy takes about a day of driving. Also as weird as this may sound your alternator might be going out. If your problem doesnt go away by iteslf after driving around for a while, you might want to get your alternator checked out.
Marcin
Registered User
Joined: Jun 2002
Posts: 2,456
From: sarasota, fl
Originally posted by LWillmann
You can use a dyno to work with the part throttle tuning. No one ever said you HAD to run just WOT on a dyno. You can get all of the tuning done at one time, in one place.
You can use a dyno to work with the part throttle tuning. No one ever said you HAD to run just WOT on a dyno. You can get all of the tuning done at one time, in one place.
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