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3800Sc/4t65e RPM/ mph by Lou6t4gto
Started on: 07-10-2015 07:25 AM
Replies: 8 (193 views)
Last post by: Lou6t4gto on 07-10-2015 10:49 PM
Lou6t4gto
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Report this Post07-10-2015 07:25 AM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
2 things RPM related. in my 3800SC / 4t65e-HD conversion, it's reading about 1700 RPM at 40-45 MPH. is that Correct ?? (Setup is originally from a 1997 Riviera) Also , from a dead stop, shifter in Drive, put the pedal to the floor, it doesn't seem to shift out of 1st until I let off the gas. (Tach reads over 6000 RPM, then I let off the gas and then it shifts) * At part throttle it shifts perfectly .* Don't want to hold it to see what happens if I don't let up. What's up with that ? Shouldn't it shift at about 5-5500 ?? Thanks
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Report this Post07-10-2015 11:27 AM Click Here to See the Profile for TXGOODClick Here to visit TXGOOD's HomePageSend a Private Message to TXGOODEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don`t know about shift points but mine, in 4th gear turns about 1900 at 70 MPH.
Also, I don`t know how your shifter is set up but when mine shows drive its only in 3rd gear because of only 3 indents in the original shift window.
4th on mine is somewhere between drive and neutral.

[This message has been edited by TXGOOD (edited 07-10-2015).]

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Lou6t4gto
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Report this Post07-10-2015 11:37 AM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
I just drove my wifes Formula Firebird. it turns about 15-1600RPM at 45 MPH, But it has 3.42 gears ! I know a 1997 Riviera didn't come with those gears , did they ? and what can I do" about the WOT shift point ? was the setting changed when the computer was re programmed ? (Can't remember off hand who did it, But I sure didn't ask for it.
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TXGOOD
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Report this Post07-10-2015 11:44 AM Click Here to See the Profile for TXGOODClick Here to visit TXGOOD's HomePageSend a Private Message to TXGOODEdit/Delete MessageReply w/QuoteDirect Link to This Post
I`m not real familier with the way the computer works because my car was built for me.
I was having a problem with my car not shifting into overdrive and it wouldn`t lock up the torque converter but that was due to a 12v wire that controls the 1-2 and 2-3 shift solenoids not getting a good connection.
Maybe one of the guys that program the PCM for the 3800 will chime in.
Mine was done by Nosrac.
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nosrac
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Report this Post07-10-2015 11:53 AM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:

2 things RPM related. in my 3800SC / 4t65e-HD conversion, it's reading about 1700 RPM at 40-45 MPH. is that Correct ?? (Setup is originally from a 1997 Riviera) Also , from a dead stop, shifter in Drive, put the pedal to the floor, it doesn't seem to shift out of 1st until I let off the gas. (Tach reads over 6000 RPM, then I let off the gas and then it shifts) * At part throttle it shifts perfectly .* Don't want to hold it to see what happens if I don't let up. What's up with that ? Shouldn't it shift at about 5-5500 ?? Thanks


Whom Programmed your PCM? Do you have performance shift in your harness?

Stock shift points are 5300rpm at 75% throttle.

RPM, MPH along with TPS and PCM programming contribute to when it will shift.

Be sure to use 3rd for WOT runs and spirited driving due to higher line pressure.
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nosrac
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Report this Post07-10-2015 12:07 PM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post
I BAD PCM that I programmed that didn't shift the trans correctly. Ended up trashing the PCM.

Also, different Trans gears ratios and tire/wheel combo will effect shifting. I had a converted 4T65e to 4T65e-HD in my 86 so my Gear ratio was 3.05 plus I had 18" wheels and 245 tires to match the GTP overall diameter.
I tweaked the trans setting to perform at the track and my car always shifted perfect and Never had an issue, Although, my car was program for 2.93 gears.
However that exact same Trans programming had issues shifting out of WOT in two other 2.93 gear ratio cars, and NOT really sure why.
My Guess was either Harness issue, Bad PCM or Bad Trans, or just too aggressive PCM settings for that particular Trans as they all don't perform the same..
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Lou6t4gto
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Report this Post07-10-2015 01:29 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
no "performance shift". engine and trans are Totally Stock and totally rebuilt with only 8 miles on both. 16" wheels with 235/60 rear tires.
Can't remember Who reprogrammed it, It was one of the guys on here that does it a lot. (was $150 as I remember about a year ago)
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Dennis LaGrua
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Report this Post07-10-2015 08:52 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
First step. Check the speedometer speed compared to the speed shown on your GPS. IIRC my 3800SC reads about 2000 RPM around 70 MPH. There were several different FDR's on 3800 powertrains over the years

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Lou6t4gto
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Report this Post07-10-2015 10:49 PM Click Here to See the Profile for Lou6t4gtoClick Here to Email Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
Isn't the final drive determined by the Gears and chain in the trans ? I rebuilt it, but never thought to do a tooth count.
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