Help! Car shifts incredibly rough! in SD mode
Thread Starter
TECH Fanatic
Joined: May 2004
Posts: 1,030
Likes: 0
From: Wichita KS
Help! Car shifts incredibly rough! in SD mode I have been driving my car in SD mode for the last few hours while doing some logging and trying to get my VE table under control, I know that the MAF has been giving me problems, and I am tempted to just keep running my car in SD mode for awhile to see how I like it.... BUT all my shifts have become much rougher, and my 1-2 shift, at 1500 - 1900 rpm shakes the whole car! It cant be good for it... At these low rpm's it seems to be shifting as hard as it does at WOT!! How can I change this? I already messed with the shift speed and shift pressure tables down low, but they aren't set extreme at all! Is there something i am overlooking!?!?!? help me please!
Nathan
Nathan
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
I believe that on earlier cars when you fail over to SD the PCM commands full line pressure for the transmission ...
I've seen several posts about this not being the case on some OS's ... I believe all 01 and 02 were fine... not sure about 00 (my trans is vacuum modulated). Can any answer for sure once and for all?
ALso I wouldn't recoommend runnin in SD anymore till this is verified... 100% line pressure all the time isn't good for the trans
I've seen several posts about this not being the case on some OS's ... I believe all 01 and 02 were fine... not sure about 00 (my trans is vacuum modulated). Can any answer for sure once and for all?
ALso I wouldn't recoommend runnin in SD anymore till this is verified... 100% line pressure all the time isn't good for the trans
I was concerned about this as well when I started tuning my car. It would slam into drive and reverse from park and shift extremely hard. I could get the car sideways on the 1->2 shift with only about 50% throttle and shifting at 4k rpm. From the research I did, the earlier years (our 98's seem to be the worst) revert to 100% line pressure all of the time when a maf failure occurs.....and there ain't a damn thing we can do about it. I logged in SD mode for about two weeks and haven't had any adverse affects to the tranny since then, and that's been a couple months ago. It kinda makes for a fun drive though, huh? 
tune your MAF and the car will be back to normal. I can't even tell if i'm in SD or MAF unless i got the SES light on.
look through the stickies for the long (VERY long) explanation, but if you just want the tool, just go to www.allmod.net/hpt
look through the stickies for the long (VERY long) explanation, but if you just want the tool, just go to www.allmod.net/hpt
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Ask HPTuners: they can modify your program to don't have 100% line pressure when MAF off.
I tuned the VE table disconnecting the MAF and driving carefully, it works (just lift your foot when you feel the car gonna shift and it won't jump).
My MAF is back, it was just to chech the VE.
By the way: why do you want to run SD? Your car isn't that modified...
I tuned the VE table disconnecting the MAF and driving carefully, it works (just lift your foot when you feel the car gonna shift and it won't jump).
My MAF is back, it was just to chech the VE.
By the way: why do you want to run SD? Your car isn't that modified...
Staging Lane
Joined: May 2005
Posts: 54
Likes: 0
Originally Posted by WS6snake-eater
Just e-mail chris over at HPtuners, and send him your bin. He will rewrite the cal to not revert to full line pressure, and send you the bin back. At least that's what they were doing.
Yup--what he said. Chris fixed the bin so I could SD tune my 98. Works great.
Thread Starter
TECH Fanatic
Joined: May 2004
Posts: 1,030
Likes: 0
From: Wichita KS
ok, thanks guys... Its not that i am worried about the maf tuning, i just am not so fluent with it, and i kinda wanted to run in SD mode for awhile, and compare how things went is all! I dont like my MAF!!!