Tuner Driver assist help
Thread Starter
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
Tuner Driver assist help
1993, 396LT1 A4 2800 rpm converter , 42# injectors, 3.75 gears, long tubes, heated O2 sensors. Runs great, with the exception of cruising at about 1800 rpm , plus or minus 200rpm, in OD.. It seems to buck a little, like a little surging, causing the driveline to slap, like hearing u joints are broke.
U Joints are new, driveline is solid with D44, Ikerds diff, and I cant move any of the half shafts or driveshaft by hand when in the air.
If I drop a gear, to 3rd it all goes away, even when I get in same rpm. Maybe not as pronounced due to speed, but I cant hear it
So, in tuning, what parameters can assist a barely above idle/throttle to keep car from bucking/surging a little.
IAC is failry new, TPS is fairly new. Battery, Alternator new.
Its been doing this for some time, but just now going to tackle it... PCMforless, and 3 other tunes available. None have ever been able to get this surge issue worked, as we couldnt see any symptoms to show it, via TTS datamaster.
U Joints are new, driveline is solid with D44, Ikerds diff, and I cant move any of the half shafts or driveshaft by hand when in the air.
If I drop a gear, to 3rd it all goes away, even when I get in same rpm. Maybe not as pronounced due to speed, but I cant hear it
So, in tuning, what parameters can assist a barely above idle/throttle to keep car from bucking/surging a little.
IAC is failry new, TPS is fairly new. Battery, Alternator new.
Its been doing this for some time, but just now going to tackle it... PCMforless, and 3 other tunes available. None have ever been able to get this surge issue worked, as we couldnt see any symptoms to show it, via TTS datamaster.
Burning Brakes
Joined: Mar 2005
Posts: 1,082
Likes: 115
From: Richmond Hill Ontario
May be able to be adjusted in Tune. Want to make sure the VE / Timing in that particular MAP/Rpm and surrounding cells are consistent. You may also want to look at your TCC settings.
Racer
Joined: Feb 2020
Posts: 483
Likes: 109
From: Fairfax, Virginia
Does it get more pronounced going downhill?
Cruise control on?
Is the TPS reading consistently?
The TCC locking and unlocking could definitely cause it, and so could a fluctuating TPS signal, it could be transitioning in and out of DFCO if the TPS signal is noisy.
Cruise control on?
Is the TPS reading consistently?
The TCC locking and unlocking could definitely cause it, and so could a fluctuating TPS signal, it could be transitioning in and out of DFCO if the TPS signal is noisy.
Last edited by ThatOneKid; May 4, 2021 at 01:37 PM.
Thread Starter
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
Thread Starter
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
Not sure if the cruise makes any difference as I never use it at that speed.
TPS is reading fine. I have reset it a few times to ensure its okay, and changed it to anther one. No change.
If the TCC is locking and unlocking, what speed should I change it too? Higher? In OD only?
TCC is lock 47mph low
42mph Unlock low gears
TCC lock high gears 56mph
TCC unlock high gears 42
TCC unlock prevention speed threshold is 64
Burning Brakes
Joined: Mar 2005
Posts: 1,082
Likes: 115
From: Richmond Hill Ontario
Also according to calculator if you are using 26' rear tire @ 1800rpm in OD (0.70 ratio) you should be at about 53 Mph hovering right around your Lock up value of 55Mph. Try increasing your Lockup value to 58 or 60.
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Thread Starter
Race Director
Joined: Jan 2012
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From: United States
Put in new program and drove vette. Draw significantly better. I did find some hills in wind down and nothing really changed at that speed. I did notice that if I barely touch the brake the chatter went away. Obviously it unlock the converter. But it is a vigilante with less than 5000 miles on it not hard miles.
Tomorrow I will use new lock up speeds.
currently repairing inlaws laptop.
Tomorrow I will use new lock up speeds.
currently repairing inlaws laptop.
Last edited by krackenvette; May 5, 2021 at 01:20 PM.
Thread Starter
Race Director
Joined: Jan 2012
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From: United States
Anyways. I am not sure what tables to compare to on Tuner Cat to see what the differences were in his tune...
But, I will change the lock and unlock and run it Friday, my last day off before traveling off to work outside USA
Here is the VE tables, as you mentioned. The old tune was brought up first, and then I compared by using new tune I just used today..
Last edited by krackenvette; May 5, 2021 at 03:43 PM.
Thread Starter
Race Director
Joined: Jan 2012
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From: United States
I will try my best when I get home not sure about the data logs though. What kind of files are the data logs I have to go on an old hard drive. I know I should have some. Still have laptop and jusy converted to ssd drive, via clone.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
Unlock the convertor when the throttle goes below 3% and see if this solves the problem? My heavily modified 406 would buck some transitioning from power to no power when you were basically coasting and it was eliminated by unlocking the convertor when I coast.
Last edited by bjankuski; May 6, 2021 at 11:38 AM.
Thread Starter
Race Director
Joined: Jan 2012
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From: United States
What table do I change. Headimg home now.
Thread Starter
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
Okay, here are some older TTS Datamaster runs, they are the .uni files. The two text files just need extension changed to .uni to work
And here are the two bins files I am working on for the 93 Corvette.
Bin 1 was the file where I had more bucking, surging etc.
Bin 2 is the newest one I used..
And here are the two bins files I am working on for the 93 Corvette.
Bin 1 was the file where I had more bucking, surging etc.
Bin 2 is the newest one I used..