4l80e PI3800 triple disk chatter off idle

[jay_rich]

Figured i would move/add this thread under here.

Here are some specs

2005 5.3L, Ls6 cam, gt45 turbo
3.23 rear
1997 4l80e rebuilt with hd2 kit
Precision industries 3800 triple disk

Everything seems to be good except when im pulling away from 1st gear. You can hear a grinding/rattling noise until like 5mph or so. unsure if its a line pressure issue?

Basically took a stock 2002 van 4l80e tune, upped the line pressure around 5-10%, upped the shift points and lowered the desired shift times.

I have never tuned an auto before. Any help?

Thanks

Jay

My current tune (bit rich) and latest log is attatched. Mind you the log is mostly 4th gear with a couple 1-2-3 shifts later in the log. Dont mine the 4 degree retard, Im thinking my exhaust touching the frame rail and poly mounts are causing that.


Attachment 18544
Attachment 18545

[joecar]

The pressure regulator can sometimes buzz, but it sounds like a buzz and not a rattle.

Thinking about it, the rattle may be related to the flex plate.

[joecar]

Someone tells me it might be gearset noise.

Did it just start happening, or was it always happening.

[jay_rich]

Litterally just thought of it. I got a TCI flexplate and totally forgot to grind the powdercoat off. Gonna check the bolts tonight.

Also to add I only have like 60km on the car it started happening pretty well after my first outing. Drove the car around (maybe for 5min) then brought it home to work on the power steering. Next outing I drove around and did a couple 60% throttle 4psi or so pulls then noticed it the first time I was at a complete stop then started moving at like 4% throttle.

My friend said his Firebird did the same thing after installing the same flexplate. Took a couple outings then they all backed off.

Jay

[joecar]

...

My friend said his Firebird did the same thing after installing the same flexplate. Took a couple outings then they all backed off.

The flexplate bolts backed off, or the TC bolts/nuts...?

[jay_rich]

His flexplate bolts backed off.

Well just looked at mine. Not the case everything seems good and tight :(

Jay

[jay_rich]

Just hooked up a pressure gauge to the port.

185psi Park
185psi Drive
270psi Reverse

Safe to say I dont need more line pressure. Kinda lost now.


Jay

[jay_rich]

Looking over my log I noticed my TCC switch is wired backwards. I mixed up my ground and brake switch wire on the relay (1987 camaro so I had to change the output to be ground when pressed) That solves my Lockup not coming on. Unsure if it will have any effect on the low rpm chatter.

Jay

[joecar]

Your line pressure is a little high, but its ok.

The TCC override switch being wired backward should not cause the TCC to make noise... but listen anyway to see if there's a difference now.

[bmc1025]

If you drive around in manual first is the noise more prevalent? If so it is more than likely just a noisy gear set. Some 4l80 have straight cut gears usually 4l85e out of a heavy duty applications, and for some reason 2500 vans.