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.


18544
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.

[Chevy366]

4L80e's are bad about tailshaft/extension housing bushings backing out.
Trans should not have grinding/rattling noise, not a good sign, slight planetary gear whine but no grinding/rattling.

[jay_rich]

Well pulled the trans to check the flexplate bolts. Everything seemed fine. I yanked it and ground the powder coat off anyways. The sound seems to only come up once I do a pull. I drove the car for around 10min the other day (before pulling the flexplate). No noise at all, did a small burst run like 4psi then when I came to a stop and started moving the chatter came up. Sounds like I may need to call the builder. Really hope its not to do with my converter.

Jay

[joecar]

...
The sound seems to only come up once I do a pull.
...

Have TCC checked. Also, check engine crank endplay.

[jay_rich]

I have contacted my trans builder and will be going by his place for a test drive on saturday. Hopefully its a familiar noise to him. Like I said everything seems to check out good, temps, engine and trans, oil pressure etc.
Only other simple thing I can think of is double checking fluid level by dropping the pan and looking at where the dipstick sits. Im using the dipstick that came with the trans, only mod I have done to it is cut the end of it down (part thats in the pan) as I couldnt install the dipstick with the trans in the car without cutting it down. Took off around 1" maybe somehow im getting a false reading?

Jay

[Chevy366]

Yeah kind of sounds like the TCC, if the TCC is failing it will make a rattling/grinding noise, but so will a bearing inside the trans.
Dipstick length is not going to make one rattle, but to low of fluid will.

[jay_rich]

Well I know on my last log TCC was not commanded once due to the low speed/gear. All my last cruise was around 70km max, and every pull was 2nd gear to 4300max RPM. So it never commanded lockup. Also this was an issue before my TCC was even wired right. All the diagrams online had me wiring my brake switch wire to an 87a relay, after 1 hour of trying every possible way I switched it to regular 87 and was showing the correct command on my scanner. (brake depressed/released)

Figure after dropping the pan and double checking level that should pretty well get the basics out of the way before my builder rips it apart. Really hoping its not converter related since its a very pricey piece that is supposed to be new and never ran.

Jay

[jay_rich]

To update this I drove the car out to my tranny builders house (about a 25min highway drive) then drove him around for 10min doing all light throttle stuff and the car didnt make a single noise, drove it around the city for another 20min or so all good. Let the car cool down for like 5 hours then drove home and after like 5min it started doing it again. Seems to be happening when the trans temp is in the 140 range. That could be a coincidence though. I havnt had time to get back out in the car to test anymore. Hopefully next week Ill get some more testing in. I do have a car show in town on saturday so maybe it will pop up again.

Jay

[joecar]

Jay

What ATF are you using...?

So you think the TCC slips when the ATF is not yet warmed up...?

Look at the TCC Max/Min PWM/pressure tables, set the Max table to max value (if not already) and set the Min table close to max value.

[jay_rich]

im using generic atf. nothing fancy. I have spoke with rpm transmissions, PI converters and circleD. They all said triple disks can be quite noisy especially if my car is quiet. which is sounds stock. CircleD suggested rechecking thr converter gap. He said he has heard them chatter from being too tight. Also RPM (wbo specd the converter) said it was specd for a 427 roots motor. so thats why its much tighter on my motor.

Im gonna jack it up this week and recheck the gap. try to get it to 0.175 or so like circleD suggested and possible dump the generic brand atf and pick up some john deere hydragaurd

[jay_rich]

Well I got under the car and pulled my shim out from the converter. I had it shimmed to around .075 or so. The problem still occurs with the converter pulled back 0.200 (no shims). I have noticed though that while it is chattering, if I command 2nd gear lock the chatter is gone instantly. I also clicked on 3rd gear lock and no noise. Unsure if it was because I was already past the chatter area. Im hoping on my way home from work today i can get it to chatter again and force 3rd gear to see what happens.


I have noticed the car will not command lockup also? Anyone care to take a look at my tune? the most part it was stock then I modified it a bit copying someone elses tune. Basically adjusted all the abuse modes so it doesnt go into abuse mode. D2001-2-3 and D0301.

Anyone see anything outta wack for lockup?18651

[joecar]

Ok, time to look at this chart (post #1): 4L80E-Reference-Material&p=38965&viewfull=1#post38965 (https://forum.efilive.com/showthread.php?4305-4L80E-Reference-Material&p=38965&viewfull=1#post38965)

so noise in D1, but no noise in M2 or M3...? What about in M1...?

[jay_rich]

I will test M1 tonight. I assume by M1 you mean just pulling the shifter into 1st. Im pretty positive I tested that and it still did the shatter sound. I never realized D vs OD vs 1st actually did different things in 1st gear. I will test this tonight.

I think I will also do a C.A.S.E and log my misfires to see why the PCM will not tell it to lockup in 4th yet when using DVT I can make it lock.

Ill report back tonight or tomorrow with my outcome.

Jay

[joecar]

Yes, M1 is Manual 1st and D1 is Drive 1st, chart shows they are slightly different.

[jay_rich]

Well did some testing. Same results for M1 didnt get too much testing in as I snapped my shifter trying to force into 1st. The noise also stays once warm like 185 temps. Even idle you can hear it. Almost like something is m9ving back and forth. Sounding like its time to yank it for the builder.



Jay

[joecar]

Is there something impeding the movement of the shifter/cable...?

Also, while you're at it, check crankshaft endplay to make sure it is ok... but it does sound like a trans/TC problem.

[jay_rich]

No it was more or less my fault. When i put the 80e in I use my stock shifter and didnt have the throw set perfect. I spent a day on it and gave up so it was "close" enough for me lol. I kinda forced it in. Anyways my buddy gave me a short B&M cable. just got in from modifying it to work. Actually works better.


While I have it jacked up I will check. You would think if the motor had alot of end play then the thrust besring would be shot? oil pressure is fantastic etc. Im ruling on trans since i forced 2nd 3rd and 4th from idle and it doesnt make a peep


Jay

[joecar]

It does sound like the trans.

[jay_rich]

Well I dont have much to update on the noise but I think my TCC should lock fine now. I was installing my 2 step and noticed I wasnt getting power when the pedal was pushed in. So I redid my TCC relay wiring and got that all sorted. What happened was I tapped into the grey wire I was told to on the pedal. Turns out that's wrong, it was the YELLOW wire I needed. No wonder I had to wire the relay to 87 instead of 87a to get the scanner to read the pedal correct. NOW it reads correct AND has 12V when pressed down. I havnt tested anything but im pretty confident. I will still need to pull the trans for the builder to go through, I have just been too busy to even bother looking at the car.

Jay