Is my TCC bad
The other day I noticed that it felt like my TCC was slipping when commanded locked.. I looged some data and was wondering of anyone would confirm that the TCC slip RPM should be alot lower than it is monitored? See my logs.. I suspect when the TCC is locked the TCC slip rpm should be little to none..
EFILive newbie
1999 Camaro SS A4 | LME Forged 347 | Yank SS4000 Stall | 226/234 Cam | Patriot LS6 Style heads 2.055 / 1.57 57cc 11.3 SCR | FLP Long tube headers
Joel,
I'm having trouble opening the zip (aarrgh, I'm having problems on my home pc), so I haven't looked at your log... but...
some slip is acceptable (say no more than 50-100 rpm) since the stock TCC is only "half" a clutch (torque can make it slip easily);
and you have to correlate the slip amount with TCCMODE... slip should be low when TCCMODE is locked/applied, slip can be anything otherwise.
if you could post a screen shot (PrntScreen, save into file, reply to post, do Manage Attachments, upload) of your chart dashpage that will help me... thanks.
Joe
Here is some screen shots.. Forst is idle and second is cruising @ 50mph..
EFILive newbie
1999 Camaro SS A4 | LME Forged 347 | Yank SS4000 Stall | 226/234 Cam | Patriot LS6 Style heads 2.055 / 1.57 57cc 11.3 SCR | FLP Long tube headers
Joel,
Can you log TFT (trans. fluid temp.) also...?
Do this...
At steady cruise, record the MPH and RPM...
Then use this formula to see if the MPH and RPM correlate correctly:
RPM = MPH * 336 * gear_ratio * axle_ratio / tire_diameter
where tire_diameter is in inches;
if they correlate correctly, then the TCC may not be slipping, but probably the PCM is computing incorrect data or the TCCSLIP PID scaling is incorrect.
Joe
Maybe you just have a broken TCC soloniod case?
"If you can leave a black mark on the pavement, from the exit of one corner to the braking point of the next one, you have enough horsepower."
wait4me has a good point...
Joel, how many miles are on your trans...?
Originally Posted by joecar
Brand new just re-built 1200 miles ago.
EFILive newbie
1999 Camaro SS A4 | LME Forged 347 | Yank SS4000 Stall | 226/234 Cam | Patriot LS6 Style heads 2.055 / 1.57 57cc 11.3 SCR | FLP Long tube headers
That part could have gotten cracked if they forgot to pull it out before pulling the front pump. USUALLY that is a part they wont replace because it is the whole trans harness also.
"If you can leave a black mark on the pavement, from the exit of one corner to the braking point of the next one, you have enough horsepower."
Well I can command the TCC to lock via the scan tool and nothing happens.. I tried it while stopped and I guess if it engaged it would kill the motor, but it did not the RPMs stayed at a steady 1000rpm idle speed. SO I would guess the TCC soleniod is shot?
EFILive newbie
1999 Camaro SS A4 | LME Forged 347 | Yank SS4000 Stall | 226/234 Cam | Patriot LS6 Style heads 2.055 / 1.57 57cc 11.3 SCR | FLP Long tube headers
Joel,
I assume you commanded both solenoids, right...?
It seems to me that the PCM requires several conditions to be met before it allows the TCC to be overriden:
- GEAR must be 3rd or 4th
- VSS must be above some minimum
- ECT must be above some minimum
- some others that I don't know
The PCM is trying to protect the TCC and the vehicle;
So you have to either lift the rear (30-40 mph is good, don't go above this, and make sure the vehicle is SECURE... safety first!), or take a buddy with you on the test drive;
When overriding the TCC, if you monitor the various TSTATE pids (in addition to TCCMODE and TCCDC) you'll see that the PCM does not command the TCC while the conditions are not met...
(this makes me think there are some unknown tables for setting the condition parameters for TCC override)
It may be wise to pull the pan and inspect the solenoid and it's wiring;
I think I saw a solenoid kit where you cut the old one from the harness and crimp on the new one (using specially supplied piercing crimps... this is how it's done on other GM trannies)...
Like Jesse said, the TCC sol. may have been damaged when the pump was pulled from the front of the case with the solenoid still in the bottom of the pump (it requires quite a bit of force to pull the pump as it fits very snug in the case);
Joe
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