New engine and 4l60e combo, slipping in 4th

[abc]

I have a fresh rebuild of engine and trans combo in a C5 vette, so for the most part untested. Now 383 LS1, cent. blower, rebuilt trans with 3200 stall. On first test drive just to verify all works as it should, I noticed 4th gear was slipping excessively. After checking fluid level again (NPF) I captured a few logs and now I think it's slipping in third also. This is tough for me to feel as I have no experience with this exact combo and have not put any power to it to know what it may feel like as the RPM increase. Is there a way to know or anything in the logs that may point to a smoking gun? I'm just now trying to sort out the data and was thinking you guys may be able to help me fast track my learning.

I was dragging the brakes in a few situations in an attempt to put more load on the trans in an attempt to learn something from it without applying too much speed and power to the engine. When I was doing so, pay little attention to the timing reduction as I believe I have the blower tensioner miss-adjusted and it's a false knock, maybe. Either way I will adjust the tensioner and check for knock in the next log.
2000 vette 13.hpt
2.hpl
1.hpl

[edcmat-l1]

If you had the trans built locally I'd take it by the builder's shop and let them drive it.

What converter is in it?

[abc]

3200 stall, brand new converter. The trans was not built locally and there have been suggestions that the tune file may be the culprit. I was hopping that someone here may have enough experience on the transmission side of a Gen 3 platform and could point to or rule out a smoking gun in the tune file.

The more I test it, the more I think it's also slipping in 2nd and 3rd. I have not pushed the combo above atmospheric psi at this point, but the engine runs more than acceptable below boost while I try to sort out this transmission issue.

Any help is appreciated.

[ns158sl]

hpl1 looks fine? hpl2 seems like the converter isnt holding lockup. Do you have shaft speed PIDS to log?

[abc]

No, I do not have shaft speed to log.
The converter will not stay locked in anything other than extremely lite load, such as flat or down hill. I am assuming rpm rate of change or something similar will also unlock the converter, this is just a guess from me as I try to make sense of what is happening.

I assume low line psi will also will prohibit the converter from locking up well.

HPL1 at the end of the log, I was going down hill, that's why it looks acceptable.

I need to understand TCC Slip in the PID's. I'm not sure if it's an actual measurement or a result of an internal formula based on rpm, gear ratio, and MPH?

When the TCC is locked up and lite load on vehicle, the slip is very low to zero. When the TCC is not locked up, the PID channel is showing large deviations. Why would it show a slip when the TCC is not supposed to be locked up? I suppose that question has no bearing on troubleshooting the problem.

[bk2life]

is the trans 'built' or all stock with a stall?

i had problems with rpm dips somewhat like youre talking about. Only see/hear it on long trips.
Ended up turning off PWM in the tune for the converter. I didnt need it with my combo/stall/trans.
you might try that

[abc]

Trans is built. I do have the PWM for the TCC circuit almost maxed out so it now does engage the TCC almost instantly when commanded, but it would not do that before I started adjusting the Force motor current. I now believe the problem extends to 3rd gear and possibly 2nd. As I add line psi via decreasing the Force Motor current the problem does show less signs of an issue but still is excessively slipping in 3rd and 4th, so much so that I believe if I started to add power in attempt to verify my concern with more power it may just go up in smoke.

I also need to learn the relation ship between the TCC lockup/torque converter and the transmission. Now that I have added line psi, the lock up clutch seems to function normally and during light acceleration the trans appears to not slip. When the TCC lock up circuit is active, does it divert psi to other parts of the trans that would help apply more psi to the 3/4 clutch pack or something that would help keep it from slipping?

[Tranzman]

Trans is built. I do have the PWM for the TCC circuit almost maxed out so it now does engage the TCC almost instantly when commanded, but it would not do that before I started adjusting the Force motor current. I now believe the problem extends to 3rd gear and possibly 2nd. As I add line psi via decreasing the Force Motor current the problem does show less signs of an issue but still is excessively slipping in 3rd and 4th, so much so that I believe if I started to add power in attempt to verify my concern with more power it may just go up in smoke.

I also need to learn the relation ship between the TCC lockup/torque converter and the transmission. Now that I have added line psi, the lock up clutch seems to function normally and during light acceleration the trans appears to not slip. When the TCC lock up circuit is active, does it divert psi to other parts of the trans that would help apply more psi to the 3/4 clutch pack or something that would help keep it from slipping?

The Force motor that operates on a .1Amp-1.0Amp scale. .1amp is full line pressure 190-225 (depending on the modifications to the pressure regulator boost & regulator valve. 1.0amp is the lowest pressure and should be around 70-90psi.

No it does not divert any pressures from say TCC & the 3-4 clutch. Line pressure does get routed to more than 1 circuit similar to electricity in a house. 200amp supply for several 15-20 amp circuits. the difference is that line pressure is constant to all circuits and gets raised or lowered based on load. Load is determined via 3-4 things depending on the tune SD/MAF. These items are TPS, MAF, MAP & VSS. The PCM calculates Line pressure & shift speeds from TPS, the commanded item. It verifies load via MAF/MAP & calculates pressure rise. Then uses the VSS input to calculates a shift speed.

Because 4L60E's are load based and I don't see a load % beyond 50%. It could very well be slipping and you just can't feel it. When things are just slightly wrong you may not be able to feel it. For example: When it should show 80-90% load and only shows 50% this may mean that the transmission PSI is lower (say at 150 PSI) than expected (190-200PSI) and could be slipping. This type of slip only shows up after being driven awhile and after the 3-4 clutch is completely gone.

From about 20-40 mph cruise at approx 5-10% throttle, when you accelerate & get to about 35%-45% throttle it should show 80-90% plus load.

If you have another gen 3 vehicle (or a friend has one) that works correctly hook it up and drive that and look at the load %, desired engine torque, delivered torque, pcs desired, pcs actual, tcc slip & etc. Take a log of a similar road test of both vehicles and compare them. This will give you some insight...

I changed PCM's for a whole separate issue but now my own vehicle doesn't show more than 30% load. I cannot find enough detail on what table in a tune helps calculate the load percentage. Here is 2 log files that I have done with both PCM's. The 2005 Siverado will go to 96% load but the 2004 SSR will not. I have verified with a pressure gauge that it will make 210 PSI in D at 2000 RPM's.

Attachment 145723 Attachment 145724

[abc]

Thank you for your time and thank you for sharing the info.
Your suggestion of comparing to another vehicle is one of my next steps and I'm lucky enough to have built one that lives in my garage. That's one of the puzzling parts for me. I copied over the transmission tables and my trans will not function with the same force motor current table as the exact same car sitting beside it. I have been learning alot in the last few days as to what may be causing it. I will look at your logs tomorrow and share my most recent tune and most relevant log to go with it. You will see, I have gone too far with the force motor current on the last test.

More testing will have to wait until Thursday or so as I have discovered a radiator issue and will fix it tomorrow.
most recent high line psi log.hpl
current in car 2000 vette.hpt

[edcmat-l1]

I would add that a high stall torque converter makes it even more difficult to feel a slipping trans, especially if you're not used to driving a loose converter.

The TCC unlocking under light throttle input can be tested pretty easily. Use your scanner controls to lock the converter and then tip into the throttle some and see if it stays locked up.

[abc]

Tranzman, I went to look at your logs for the education of it and it looks like they were not uploaded correctly. I believe I also need to learn more/understand more of the relationship between the inputs that determine the load perceived in the ECM and how that affects the calculated desired line psi.

Ed, your are correct in knowing I'm fighting a learning curve with a semi loose converter. I have owned only hot rods with manual trans. and these two are the first moderately hi HP vehicles I have to drive with auto trans and semi loose converters. The first one we put together, to my suprise feels very connected to the throttle pedal under lite load and well below the stall speed. Only when you jump on it, does it flash up to the desired stall. The second one we put together doesn't feel nearly as connected to the throttle pedal. When easily rolling in the throttle for lite acceleration it does seem to quick to reach the desired stall and exceed it while still feeling spongy or disconnected to the drive wheels. With that being said, the more force motor current I decrease the better connected it feels.

Do you guys know what's happening on both Force Motor current tables? Mine has a Positive table and a Negative table. Should they both be reduced the same amount during these tests? Do I assume it is similar to adjusting the sine wave to control the duty cycle? Do you guys have any insight on this?
I have noticed in the special functions I can adjust Force Motor Current on the fly, I'm waiting on a helper for that test. As most of you know, for a hobbiest, understanding what the data is telling you is one of the biggest hurdles, just takes seat time I suppose and learning from the mistakes.

Ed, in your experience, is it worth for you to offer your expertise in the form of proof reading a tune file and reviewing logs in an attempt to solve issues like the one I'm having now? If so, what would it cost for you to put your eyes on my files for a professional evaluation or is there not enough to be viewed/learned when you do not have the vehicle in your possession?

[Alvin]

So many people overlook fluid levels. You can fill a fresh build completely up.. go for a drive and recheck to find it a quart or two low. Just half a quart is enough to get quite a few to slip.

A TBSS for instance will slip with the fluid is on the low side of the "FULL" line.

The positive and negative tables can be copied to each other. I haven't found one yet from the factory that wasn't the exact same numbers.

[abc]

How much is too much fluid do you think? As there is no hole above the pan to gasket surface, I have installed a hydraulic fitting so I can force fluid in to fill it above the fill check bolt. I wonder if a quart or two over full while running would cause a cavitation issue? If so how would that be felt?

[edcmat-l1]

Tranzman, I went to look at your logs for the education of it and it looks like they were not uploaded correctly. I believe I also need to learn more/understand more of the relationship between the inputs that determine the load perceived in the ECM and how that affects the calculated desired line psi.

Ed, your are correct in knowing I'm fighting a learning curve with a semi loose converter. I have owned only hot rods with manual trans. and these two are the first moderately hi HP vehicles I have to drive with auto trans and semi loose converters. The first one we put together, to my suprise feels very connected to the throttle pedal under lite load and well below the stall speed. Only when you jump on it, does it flash up to the desired stall. The second one we put together doesn't feel nearly as connected to the throttle pedal. When easily rolling in the throttle for lite acceleration it does seem to quick to reach the desired stall and exceed it while still feeling spongy or disconnected to the drive wheels. With that being said, the more force motor current I decrease the better connected it feels.

Do you guys know what's happening on both Force Motor current tables? Mine has a Positive table and a Negative table. Should they both be reduced the same amount during these tests? Do I assume it is similar to adjusting the sine wave to control the duty cycle? Do you guys have any insight on this?
I have noticed in the special functions I can adjust Force Motor Current on the fly, I'm waiting on a helper for that test. As most of you know, for a hobbiest, understanding what the data is telling you is one of the biggest hurdles, just takes seat time I suppose and learning from the mistakes.

Ed, in your experience, is it worth for you to offer your expertise in the form of proof reading a tune file and reviewing logs in an attempt to solve issues like the one I'm having now? If so, what would it cost for you to put your eyes on my files for a professional evaluation or is there not enough to be viewed/learned when you do not have the vehicle in your possession?

First question is, what name brand converter is it? The stated RPM stall speed really isn't the best way to describe a converter as a 3500 stall speed from various companies will all feel very different. There are loose 3500 converters, and tight 3500 converters, and that goes for any stall speed.

A buddy of mine had a 5500 in his race car and I swear that thing flashed to over 7 grand. It went down the track and you never heard it shift. Sounded like it went down the track in 1 gear slipping like crazy the whole time.

I would put the trans tune back to stock completely and see what it feels like.

Like Alvin said, make sure the fluid is full. If you're in doubt, add half a qt. Aftermarket pans, dipsticks, etc. make checking them even more tricky.

Do you have a friend local to you who is more familiar with how it should feel? You have a decent local speed shop who could drive it maybe?

I would use your scanner and lock it in different gears and roll into the throttle. See if you can make it slip or blow through a gear. Try it in second, third, try the TCC, etc.

[abc]

First question is, what name brand converter is it?

It's a Circle D. I asked them to build the same converter we have in the (for the most part) identical combo. I did talk to Circle D about the converter and it's relationship with the trans, at this point I have no reason to believe there is a converter issue. One of many questions I asked them, "Is it possible they could miss the desired stall by more than 700 rpm?" Of course they answered, it's unlikely to miss by that much with this combo.

I would put the trans tune back to stock completely and see what it feels like.

I've tried that, no bueno. Builds heat fast, slips in 3rd and 4th for sure, converter won't stay locked up if any scenario except coast and lite load down hill and flat ground.

Like Alvin said, make sure the fluid is full. If you're in doubt, add half a qt. Aftermarket pans, dipsticks, etc. make checking them even more tricky.

I'm fairly certain fluid level is not the issue. I have had it what I would consider over full down to perfect factory level.

Do you have a friend local to you who is more familiar with how it should feel? You have a decent local speed shop who could drive it maybe?

I'm thinking I may need a second set on hands on it just for a sanity check. I do have what is for the most part an identical combo at my disposal and I logged it last night in an exact scenario as my troubled combo. I logged up hill lite load in third looking for TCC slip and temp. change. I will attach the log if anybody wants to compare for me and see if I'm missing something.

I would use your scanner and lock it in different gears and roll into the throttle. See if you can make it slip or blow through a gear. Try it in second, third, try the TCC, etc.

I like this idea. I have been hesitant to do this for fear of having to take the trans back out. I want to diagnose as much as I can and see if there is a fix on the digital side or a fix in general without having to remove the trans. I'm gonna run some more tests in the next day or so. In order to run a heavier load test I will have to start the loaded part of the VE table tuning. I think I may have put one pound of boost to this thing at the most right now. I guess at some point I need to put a mechanical line psi gauge on it and see what that tells me?

Tranzman pointed out the fact that the load data looked low. When I compare it to the known good combo, it looks very similar. In this situation, I think the load data looks low because it is, I have not begun to apply any heavy power. It's likely this combo will make 900 to 1000 at the crank when proper.

Here is a short uphill moderately lite load log of the known good combo.
red rocket cold down and up hill .hpl

[abc]

I ran a few tests last night and now I have an idea how to compare apples to apples with both cars, I will get that done tonight. In the mean time, do you guys know what the relationship is with the trans cooler/lines and line psi? If you were to plug the trans cooler lines completely off how would that affect the transmission other than the obvious heat issue?