LS3 with 4L70e troubleshooting

[Iziks]

As the title says, LS3 with 4L70e and Atomic MSD controller. Excuse me if I use the wrong terms, but it feels like the transmission is slipping or not fully engaging. It just seems take take a large amount of revs to get the car moving and is fairly non-responsive. After a short drive, it does seem to get somewhat better.

I know nothing about transmissions, so please point out what may be obvious to you. The trans controller is reading the gear input, RPMs, and TPS. It has thrown a TPS error (which I cleared) but the TPS appears about right while driving. I think I have all the other settings correct in the controller.

Fluid level checks out, but it did not take as much on initial fill is I would have thought. I assumed that was because the trans came mounted to engine and still had some fluid from testing.

I have only go karted it a couple times and probably only a 1/2 mile at most.

Engine and trans were purchased together from BPE as I was hoping to avoid these kind of issues due to my lack of technical knowledge in this area. I have reached out to support, but have not heard back.

Any thoughts are appreciated

[Mastertech5]

It sounds like the fluid is low. Make sure you check the level when it's warm and running at idle. If you added an aftermarket dipstick and tube it may be set up with the stick too low in the pan thus reading full when it's not. That trans takes approximately 10-11 quarts when dry including the torque converter. Don't drive it like that or you will burn the clutch packs. That trans also has a variable pressure control solenoid. Make sure your controller can control it.

[edwardb]

X2. Fluid level was the first thing I thought of as well. For my truck build with a 4L65E from Gearstar Performance Transmissions and HGM controller, it also didn't shift well at first and reverse didn't work. Fortunately, that was while it was under construction on the lift so no driving time. Gearstar and HGM both diagnosed it as low fluid. It came with fluid in it and I assumed it was at the proper level. Bad assumption. Plus the aftermarket Lokar dipstick was way off. They are universal and need to be adjusted. After correcting the dipstick and adding several more quarts, all good. Now driving.

[Iziks]

Thanks for input. It is an aftermarket dipstick, but I thought I set it to match the low/high lines and the factory one by measuring from the lines to the same point where the dipstick tube attaches to the transmission. I will do some more checking and report back. Working on some engine stuff, so it will be a bit

[JimLev]

I also used the Lokar dipstick with my 4L65e and wondered if the markings were correct. After filling it to the full mark and checking it while idling in the driveway it was good. However after taking it for a ride the level was way low. I had to add another 1.5 quarts. I don’t thing the converter got filled up from just idling. I talked to a local tranny shop, they said the correct fluid level is at the top of the pan at the gasket.
My latest issues is the converter clutch doesn’t always lock up.

[edwardb]

I also used the Lokar dipstick with my 4L65e and wondered if the markings were correct. After filling it to the full mark and checking it while idling in the driveway it was good. However after taking it for a ride the level was way low. I had to add another 1.5 quarts. I don’t thing the converter got filled up from just idling. I talked to a local tranny shop, they said the correct fluid level is at the top of the pan at the gasket.
My latest issues is the converter clutch doesn’t always lock up.

My Lokar dipstick was way off. Fluid level to the top of the pan at the gasket is correct. I estimated this location and realized I had to cut the dipstick accordingly. Later, because of a leaking transmission pan gasket, I removed the pan to replace the gasket and used that opportunity to get the dipstick length exact. My estimate was close but not quite right. I can only say check that Lokar dipstick carefully.

[Iziks]

Yep. Had a chance to add some fluid and test. Definitely the problem. Thanks a bunch for the help!

Now chasing done a fuel pressure problem…