trans and vss installed
Attachments
Last edited:
When I seen you mentioned that it was seeing speed at idle, not moving I was going to mention that you probably have the input shaft speed and vehicle speed sensors swapped.So I think I figured it out,
64nailhead is absolutely correct, something whacky was indeed going on 🤣
Fitech has 2 plugs for the transmission,
The VSS 2 pin, and the round connector,
On my transmission, the front sensor located above the shifter is the ISS, input speed sensor,
And the one towards the rear has a dummy plug where the VSS reads from.
the sensor needs to be swapped from iss to vss front to rear, I believe that’s why I’m having these issues, and trans is going into limp mode, I was told the trans came from a 2wd van, some one didn’t know what they were doing and switched the sensor locations, hence why it’s plugged, and probably why they sold it because they couldn’t get it work correctly, or it was a rebuilt unit originally from a 4wd, they changed the output shaft and tail housing for a 2wd application, and put the sensor in the wrong spot after converting it, I guess I’ll never know the story behind it, but all I can do at this point is pray there is a reluctor ring and swap them and see what happens, This answers why ive noticed it short shifts into second and searches for gears, and why I’m showing speed in idle, and why I’m really maxing out the mph as if it’s slipping,
I assumed a 2wd pullout would have already been ready to go, and by the grime on it, and not freshly cleaned, i never would have guessed it was switched or some one messed with it, I definitely overlooked it. I thought it was just the fitech speedo calibration needed adjustment, but I’m also not that familiar with 4l80 until doing lots of research and reading and it finally clicked staring at my ceiling keeping me up at night 🤣When I seen you mentioned that it was seeing speed at idle, not moving I was going to mention that you probably have the input shaft speed and vehicle speed sensors swapped.
FWIW, I live on Drag Lites - I have three sets (recently grabbed another set) for street tires, drag radials, and slicks. You should have no concern about their safety as long as you have proper wheel bolt engagement.
Regarding the breaking up, you need to review a datalog, but my 1st guess would be fuel pressure is nosing over. I seen you're using a Corvette style fuel filter/regulator with the return in in it. Ummm, I usually refer to those as 'damn Corvette filter'. I've remote tuned two cars with those and they create issues with Holley for most any motor is boosted or a fair amount hotter than stock. I'm not saying that is your issue, but I'm confident that it's not helping you.
I understand completely, my bad, I reworded my previous post lol, to clarify what I meant by “threw me off” as in seeing the sensor in the trans and assuming it was the way it’s supposed to be since it had a 2wd tail shaft housing, not in regards to what you said about checking the sensors, you are more than helpful and I appreciate the input completely, sorry for the misunderstandingI don’t think I was clear. Both sensors and sensor connectors are the same, one is towards the front of the trans and the VSS is towards the rear. I’m curious if the FiTech datalogs input shaft speed?
Holley does and it’s extremely handy for determining converter slip %. The input shaft speed divided by rpm is converter slip %. It makes it simple to see where the converter is grabbing and where it isn’t.
Ok, i will definitely adjust it! Thanks for the tip! Makes total sense 🙏✍🏻Do yourself a favor and set the unlock speed 4-5mph below lockup speed to stop shuttle shifts when you’re trying to drive right at the converter lockup speed. Ask me how I know about this.
And you’ll want the converter unlocking somewhere in the area of 50% TPS. This will help the car accelerate and ‘get up’ on the converter. For a boosted application that needs to be a bunch lower. But my experience has found somewhere between 45-65% TPS is about right. This setting depends on vehicle weight, hp, cam, etc. But basically, when you want it to get up and go, unlocking the converter will help immensely.
So I’ve found a bunch of issues hopefully none have caused any catastrophic damage
-passanger exhaust header was leaking due to having to bang the exhaust a bit to clear the frame, causing passanger side to run lean, hopefully the lean popping didn’t burn anything, I scoped it all, the valves look a little bit tan, same with piston top, but spark plugs are all intact, I guess we will see.
-I had 3 melted spark plug wires arcing against the header. I was using Taylor’s 10mm red with protective sleeves, but the reviews I’ve been reading say they are crap, arcing could have damaged alternator? But definitely was causing some crazy misfires, the fitech really isn’t good at picking up fault codes, I was using a used 105 amp corvette alternator that was at 13.8-14 volts, definately contributed to unknown electronic issues, just installed a c5 145 amp.
Ordered a set of accel ceramic wires 9004c race extremes, hopefully these stand up to the heat
-I had cheap fans that came with the radiator one crapped out after the alternator replacement, probably since it saw 15 volts due to low charging and weak battery, and car slightly overheated to around 240* Im praying nothing got damaged
Just ordered Dorman ls f body/corvette fan assembly 620-634
-I replaced the intake Manifold donuts/orings to felpros since fitech ones are crap anyway and at this point just may as well alleviate all possible leaks.
The weld draglites are perfectly fine for street use. I had them on a few cars and the weld Pro stars.So after driving it today, with the computer update, it does shift to overdrive, and does now lockup, in lockup it’s right at 26-2700 rpm cruising, when i tap the brake tc unlocks, stays in od and jumps to about 3200. I want to say the TPS readings were throwing it off causing erratic shifts.
BUT, the VSS is way off, fitech was closed over the long weekend today to do some troubleshooting and how to calibrate it, that also can be throwing off the shifts and OD/TC lockup.
It shows 7-11 mph at idle which is weird, checked the vss connection to make sure pins weren’t bent.
Also, it’s definitely breaking up under hard acceleration which I may have took for the trans slipping, when I ease into the throttle it will pull like a train, but when I just hammer down it starts choking, tell tale sign of starving for fuel or bad coils, spark plugs are light, not fouled, but again, that vss may be throwing off the tables for rpm to speed, who knows, I ordered 4 new rims as well, I don’t feel comfortable street driving on the weld draglites, I prefer steelies, rear 15x10 5x4.5 currently running 27.5s, fronts are 15x7 5x4.75 on 205s it’s parked until they come in.
Thanks for the input and help, will keep you all updated and let you know what the verdict is
GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.