can the converter lockup in 3rd gear? i feel like the car isn't shifting into 4th, the rpm's just don't seem to match what my speed should be. i have 4.56's with a 28" tall tire, according to http://www.f-body.org/gears the car should be running 2700rpm's at 70 mph. it simply is not going 70mph. i cruised at 3200rpm's to school today and it felt like i was running about 65mph.

i feel the car go shift 1-2, 2-3, and then it shifts again, but it could be just my converter locking up. the math doesn't work out with what my results are, and i'm wondering if i missed a wire somewhere to command it to do 3-4 shift.

 

ok guys, i'm still having a problem. we put a scan tool on it today and did nearly 4 hours of trouble shooting and we're still not getting 4th. i do have the converter locking up and it is now wired up in such a way that the brake pedal controls it like it should have coming from the vehicle the motor/trans/pcm came out of.

another thought that ran through my trans builders mind was the Transmission Range Sensor. he did a swap in an 01 blazer, but he used f-body motor/tranny/harness and they ended up using an externaly mounted switch on the transmission itself where the shifter cable hooks to the linkage.(like in the trucks) the only problem with that is my schematics only shows 2 wires going into said switch (supposed to be on the shifter itself in the f-bodys?) where he said his external switch had 7 wires?

also, i guess the 3-2 shift solenoid is supposed to be off in 1st gear and engaged in 2,3, and 4...well...mine is backwards. it's engaged in 1st and off the rest of the time. (this is why we suspected the range sensor because we're thinking the pcm doesn't know what gear it's in so it gives that solenoid false signals)

we're also thinking that the solenoid itself may just be bad.

what are you ls1/4l60e guys doing to make everything work correctly? this is making no sense and is truly making me crazy so any help would be definitely appreciated! 4.56's and no OD is making this car hard to drive around!!

 

i now have all 4 foward gears from my 4l60e! the billet fourth gear servo that RPM uses is a piece of junk. put a gm unit back in and it works like a charm! figured i'd let ya'll know...