I've been having problems with my 1st gear shift hitting the rev limiter. I did some logging, and noticed that my input shaft RPM is literally slightly over HALF of my engine RPM in 1st gear. Can anyone explain to me why that would be?

As far as my setup, it's a FLP tranny and a TCI 3800 torque converter (2.7 STR).

 

Input shaft is the output of the converter, flywheel is
the converter input. You are seeing 3000RPM of slip I
guess. That's abnormally high in my opinion, though I don't
have such a high stall myself.

 

I'm running out of ideas trying to troubleshoot this damn setup
I sent the TC back to TCI to have it examined. Came out 100% fine, so I paid 2 way shipping AGAIN for this thing. I talked to Chuck at FLP about the TCC still/never not locking up. He was kind enough to send me a new internal harness w/TCC solenoid. Changed that out, still won't lock up. And this thing is still hitting the rev limiter at the top of 1st (set shift RPM at 5700, rev limiter at 6800, and shift mph 7 below where it actually shifts). I've heard that the engine bases shifts off input shaft RPM on '98's so I've been lowering that a LOT. I'm gonna drop it down to 3150 rpms at WOT in 1st tomorrow and see if that fixes it.

 

Oh, and also took it to a tranny shop and had them check to see if the PCM was actually sending a signal to the TCC to lock up. They said it was sending a signal to lock it up, but the tranny wasn't responding...

 

Did you log mph also?

Starting at 5000 rpm post up for every 100 rpms:
MPH
RPM
INPUT Shaft

I suppose you've done this, but when was the filter last changed?

 

The filter is new in the tranny, 1300 miles.

I'll post a fresh log tomorrow after I reconfigure my trans logging points.

 

mine is doing the same damn thing. rev limiter 6800. shift commanded at 5900 and 39 mph. i keep going down in commanded rpm but it stays the same. it just started doing this one day. but my converter locks up normally. it threw a code after it started happening i belive a p0751. no first or fourth shift. but hasnt ever since. i will be back in here with some info on my input shaft speeds

 

Try this. Log your input shaft rpm, output shaft rpm, engine rpm, and current gear. I noticed that I don't hit cutoff rpms until I hit the next gear, according to my logs. At that moment, all 3 rpm logs spike, telling me it's my tires slipping enough for the motor to rev to the cutoff limit. To me it seems like it's hitting the rev limiter first, but the log is saying otherwise.

 

i'm gunna try a new shift soleniod but i havent got around to it yet. i will log that stuff this weekend and see whats up

 

ok its definetly in 2nd gear when it hits the rev limiter. whats weird is that the trans input speed drops to 5000rpm but the engine keeps climbing another 300-400 rpm.very interesting

 

mine used to hit the rev limiter when i did a close to max down shift, in other word my max mph for up shift is 44, my down shift is 39, make sure this also corrisponds with your upshift/downshift table at 98-100% tps. So if I was at 39mph in 4th gear and nailed it ,it would slam down to 1st gear (nice on the neck muscles) then at 44mph it would slightly hit the rev limiter because the SHIFT TIME was not edited low enough... also since both paramiters must be met to complete a shift you can have your shift rpm slightly lower so that the one paramiter is met and then its waiting for the second one..being mph. you can also try switching these around in the 98-100% table and max shift cells. have the rpm at the desired shift rpm but have it meet a lower mph first and then wait for rpm to be achieved to complete the shift. If this still hite the rev limiter lower you shift times to "zero" at wot (100%tps) this should clear up the hitting of the rev limiter in 1ST gear. With your lock up I,m assuming all your upshift cells are higher then your down shift cells and lock up cells are higher then the unlock cells by quite a bit for a stall.? LOck ups should never occure during 1st or 2nd gear, and they should only occure after a shift into 4th unless you are driving in 3rd. A nice trick to edit is make your 1st half of your lock up in 3rd gear table the same mph as the upshift to 4th gear...this assures that a lock up will not happen untill the shift is completed into 4th gear ..then you can have from say 25% tps lock up in 4th set at 50mph so that as the shift is complete at any tps over 25% the converter will lok right away and then have the unlock set at 5-6mph less for any given tps setting.

 

Any chance the input shaft rpm sensor is damaged?