Shift Points seem off..

dougstruck · Sep 21st, 2006, 05:23 PM

New guy here...be kind. I have a 91 hardbody V6 SE. Transmission went south on me and replaced it with a re-manufactured from a place in Arizona. Before installing the transmission, the local shop replaced and 'fiddled with' and replaced (groan) the throttle position sensor.
After messing with it for a week I told them to let me have the truck back and took it to a known reputable mechanic. He discovered the TPS had been set all the way to one way (the far end of detent). When it was set to detent I got all 4 gears back but the idle was high once the engine heated up. Plus, the shift points are weird..like 1st to 2nd is at 12 MPH, 2nd to 3rd doesn't happen until 35 mph regardless of the load etc, and 4th doesn't happen until 50 mph.
Is this all a result of the mucking around with the TPS or is my ECM going bad? Any suggestions are REALLY welcome. I love my Nissan (18700 miles and counting) but I hate paying their shop rates.

Thanks...I'll be watching...

**88pathoffroad** · Sep 22nd, 2006, 12:01 AM

The procedure for adjusting the TPS requires a voltmeter, nothing more. It does (in part) control shift points and idle, yes. I'd have the TPS set properly before troubleshooting anything else.

dougstruck · Sep 22nd, 2006, 08:56 AM

Thanks....I didn't mention that the shift from 1st to 2nd is smooth but tight when cold, but as the engine heats up the shift gets really hard between those gears. I'm all for an 'authoritative' shift, but sometimes it's almost painful.
You think a correct TPS adjustment will correct this as well? I understand the potentiameter (sp?) in the TPS measures ambient heat as well as throttle body blade position etc...but would that effect how hard the shifts occur?

Thanks again.....