Shifting Too Early At WOT

[farley463]

The car is a 97 Monte Carlo, I just got the trans put back in after getting it rebuilt. So far I've driven it over 400 miles and everything seems to be working correctly and it drives fine, but my shift points are way out of whack. It used to wind all the way out to 6500 through all gears, now it will shift at usually about 5500-5750, even in manual first. I just put a TPS on it today because I was getting a code for the old one, and that didn't solve the problem. Anyone have any ideas?

[Dave96z34]

Do any radiator mods? Whats your coolant temp? The 97 with a 180 tstat runs too cold and short shifts like a mother fucker. Need to re-tune the pcm to fix that.

Or who every rebuilt the trans messed up the valve body.

[farley463]

I'm running a stock radiator right now with just straight water because I'm trying to flush the cooling system out. It seems to sit at about 160 while driving and I can always hear both fans on. It did that before I pulled the trans but it always went to 6500. Now it'll usually go to 5500 or 5750, sometimes 6 grand and very seldom 6500. Wish I had the money to say fuck it and get a 284 for this damn car.

[Dave96z34]

160deg is low let the car sit and get hot an do a hole shot tell me what happens.

284 is cool but a built 4t65 is the way to go. Im burning threw clutches one every 2 years none supercharged.

[farley463]

Yeah I just got mine rebuilt after I blew it up doing reverse donuts. That was a 600 dollar mistake that ill never make again. Anyways ill try that. One thing I did notice is that even when its cold, when I first start it up both fans immediately kick on. Maybe I should unplug one and go for a drive. Sound like a bad ECT?

[farley463]

Well I put a good ETC on from my parts car and the fans still run at all times, so I pulled the plug for the primary fan, took it for a drive and she got up to 190 and started shifting like normal again. I'm picking up a 195 stat for it and I'm gonna swap that out tomorrow. I think the one in there now isn't right for the engine.

[Schurkey]

Changing to a 195 thermostat for the coolant isn't going to fix the electrical problem in the fan circuitry.

"I" would fix the electrical, see if the coolant thermostat problem doesn't solve itself when the fans work properly. You can always replace the coolant thermostat later, if needed.

[3400-95-Modified]

All shift points for hot and normal RPM WOT related are 6250 in a stock Monte Bin... So yeah no idea why your having the issue you are.

The speed points are 42 for 1-2 and 80 for 2-3... Are you reaching those speeds before the RPM value? I can't remember which one is priority.

If it's shifting normal once the temp was passed 160, that's a bit odd but the ECU could have been locking it in a open loop mode somehow.

[farley463]

All shift points for hot and normal RPM WOT related are 6250 in a stock Monte Bin... So yeah no idea why your having the issue you are.

The speed points are 42 for 1-2 and 80 for 2-3... Are you reaching those speeds before the RPM value? I can't remember which one is priority.

If it's shifting normal once the temp was passed 160, that's a bit odd but the ECU could have been locking it in a open loop mode somehow.

Hmm. The tables might be different with a 65e instead of a 60e, because before I ripped it apart to get the trans rebuilt it would always wind out to 6500. My first to second shift would occur around 45-50ish and it would go into 3rd at exactly 90mph. I don't know what's causing the fans to be on all the time. I put a good working ECT in my parts car and I'm still having that problem. I did install a 195 stat in it today and it seems like now it will warm up to about 200, it will shift normally, then the thermostat will open, it'll drop down to 160, then it'll short shift again. If I unplug the primary fan it will stay at 190 so I'm starting to think about running one of my switches on my center console to power one of the fans instead of having them run constantly. Any ideas?

[3400-95-Modified]

This is what you need to do... You need to find the problem that's causing the ECU to command the fan on... wiring in a switch is just rigging it to work the way you want, not solving the issue.

Changing to a 195 thermostat for the coolant isn't going to fix the electrical problem in the fan circuitry.

"I" would fix the electrical, see if the coolant thermostat problem doesn't solve itself when the fans work properly. You can always replace the coolant thermostat later, if needed.

And the values I posted are for your 65e... I pulled up a 97 Monte bin file and pulled the numbers from that. Just because it commands a 1-2 shift at 6250 does NOT mean it happens at that RPM It will over shoot, it's called shift delay, and IIRC the MPH and the RPM both have to be met in order for it to shift, unless of course it's going into a limp which is probably what it's doing when its 160*

[farley463]

Alright, sounds like its time to do some digging then. This would probably be much easier to figure out if I had a scanner with datastream so I can watch what the sensor is actually reporting.

[3400-95-Modified]

Scantool.net

I have the OBDLink tool I use to check readyness on various models I have... I use DHP to do my tuning though. OBDWiz seems like a decent program that would let you see some numbers.

Search ebay for a better price if you want.

[farley463]

Well guys I figured it out, it was my A/C Pressure Sensor. I've slowly been getting the parts together to get my A/C working again and remembered that that sensor will kick on both fans if the compressor is running. Unplugged that and now the fans are operating normally again. I have yet to take it for a drive but I imagine it'll be running at 190 again like normal.

[3400-95-Modified]

Well then.... That solves that issue

[farley463]

I guess so, lol. I guess the sensor must have thought the compressor was running due to the low/no pressure on the low side, which signaled it to kick on both fans. That sensor must affect a lot because now that I unplugged it, it runs smoother, my PO300 is gone and my SES light turned off. I took it for a drive and now she stays nice and warm, and it sure sounds good screaming at 6500 again. Its a win-win-win!!