I have a 2002 3.0 Escape. All running great, thanks for help from this group. I have a question about where engine load/vacuum is sensed for determining shift point?

I replaced all of the dry rotted hoses in the vacuum recently when replacing intake upper & lower gaskets. since then, I've noticed the shift points aren't quite the same as before. The tubing I used was slightly smaller that the OEM, but otherwise, everything is plumbed up as before.

When accelerating, the engine does rev a bit more than before, before the tranny moves to the next gear. I can ease up on the throttle just slightly, and it'll shift up. If I'm not accelerating hard, it seems to shift fairly normal. Going up slight grades it doesn't want to shift as soon as it should, but on level ground it shifts fairly normal under light load. Going down grade it shifts quickly, as one would expect. This is why I felt it might be somehow related to engine vacuum.

Is there an sensor somewhere, a restrictor in the vacuum tubing, or a vacuum modulator I might look at? I've double checked the vacuum tubing and found no leaks.

Thanks,
Dave

 

I don't think the transmission has a vacuum modulator as was used in the older models. The vacuum in the intake should be higher across the board if you had leakage from the hoses/tubes previously. The computer !should! be upshifting sooner with higher manifold vacuum, as higher vacuum indicates less load, so upshift is not out of reason.
The computer gets vacuum reading from the MAP sensor, Manifold Absolute Pressure. If the signal was off, indicating less vacuum, the ECM would keep the transmission in a lower gear longer. There is a table of Hz values for the MAP sensor at given pressures. It can be checked for accuracy or being in/out of tolerance. If the VSS information being fed to the ECM (and speedometer) is wrong, the computer could be shifting at the wrong speed.
tom

 

Thanks Tom. I'm wondering if I have a little issue with the vacuum hoses I replaced being undersized a bit...I had a smaller size hose to do this with. Do you know where the MAP sensor is located?

 

I've been searching the internet high and low to locate the MAP sensor for the 2002 3.0 V6 Escape. Lots of people are confusing it with the MAF, but I can't locate the MAP sensor. I've even searched on autozone and such for the replacement part to see what it looks like, but can't find one before 2005. I went out to the truck, popped the hood, and searched every device that is connected to vacuum...no luck. Unless it's somehow combined inside of the control portion of the evaporative emmisions control, I'll be darned if I can see one. Anyone have any ideas on this?

 

WB4IUY, do you have a vacuum diagram on the radiator support or the under side of the hood? If so, it should show the MAP sensor if equipped. I have not looked, but read in the Service Manual(DVD) that the 2007 I have has both MAF and MAP. I assumed it performed the 'throttle pressure' function that was done by cable or lever/rod linkage from the throttle to the transmission. May be that yours doesn't have one.
Looked at EBSCO online library. No throttle link or cable connection on the '02 model noted in the 'external controls' section. Just shift cable and bracket, park range switch, shift lock actuator, gearshift lever.
tom

ADD...
After looking at the transmission electrical diagram, I realized the trans has the MAF, and TPS, along with turbine shaft speed sensor, output shaft speed sensor, all fed to the powertrain control module. And that has control of the solenoids that make the transmission shift, lock the converter, etc.
So, MAF and throttle position sensor should tell the computer how hard the engine is working, and thus signal for upshifts as desired.

 

Makes more sense, I'm guessing the 2002 doesn't have a MAP. I do have the under-hood diagram, and no MAP is shown. Engine is working great... no intake leaks, ECU controlling the idle speed correctly via the AIC (an indicator of intake leaks on the Escape, and have been down that path on this one, hehehehe), decent economy, smooth shifts, etc. Just the oddity of having to raise the intake vacuum slightly by easing up off the accelerator slightly to get it to shift sooner. I see no other vacuum related devices that could be providing feedback to the ECU for engine load. Maybe the earlier models makes the determination by MAF & TPS feedback. I could slot the screw holes on my TPS and make a minor adjustment there, just as an experiment, to see if it impacts shift points.

 

One other thing you could do is disconnect the battery, step on the brake pedal and re-connect, or leave disconnected for ~10-15 minutes. That would cause a re-learn of idle speed control, etc, along with whatever is 'learned' by the transmission. I read that it does learn drivers habits though I have no idea where they are stored. Maybe things have changed with a sealed up intake.
tom