RPM's seem high after injectors and brake upgrade.

[LarryH88bt]

88 renix 4.0 auto. 

 

Did a 2000WJ master cyl and booster upgrade and Ford 19lbs v8 injectors not too long ago.  It runs and stops far better but the RPM's have changed, so has the overdrive.  Once its all nice and warm it idles in park at 900, which seems high, the old injectors it idled around 500-600.  Also the overdrive isn't kicking in until almost 50.  It used to go into OD around 40. 

And at highway speeds, it still seems high, doing 55 I'm almost at 2000 rpm, used to only be around 1600 in overdrive at 55.  60-65 I'm closer to 2500 rpm, again, used to be around 300-400 rpm lower before I changed the injectors.

 

I did adjust the torque converter thingy, the white box at the brake pedal, and the TC works just fine.  I had to remove the throttle cables to do the injectors but everything there seems in order.

 

Or were the old injectors just total junk and this is how its supposed to be?

 

Could the 10 overbore, pistons, and the HO 4.0 camshaft be part of it?

[Jackrabbit41]

I did the injectors as well and my rpm seemed to go up a tad too but nothing much

[Crash]

IIRC, idle spec at temp is 750 in drive. So, 900 is just fine. Checked and adjusted TPS? Maybe RPM was incorrect before? And are you sure that the TC is kicking in at speed? 

Guessing you have 3.55 since you have an AW4, what tire size? 

Maybe look up a gear ratio/tire calc, plug in your numbers and see what RPM you are supposed to be running. 

[Eagle]

And at highway speeds, it still seems high, doing 55 I'm almost at 2000 rpm, used to only be around 1600 in overdrive at 55.  60-65 I'm closer to 2500 rpm, again, used to be around 300-400 rpm lower before I changed the injectors.

 

I did adjust the torque converter thingy, the white box at the brake pedal, and the TC works just fine.  I had to remove the throttle cables to do the injectors but everything there seems in order.

It sounds like either you're not really getting 4th gear (overdrive), or your torque converter isn't locking up. For reference, the overdrive ratio is (IIRC) 0.72:1, so your direct (1:1) RPMs for any chosen speed would be the overdrive RPM divided by 0.72. The overdrive 1600 RPM (which is incorrect, on stock tires 55 MPH in OD should be 1733 RPM) would be 1600/0.72 = 2222. The torque converter not locking up would also raise the RPM, but there's no way to calculate that mathematically.

 

Could the 10 overbore, pistons, and the HO 4.0 camshaft be part of it?

Nope.

 

Reference: https://docs.google.com/spreadsheets/d/1pHFuhGgj6dQDfzyfFJH5z7NCDLW2KX3ABQgAJr3lBvM/pub?hl=en&hl=en&output=html

[LarryH88bt]

Aw4 yes, stock 235x75 tires.  My 'used to be' was just a guesstimate. 

I adjusted the TPS a while ago, haven't touched it since.  I'll have to try moving the TC thingy near the brake pedal.  Should it be compressed or totally off the brake pedal? 

 

Driving my Subaru on the highway the other day, a four cylinder, I watched the RPM, same as the jeep in OD, so my Jeep is definitely too high, a straight 6 should not be turning as fast as a little four banger.  I do 'feel' it going to overdrive, I can manually move the shifter down to third and the RPM's go up, pop it back into OD but the RPM's don't drop as much as they should.  So the TC isn't locking?

 

Thanks.

[LarryH88bt]

Turned the white box a couple times so the plunger was compressed a bit, didn't change much.  I got on the highway and manually shifted from 3rd to OD a few times.  The RPM's do drop going into OD but still stay higher than they used to.  And it still stays in 3rd around town, chugs along around 1900 at 40mph, used to go into overdrive around there and roll around at about 1500 at 45mph. 

 

Going to check under the hood again because I did have to remove the throttle cable to do the injectors.  Might as well readjust the TPS again while I'm there.

[LarryH88bt]

TPS adjusted within range according to my hayne's manual and one other source.  It's reading .84 closed and 4.35 wide open, book and the other source says between .5 closed and 4.8 open is normal.  Throttle Valve cable adjusted fine.  Going to try testing the white TC switch near the brake pedal and adjusting the brake light switch again. 

[cruiser54]

TPS adjusted within range according to my hayne's manual and one other source.  It's reading .84 closed and 4.35 wide open, book and the other source says between .5 closed and 4.8 open is normal.  Throttle Valve cable adjusted fine.  Going to try testing the white TC switch near the brake pedal and adjusting the brake light switch again. 

Use my TPS adjustment procedure. In my link below. Tip 8.

 

to adjust the TCC switch, simply depress the brake pedal, push the TCC switch toward the pedal and the let the pedal return. Done. 

[LarryH88bt]

No change with the above.   Tried some different positions for the TC switch at the pedal again.  Brake lights work fine, I know that switch has something to do with the TC as well.  Might have to check the solenoids next?  Seems like a stretch since the trans was rebuilt by the previous owner ten years ago and I haven't put more than 20k on the truck since.  But I won't test them until probably April next year :D  I only drive it once or twice a week and probably not at all once the city starts salting the roads.