losing power in 4x4?

[ryanapfel]

so i just bought this truck(for $100)1988 bronco 351w and it had some problems which i fixed. it runs and drives fine and i finally got it trail ready. got it out there, threw it in 4x4 and it took about 2500 rpms to get it to go at all. no grinding or unusual noise. so i figured this was normal(obviously i figured wrong) got to this lil hill and tried to climb it. floored, it wouldnt even attempt to climb this little hill. no tire spinning. just no power. im not sure at this point what it could be. also, when i was backing down this hill i kinda fell into a hole. floored in reverse i couldnt get outta this little hole. put it back in 2wd and it pulled right out? thanks for the ideas

 

[miesk5]

yo Ryan,

Is it the Manually shifted BW 1356 or the Touch Drive (electric shift)?

Were you in 4x4 High during the incidents?

1356 Electric Shift Operational Test; "... (engine off, hubs disengaged), crawl under the truck with the transfer case in 2HI, you should be able to grab the front drive shaft and turn it by hand. Also with the hubs disengaged you should see the front axles turning freely. Now engage the hubs and you should not be able to turn the drive shaft by hand. Jack the front wheels off the ground with the hubs engaged, turn the drive shaft by hand, the wheels should turn. The 4x4 light should not be on in 2HI, when in 4LOW you may have a low range light on, (not all trucks have that light) at least mine doesn't..."

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums

TAKE TIME to Read this; most seem to skip over bec they have said it is too long to read.

Four Wheel Drive (4X4) General Information, Operation & Troubleshooting TSB 92-1-8 for Bronco, F Series & Ranger (COMPLETE); Includes Electric Shift On The Fly (ESOF) Troubleshooting & Hub Operation; same for 87-96; exc for that in 87; power from Fuse 6 (15 amp) to "ELECT SHIFT CONTROL MOD" WHT-PPL and CB 12 (30amp) to "ELECT SHIFT CONTROL MOD" BLK-WHT; SEE A7 and A8 in the 4x4 diagram, it shows those two wires BLK-WHT as BK/W from SHIFT MODULE to P1 BATTY and and WHT-PPL as W/P to P2 Source: by Chilton

Could be the 1356 clutch or..

see page 8

such as; "...Shift From 2H to 4H Results in Chatter and Clicking Noises From The Module, But No Shift

Typically, in this situation the motor hunts for 4H, but overshoots, then hunts back and overshoots the other way. After 7-10 seconds, with lots of clicks and chatter, the module gives up and returns to the default, which is 2H. This problem is normally not the sensor input. It is usually the result of the motor running too fast or braking too slowly to allow the module to position it accurately. The motor must be replaced.

Shifting on the Fly Isn't Smooth and May Require Stopping in Order to Complete the Shift

Look for problems with the electric magnetic clutch. If the racheting or grinding goes on for more than four seconds, there may be a problem with power to the clutch from the shift control module, the clutch ground or the clutch itself. Check the wiring harness as well..:

etc,

 

[ryanapfel]

i never tried 4low i was in 4high. its a manual shift. did all that test and everything checks out as you say it should. mine has a low range light so i know it was in 4high. also, after reading that im wondering if my intake leak could be causing the problem, when i got it the intake ears (where the bolts go through) were cracked off on both inside bolts. so basicly its being held on by the 3 outside ones only. makes it idle high but i never noticed any power loss in 2hi.

 

[Bully Bob]

Hi Ryan..,

1st. you need to fill in your info. pages so we will know what we're work'n with here. (so far, only you know)

(folks will lose interest if you don't)

For example, what trannie.? (assume it's an auto)

Should be no diff. taking off in 4H or 2H.

 

[ryanapfel]

Okay so i tried that when i first signed up and i couldnt find a spot for my truck. I just put info into my "about me" part. Just went to pick a part and got a new upper intake. Hopfully that fixs my power loss problem. Also if anyone happends to knoe the torque spec on that aluminum i would appreciate it. Dont wanna crack it like the people before me.

 

[ryanapfel]

Btw your correct. It is automatic 3 speed no od.

 

[Bully Bob]

Click on your name..... then click on "edit my profile" (near upper right) then click on "change your signature"

 

[ryanapfel]

Im gonna go ahead and retract my first statement. I now believe that it has almost no power even in 2hi. I mean it will drive fine but it takes alot of motor to drive up to my house. Its a pretty good hill but still. I feel like this thing should be able to climb a tree if i ask it to

 

[ryanapfel]

Just got this as a offroad toy. Took it out. Tried to go up a little hill and it wouldnt make it even when it was floored. Just reved to high rpms and didnt go anywhere. No tire spinning. Just no power. What could be the problem? I was in 4hi durring this. It drives down the road decent but you really have to make the motor work when going up a grade. Could ut be from having 35 inch tires with 3.55 gears?

 

[Krafty]

do compression test on all of the cylinders to see if there is any life left in it.

 

[miesk5]

yo RYAN,

I think you have a vacuum leak; go thru the leak test here http://broncozone.com/topic/22770-low-idle/

Check timing

 

[Bebop Man]

3.55 gearing + 35" tires + automatic = sucky low end torque. Move down to 31" tires, or up to at least 4.10 (maybe even 4.56) gears. Transmissions.... Well, I'm not a fan of autos on the trail, but you could look at changing out the torque converter for one with a different stall speed, so as to capture some of that lost lower rpm range power.

 

[Bully Bob]

The whole idea/fun of 4x4'n is gett'n in 4xlo-range..., driving 'round, up & down, etc., slow & easy. (4xhi-range would be for normal dirt roads.)

Sooo.., ya, in the dirt/hills, with 35's, you should be in low range. Like Bebop says, "The big tires & 3:55 gears is not a good combo."

(check the gear ratio/tire/power band charts. You likely should have 456's)

However, I don't think that's your only problem. Do check for vac. leaks but, it sounds like the trannie is slipping.

---"Just reved to high rpms"--- like what.?

Do you have a tach..?

Trannie fluid color/at proper level..? Does it smell.?

"....make the motor work when going up a grade."

Assume this means on the highway. This shouldn't happen.

P.S. I merged your two posts.., being the same subject matter.

 

[90bronco86]

yo Ryan,

Is it the Manually shifted BW 1356 or the Touch Drive (electric shift)?

Were you in 4x4 High during the incidents?

1356 Electric Shift Operational Test; "... (engine off, hubs disengaged), crawl under the truck with the transfer case in 2HI, you should be able to grab the front drive shaft and turn it by hand. Also with the hubs disengaged you should see the front axles turning freely. Now engage the hubs and you should not be able to turn the drive shaft by hand. Jack the front wheels off the ground with the hubs engaged, turn the drive shaft by hand, the wheels should turn. The 4x4 light should not be on in 2HI, when in 4LOW you may have a low range light on, (not all trucks have that light) at least mine doesn't..."

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums

TAKE TIME to Read this; most seem to skip over bec they have said it is too long to read.

Four Wheel Drive (4X4) General Information, Operation & Troubleshooting TSB 92-1-8 for Bronco, F Series & Ranger (COMPLETE); Includes Electric Shift On The Fly (ESOF) Troubleshooting & Hub Operation; same for 87-96; exc for that in 87; power from Fuse 6 (15 amp) to "ELECT SHIFT CONTROL MOD" WHT-PPL and CB 12 (30amp) to "ELECT SHIFT CONTROL MOD" BLK-WHT; SEE A7 and A8 in the 4x4 diagram, it shows those two wires BLK-WHT as BK/W from SHIFT MODULE to P1 BATTY and and WHT-PPL as W/P to P2 Source: by Chilton

Could be the 1356 clutch or..

see page 8

such as; "...Shift From 2H to 4H Results in Chatter and Clicking Noises From The Module, But No Shift

Typically, in this situation the motor hunts for 4H, but overshoots, then hunts back and overshoots the other way. After 7-10 seconds, with lots of clicks and chatter, the module gives up and returns to the default, which is 2H. This problem is normally not the sensor input. It is usually the result of the motor running too fast or braking too slowly to allow the module to position it accurately. The motor must be replaced.

Shifting on the Fly Isn't Smooth and May Require Stopping in Order to Complete the Shift

Look for problems with the electric magnetic clutch. If the racheting or grinding goes on for more than four seconds, there may be a problem with power to the clutch from the shift control module, the clutch ground or the clutch itself. Check the wiring harness as well..:

etc,

If you have automatic hubs will you still be able to spin the front driveshaft with the tires on the ground and in 2hi?

 

[ryanapfel]

Im pretty sure whoever said i have a vacuum leak is right. I have a few lines that are broken off. Is there some diagram or somthing that shows where all these lines go? Also i took the throttle body off to clean it and noticed there was no gasket inbetween. Could that have been part of my problem

 

[miesk5]

yo Ryan

Vacuum Line Routing Diagram in a 88 5.8; "...Back to front on the pass side of brake cylinder, fpr, tad, tad, erg or on right side of plenium in diagram..."

Source: by inxy at http://i1101.photobucket.com/albums/g423/inxy/88%20Bronco/BroncoVacuumlines.jpg

 

[ryanapfel]

Awesesome. Thats perfect. I know the yellow one is broken. What is "airD" and where can i find it. Since ita broken off im not sure where to plug it in. Also im pretty sure the airb is broken too.

 

[ryanapfel]

Also, if anyone knows the size diameter tube i need to get and where i can get it, i was thinking autozone or even homedepot but not sure. I think im just going to replace them all to be safe

 

[ryanapfel]

Size is 1/8 or 3mm and autozone carries it all. Fwi you need about 30 feet to redo all the lines.