Loss of Power - Stuck in 3rd Gear?

[penzfan11]

91 Bronco with 5.8L, automatic trans.

This morning when I put it in Drive and stepped on the gas the truck barely moved. The engine was reving at about 2000 rpm, but the truck was just creeping. It felt like it was in 3rd gear. Reverse works fine. I dropped it to 1st gear and 2nd gear and it moves better but I can still the lack of power.

Even after I slowly get it up to 50-55 on the highway, there is no power when I give it more gas. If give it too much it bogs down and starts to sputter. A slight incline on the highway and I slowly lose speed because I cannot give it gas to accelerate.

This happened once before, but working it back and forth in the street seemed to eventually fix it. I drove it 10 miles this morning and it was still doing it.

I just replaced the plugs, wires, cap, rotor and fuel filter.

Appreciate any advice.

Brian

 

[Miss Kitten]

it sounds like the tranny is going into limp mode

have you checked the fluid in your trans lately?

i would start with a fluid and filter replacement and see if that helps

 

[penzfan11]

The fluid level is good and still looks clean. I haven't checked the filter.

I went out at lunchtime to try to drive it and it drives fine.

One thing I did notice both times this happened is the idle increases from 700 to 1200rpm. Normal idle is 700-800, but this morning it never dropped down from 1200 even after I drove it for 10 miles. Is the high idle tricking the trans. into thinking it should be in 3rd gear or overdrive? two hours ago when I tried it, the idle was back down to 700-800.

Could it be throttle position sensor, idle speed control actuator, choke thermostat?

 

[BroncoJoe19]

I'm far from an expert, and know just about nothing about transmissions, but I know a little bit.

You have an E4OD trans which is computer / electronically controlled. The computer takes info from the VSS, TPS, MAP and vacuum (I guess) to in part determine the load on the engine.

I'd start buy pulling diagnostic codes and seeing where that leads. All you need is a four inch piece of wire and the ability to count to ten.

How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway

Howto Pull Codes 1983-1995 Broncos, Mustang, F series Trucks, Econolines, 302, 351 and more

 

[GDare]

Had this same problem, turned out to be a MAP sensor... it cost me about 250 to replace (labor and diagnostics included)

Could be the same for you. Goodluck /emoticons/[email protected] 2x" width="20" height="20" />.