'90 ranger no balls

[nesralyrrej]

So I have a '90 ranger 2.9 junk and it has absolutely no power, I am at altitude(6000 feet) but my 87 2.3 ranger on bigger tires had way more power. I've checked everything I can think of.

Timing with the spout unplugged

The fuel pressure regulator

Map, iac temp sensor..

New cap, rotor, plugs, wire, coil.

Drove the truck on the highway with a fuel pressure gauge on too see if it lost pressure under load

I read somewhere giving it a vacuum leak could help diagnose something and I tried it last night and all I got was less power and a c.e.l. Which is usually never on

So it's so gutless it loses speed in 5th gear on flat ground floored and I'm only gettin 7-8 mpg so any help would be great as I need this truck to take me 40 minutes up into the mountains

 

[Spott]

First, what's your axle gearing? The moron PO of my '88 2.9l swapped some axles in with gearing way too high for the tires he installed. I can't use 5th gear at all, and it has a 0-60 of 15 seconds. I'm about 4500ft ASL. (I'm working on a gear swap in the near future.)

Second, assuming your gears are suitable, how's the engine? Doors it have strong bright spark? Did you notice any funny colors on the old spark plugs? Can you put a vacuum gauge on it idling, and tell us both the reading, and what the needle does? Can you do a compression check? Does it run smooth, or does it hesitate or stumble at times? Do you have any codes stored in the computer? Does it have any vacuum leaks (test by spraying carb cleaner around the vacuum hoses and fittings while idling, and see if the engine revs up at any point)?

 

[nesralyrrej]

Spark plugs were just black, the vacuum gauge sits at 14 and kinda floats between 14-15 as far as gearing I'm 99% sure it's stock 3.73. It idles smoother then any of my other cars (cams haha) and it does hesitate usually after I shift rarely when I take off though I'll check for vacuum leaks, and as far as I know it doesn't have any codes but I'll check again

 

[Big Jim M]

Simple gear ratio check: Jack up one back tire, mark the driveshaft and the raised tire with chalk, turn the tire exactly one turn while counting the turns of the driveshaft. The driveshaft will turn EXACTLY what the gear ratio is. So 2.73, 2.21, 2.55, 4.11 are all easy to see on the axel turns.
Then tell us what gears are in there and what height tires you have.
The reason stock tires are so short is because Ford was thinking about 6,000 feet when they put them on there.
Big Jim

 

[nesralyrrej]

Alright I'll go check that now

 

[nesralyrrej]

So for one rotation of the tire I get like 1.8-1.9 rotations of the drive shaft

 

[nesralyrrej]

Unless it's every half a turn lol I've never heard of a 1.9 gear ratio

 

[nesralyrrej]

As I look again it's probably closer to 1.7

 

[nesralyrrej]

Also I'm on 10 ply 245 75 16 and that's just under 31"

 

[RonD]

14" vacuum at 6,000ft would be 18" at sea level so on the low side but not that low.

The black spark plugs means the computer is running it rich and doesn't know it, adding a vacuum leak and getting the CEL means fuel trim moved Lean and computer saw that.
How old is the O2 sensor?

Computer gets MAP sensor air pressure and uses that to set 0 fuel trim, it then checks O2 sensor's voltage for oxygen level in the exhaust to trim the air:fuel mix to the oxygen level in the exhaust so it isn't too high(lean) or too low(rich)
If fuel trim has the injectors opening too long or too short for the MAP sensor data the computer will turn on the CEL, like when you caused a vacuum leak, injectors were now opened to long for the amount of air, although MAP systems are a bit different than MAF system in that they are not as adaptable to changes.

I would check the MAP sensors connector and vacuum hose, and change the O2 sensor.

Also using the vacuum gauge check for exhaust pipe blockage, a little back pressure causes alot of power loss.
Also an exhaust manifold leak sucks in air, O2 sees that air as lean exhaust so computer runs engine too rich and there would be no code.

 

[nesralyrrej]

Oxygen sensor is stamped ford song assume its stock, the vacuum line to the map is fine and the map it's self holds vacuum (checked with a hand pump) I can't hear any exhaust leaks from the headers and I have checked the vacuum pressure at higher rpms (3500ish since I don't have a working tach) and it goes up as it should, not down like its a plugged cat.

 

[nesralyrrej]

Actually Ron, I'm gonna assume your last name is danger lol, when I rev it now it seems to stay at about 14 in when I let off it goes up to 20 then quickly back to 14-15 also I found and fixed one small vacuum leak, now am at 15-16

 

[Hagan]

Did you jack up ONE tire when checking the gear ratio?

Btw O2 sensors do degrade over time. It may not set off a CEL.

 

[Spott]

You have to double your shaft rotation number, because you've only got one wheel off the ground and the differential averages the motion/speed of both tires. Sounds like it's probably a 3.45, the same as I have.

If you're running 31" tires, you probably need 4.10 or even lower gearing for power and economy; I've 235/75/15's on mine (just over 28") and the math says I ought to be running 4.10's.

Solve your fuel/air problem first, before you worry about gears.

Also, remember that this engine doesn't produce much power at low RPM's, the horsepower peak is about 4800. It cruises well on the highway at around 3000, and if it's running below 2000 it's not getting much power from the fuel it's using (it's sort of "lugging down" at those speeds.) I like to shift at about 3200. It might be a good time to fix your tach.

 

[nesralyrrej]

Yeah I only jacked one tire up I can post a video up if you would like lol