98 Ford ranger 2.5L w/ No power and bad mpg

[RangerDanger1998]

I need some help!
Since I bought this truck a year ago its gone to hell.
I'm getting like 14 MPG, my truck has no power, and it idles like its misfiring.
the MPG is so bad that when i drove it about 5 miles today with a trailer on it that just had a small rider mower on it, my gas gauge went down a .25 of a tank. I get if I was getting good power and went through gas but i can barely pull my trailer that's only a 5 x 8 with a mower. Now it didn't always do this when i bought it and i do some off-roading with it. Any ideas on what it could be? It did have a bank too lean code that went away after i cleared the codes and it never came back. Help would be appreciated!

 

[RangerDanger1998]

Addon: Ive been told it could be multiple things such as iac, intake manifold gasket, vacuum hose leak, fuel pumps going bad, etc, etc. Ive replaced the upstream o2 sensor, spark plugs are new and spark plug wires are new, Im lost on what it could be.

 

[RonD]

Welcome to TRS

Lack of power and low MPG go hand in hand.
If you have less power you push down on the gas pedal more, so.........MPG goes down

A few things to look for first, and I am assuming engine is running perfectly, just no power, so idle is smooth and there is no pinging or knocking after warm up.

On cold starts does the idle RPM go high, and then slowly go down over the next few minutes as engine warms up.
That's the IAC Valve working

After engine is warmed up, unplug the IAC valve while engine is idling, RPMs should drop to 500, or engine may even stall, either is good it means no vacuum leak.
If RPMs stay high, 700+, the you do have a leak.

Test for a leaking fuel injector.
Press gas pedal down to the floor and hold it down all the way.
Turn key on
Try to start engine, holding gas pedal down
It should NOT start, it should NOT fire at all, just spin, fuel injectors are shut off

If engine starts then you could have a leaking injector
OR........your throttle cable has stretched and you no longer get full throttle, lol.
Look here: http://www.therangerstation.com/Magazine/Summer06/throttlecablemod.htm
Throttle cable has stretched over time and you no longer get full throttle, this mod shortens the cable back to factory spec, just a couple of zap straps.

After making sure throttle is wide open using gas pedal repeat test, test can't work unless computer sees wide open throttle before starting engine, that is what shuts off fuel injectors.
As soon as gas pedal is released or engine RPMs are above 400, computer restarts injectors.
This is called "Clear Flooded Engine Routine" it is in all fuel injection computers


Could be timing belt is at the end of its life and valve/piston timing is off a bit, this causes lower compression so lower power.

When was the last time belt was changed?

Do you have a compression gauge?
2.5l has 9.1:1 compression ratio, that should be about 163psi at sea level to 2,000ft

If you are in the 140psi range then belt needs to be replaced


And just to clarify, on a 4cyl engine there is only Bank 1, no Bank 2(that's for V6/V8 engines), but you do have two O2 sensors
Bank 1 sensor 1 is the upstream sensor, the one you replaced, this one is used for air/fuel mix fine tuning
Bank 1 sensor 2 is the downstream sensor, the one after the Cat Converter, this one tests it Cat is working, it won't effect short term fuel adjustments

 

[RangerDanger1998]

Ill try resetting fuel injectors. the belt is new, i got it replaced when it snapped on me, got a shop to fix it for me, I do also have an aftermarket exhuast. Goes cat, then a foot of pipe then flow master, then another foot with a 90 degree pipe coming out before the rear tire. i started getting like backfire when id let off the gas when i put the exhuast on, not sure if that could be the issue of all this. I checked fuel pressure and it was good, not sure if the fuel injectors are bad. Also the Idle is always bad. No matter if its warm or cold, wither i drive it 10 miles or 0 miles. And it doesnt get any better. Does that help at all?

 

[RangerDanger1998]

I pressed the pedal all the way down and tried starting it. Had a crank no start till i let of gas and tried starting again.

 

[RonD]

Injectors are not leaking then, and throttle cable is OK

So the power was good after new timing belt?
And power drop is a recent occurrence?

Do you have an EGR system?
Because the idle is rough the EGR valve could be leaking exhaust gas into the intake, this will reduce power as well.
Locate EGR valve, it will have a vacuum line attached.
Start engine
Remove that vacuum line from the EGR valve.
If idle smooths out and goes up then the EGR Modulator/solenoid is bad, it is leaking vacuum causing EGR valve to open when it should be closed.
EGR system is only used to cool cylinders when engine is under a load, it reduces NOx emissions which spike high when cylinders get too hot.

If there is no change when vacuum hose is removed then it could be the EGR valve itself that has carbon build up and can't close tight any more.
Without removing it that's hard to test.
You can put a vacuum hose on the EGR valve, and with engine idling, suck on the other end of the hose, that should pull open the EGR valve making idle worse, then release suction and see if it will close.
If you suck on the hose and nothing changes in the idle or it doesn't hold the suction pressure then EGR valve is bad.

Your fuel pressure on a 1998 Ranger should be 60-70psi, earlier Rangers had 30-40psi, 1998 was the first year of the higher pressure "Returnless" fuel system.
At the back end of the fuel rail is the Pulse Damper, it will have a vacuum hose attached, remove this hose and check it for fuel or fuel smell, if found replace Damper.
This vacuum hose it used just for safety reasons, if Pulse damper's diaphragm should leak fuel won't drip out onto hot engine parts, a bad thing, but if it does leak fuel will be sucked into intake causing over rich fuel mix, which also fits your symptoms.

As long as the exhaust pipe from Cat back is the same diameter or larger it is fine to use.

But you could have a clogged exhaust in Cat forward, that will cause your symptoms.
Vacuum gauges are not expensive, under $25, and can tell you alot about engine conditions, on any gasoline engine.

Any gasoline engine should have 18"-21" of vacuum at idle.
Good read here on what you can test using a vacuum gauge: http://www.gregsengine.com/using-a-vacuum-gauge.html

Clogged exhaust is there along with valve timing/low compression, I think it would be a worthwhile investment, for anyone planning on owning a gas engine vehicle and doing some DIY work.

 

[RangerDanger1998]

After i got the timing belt on it seemed okay. But it was half a year ago so i could be wrong. I knew the bad idle starting occuring over time. To the point i didnt realize it till one day it was like shaking my shifter around violently. The power lost seemed to occur over time. Whrn i hit gas the truck like accelerates slow and you can hear the truck sounding like a fan shooting out exhaust? I did try sucking on vacuum line on egr and my truck almost stalled so i think thats fine. Could be wrong though

 

[RonD]

I would put a vacuum gauge on the intake and see what it tells you.

 

[RangerDanger1998]

I have it was at about 20 and it would bounce within 3 marks. But here and there it would jump around
This page showed me leaky valves. The way it acted but it was still up near 20. http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.shtml

 

[enjr44]

The vacuum on most fours bounces around some at idle (long time between intake pulses). The big jumps are probably misfires. Plugs, wires? How does it do at say 2k rpm?

If you are getting backfire out of the exhaust when letting off the gas there is un-burned fuel either lighting off in the cat or maybe the muffler. It sure isn't supposed to be there. That went away with carburetors.

But, your symptoms also sound like a clogged exhaust system?? Had the cats clog up on a 302 once because it ran rich too long. And it displayed everything you are describing.

I think you need to get some real time data using a code reader. Maybe like one of those adapters and apps you can get for an smart phone. With that data you cans see what you have.

 

[RangerDanger1998]

At 2k its smooth but you can kinda hear unsteady rpm. It has a new cat and exhaust (flowmaster) on it so i dont think its clogged they were replaced at same time cause of a exhaust leak.
What kind of data adapter should i get?

 

[RangerDanger1998]

I ordered one of those Bluetooth obd2 things for androids but in the mean while is there any other test i could do?
Addon: I tried sucking on egr to create vacuum and it would make idle go low and almost stall.

 

[chewy012]

I haven't read MUCH of this thread, so I'm sorry if I suggest stuff already covered... But, have you checked your sparkies? Your condition sounds a helluva lot like the time I connected the right wires to the wrong spark plugs. Or... Is one of them Fowled? Could be a worn valve leaking oil past and putting a coating on one've your plugs.

Sent from my XT1254 using Tapatalk

 

[chewy012]

I just read through... You did timing belt work?

Bro I'm wondering if it's not a valve that's not sealing..

What do your sparkies look like?

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[RangerDanger1998]

Ill take a look at the spark plugs and get back to you. Im thinking its valves because when the timing belt broke i was foing about 40mph and the pistons could havr bent a valve or something.