I have a 94 3.0 5 speed 2wd ranger. Here recently it's been acting up, no check engine an no codes (well can't find them if there because obd1 is a pain). Anyways, the truck will start everytime I try an start it but sometimes it will kill itself on immediate startup, I wait a second, fire it up, and it's fine. Always done that since I got it. But now when driving down the road it will sputter an have a MAJOR loss of power it just won't go no where. Only when driving. When idling sometimes the truck will drop to 500 rpm then back up to 1000rpm but it doesn't sputter or miss at idle. I have replaced, coil, plugs, wires, cap an rotor button, upper intake gasket, lower intake gasket, an when I did the intake I found a cracked injector an a bent pushrod, replaced those. Fuel pump is new, fuel filter is new, as of 5 minutes ago. Motor is timed to 10° BTDC as manufacturer specs. Truck has 199k on it but it ran like an absolute Champ before this. An every once in awhile it won't sputter an will run just fine. Any help is appreciated and very much needed I'm at a loss an don't know what else to do. Need this truck it's my daily
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UPDATE: unplug MAF while running, does nothing. Unplug IAC while running, does nothing. Was some oil in intake hose when I did the intake gaskets

 

If you unplugged the IAC valve with engine warmed up then RPMs should drop to 500 or engine may stall either is good it means no Vacuum leaks
If RPMs don't change then there is a problem

Read here on cleaning IAC Valve: How to: IAC valve cleaning thread (w/pics) | Ford Explorer and Ford Ranger Forums - Serious Explorations

After you have IAC valve off, plug in its wires
Turn key ON
IAC Valve should open all the way
Unplug the wires and it should Close all the way
Repeat plugging in and unplugging the wires to make sure it is working and not sticking
Clean it in any case

If it isn't moving at all test wires for 12volts with key on, one should be 12v the other Ground
If it has voltage then replace IAC Valve

I would get a Vacuum gauge, $20, very good tool for any gasoline engine
A gas engine is basically an air pump, self powered but still just an air pump
Best way to test a pump is to test its pressure or lack of it, and thats where vacuum gauge helps.

Good article here on using one: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
Don't let the carb and points stuff throw you, fuel injection and electronic ignition works EXACTLY the same

What would interest me on yours is the Blocked Exhaust testing, but all the tests need to be done

Older Cats and mufflers can get broken pieces inside, they slide out of the way and then back in the way cause odd power losses

MAF(mass air flow) sensor may or may not be used at idle, depends on the software
The computer "knows" it is running a 3 LITER engine, so it "knows" how much air should be coming in at any given RPM and throttle position, MAF sensor is used to fine tune air/fuel mix as are the O2 sensors, both are needed but engine can/will run without them

 

I will try some of this, I unplugged the iac an maf an it did not change anything at all. I have a true dual straight pipe 1 3/4" 45° front of right rear to 2 1/2" that ibput on it. I will test vacuum, which I know it has some type of vaccum leak in the brake booster because at idle if I push the pedal hard enough it will make it idle higher. It had done that since I got it an never made it run like this.

 

All Rangers had Tuned exhaust, as long as you are using stock exhaust manifold(or headers made for 3.0l Vulcan engine) and same size pipe at collector what you do from there to the back won't matter as long as you don't go smaller

It reads like IAC Valve isn't working

And whats the temp gauge look like, does it get to just below 1/2 after warm up
Computer needs engine to get to 185-195degF for best performance and MPG

 

I am curious about the bent push rod you found.

how bad was this push rod bent?

has this engine ever backfired since you owned it?

Sure the push rod could have bent from metal fatigue but I think you may have another issue like a bad lifter or like mentioned the engine could have backfired.

the sputtering your experiencing could be a backfiring condition.

If this is the case i suspect the ignition system and or wiring.

many years ago I worked on a Ranger I do not remember the year of Ranger or engine size yet the symptoms were very similar.

that truck would not start, it had an occasional backfire when trying to start it would start after a while then die.

It had been to many shops no one could find the issue, Like your truck no codes were found.

During the diagnostics ( while doing a wiggle test ) I got lucky and stumbled across a bad single wire connector that suffered a bad connection that turned out to be the cause.

I was very busy at the time and did not even take the time to find out what circuit the wire was from. I just test drove the truck after I repaired the wire and did my best to make sure the problem was fixed.

After about 30 engine starts and a few road test I was confident the truck was repaired

the guy came back after 3 months to have other work done and said the truck ran great.

I am not saying this is your problem however I highly suggest checking all of your electrical connections especially any connector that has anything to do with the ignition system.

Back in the day I used to used a Sanp on MT2500 scan tool with the trouble shooter cartridge.

This tool is very helpful for diagnosing problems like this and can be found very cheap on eBay or craigslist since they are obsolete for the newer cars.

 

The pushrod was not terrible but it was bent enough to when set on a flat surface an rolled it has a very visible bend to it. The engine had never really seemed to warm up all that much. Doesn't even go up to the "N" on normal on the gauge. When I start the truck on a colder night like last night was kinda chilly, start to drive an it does backfire an does backfire quite a bit but then it will stop

 

You need to replace thermostat with stock 190-195degF model

The computer can operate the engine efficiently at a lower temp

Back fires are usually from misfires, the air/fuel mix is not burned in the cylinder on a misfire, and when it is dumped into the exhaust manifold the next cylinder that fires on that bank ignites the unburned mixture which explodes in exhaust pipe.

If you put on new spark plug wires make sure you followed the correct firing order

Seen here: Ford Ranger Firing Orders

 

I replaced the thermostatwhen I did the intake gasket. I replaced the wires an they are all in correct order

 

Since you replaced the thermostat have you double checked the coolant level?

If the engine, hoses and heater core etc are not completely full or anything has air trapped in it the heater will not operate correctly and the Temperature gauge may not operate properly either.

If this truck is still backfiring while under a load I suggest not driving it or you will be taking the engine back apart to replace more push rods. If they are not damaged already.

Have you checked and rechecked all of the electrical connections?

I just noticed on one of your post you mentioned a leaking brake booster.

If you know you have a vacuum leak how about plugging off the line going to the booster temporarily until you get things sorted out.

The vacuum booster may or may not have anything to do with your problem but it should be isolated until you get it diagnosed to not further complicate things.

I do not suggest driving it with this vacuum line plugged however you shouldn't be driving it while it is backfiring either.

When you reinstalled the pushrods how did you do this? What procedure did you use?

I am not familiar with this engine is it the type that is non adjustable where you just tighten down a bolt or does the rocker arm have a lock nut like small block Chevy's?

 

My truck is basically my job lol so I don't have a choice but to drive it, as much as I wouldn't like it, if it blows up I'll take my Trans an put it in my 2.3 an call it a day. Coolant level is good, I have triple checked all my connections. The rockers are non-adjustable NOT like a sbc

 

Well if your out of ideas the only thing I can suggest is to buy or borrow a Sanp on MT 2500 with the troubleshooter cartridge and start running some test.

One thing before I forget have you tried disconnecting the spout connecter to see if your symptoms change or get better?

Your truck should have a thick film module either mounted to the distributor or on a heat sink and it should have a pick up module

Either of these or both of them could be defective.

The Snap on tool mentioned earlier makes it easier to diagnose.

If disconnecting the spout connector clears up or changes the problem it is a clear indication
That one of these parts is bad.

It has been so long since I worked on one of these older trucks I forgot which part would be bad however my gut tells me it is an indicator that the thick film module is bad. If disconnecting the spout connector clears up or changes the symptoms.

Normally not always when the pick up in the distributor goes bad the insulation will soften and will crumble apart early signs of this is discoloration and you can easily make a mark on it with your finger nail.

If the module is still fresh looking and feels like hard plastic it most likely is still good. However I have seen a few fail while they were still in good shape but those were likely cheap aftermarket parts.

 

I have tried to disconnect the spout, I did that to get in perfectly in time with a timing light, but the thing is is that it doesn't run rough at idle only when there is a load on the motor, can I disconnect the spout an drive it? See if it helps? Am also Im not sure what thick film module you are referring to? By the way thank you guys for your help any an all is much appreciated!!

 

The thick film module is also referred as the ignition module

Yes you can drive it with the spout connector unplugged

The spout connector is disconnected as you know to get the base timing set

It may be underpowered but if it runs better you know your on the right track

The module is normally mounted to the distributor on older fords but at some point they moved it to a aluminum heat sink on the fire wall or fender I think

 

Look up on YouTube you should see plenty of people showing how to test either parts for your truck

 

I will try a few things and get back to you!

 

first thing, I disconnected the spout, drove it an it is NOT doing anything different

 

Is the pick up in the distributor soft or discolored - burnt looking?

 

What do you mean by the pickup?

 

It should look like this

https://www.autopartsway.com/part.cf...fde6gwod7celvq

You have to pull the cap and possibly the rotor to get a good look at it