94 Ranger bucking/stalling - Pulling my hair out! HELP!

94 Ranger bucking/stalling - SOLVED !!!!

I have a 1994 Ranger 2WD with a 2.3 engine (2 plugs per)... Manual transmission.

I rebuilt the engine and truck some years ago for one of my kids. It's ran PERFECT with no problems whatsoever. Since then, the truck was passed down to my youngest brat. It has been sitting for 2-3 years until he got his drivers license.

Fast forward to today...

The truck still runs GREAT. Purrs like a kitten; HOWEVER... when we took it out, the check engine light keeps going on/off and the truck intermittently stalls/bucks at lower speeds. The truck runs great, but it's as if you are turning the ignition switch on/off. When it stalls, you can back off/on the gas pedal and it will run fine until it does it again. It does this most often at lower speeds, but I also reproduced the problem while sitting in the driveway in neutral when revving the engine fairly high. Engine revving... poof... no nothing... bump the gas and back on it goes.

The only time it doesn't happen is when the truck gets up to highway speeds.

If I'm reading the OBD code flashing correctly, the computer seems to be tossing a code 57 which has to do with the neutral safety circuit? That switch is on the clutch pedal and works fine. Besides, I don't see how that switch would cause the engine to die while on the road. The CEL and the cut-out may not even be related; however this all seemed to happen at the same time.

The CEL has NEVER came on since I rebuilt the truck. This has somehow happened when it was sitting. I've checked all connectors, the TPS sensor, MAF, etc.. all seems to be fine. I've checked all relays, fuel pump, etc. What am I missing?

It's clearly an electrical issue, but where do I look? What makes the engine shut off dead cold and then back on again when you bump the gas peddle?

Sorry for the long post, but I thought I'd give as much information as possible. As most of us know - intermittent problems, especially electrical ones, SUCK!

Thanks,

SJ

One of my favorite topics is catalytic converters they go bad from sitting it's happened to me on two or three vehicles over the years. Clutch switch could be intermittently cutting out I don't know Ron's the electrical Guru on this site.

It's definitely not my cat convertor... since the truck doesn't have one .
It's always ran fine without one. For some reason the time it sat did something - I just don't know what. Very frustrating!

I bypassed the clutch switch just to rule it out and it tested fine. I shook, twisted poked and prodded every wire I thought might cause it... and no joy.

When the engine bucks/dies, you can put the gas peddle to the floor and it stays "dead"... as soon as you lift the gas peddle back up, the engine kicks back on. Usually in first or second gear. It will do it in any gear, but mostly at the lower ones.

And even stranger - the CEL continues to go off and on... with no apparent pattern. Not a constant blinking... sometimes it stays on for several seconds and then off a few, then on again. Random.

Ugh! Almost ready to pull out the baseball bat!

Start simple. Check the plug wires for infinite ohms, i.e., the carbon infested fibers are broken. It can cause weird reactions. Check fuel pressure. AND check fuel delivery volume. When you step on the gas, the TPS sends the computer a change in volts, and the MAF reports new air flow info. The computer jazzes the injectors to cover for the air flow delta, air moves quick, liquid fuel(more mass) takes longer, so the extra pressure/time bump will make it richer until the flow catches up. More or less.
You back off the gas, demand goes down, the engine/trans rock back in their relaxed, un-torqued position, and vacuum in the intake increases.
Have you checked that the actual ignition switch(electrical part) is not sensitive? As they age, they can start to decompose in place(actually, start to come apart, and have flaky contact in some cases). Mine got bad so it would start, shut off, start, shut off, etc until I held onto the key instead of letting it spring back from START. Then it got so it would just stop now and again. They are cheap if you need one.
tom

thought: The CEL could be coming on because you lost power... and it is resetting itself just as happens when you first turn the key to ON- all lights get lit - no actual code, just woke up again.

Thanks for your replies!

I'm going to start voltage traces today and see what comes up. If I read the CEL codes correctly (OBD1 flashy-thingy is confusing)... I think I came up with these codes:

157: Which I think is/was stored as I had the MAF disconnected at one point.
543: Fuel pump/battery to PCM (This one makes a little sense to the problem).
556: Fuel pump relay primary circuit issue.

I posted a video of the KOEO code flashy... I was hooping someone would help me confirm I'm getting the codes counted right:

https://gab.ai/tv/watch/35019

I don't really care about the emissions part of this issue as the truck is more than 20 years old and does not have to go through any I&M inspections, nor do I live in an I&M area. The Catalytic convertor was removed when I rebuilt the engine and it has always ran great (nor has the CEL ever came on until now). I think the codes are pointing me in the right direction though.

The plugs, plug wires, fuel pump and ignition switch were all replaced when I rebuilt the engine, so they really don't have that many miles on them (although I realize sitting can deteriorate things). The engine doesn't miss a lick... runs perfectly, plenty of power until it stalls. Once the stall is over - all is well.

I've also fiddled with the ignition switch while it was doing it's stalling and it made no difference. When under the 'stall' condition, you can put the gas pedal to the floor and it makes no difference. It's a dead stick. Soon as you let up on the pedal, the engine kicks back on immediately. It really only wants to do stall in lower gears/speeds.

I pulled the fuel pump relay while it was idling in the driveway to see if it would reproduce the immediate stall - and it did NOT. It took a few seconds to run out of gas as you would expect. The fuel filter does need changed, but I highly doubt that's the issue as the stall and recovery are immediate. I've had clogged filters on other engines so I know what they do. Generally they are gradual, especially at higher speeds/RPM/temperature.

I also tried reproducing the issue in the driveway by revving the engine high in neutral and it DID cut out. I've tried this a few times, but so far it only did it only once in the driveway. If you take it down the road, it starts the stalling like you're on the back of an angry horse... buck you like crazy while it stalls/recovers.

I tried pulling the ECM relay too while in the driveway and it DID produce the same effect - an immediate stall (obviously - you're killing the computer). So that's where I'm going to concentrate my looking today. I did try swapping the relays around and tried a new one and it made no difference.

The truck has been sitting for a long time - so WTH could have busted during that time (Fords are famous for this aren't they?) .
I'm not ruling out a bug or something has crawled into something either, but I have no idea where or how that could cause this issue.

Power is being interrupted - question is where and why.

Give me my old 1976 any day! I love it's fire-breathing, no emissions, no computers, no nutin big block!

Thanks gain everyone...

Another quick update:

The engine is definitely tossing a consistent code 157 (MAF low voltage).
I'm trying to find a guide on what all the voltage pin-outs supposed to be. The Haynes manual doesn't give that info on thier schematics unfortunately....

Did you check the technical pages right here on the site? http://www.therangerstation.com/how-to/ford-ranger-wiring-diagrams/

Thanks for the replies everyone!

Denise: I did check the tech pages, but I could not find any pin-out voltages

Tom: I replaced the plugs, plug wires, fuel pump, fuel filter and ignition switch when I rebuilt the engine (also the entire front suspension/tires), so they don't have very many miles. The truck runs perfect and smooth other than this stalling issue.

My kid only drove this truck for maybe a year or so. The fuel filter could probably be replaced, but I highly doubt the stalling is cause by it. The stall is immediate. I've dealt with bad fuel filters on other rigs (both EFI and carb) and they generally give a 'slow running out of gas' symptom and at higher RPM/speed/temps. When it stalls, you can smash the pedal to the floor and it does nothing. Dead stick. Only when you move the gas pedal back up it will come back to life.


More update:

I removed the IAC to clean and test it. The valve is bad. You can hear and feel the solenoid activate, but the valve won't move. It's definitely busted.
Question is.. would it cause the stalling I'm having? I don't see how it's related, but then again all of the info is sent into the computer so? Yea, I'm old-school, but learning all this fancy 'puter stuffs!

I also did checks on the MAF as the computer keeps tossing a 157 code. Here are the results. I don't know what the pass/fail voltage are though... Anyone know? I've watched a few YouTube vids. The terminal D voltages seems a bit low?

Engine OFF:
Battery voltage: 12.8v
Terminal (A): 12.3v (neg VOM lead to battery)
Terminal (B): 12.3v (pos VOM lead to battery)
Terminal (C): 12.35v (pos VOM lead to battery)
Terminal (D): na

Engine RUNNING:
Battery voltage: 14.6v
Terminal (A): 14.62v (neg VOM lead to battery)
Terminal (B): 14.52v (pos VOM lead to battery)
Terminal (C): 14.57v (pos VOM lead to battery)
Terminal (D): .07v at idle, ramps smoothly to about .40v at high RPM. Voltage lowers smoothly when RPM backs down.
Voltage between pins (A) and (B): 14.65v


CEL codes produced:

Engine OFF, Key ON: 157 (MAF Sensor below minimum voltage)
Engine ON: 998 and 157 (Hard fault present)

DPFE valve appears to be OK:
Brown/green wire: .62v
Brown/white wire: 5.04v

EGR valve has no leaks and the valve moves when vacuum is applied.

WHEW!

It's late and I'm going to try and go ten-toes up... and get back to this mess tomorrow!

Thank all!

If you do not have a PDB - power distribution box - then you have a bunch of ring terminals on the + side of the starter relay. It is difficult/tedious to get the rings aligned so they will all 'lay flat' and not make poor connection when you try to tighten the fastener.
It is possible you are losing power intermittently via that mess. Grab onto the bunch and try to turn them around the axis of the relay post. They should not turn easily.
I replaced the relay, and had a good time fanning out the terminals to allow them to make good continuous contact. FWIW.
tom

I've checked all the terminals and cleaned them. They appear to be OK. I replaced the battery cables and a few of the other wires when I rebuilt the engine. Again, everything was working fine until the truck sat.

I've wiggled wires and components that I can think of, poked, prodded... screamed. For some reason it only stalls consistently while driving in lower gears/speeds.

It stalls - back off the gas pedal and it comes back... wash - rinse - repeat... Get to highway speed - it will run all day long.

It has a bad IAC and possibly bad MAF. I'm trying to find out what the normal voltage ranges should be on the MAF. Mine seems quite low (.07v to .40v), but I'm wondering if the bad IAC has something to do with those voltages. The IAC is slightly open, but it doesn't move. I don't think either will make the truck stall like it does, but I'm willing to entertain anything at this point!

Back outside! I'm going to look over the relay box and components today. Maybe there's something hanky in there around the EEC relay. It's about the only interrupt I can think of that would immediately kill the engine. Maybe it's dropping out. I've tried a different relay but it didn't help. Maybe the power TO the relay is getting killed intermittently somehow.

Well, today's adventure still didn't solve the mystery.

Update:

Detached the relay box to take a look underneath. Nothing broken. I pulled on many of the wires but none gave way, so I can assume they are good.

Replaced the positive wire from the battery to the starter relay.
Replaced the positive wire from the relay box to the starter relay.
I used heavy duty 4 gauge welder wire I get from battery shops.

The original wire between the relay box and starter relay did have slightly burned/overheat marks where it attaches to the relay box, so I figured replacing the wire with a larger one wouldn't hurt. The wiring on early Ford's was never the greatest and most could have certainly gone a gauge or two larger (IMO). I also solder everything.

I cleaned all grounds that I could find.

Unfortunately none of the wire upgrades and cleaning solved the stalling issue. I didn't think they would, but the upgrades didn't hurt. Nor did they cost me anything as I had the extra wire.

I re-checked the voltages to the MAF to see if they came up any after replacing the battery supply wire (hoping a higher amp wire would help), but the voltage seemed to go slightly DOWN? So I'm not sure if I'm still looking at a bad MAF or if the defective IAC is playing into it.

Tomorrow I'm going to try connecting an LED light to the EEC relay so I can check if it's dropping out while I drive it. I can either confirm or rule-out if it's a true electrical failure. It sure seems like it as the engine stalls/recovers way too quickly to be a fuel issue.
I also had a thought: AMPERAGE. Even though the alternator is producing enough voltage, I haven't checked its amperage yet. If it's too low, that might explain a few things. Something like a relay might be dropping out at a higher RPM when power is being demanded? Back to checking that wire between the alternator and starter relay. I did a quick inspection of it, but not at the alternator end.

QUESTION: Could a faulty cam or crank sensor cause the intermittent stalling? Or are they pretty much a go, no-go type of part? (either they work or they don't) ? I don't know enough about them.

To be continued....

SJ

STALLING PROBLEM SOLVED !!! This is one for the books techs!

Oh how the mighty can fall from the littlest things...

The MAF was working, but at a MUCH lower output voltage, so I decided to take the MAF housing off the air box and completely clean it. I already cleaned the MAF itself, but it didn't fix the problem. I took the small plate that's at the end of the MAF housing off and found a spider nest! It looked a lot like cotton. Dunno how this industrious little spider found its way in - but it did

Once I evicted the cotton spider nest, my MAF voltage returned to normal: Around 1v idle and 2.8v snap-throttle. Engine no longer stalls! YAY!

There was enough air flowing through to run OK at idle, but once you got going down the road, the engine would stall. It acted like you turn the ignition off/on quickly. This puzzled me to no end. Maybe the techs have ran into spidery-clogged MAF's before, but I sure the heck haven't!

My guess is (techs - please correct me if I'm wrong):
At idle, there was little air passing through the MAF due to the spider nest, so the computer said there was lower MAF voltage than normal, but not enough to kill anything. Once I went down the road and increased FUEL and AIR demand - the amount of air across the MAF stayed relatively the same, so the computer said WHOA! WRONG MIXTURE! Too much fuel and not enough air, so the mixture was leaned back and killed the engine. Or something to this effect? I think this is why it felt like an electrical stall rather than something else. Perhaps a little of both?

Am I right? Or close?

Why it wouldn't do this consistently in the driveway is still a mystery. I could rev the engine high in neutral and it would not stall (actually it did - but only once). I'm wondering if the speed sensor had something to do with this?

In any event... truck runs beautifully again! Lotsa power and I didn't throw a bunch of unneeded sensors at it like (unfortunately) a lot of people do.

So guys... if your engine is stalling and/or has these symptoms, CHECK that MAF inside and out!

1. Vehicle has sat and/or stored for long periods and has signs of arachnid activity.
2. CEL is on and tossing codes 157, and possibly 543 and 556.
3. Stalls/bucks at lower speeds like the ignition is being turned off/on.
4. When stalling, you can press gas pedal to floor with no results (dead stick).
5. Engine recovers quickly if you lift up on gas pedal.
6. MAF has correct supply voltage, but shows low voltage on signal wire (pin D) at idle and high RPM. (CEL code 157).
7. Engine runs fine in your driveway, but stalls when driven.

Clues:
1. Sat for a long time between operating.
2. Good supply voltage to MAF, but low output on signal wire.



Thanks to everyone who helped out!

Oh and I had a little fun with some photos... Enjoy!