Hey gang - new to FTE, but glad I found you. A novice for sure, but capable of learning. I've recently purchased a '98 b4000 with the 4.0 (maybe redundant, but oh well) with 220,000 that I knew had a problem with an intermittent stall/hiccup while driving. No particular time this would occur, under load, cruising, low RPM, high RPM....just whenever. I was happy to get the truck and went to work tuning it up, thinking it would become more clear what the root of the problem was as I swapped out the usual tune up stuff. Air filter, oil change, plugs and wires, fuel filter, transfer case and rear end fluids (of course I'm aware they would not be the culprit, but hey, I like my little 4x4).

Of course, the tune up stuff made a difference for a little while, but the hiccup always comes back. The gas mileage has gotten better. And when it's running right... it sounds great. Nice, deep, throaty exhaust with much better power than before. But it always goes back to the hiccup and poor power. MAF? O2? Clogged Cat?

 

Welcome to FTE.

Good idea to begin changing the fluids, don't forget the tranny, brake & power steering fluids & coolant.

If you have an auto tranny & seeing as how you like turning your own wrenches, there are helpful posts on doing a full fluid pump out of the tranny, power steering & brake system, in the "Tech Info" thread, atop this forums thread listing page.

Lots of other good wrench turning info there too, so be sure to check it out.

Now, to your intermittent random stall, do you have a CEL lit????

If so, have the computer scanned for troble codes, as they can provide good trouble shooting clues.
Most autoparts stores will scan at no charge IF the CEL is lit. Post ALL of the code Numbers found.

If no CEL, or codes are found, it's likely something the computer isn't monitoring, so you need to determine if it's a lack of spark, or a fuel delivery problem & it could be a number of things on the 4.0L.

Maybe carry a fuel pressure gauge & inductive timing light & check to see whats missing when it decides to stall.

If you don't have, or can't come by a pressure gauge or timing light, when it does stall, do the dash warning lights come on & will it crank ok????

Do you hear the fuel pump run for a couple of seconds at KOEO before cranking the engine & will it then restart without delay????

If you can't hear the fuel pump run & shut off, check/thump the underhood power distribution box fuel pump power relay, or swap it out for a like relay not needed to run the engine, like the A/C power relay. These power relays are a common problem part.

Check for voltage drop to the fuel pump at the in cabin inertia switch. It's in cabin, passenger side foot well, just above the carpet.

Trip & Reset the in cabin fuel pump inertia switch, or disconnect it & try a temporary bypassing jumper in the electrical connector. There have been reports of faulty high resistance inertia switches.

If you have the Super Cab, check under the cab below the drivers seat, where a wire harness feeds through the floor board, as the wiring is known to chaff through & randomally short out. so with the engine running, give it a wiggle test & see if the engine stalls.

There is a TSB out on how to fix it & Rockledge has a nice thread on how he fixed his & I think it's in the Tech Info thread.

A whole bunch of thoughts for consideration, let us know what you find & how it goes.

 

Thanks for the direction, Pawpaw. The engine does not die when the "hiccup" occurs. Rather it seems to be an abrupt, instantaneous, brief (snap of the fingers brief) and nearly complete interruption of power.

It feels like when this occurs the "jolt" back to normal power is so severe that it may actually damage the tranny or another component of the drive train. And it does seem to be completely random.

As far as the CEL, it's burnt out or been removed. I've had the truck for about a month, but have known it for a couple of years and have known it to always have poor power, poor gas mileage, the hiccup, and never have the CEL on.

Regardless, I suspected the CEL being out and had it diagnosed. I can't remember all the codes - they were multiple - but, I'll be sure to check out the printout the automotive store gave me and post them soon.

In the meantime, it is a super cab and I'll check under the drivers seat. It does "feel" like an electrical issue.

Thanks again.

 

With the hiccup symptom, I've had that once, it would just suddenly randomly cut out at idle, or running, like someone had quickly turned the ignition switch off & back on again & once in a driving rainstorm it really acted out on a pull.

The problem was found with a "wet down" test, with a spray bottle of water, of each plug, wire & the coil pack & it turned out to be a cracked external insulator on #6 spark plug!!!!

Also the coil pack is known to crack, out of sight underneath & arc to ground, so if everything else checks out, pull the coilpack & have a look see underneath for cracks, or carbon tracks.

I also found my then new 99 Rangers colpack electrical connector loose, where it plugs into the coil pack, because the coil packs molded on plastic snap lock fastner part on the coil pack was broken & it was letting vibration cause the coil packs electrical connector back out.

More thoughts that have come to mind.

 

Thanks for the heads up on the cracked coil pack - I'll make sure to check it out. In the mean time I'll post the codes that were pulled by the automotive parts store.

P0133
P0401
P1132
P1131
P1309
P0174
P0171

Yup - 7 of them. Now I have since changed the fuel filter and did notice a difference in power right away, though it did nothing for the hiccup. But as you would suspect, in a matter of time the power did drop off and the hiccup continues.

The 4 day weekend will give me chance to check out the coil pack and do the wet down test. I like the possibility of the electrical ground out due to the complete randomness and brevity of the hiccup occurrence.

As for the codes - I'll make sure to bring the truck in to get it diagnosed at the auto parts place again. It's a 75 mile trip to the store, so I need to be sure to make it a productive trip (wet test beforehand).

 

OK good feedback on the code numbers & they offer up some clues on the lack of power, but not much on the intermitent hiccup.

P0133=Bank one up stream O2 sensor slow response, so it sounds like it's old & lazy & needs to be replaced. I'd replace the Bank 2 sensor also, as it's probably the same age & if they have 75-100K miles on them, it's time for replacement, as most folks replace O2 sensors at 75-100K miles.
The O2 sensors can affect driveablity.

P0171 & P0174 are lean codes for bank one & two. Things like leaking intake manafold gaskets, stuck open PCV valve, leaking vacuum line, dirty MAF sensor, low fuel pressure, are common problems.

If you come to suspect the MAF sensor & want to try cleaning it, remove & Carefully clean it with a plastic safe, non residual cleaner, like CRC MAF Sensor Spray Cleaner. Let it cool before leaning & Don't touch it's sensor. Keep it squeeky clean during re-installaton.

P0401=EGR flow insufficient. Could be a vacuum leak in the EGR valves control plumbing, a clogged/carboned up EGR valve, leaking EGR valve, or it controlling vacuum switching valves diaphragm, or an old rusted up falling apart EGR valve.

P1131 & P1132= Lack of O2 sensor switching, 1131=lean, 1132=rich. Could be old tired O2 sensors, dirty MAF sensor, or maybe tied into the above EGR trouble code, or some combination there-of. The lack of switching part sorta sounds like old, worn out, slow response O2 sensors & with 200K on the engine, if they've never been changed, I'd look into doing that, as they've lived two life times.

P1309=Misfire monitor AICE Chip fault. Look to the CMP sensor, it's wiring, or it's installation/alignment, or it's electrical output.

If you replace the O2 sensors, or find & fix a vacuum leak, ect, be sure to pull the battery B- cable for 15 min, or so, to wipe the computers KAM memory, so the computer can begin to build new fuel trim tables with the new, repaired, or cleaned parts.

Looks like your gonna have a busy weekend, let us know how the wench turning goes.

 

So I was able to get some work done on the truck this weekend. The MAF sensor and the EGR system, aside from the valve itself, has been replaced on the component level.

New Vacuum Solenoid and Pressure Feed Back Sensor - broken vacuum line fitting was found on the vacuum solenoid and when replaced the pressure feedback sensor began to melt(!! WTF??) So it was also replaced.

I have not taken the EGR diaphragm off (as I had no new gasket to replace the old) to clean it and am looking for an effective cleaning method.

The result of treating the EGR system has been a noticeable difference in power and gas mileage - BUT the hiccup continues.

At least I can now report the hiccup seems to occur when the motor has been warmed up to running temp and driven for a period of about 30 minutes, then seems to occur only when the motor is asked to respond to an increased load (i.e. going uphill)

I will have a chance to bring it into town and get it diagnosed at the auto parts store later this week, but until then I will pick up an EGR gasket, remove the existing diaphragm, and attempt to carefully clean the component.

 

Good feedback & find on the EGR control system vacuum leak.

Given your above input about the hiccup occuring during engine load @ throttle up, slow O2 sesnor response time, the TPS & maybe a spark problem come to mind.

Of course you have a set O2 sensor trouble code for slow resonse, so imo both of the O2 sensors belong high up on your suspect list, as they figure in on fuel trim & with slow O2 sensor resonse, it'll corrupt fuel trim & the fuel trim tables.

Check the TPS resistance value, with a throttle sweep, monitored using an analog multimeter & look for any rough, unsteady movement on the meter, as the throttle is slowly opened from the closed, to wot position. The resistance value should change smoothly, without any unsteady readings.

If that checks out ok, as i posted above, maybe have a look at excessive spark plug gap, or some other ignition system anomaly, like faulty plug wires, cracked coil pack or plug insulator damage, ect, causing a weak spark.
Maybe consider doing a "wet down test" at night, of each plug wire , boots on both ends & the coilpack, using a spray bottle of water & lookng for arcs, sparks & or a rough idle, might help isolate any problem there.

Keep us posted on your trouble shoot.