Part 1:
replaced all three spark plugs on the passenger side since 8:30am this morning, not that bad, actually a piece of cake, preparing for the job takes more time than removing/replacing the plugs.

two are accessible with the wheel removed, and the rear easily removed through the doghouse. I applied anti-seize to the threads and dielectric grease to the wire connectors.

the 3 plugs removed so far are Autolite AGSF-22FM and I'm installing Autolite APP-103 as you all told me to do.

in my non-expert opinion, the plugs removed look ok to me, sort of brownish, but otherwise clean and no signs of anything abnormal. If it keeps missing when cold then it must be the Coil Pack.

PART 2: finished at 3:30 pm. The rear driver's side plug came out easily through the front, extending my arm to it, the front plug I accessed through the wheel well opening. It was the middle driver's side spark plug and wire that gave me a fit; The two EGR tubes and hoses are in the way. I used only the spark plug socket and a 3/4" wrench to turn it and then removed it by hand, neither spark plug was very tight. the 3 driver's side plugs I removed are also Autolite AGSF-22FM. They look in the same condition as the passenger side plugs.

the mid and rear driver's side plugs are better accessed by inserting your arm over the power steering pump; I had a lot of light from a lamp I inserted through the doghouse.

the engine started inmediately from cold, appears to not be missing and idling was very smooth for the first time since I bought it, reminded me of the old '92. We'll see when I take it for a drive.

Also replaced the thermostat yesterday, and got the throttle splash/ice shield, both from the Ford dealer.
The Ford parts man tells me there is only 1 thermostat listed for the '97 Aerostar 4.0, not two as I thought.

I did not like the thermostats I saw at Autozone, they looked really el cheapo, (made in Indonesia), particularly the o-ring seal looked like a cheap rubber band. The Ford stat says made in Germany, not cheap but it looked high quality and precision-made including the seal. The one I removed was the Autozone variety, now I know better.

 

That factory thermostat is well worth the money, The last one I bought was $22.00 from my Ford dealer as well. You sure can feel the weight difference and quality as well.

 

bet the miss on your '97 is wires, the engine compartment heat especially in FL kills them in few years. I tried the supposed exact match A/C Delcos supposedly built in same plant with same components but went back to the Motorcraft wires. work and last far longer. expensive even at the Rock.

or the MAF is dirty
or O2 sensor is tired, they wear out burn out from heat. service replacement item every 50k>100k

exact air/fuel mixture especially under load in the '97 4.0L is critical because it uses Ford's "fast burn" head combustion chamber design, not a Ford better idea. The 2 part combustion chamber makes for uneven fuel distribution across the whole C. chamber =s uneven combustion. hot and cold spots.
Most of the rock climber creek crawler boys go back to the old head design for better performance.

Rebuilding The Ford 4.0L Pushrod V6: Engine Builder
1995-’97 Ranger, Explorer and ’97 Aerostar
When the head was redesigned in ’95 with the heart-shaped, fast-burn chamber, the piston had to be changed to maintain the same compression ratio with the new, smaller chamber, so the dish was noticeably larger (3.10˝ vs 2.40˝) in diameter.



Coil packs in these are extremely reliable, never seen one fail in lots or Rangers, Explorers and some Aeros.


Motorcraft thermostats, what the dealer sells, are half the price online or at many auto parts stores. Mine orders them in for me, phone call and pick it up

RockAuto.com also carries the M/C TS. still 3 times the price of the Stant Premium Stainless Steel Superstat I like but last twice as long.

any pictures of bloody hands/arms or blood soaked mech. gloves?
worthless Aero spark plug changing post without blood soaked pics

 

I have it down and can change them in 30mins flat. I even scrub the under side and wash it off while its jacked up.

I just did my inner tie rods today, greased the front bearings, the ball joints, installed new door panels in the doors, painted the under side while it was up and greased all the cables. I got me a bag full of cable and wire loom covers, radiator hose covers upper and lower, and some cleaned and painted bolts to install Sunday.

I use the Mobil 1 grease as well. It resist salt spray and good too 375 degrees.

 

yes, that's what I paid at the Ford dealer. If I overpaid, well the parts guy went out of his way to find me a nos splash/ice shield, I was already there, had already seen the t-stats at Autozone, and he had one there which convinced me there was a giant difference.

also I got eight Autolite APP-103 for $20.00 (total including delivery) at eBay. With the Autolite Rebate of $9.00 for 6 plugs, they will have cost me $11.00.

I'm happy with the results, replacing the plugs was not as bad as I expected, took me the whole day but I also learned about the 4.0 liter, rotated the tires, etc.

 

haaa! I was very careful today, no busted knuckles, no accidents, only right arm scratched from the driver's side plugs contortions. I used a pair of very good nylon & rubber gloves which fit tight like a "skin" and retain the hand's and finger's "feel" when holding small parts. (Autozone).

yes, the plug wires seem fine, like new, I don't know what brand they are, the plugs are orange/red, the wires are black.

if the missing continues, (I definitely agree it is something electrical), then new Motorcraft wires and O2 sensor. Not going to use aftermarket with these parts.

I cleaned the MAF a month ago, it was clean but I cleaned it anyway. No change. What I did notice is the throttle butterfly dirty/greasy with grime, but there's a sticker there that says "Do Not Clean Intake"

the weird thing is that when the van warms up, and the thermostat has gone through more than four open/close cycles and has stabilized, the missing disappears and the engine starts running beautifully. It has a lot more power than my old 3.0, it "sprints" at red lights and I can beat BMW's, Hondas, Toyotas, and even Chevys and Fords. My girl would say "you never grew up" and I agree !

 

I had to restore my door panels, they are a strange color (Mocha/Rose-Beige), and I've yet to find another set in perfect condition, they're always grey and destroyed. The rest of the trim is like new but the front door panels were falling apart. I used fiberglass to reinforce the cracked plastic "forms" from behind, a vinyl repair kit to fix tears, then I went to a local automotive paint place, they matched the color with vinyl paint and I sprayed the vinyl sections, perfect match.

I've been working in that '97 since May 20, it's become an addiction but I don't mind. It is looking like a new vehicle. Being a Jaguar collector/refurbisher, you can tell I'm picky. I can do the plugs in any of my two Jags in 15 minutes! (inline 6's)

 

Did you check the cold start bypass valve behind the intake TPS. It stops extra air from coming in till it warms up.


I got one complete good one that is light blue drivers side. The plastic is 100% good and it has the padding in the door and the lower map pocket that are in good condition. I been looking for the Tan, Red piping trim for my Eddie Bauer. I will find some one day, I just watch the Yards and graigslist.

 

What I did notice is the throttle butterfly dirty/greasy with grime, but there's a sticker there that says "Do Not Clean Intake"

Ford had one of their brain fart Not So Good Ideas and teflon coated the throat of the TB to prevent dirt from sticking. As you can see, a total failure. The Not So no stick wears away at the idle plate position anyway so dirt/dust/goober/hairballs/fried tacos and and goop that gets sucked back from the PCV builds up anyway.
Clean every 20k with TB cleaner or when it's grimey. I wipe with a rag soaked with cleaner, gloves and engine OFF.
Good time to spray/douche the top end head runners, injectors sticking into the runners, intake valves and combustion chamber with your favorite spray in cleaner. Use lots, flood the engine out and let hot soak for an hour. Then out to the freeway and watch the carbon smoke burn. Mosquito killing clouds.

Years ago, I played punch the rabbit thru a couple lights with a kid in his Honda goblat with the 12" exh. tip. Got him so upset and perturbed with the old Aero 4L making those wild air sucking turbo sounds next to him and he couldn't get away, gave me a dirty look when we were roaring side by side and I'm starting to pull away. See him reach over and hit his Nitrous switch.

that's all she wrote Bugs, could hear his engine rev to 10000+ and blast away. wife is screaming in my ear about not racing and going to get arrested and she's not going to bail me out.
got down the road less than a mile and here's the kid out of his Honda and it's got a parts and oil trail leading up to its gut pile on the shoulder.
I wave at the kid and drive on.

 

ok I'm cleaning the butterfly and bye bye to the sticker.

those noise-producing stainless steel tailpipes in little Hondas? so ridiculous. It's the equivalent of attaching balloons to the bicycle spokes to make it sound like an engine. I want to find out where they live, show up at 3:30am with a cement truck and a hose, and fill their tailpipe with concrete.

 

well yes I've looked at the CSBV, but I haven't removed it, I wouldn't know how to test it.

there's an Eddie Bauer with the red piping interior at my local salvage yard with the Mocha door panels but they are destroyed.

 

reset the PCM KAM memory which stores the learned for current conditions engine parameters by disconnecting the neg. batt cable for 30 sec. after each engine component change such as after your tuneup.

PCM then starts from factory defaults and relearns air/fuel, shift points etc for correct running engine with new components.

 

I was going to do that, but it started and idled so good yesterday after replacing all 6 plugs! I'm afraid to screw it up! Should I do it anyway?

I do have a puzzling issue: the Red, Brake dash light does not self check; Is it supposed to? (my 1992 Aerostar didn't self check), the Red light comes On and Off fine with the emergency brake lever; I removed the emergency brake switch to clean it just in case, it was clean if not new; But still no self-check.

I also have the amber RABS light ON all the time. I have the '97 Ford Service Manual now, I've gone through the troubleshooting steps at least 3 times, even replaced the Diode & Resistor, (they were fine darn it), and the RABS light still stays ON. The last troubleshooting took me to the Step 5 conclusion: "Ignition Switch Bad". I don't believe it. (though sometimes it is hard to remove the key).

I have no bad stop light bulbs, all work fine, fluid level is fine; (unless the Reservoir float level switch is bad). Can the Fluid Level Switch be replaced without removing the reservoir and having to re-bleed the brakes? (the Manual does not say, all it says is "Replace Fluid Level Switch".

if I start the engine with the foot on the Brake Pedal, the amber RABS light self-checks and stays OFF until I release the pedal, then it comes back ON.

 

I would like to know where you got your information. Ford went to the fast burn chamber to solve the head problems that plagued the previous generation. The old slower burning heads needed a lot of timing advance, more advance means more opportunity for pinging and detonation, which in turn causes the heads to crack. An old 4.0L head with more than 150,000 miles without a cracked head is actually rare. If the mixture goes even slightly amiss, the problem gets worse. This problem was so common that Ford even had their own private label combustion chamber cleaner pretty much just for the 4.0L and they would often advise removing the octane plug to prevent pinging.

The fast burn head allows a 10 hp bump with less timing advance so pinging is actually less likely. The cylinder head cracking issue was also solved. Having seen and used both, I'd take the fast burn head any day. However, the heads do have to be matched to the application. Using a fast burn head on an older slow burn engine will actually melt the pistons. This is due to both the increased compression ratio and the increased burn speed. If the fast burn pistons was used and a tuner to pull the timing, the fast burn head could be used on an older engine.

Both designs however have lousy exhaust seats, few engines with 120,000 miles or more have good exhaust seats, they start receding into the head, which causes lower compression, decreased performance and efficiency, rough idle, and eventually it will start causing misfires. It also increases the strain on the lifters and accelerates pushrod wear and increases lifter noise.

 

experience and the real world Khan
if the 4.0L fast burn heat were so popular, it would still be around or at least lived longer, not just 2 years, replaced by the hairball 4.0L conversion to single overhead cam.
it went the same way as useless dinosaurs, replaced by more successful designs