Cause for fuel cutout? Like speed limiter but at low speeds.

[JoshT]

This about the 2000 Explorer 5.0L drivetrain swapped into my 99 Ranger. FWIW all systems compatable between the two, same fuel system, pats, etc.

What I am experiencing I can best describe as a fuel cutout. It literally feels like what it does when I hit the speed limiter, except I'm moving about 5 mph, not 105 mph.

Fire the truck up and it seems to idle fine, it free revs fine. Place into reverse and it starts ok then acts like a speed limiter has engaged. Sit still at an idle or into neutral it clears up and idles fine. Into drive it feels like the fuel is cut or a speed limiter is engaged.

It was driving fine until Thursday. So what changed Thursday you ask? Installed Ford Performance 24lb/hr injectors and a tune from a reputable tuner.

So far I've checked all of my wiring and plug wires, everything is correct. I've done a smoke check on both intake and exhaust side, no meaningful leaks. I swapped from the Screaming Demon coil packs, back to the old Motorcraft coil packs, no change in condition. I swapped the aftermarket IACV that was working fine on stock tune for a known working Motorcraft IACV, no change in condition. I swapped from the 91 octane tune that the tuner provided to the 87 octane tune they provided, again no improvement.

Having a wideband hooked into the SCT tuner for datalogging, I can see that when it does this fuel cutout that the wideband is pegged lean. I just can't figure out if there is anything that I could have done when swapping in the injectors that could have caused this.

I sent a datalog of it doing this to the tuner to get their input, but don't expect to hear back before next week. Trying to identify other potential causes in the mean time.

 

[JoshT]

Forgot to mentione, I also checked fuel pressure. This has the returnless fuel system. At idle the fuel pressure is solid in the low 60s PSI. When the"fuel cut" happens I can't see the gauge well because of the angle from the driver seat, but I can see that the needle does not move from idle position. So it does not appear to be a fuel pump or fuel filter. If either of those were the problem, I'd expect the fuel pressure to drop at the fuel rail.

 

[JoshT]

Looks like it's a tune issue.

Late yesterday I switched to the 87 octane tune that they sent, I wanted a low octane just incase I Was somewhere that I had to use it. Same problem.

Today between working on the F-250 I decided to see what would happen if I stuck the factory tune back in it. Symptoms disappeared. Fired up, dropped into reverse and backed around the house with no issues. Dropped into drive, and back around the house with no problems. Took it up to the end of the block to get a little more speed, and no problems. Wideband was showing it was running on the rich side, but iw was running and drivable.

Shot another email to the tuner with this information and hopefully they'll have me good news and a fixed tune int he next day or two.

 

[410Fortune]

So the 24# injectors are for a returnless fuel system correct? Meaning 24 gph at 64 psi?

There is no fuel cutoff in a 5.0
Only a fuel pump relay and it is on or off when commanded by the pcm

What could have happened during install is any debris inside the fuel rail can plug up the inlet on an injector
Same goes for the spray nozzle, any dirt or debris picked up when droppong injectors in can block the spray pattern

Seems like a tuner issue for sure.. let us know what they say
I like to listen to all 8 injectors fire click click click can also bench test them if you suspect a bad one

 

[JoshT]

They were brand new 24 lb/hr Ford Performance injectors, installed into a 64 psi system. Ford lists all of their injectors at something like 38.5 PSI. Doing the math, that would put them about 30 lb/hr at the Explorer's PSI. Don't have the spread sheet with numbers handy. All information that was provided when the tune was ordered.

I assumed it was cutting fuel for some reason. The AFR shown by the wideband had it going super lean if I was reading the output right. I know that something happens when the speed limiter cuts in and if felt a lot like that based on the limited times I have hit it.

No chance for contamination during install. Old injector removed, new injector immediately installed out of the package. No chance for debris to enter the injector and no debris around the port to get in when they were removed.

It was a tune issue. They sent out new tunes this week and they seem to be working fine. It appears to have been an issue with a setting in the tune file though I'm unclear as to exactly what. When I spoke with the tuner months ago I expressed desire to retain on device settings provided by SCT (rev limit, speed limit, shift points, etc) and was warned that it sometimes caused problems, kind of a trial and error thing. I still requested them try it then I ordered the tune.

With the replacement tunes they said it had to do with non-stock rev limit being set in the tune. I never asked the to raise it, when their form asked I responded with "recommended". I don't know what the rev limiter is set at now, probably should ask. The on device adjustment were also disabled. I don't know which thing actually fixed it.

They talk like it shouldn't need further tuning, but I'm probably still going to pull long and get their input. I paid for a service and I want to get my money worth out of it.

I think my next big job will be to improve braking. With the AWD transfer case they there don't have enough holding power for a decent launch. I don't intend to be racing the truck, but I would like the option. Planning for a brake fluid flush first to see if it is any improvement. I'm hoping so because the next step would be pads, and I'm not that close to needing them yet. When it's time for pads & rotors, I'm probably going to swap to 04+ Ranger knuckles with their slightly larger rotors. Explorer rear axle is also in the slate, but that's waiting until I also swap in the front diff for matching gears. 3.73 vs current 4.10. With the 5.0L power, the 3.73 would be more desired for my normal usage.

 

[410Fortune]

02-04 sport and sport trax also have the larger rotors up front, you only need the knuckles and larger rotors.. all other parts the same

I like to completely delete the factory abs system not only weight savings but the factory abs is lame pedal pulsing bs that seems to engage at the wrong times. I grew up in Colorado and learned to pump my own pedal

Hydroboost is also an option that is on the table but usually the larger front rotors with some good pads and maybe a new booster and master cylinder, no intake or vacuum leaks allowed = adequate brakes for 4500# suv

 

[JoshT]

02-04 sport and sport trax also have the larger rotors up front, you only need the knuckles and larger rotors.. all other parts the same

I like to completely delete the factory abs system not only weight savings but the factory abs is lame pedal pulsing bs that seems to engage at the wrong times. I grew up in Colorado and learned to pump my own pedal

Hydroboost is also an option that is on the table but usually the larger front rotors with some good pads and maybe a new booster and master cylinder, no intake or vacuum leaks allowed = adequate brakes for 4500# suv

I'm aware. The rotor upgrade has been on my to-do list for a while, but I've been trying to wait until brakes were needed again.

Have personally not had a real ABS related problem and see no need to delete at this time.

Hoping that I can forgo the Hydroboost in favor of a flush, good pads, and rotor upgrade. Already know that there are no vacuum leaks, spent a bunch of time getting that stuff sorted before ordering up the tune. Booster and master don;t seem to be issues either, I think it mostly needs a brake system tune-up (flush and bleeded) and the mentioned upgrades.

 

[VR4]

02-04 sport and sport trax also have the larger rotors up front, you only need the knuckles and larger rotors.. all other parts the same

I like to completely delete the factory abs system not only weight savings but the factory abs is lame pedal pulsing bs that seems to engage at the wrong times. I grew up in Colorado and learned to pump my own pedal

Hydroboost is also an option that is on the table but usually the larger front rotors with some good pads and maybe a new booster and master cylinder, no intake or vacuum leaks allowed = adequate brakes for 4500# suv

wheel bearing is also different. sport/trac knuckle, hub, rotor. caliper/bracket can interchange but newer one uses phenolic pistons instead of steel so pads need to match the caliper of choice

 

[JoshT]

wheel bearing is also different. sport/trac knuckle, hub, rotor. caliper/bracket can interchange but newer one uses phenolic pistons instead of steel so pads need to match the caliper of choice

Actually the wheel bearing is the same. Knuckle, wheel bearing, rotor, and caliper bracket are the same between those Sport Tracs and the 2004-2010/11 Ranger. The difference is apparently the piston in the caliper which also requires a slight change to the pads (different size clip) to work with said caliper.

98-00 Rangers definitely have a different wheel bearing since they came with locking hubs up front. Can't use those with the live axles, but they could be installed on a later model truck if you also installed the matching axles and locking hubs.

On paper the wheel bearings are different between the 01-03 and the 04-11 Rangers, but in practice they are interchangable. At worst you need to keep the bearings with the matching year range CV axles, but I've never heard of anyone having problems with mixing and matching.

Kicker is that you can allegedly even use the 98-03 Ranger calipers on the larger discs. I have no first hand experience, but that is the report from past swappers.

My truck is already converted to live axle. All I really need is a set of knuckles and rotors to do the conversion. If I opt to install new calipers, the Ranger version is slightly cheaper, so I'll probably stick with that.