Fuel Injector Not Working. How do I find the bad one? Need help!

[BTR]

2000 Explorer XLT 4DR 2WD 4.0L SOHC JOB 1 (VIN E). 5-Speed Automatic O/D 5R55E. 152,000 miles.

I replaced the fuel injectors and seals (adapters). The injectors are refurbished OEM. On initial startup and an extremely short test drive, it feels and sounds like it’s running on 5 cylinders. The CEL did not come on.

I need to determine which fuel injector is not working. HOW do I do this? Any and all help would be greatly appreciated. Many thanks.

 

[donalds]

You can use a 9v battery to energise each injector 1 at a time
Test resistance 14 ohms or close to it
Sure you didn't swap 2 connections

 

[BTR]

Roger that (re using a 9-volt battery). Excellent suggestion. Thanks!

1. I'm going to gather some ODB data. Maybe it'll at least steer me to the bank with the bad injector.
2. I'm going to attempt the stethoscope procedure. However, given the upper intake manifold is in the way, this may be challenging.
3. I'm going to try the "cold header" procedure. Maybe this will identify the bad cylinder.
4. As a last resort, I'm going to pull the plug wires one at a time. Maybe this will identify the bad cylinder.

Good idea. I'll go back and check the connections to make sure I didn't cross any of them. The harnesses are pretty short and are "shaped" toward their locations, so I (think) I got them connected properly. But, I'll double check.

Other than the 4 tests listed above, does anyone know any other ways to find the bad injector?

 

[BTR]

OBD data shows Bank 2 STFTs fluctuating in/out of the the +30s and low +40s. I've never seen my STFTs this high before. Am I correct in interpreting this to be a clogged or non-working injector in Bank 2?

 

[BTR]

All 6 fuel injectors pass the stethoscope test, i.e., they all sound the same... clicking consistently... no differences in volume.

On a warm idling engine, Bank 1 LTFTs have climbed to +14 and Bank 2 LTFTs have climbed to +25.

The CEL has not come ON.

At warm idle, RPMs are surging in a consistent pattern.

Do I have a vacuum leak? Or is it something else?

 

[Motorhogman]

I'll assume you have that plastic lower manifold ? The one that uses wood screws. My hard learned lesson with that manifold is you only get 2 maybe 3 times pulling the upper and replacing. Seems the 3rd round of torque the plastic strips out. Just my lousy experience with my 2000 sport SOHC. Thus a vacuum leak.

 

[BTR]

Yes, I have the SOHC Job 1 (VIN E) engine that has the 2-piece intake manifold. So far, I haven't stripped the screw holes that hold the upper-half to the lower-half. I replaced the upper gasket a while back and it still has some "thickness" to it. I've never replaced the lower gasket. Do you happen to know the torque specs for the lower-half? I plan to replace the gasket.

 

[donalds]

Yes, I have the SOHC Job 1 (VIN E) engine that has the 2-piece intake manifold. So far, I haven't stripped the screw holes that hold the upper-half to the lower-half. I replaced the upper gasket a while back and it still has some "thickness" to it. I've never replaced the lower gasket. Do you happen to know the torque specs for the lower-half? I plan to replace the gasket.

Try and listen carefully
1st take off the intake manifold upper and lower second take 1⁄4" drill bit
drill out the threads holes in the upper intake manifold
the lower intake manifold needs to be new the plastic holes are striped out experience tells me this over and over again
Buy drilling The threads in the upper intake makes it so the threads not working against each other
you only want the bottom threads to pull down the the upper intake the upper intake is threaded but the threads are not used they just work against the other lower intake threads
1\4"drill bit clean up the threads in the upper intake

 

[BTR]

Yes... interesting... I have noticed that the upper-half is threaded. It didn't make sense to me, but I rolled-with-it. Now, I'll do what you did. Many thanks!

 

[BTR]

P. S. Do you know the troque spec for the lower-half?

 

[donalds]

It's like 80 inch lbs but I'm not 100% sure 80" lbs is a decent amount of torque
For small boat like that

 

[donalds]

As far as the upper intake screws after you fix the holes you only tighten them down till it crushes the gasket s
Use a small wrenches quarter inch tools hand tight

 

[Exploder321]

P. S. Do you know the troque spec for the lower-half?

If you're running a screw into plastic? A couple of inch pounds at best... just snug to the feel - don't want to strip the plastic.

 

[Motorhogman]

Yes, I have the SOHC Job 1 (VIN E) engine that has the 2-piece intake manifold. So far, I haven't stripped the screw holes that hold the upper-half to the lower-half. I replaced the upper gasket a while back and it still has some "thickness" to it. I've never replaced the lower gasket. Do you happen to know the torque specs for the lower-half? I plan to replace the gasket.

upper/ from my Ford manual.

 

[Motorhogman]

lower

 

[donalds]

I dare you to tighten them up that much please take pictures of the stripped plastic threads and broken bolts in the head
After 3 lower intake plenum s I learned a lesson
I'm not trying to be an ass I've just been there a time or to

I would show u the parts but I think I blew them up or used them for target practice

View attachment 441320 lower

View attachment 441319 upper/ from my Ford manual.

Ask @Lee's Automotive

 

[BTR]

@Motorhogman and @donalds - Thank you! Very helpful. Instead of 13, I'm going to go 10 ft. lbs. on the lower intake manifold. Do you think 10 will be OK? I don't want to strip the aluminum.

 

[donalds]

@Motorhogman and @donalds - Thank you! Very helpful. Instead of 13, I'm going to go 10 ft. lbs. on the lower intake manifold. Do you think 10 will be OK? I don't want to strip the aluminum.

Sounds fine still a lot but sounds ok to me

 

[Motorhogman]

Sounds fine still a lot but sounds ok to me

I agree with backing off. Many years of experience working on Harley engines. They call for 120 inch pounds, I'm only going to 90. Never had a problem. I'm sure I did the same last time I worked On My Ex sport. Just didn't think to mention it. Suffering from OLD syndrome.lol.

 

[410Fortune]

you for sure need to re seal the lower plenum as well................ no cel after a few drive cycles = the injectors are likely fine
a bad injector either doesn't click (not opening closing) or it sticks open

2000 was 23 years ago those O RINGS Are dry and not sealing
I would never take the upper plenum off a job 1 and not re seal the lower plenum as well


you have done an excellent job thus far! I know its a PITA but the more times you remove that intake the better you get and the easier it gets

Have you considered changing your timing chain tensioners? with the intake off is the perfect time to do the drivers unit