Unsolvable Explorer Rough Idle. Any OBD II experts?

[Cashcrazy]

Thank you. Does anyone know the location of the CKP and CMP? It does sound like these sensors could be the issue.

 

[Tech By Trade]

Crank sensor is on the harmonic balance, cam sensor is on the top front of the driver side valve cover.

 

[2000StreetRod]

CKP sensor:

The left red arrow points to the connector.

 

[Cashcrazy]

Thank you. Crank sensors are cheap so I am going to give it a shot. The sensor on the master cylinder and sensor on the rear differential fully went out. I believe the IAC was also flakey so I do believe these sensors may deteriorate with age. Hopefully I can get it on this evening.

 

[Tech By Trade]

On a side note, while your looking at that crank sensor, have a real good look at the harmonic balancer. The rubber in it likes to break down and it likes to give way. Could a vibration from a this be causing that sensor to read funny? Just a thought and an easy thing to check.

 

[Cashcrazy]

I've thought about the HB and hoping that's not the issue. I really don't want to pull it to replace.

 

[2000StreetRod]

Below is a photo of a separated harmonic balancer.

 

[Cashcrazy]

I'm positive it's not separated, but I have seen small block Chevy balancers wobble at the rubber when they are worn. It still looks smooth while turning.

 

[Cashcrazy]

I ann going to the junkyard tomorrow if anyone can think of a sensor worth pulling. I'll probably pull a camshaft sensor for testing

 

[Cashcrazy]

New crank positioning sensor and still idling rough.

 

[Autolabs]

I'm sorry but I'm not familiar with your mode 6 format but I do see .33 percent misfire for cyl 6. 2 percent is when the test fails I think. If you can get it cheap enough at the junk yard grab an oem IAC. I know you have a new one, but it is aftermarket. I'm sorry if I didn't see them but have you checked Fuel pressure, vacuum, and compression?
And just to clarify...
Idle feels better at 650 vs 800-900rpm?

 

[Cashcrazy]

Autolab- I'll answer all your questions when I get home and connect to the ECM.

I scored a Motorcraft cam sensor for $5 at the yard so I'll swap it and test in a bit. I'll also pick up a fuel pressure gauge since that info has been requested. What is the normal pressure and what can I expect to see?

 

[Cashcrazy]

No change with new cam sensor.

2000streetrod- I just checked the TPS readings and it starts and 20% and smoothly goes to 93.3% at WOT. It always drops back to 20% when the pedal is released

Autolab- I cleaned the original IAC real well and put it back in. No real change. The idle might be slightly worse with the stock iac. Only one explorer had the engine at the junkyard and the IAC was gone so I didn't get a test subject.

 

[Cashcrazy]

If I miss anyone's questions or suggestion I am not ignoring you! There have been some excellent suggestions and once I start testing I start following other trails.

Here is a short video of the harmonic balancer in motion. I am going to check fuel pressure when the engine cools. I don't know if the new gauges are going to leak.

 

[Cashcrazy]

Ok.... I may have found the issue and it's not a cheap fix so if any of you are around this Saturday let me know what you think.....

I hooked the gauge to the rail and had the reading shown in the video below. After I laid the gauge down I pulled the vacuum hose of the pressure damper and re connected a few times. You can see the gauge jolt a little but remained steady. I went back and had someone rev the engine to 2k RPM and performed the same test. The fuel pressure remained about 65 and the gauge would just jolt when removing and reconnecting the vacuum line on the pressure damper. Is this normal?

 

[2000StreetRod]

When the harmonic balancer fails on your model the bonding between the outer and inner sections fails and the outer section moves forward or aft. If it moves aft the belt may jump off of the outer section and run on the inner section. If the outer section moves forward enough it will no longer be supported by the inner section and damage the radiator or something else. The belt on your vehicle seems to be running in the correct place on the outer section but I can't tell if the section is displaced forward of the inner section.

The fuel damper has a diaphragm that reduces the pulses in the fuel rail when the injectors close. It acts similar to the air tube extensions above water faucets in home plumbing to reduce the recoil in the pipes when an open faucet is shut off suddenly. The vacuum connection on the damper displaces the diaphragm toward the vacuum side allowing greater motion to counter the injector pulses. I've never disconnected the vacuum hose while monitoring the fuel pressure but I suspect it is acting normally. Your fuel pressure is normal at about 65 psi.

Your TPS readings are normal.

I've been thinking about other ignition related issues. There is an ignition noise suppression capacitor for the radio on the coilpack connector. Capacitors can fail in a shorted mode affecting the ignition. I suggest that you remove it or disconnect its ground lug to see if that has any affect. The coil pack is grounded by the mounting bolts/screws. I suggest that you clean the coilpack surface under the head of the bolts/screws to ensure a good electrical connection between the coilpack and the engine.

 

[Turdle]

Are the rear grooves of the belt discolored compared to the rest of the grooves? From this angle it seems the crank pulley is shifted forward about 3/8" and the rear of the belt is touching the rim of the crank pulley. It may be an illusion created by the video angle though.

 

[Cashcrazy]

I think the crank is an illusion. I'll have to look at belt. It only has a few thousand miles on it. I found a YouTube video with a guy claiming the fuel pressure should jump with the vacuum hose removed. The diaphragm is not cracked because fuel is not escaping the vacuum hose nipple but I guess it's possible it's stuck wide open. That would explain the rich running condition. These were $300 each at the parts store so I ran back to the junkyard and pulled a few to test. I also snagged a Motorcraft ignition coil because it was there.

 

[2000StreetRod]

When I added my supercharger I installed one of the fuel pressure/temperature sensors so I could control my fuel pump pressure with pulse width modulation.

It's a solid state device with no diaphragm and when I monitored the fuel pressure there were huge spikes of pressure from the fuel injectors closing. So I built my own simple damper.

It's just an air chamber that compresses and decompresses to reduce the spikes. It is very effective. The Aviator fuel rail has a damper on each bank.

 

[Cashcrazy]

I also found this great thread by 2000streetrod if anyone stumbles upon this thread months down the road with the same symptoms.

http://www.explorerforum.com/forums...r-ranger-fuel-pressure-test-procedure.265157/