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Category: Ford
Satisfied Customers: 24100
Experience:  ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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Ford Ranger 2000 ford ranger 3.0 flex fuel rough idle when

Customer Question

2000 ford ranger 3.0 flex fuel rough idle when warmed up. It has cleared up a couple of times ( intermittent ) but is back to rough idle. Code P0320, changed crank position sensor, cam position sensor, plugs, wires, air filter, disconnected idle air valve, rpm drops slightly suggesting it's working. PCV valve rattles. Sprayed contact cleaner in search of vacum leak to no avail. EGR appears to be o.k
Any ideas? Thanks for your help. Todd
Submitted: 5 years ago.
Category: Ford
Expert:  AMEDEE replied 5 years ago.

Did you still need help?

How did you check the cam sensor?
Customer: replied 5 years ago.
Yes, I didn't check it, just replaced
Expert:  AMEDEE replied 5 years ago.
You might just have a bad tune up parts or even a bad ignition coil pack. This is very common! You can test AMP draw on each Primary circuit of the coil pack. Only test each circuit for 2-5 seconds. Normal current draw is about 10-14 Amps, so watch the meter for fault or error messages so as not to blow the internal fuse! If reading goes high, replace coil.

P0320 Ignition Engine Speed Input Circuit Malfunction

Possible Causes
* Verify that the vehicle Antitheft system is operational
* Inspect for any Aftermarket 2-way radio problems
* Inspect for signs of "arcing" at one or more of the ignition coils
* Verify that the Inertia Fuel Switch (IFS) is set properly (reset)
Customer: replied 5 years ago.
I will check it out and get back to you. thanks Todd
Expert:  AMEDEE replied 5 years ago.
You bet!

I hope this helps. You can always accept my answer now, and repost back again later on if you have any more questions. If you want to discuss it some more just hit "reply", it's free to do so otherwise don't forget to hit "accept" and leave positive feedback if you found my answer helpful.


Customer: replied 5 years ago.

I checked the resistance of the coil, @ .9-1.3 for primary and @ 13 for secondary. These values fall in line with the manual.

I'm not sure how to check antitheft.

IFS appears to be ok

No apparent arcing

Aftermarket 2 way radio?

Expert:  AMEDEE replied 5 years ago.
Sorry for the delay!

Did you do an amp draw on each coil pack? If so what were the results?
Customer: replied 5 years ago.
I did a resistance check, according to the book, primary should be less than 5 omhs and the secondary should be between 13 - 15 omhs. Not sure how to do an amp draw
Expert:  AMEDEE replied 5 years ago.
YOu would need an amp clamp to do this test. Testing the resistance is a test..but not a good test. It only tests the component when it is stilling there stagnant... not when it is in use... which is key!
AMEDEE and 4 other Ford Specialists are ready to help you
Customer: replied 5 years ago.

I've been out of town, I was down in the mojave desert riding my Husky, now I'm back dealing with my Ranger. I'm a maint. mechanic for a large municipal water treatment plant in Oakland Ca. I know little about automotive mechanics, but feel I should be able to handle this problem. I did borrow a clamp on amp meter and checked the plug wires, I know you said to check the primary. Could you be more specific on the procedure?

Thanks, Todd

Expert:  AMEDEE replied 5 years ago.

You need to see how much current the ignition coil is pulling when the engine is running. This can be done with a lab scope or a amp meter with a amp clamp.
Customer: replied 5 years ago.
Which wires do I test?
Expert:  AMEDEE replied 5 years ago.
The power wire going to the coil.
Customer: replied 5 years ago.
There is a plug with 4 wires feeding the coil
Expert:  AMEDEE replied 5 years ago.
Turn the key on and check each of the wires for power. THat is the wire you want to check for current.
Customer: replied 5 years ago.
You said the amperage should be between 10-14, correct?
Expert:  AMEDEE replied 5 years ago.
That would be correct!
Expert:  AMEDEE replied 5 years ago.
That would be correct!
Customer: replied 5 years ago.
Thanks, I'll let you know how it goes. Could be awhile
Expert:  AMEDEE replied 5 years ago.
NO problem!