Howdy All

My 2000 Ranger developed a very rough idle recently. It was over due for a tune up so I went ahead and swapped out the pugs & wires. In doing that it looked like the original coil was showing signs of internal sparking so I replaced it as well.


Starting it back up it still has the rough idle and is throwing a 442 Code indicating a small emissions leak. I checked the gas cap and worked my way through the Engine compartment with starter fluid to solve a couple small, very small, vacuum leaks but the rough idle persists.


Since I don't have the factory diagnostic tool I can't really follow the FSM test procedures for the various emissions components.


So my first question is this. If this is as simple as a partially plugged fuel filter or injector, would the system still throw a 442 code?


If not, then the list of questions gets a lot more complicated. Any suggestions for known problem points or shop tests is greatly appreciated.


Thanks

 

You've been busy on this one & have done some good diagnostics. If you don't already have it, TSB 03-20-3 here 03-20-3 Ford Technical Service Bulletin (tsbsearch.com) has a suspect list for DTC P0442 & test methods to prove them out.
Since you seem to like turning your own wrenches maybe consider using, borrowing, or coming by the inexpensive ELM scan tool & running FORScan diagnostic freeware on the viewing device of choice as discussed here, Low Cost ELM Scantool - Ford Truck Enthusiasts Forums (ford-trucks.com), as this powerful combo is tweaked for Fords & can query All of the vehicle computer controllers for trouble code clues & put up live data PID feeds for monitoring on our viewing device choice, that can help focus a trouble shoot. Post up any additional trouble code Numbers.

Did the rough idle come about at the same time as the P0442 code & did either come about slowly over time, or suddenly after some event, like a off road excursion, or the like???
Did you opt for lowest cost store brand, OEM, or high end after market ignition parts???

Some beginning thoughts for consideration, let us know what you find..

 

Thanks PawPaw

Yes, As I approach my 65th birthday I can't believe I've been turning wrenches for over 40 years. Sheesh I'm getting old.

Attached is the same engine 1 year ago before re-install. John Deere Green goes back to other stories.

I will follow through with your suggestions and feedback all the wonderful discoveries. *>

Ron

 

I forgot to more directly address your question about the likely association between the P0442 code & the rough idle anomaly. The 442 code is for the emissions vapor recovery system, which is used to enable quicker cold starts by sucking gasoline Vapors from the charcoal cannister, which gets & stores them from the fuel tank as we drive & use fuel. These Fumes are a dandy fuel to have for a cold start as they're Easier to ignite when its cold & fuel is more difficult for the injectors to vaporize on a cold start. These vapor recovery fumes also help with faster warm-up because they promote more efficient cold engine combustion. This system is only used on cold starts & the code is for the evap system only, & this system isn't on line all the time, so isn't likely the cause of the rough idle. Depending on where in the plumbing the vacuum leak is, it could be a player in the rough idle though.

The IAC is responsible for idle speed, is a common problem part, so belongs on your suspect list. You can test it by disconnecting its electrical connector with the engine at warm idle. The rpm should Drop, engine may run rough or stall, if its working. If No rpm drop, its likely faulty, intermittent, mucked up internally. or may have electrical feed/pin/socket/or wire feed, or a contact corrosion problem, so give it a visual look-see & wiggle / thump test too.

Edit: Holding the electrical connector / solenoid end UP, so solvents & removed crud wont run into the solenoid end windings & corrupt insulation, or muck up the solenoid shaft & Cleaning the IAC internally with a plastic safe spray, may not last, it didn't for me & is probably why Ford recommends replacement when they act out. Cleaning with plastic safe CRC MAF spray cleaner, was a good trouble shooting step for me, as I knew what the problem was when it acted out again about 6mos later ( all this was about 10 years ago). Folks on this forum suggested BWD as a good brand replacement consideration, so I went that way with a Advance Auto 40% off coupon I found on line here Auto Coupons: Promo Codes for Discounts on Auto Parts, Rentals and Accessories on RetailMeNot (probably wont find that much off now days maybe 20-30% if lucky), so it didn't take as much of my gold & so far its doing fine. More thoughts for consideration.

 

Thanks PawPaw. I always appreciate clear technical direction. But now that I have replaced a few parts I'm more confused than before.

With the test results I decided to replace the IAC but the MAF also tested flaky so I added it to the list. The gas cap looked to be original and considering it was only $10, in the grand scheme of things I went ahead and added it as well.

So now I have no DTC's. In fact the dash is completely clear including the odometer. I have no idea what I might have done would cause that?

Also, the heavy vibration does seem to have softened some but is still present.This just seems like more of a rotating mass kind of vibration. I can feel it in the steering wheel, the seat of my pants, the pedals. The engine seems to start and run fine. I took it out for a short drive after all the parts were installed. Covered maybe 15 miles at most. The engine doesn't idle down like it used to so I'm now wondering about the TPS for that, - but with no DTC's I'm not rushing out to buy any more parts.

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Ok lets think about this some more. You didn't say but from the trouble codes no longer there, did you erase them with a scan tool, that wont wipe the old KAM fuel trim tables, or a battery Disconnect while replacing parts, which will erase the old fuel trim tables & trouble codes???

Parts you've replaced will affect fuel trim, so if all were faulty, so were the old fuel trim tables & those needed to be erased with a battery Disconnect, so the ECM can begin to build new ones with all the new parts in place. BUT a battery disconnect Also erases the ECM cold & warm idle strategy, thats also in KAM = Keep Alive Memory, so if not relearned before the test drive, it could corrupt idle speed in the short term, until it relearns a new strategy after numerous completed drive cycles. SO, we can have it more quickly learn a new cold & warm idle strategy, by taking a few minutes using this method, Ford Truck Enthusiasts Forums - View Single Post - high idle problem (ford-trucks.com), that works for me after a battery disconnect, so maybe it'll help some with the higher idle speed.

On the rough, seemingly rotational vibration, is it better or gone with the engine under load??? if so, check auto tranny fluid level & condition & since the engine has been replaced, engine mounts & fasteners, tranny to engine fasteners, torque converter to engine for play, are some thoughts that come to mind. If all that checks out, use a scan tool that can perform a power balance test by sequentially turning off a fuel injector, measuring rpm drop & flagging any that are suspect, for additional testing like compression, or blow down tests. Saves time doing all, as good cylinders don't get flagged.

More thoughts for consideration, let us know what you find.