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engine misses whem under load
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mdshumaker
New User
Feb 6, 2008, 6:40 AM
Post #1 of 8
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engine misses whem under load
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Hey all,
I've got a 2001, Ford Windstar LX. 3.8L V6, 146K miles. Two week ago the engine started missing. It most noticible at low speeds in OD, 1200-1500 rpm and especially on a hill or under light acceleration. It does miss at other times, namely when accelerating, but it not quite as pronouced.
I checked the fuel pressure at idle, it's 32 psi. I ran some drygas though it to rule out water in the tank. I've run one can of Berrymans B-12 through it and the current tank has a tube of Lucas injector cleaner in it. I replaced the plugs with Motorcraft Double Platinums and also replaced the wires with Motorcraft OEM parts. On advice of another forum, I disconnected the vacuum line to the EGR valve and ran it that way, but it made no difference, so
I don't think its ERG related.
I don't think it's ignition, but I can't rule it out yet. My own opinion is it's fuel system related, but I haven't been able to pin it down.
So, what do you think?? I'm open to ideas.
Marc
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dave284
Enthusiast
Feb 6, 2008, 10:31 AM
Post #2 of 8
(13808 views)
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Re: engine misses whem under load
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I'm thinking the check engine light haven't came on right? What about the coilpack? a weak spark maybe. Most time bad gas would cause a misfire the pcm would detect that and stored as a trouble code. Have you checked to see if any might be stored.?
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mdshumaker
New User
Feb 6, 2008, 5:53 PM
Post #3 of 8
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Re: engine misses whem under load
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I decided to look into fuel pressure as a possible cause. I've been told the Ford computer does not look at fuel pressure. I made a hose to extend my 16 inch fuel pressure gauge to 12 feet. My wife drove the car around while I monitored the pressure. I think it's working correctly and is probably in spec. Am I right?
Idling and just turned on - about 32 psi.
Normal highway speeds - 34-36 psi.
Stopping and going downhill - 29 psi.
Normal acceleration - 38 psi.
Hard acceleration - 40 psi.
The range is 29-40 psi and seem to adust to demand just as I would expect it to.
The missing is getting worse. It's very noticable on hard accelerations now, just when my fuel pressure is highest. In fact, even the missing when the engine is low rpm, but high load, the pressure is at it's highest levels. I think I can rule out the fuel pump and delivery system, but I'm not certain about the injectors. I have another can of Berryman's in the current full tank.
What about ingnition. How do you test the strength of the spark? What about timing? Does the computer adjust timing according to engine loading/RPM??
I don't have any equipment to test things like this. Looks like I may try the Ford dealer, since they should have the latest in diagnostic equipment.
Marc
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way2old
Veteran
/ Moderator
Feb 6, 2008, 6:25 PM
Post #4 of 8
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Re: engine misses whem under load
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See if you can find a scanner that will read rhe engine misfire monitor. This will tell you which cylinders are missing. If you know anyone that has a scan tool that can access the mode $06, it will also tell you which cylinders are missing by percentage. Your fuel pressures are just about what they should be. Good luck.
PRESSURE
Key ON Engine Running (KOER) 28-45 psi (210-310 kPa) Key ON Engine OFF (KOEO) 35-45 psi (240-310 kPa)
Being way2old is why I need help from younger minds
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mdshumaker
New User
Feb 6, 2008, 6:51 PM
Post #5 of 8
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Re: engine misses whem under load
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BTW, the car is not setting any codes to date. I've had it read and Advance and also at a shop.
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way2old
Veteran
/ Moderator
Feb 6, 2008, 7:15 PM
Post #6 of 8
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Re: engine misses whem under load
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On a long shot, have the Intake Manifold Runner Control checked to be sure it is not hanging occasionaly. As I said, it is long shot, but it controls the airflow to engine. Airflow disturbed, could cause engine miss. The code will not set unless the IMRC is hung completely open or closed.
Being way2old is why I need help from younger minds
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 7, 2008, 1:39 AM
Post #7 of 8
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Re: engine misses whem under load
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How about this being loose? Seems like plastic orig cam gear - the type that doesn't care too much for heat and I think this Windstar gets a bit toasty underhood vs some other layouts. 146K if orig worries me with these,
T
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mdshumaker
New User
Feb 8, 2008, 6:04 PM
Post #8 of 8
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Re: engine misses whem under load
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It turned out to be the ignition coil. A bit more of a job that I wanted to take on. I found a good mechanic.
Thanks for the help.
Marc
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