Ford Crown Victoria misses, hesisitates, stumbles, AFTER warmup (1989, 302)

Jan 14, 2004 3 Replies
L

Hi!



My Crown Vic runs rough and misses on light acceleration, especially at slow speeds AFTER warmup. I do not have a temp guage, but I can tell it starts exactly the same time in daily commute to work, for example.



Car has 152k miles, 302, SEFI. Relatively new spark plugs and wires (8 months or so, maybe more)



Symptoms:



AFTER WARMUP misses on light accel from stop, but goes great if you stomp on it idles rough for a bit after warm restart feels like timing is being "thrown around" miss can be felt at cruise speeds, but acceleration is still good even runs without missing warm, sometimes, or for a while, like it's "in the groove"



#5 cylinder fouls, but compression tests good 165/185 dry/wet



runs very smooth cold (minnesota cold) starts right away cold


Diagnostics:



No codes, but I recently replaced the EVP sensor which was bad (codes) in hopes of alleviating these symptoms.



Cannot hear or find any vacuum leaks.



Checked wire routing carefully for the old 7/8 crossover problem.



Actions:



I have an identical engine in a 1989 Colony Park Wagon that runs PERFECTLY (smoothest 302 I ever had)



swapped entire distributor and tfi module assembly swapped primary coil swapped egr valve swapped throttle position sensor



replaced #5 plug twice replaced #5 spark plug wire



installed new oxy sensors


Next on the list:



MAP Sensor? MAF Sensors? Temp Sending Unit? Knock Sensor? Injector? If injector bad, I would expect constant miss, not after warmup.



Any and all help appreciated!!



Thanks,



Mark


Crown Vic Victoria engine misses missing hesitates hesitation idles rough idling


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J

I had an '89 Crown Vic that drove me crazy with a miss, until I changed a 'radio interference capacitor' at one of the coils. I think it was faulty, and allowed noise to get into the module, throwing the timing way off. Clip another across, and see if that makes a difference.

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L

You know, my dad told me once that the very same thing happened to him years and years ago. Maybe you're right!

Could you hear that bleed off on your AM radio?

I wonder if I could do the test by simply removing that condensor completely?

OTOH,

Now that the EGR valve has been in my other car a couple days, that car is misbehaving, so I think that is part of the problem. Maybe I need to recheck plugs again after having installed the ego sensors and swapping the egr valve. COuld have fouled up again before I made the swap. Hmmmmm.

Thanks,

Mark

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J

No, not that I remember, but I normally only listen to FM. My wife had a '90 Topaz, and I went through changing MAPs, etc. between the two, and hit on this somehow. If you don't have a spare from an old tuneup kit, why not just clean up the connections to it (crack the coil bolts and retighten too so that you revive the ground side). If this changes your problem at all, then you are close to the source...

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