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Premium Member
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Discussion Starter #1 (Edited)
OK, was running great when all of a sudden running crappy, white smoke smelling like fuel from the exhaust. Figured no big deal, I've got a hung injector so I replaced them all. No dice. Thought maybe the pressure regulator was ruptured, replaced it, still no joy. Damn. I guess I need a PCM. Put in a reman. Guess what? Sounded great on first start up them, same same. Last code I remember from the original PCM was left bank rich, new one hasn't run long enough to set a code. I don't want to run it too long that rich as I figure it will trash the cats. Any ideas???
 

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Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
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10,036 Posts
Unplug the MAF sensor and see what it does.

You an also try disconnecting injectors (one at a time) to see if it is a single cylinder causing issues.
 

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The Parts Guy
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7,578 Posts
Another test: check injector pulse on each injector to see if any are being commanded on constant. A noid light, or even just a test light will illustrate.
 

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Discussion Starter #4
Really too nasty out to mess with it right now but I had a thought. What would happen if the TPS stripped and was stuck at full throttle? This happened right after I really had my foot in it. Would that create extreme over fueling?
 

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Registered
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In my experience, white smoke is too lean. Or is it just vapor in the cold weather?

Rather than just throw parts at it, pull the spark plugs. That will tell you if a cylinder is too rich or too lean. While you're at it, replace the spark plugs. I can't count how many times a fresh set of spark plugs fixed a mysterious problem over the years on various cars. And they are relatively cheap.

Al
 

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Super Moderator
1997 Thunderbird 4.6, 1998 Mark VIII LSC
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10,036 Posts
Really too nasty out to mess with it right now but I had a thought. What would happen if the TPS stripped and was stuck at full throttle? This happened right after I really had my foot in it. Would that create extreme over fueling?
Doubtful unless you're also experiencing a lack of shifting until you get close to the rev limiter. It's fairly easy to test with a multimeter - see the tech article in the engine section. At WOT (based on TPS feedback) the main differences in driving behavior the PCM implements are that it goes open loop and relies on MAF sensor feedback exclusively without using O2 sensor data, adjusts spark delivery and transmission behavior and locks out the A/C compressor clutch.
 
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