2001 Mercury Marquis weirdest thing happen to me

HArd to say what happened. The source needs to be identified before making judgements.

You have it flushed..a miss turns up at 40 mph...may or may not be related depending on what actions were taken, intentional or accidental. there should be no relationship.

The plugs are changed...miss moves to 55 mph....same problem as before, or was a new problem created? Such as a wire not seated, bad plug gap etc.

Need to go back and take someone for a ride, point it out and ask why. A reputable garage will take care of it if on their end. Need to find out why first.

My 2001 Grand MArquis did the same thing. I found that one of the spark plug coils started breaking down due to getting wet. I frequently have a slight miss whenever the engine is cold and maybe has moisture in the air. Hope this helps!

I a Purchased a new COIL ON plug (COP) and by the process of elimation by removing each COP and replacing old one with the new one then going out for test drive I found the bad cop.

However, this does not explain way after my antifreeze was replaced I had such noticeable miss. Then they replaced spark plugs it to minor mis to a bad cop # 8 away from the thermostat and heater hoes.

The only I a can figure had something to dowith the coolant sensor being cleaned during flush and it was more sensitive to sending messages back to the CPU saying change your spark plugs and # 8 cop is really bad know, I the CPU can not compensate these bad plugs and cop # 8, since you cleaned antifreeze in the block.

Anyone have comment on :mrgreen: my star track theory

purely coincidence my friend. these cops fail all the time. did you notice coolant at the end of the coil? ive had #4 coil failing because of a light drip from the heater core hose leaking into that cylinder. cyl #4 is the rear cyl on the passenger side.

I'm wondering if the coil had got wet during the flush?

The coolant snesor essentially tells the temperature of the coolant only.

What is the life span of COP is by years or miles ?

How long do COP last .

:?:

Some go the life of the car...Not letting the plugs badly worn help prevent failures due to ecessive power needed to fire a worn plug.

i usually see them go bad around 100,000. some as low as 30,000. some dont go bad.

So much for the 100,000 mile tune up interval.

Santa clause, Easter bunny, tooth fairy.....lol

Ok i want to drive my car 200,000. problem free. Should i change out the spark plugs every 60,000 miles and cop at same time. or change out the cop at 100,000.miles. back in the olden days 1987 if wanted to run tip top you replaced wires , rotor cap and plugs ever 24K for top performace. In the case of the newer cars with 100,000 miles tune ups no wires rotor and cap. just cop and plugs what do you recommend or seasoned tech would recommend for tip top performaring moderen car for cop plugs

HEH,HEH...IF your talkin going another 130,000 problem free, were venturing back into the make believe...lol.

If it were mine....

I wouldn't do anything with the cop unless there was a problem. Plugs about 60,000-80000 dependng on wear...The long life plugs are much better than there were...but I have seen them lose performance early sometime.

Fuel filter and transmission filter every 30,000.

Differential at 50,000.

Coolant flush every 3 years.

I don't think that has a cabin air filter, if it does every 30,000.

PCV when its a litle gummy

Tire rotation every other oil change

Oil every 3000

Power steering fluid and brake fluid when it discolors.

Plan on budgeting about 10-15 cents for repairs and maintenance and you'll probably be okay.