the car was hardstarting so i replaced the camshaft positioning sensor... on 1990 Ford Thunderbird SC

now the car bucks and surges but it starts fine now

by in Oneonta, AL on December 02, 2011
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2 answers 1 comment
ANSWER by , December 03, 2011
Your check engine light must be on. What are the trouble codes?
COMMENT by , December 03, 2011
there is no trouble codes check engine light is not on...it ran great before i changed the cps but it was hardstarting...i changed all the plugs,wires and coil...no vacuum leaks were detected...all the old plugs were evenly worn no oil on them..compression was good on all 6 cylinders...i unplugged the cps and now it runs good again but is hardstarting again...and i do run premium gas in it...is it possible i bought a defunct cps
ANSWER by , December 02, 2011
Start with the basics, spark plugs good, no vacuum leaks,perhaps check compression is even in all cylinders, look at the old spark plugs see that they are all the same color, none are mechanically damaged or oil fouled.