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Richard, ASE Certified Technician
Category: Car
Satisfied Customers: 15545
Experience:  12 years Ford Lincoln/Mercury Jaguar dealership as a technician and shop foreman reparing all makes
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Heated..limp mode n is misfiring on 2 cylinders/their puzzled n

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my 2005 LR3 went into limp mode,over heated by the time i was able to safely pull over(thermostat housing cracked,got hot n damaged engine).dealer installed remanufactured longblock.worked ok for 40 miles,then went back into limp mode n is misfiring on 2 cylinders/their puzzled n are trying to figure this out,can u help me?

Hello and welcome to


The dealer should first do a compression test on the engine and if it is not correct then a leak down test should be performed. This would not be the first time I have seen an issue with a reman engine. If compression and leak down is good then the missfiring could be due to faulty coils or possibly a vacuum leak.

Customer: replied 7 years ago.
this went into limp mode before the engine overheated(damage to the engine was secondary due to something else malfunctioning) .A new coil was already tried.
Ok I see know. The dealer should have installed new intake gaskets and seals when they were reassembling the engine so we should be able to rule out any vacuum leaks. The other possibility is clogged cat converters which can be the result of the missfire. What should be done is have the dealer document and clear the codes. Then they should disconnect the negative battery terminal cable to reset any engine adaptations. Then they should monitor the fuel trims which is what the ECM uses for fuel control. If they are high then this can be caused by low fuel pressure or volume or possibly unmetered air from a vacuum leak. They should also monitor the oxygen sensors and cat monitor sensors to see what they are reading. Of course a compression test should also be performed. Ask the dealer if they have done any of these and let me know.
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