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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 35523
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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I have a 2002 ford taurus just replaced engine with salvage

Customer Question

i have a 2002 ford taurus just replaced engine with salvage motor i used all my old components ac power steering etc i made sure i put new plugs oil used my coil and wires which are good experiencing backfire the thing i cac think of is when i switched intake plenum used old gaskets could this be the cause of the backfiring
Submitted: 1 year ago.
Category: Ford
Expert:  Ron replied 1 year ago.

Hello and thank you for your question,

Are you able to scan the computer system and see if there are any fault codes setting?

Have you verified your firing order is correct?

Customer: replied 1 year ago.
it is showing no service engine soon and yes firing order is correct
Expert:  Ron replied 1 year ago.

If you sure the firing order is correct and there are no fault codes then It could be possible the intake is leaking but it would have to be a pretty healthy leak. Dose the engine seem to be firing on all 6 cylinders?

Customer: replied 1 year ago.
as i accelerate with the car in park it seems to run better
Expert:  Ron replied 1 year ago.

Okay when it backfires is it backfiring out of the intake?

Customer: replied 1 year ago.
intake and the exhaust i am pretty sure
Expert:  Ron replied 1 year ago.

The one thing that comes to mind if its backfiring out the intake providing you are sure the firing order is correct could be a valve seating concern. Before you consider replacing the intake gasket I would consider performing a running compression test on all 6 cylinder to see if there are with in the same reading. This would tell you if there is a valve seating concern and should be checked first.

Customer: replied 1 year ago.
is it possible to have stuck valve since it is salvage motor and it could have been sitting for a while if so would running it more help unstick the valve
Expert:  Ron replied 1 year ago.

It is very possible and the running compression test would verify if that is the case. The running compression reading is usually about half of the cranking compression reading and should be pretty close to the same on each cylinder. Any cylinder with a valve concern will show lower readings.

Customer: replied 1 year ago.
well thank you for your input just running out of money and was hoping for an easy fix like intake plenum gasket
Expert:  Ron replied 1 year ago.

It would have to be a very large leak and you would normally get the computer to set some lean codes due to the leak. I would start with running the compression test. In most cases a backfire can only be caused by either ignition timing (spark) or by a valve train concern.