My 89 XJ6 starts up fine and after about 12/15 miles driving the engine drops down to about 1000/1200 rpm and will not move up. Engine starts to run rough and sounds like it may be backfiring. I can drive it home and after it completely cools down it will start up again for another cycle. Changed fuel filter, pump and plugs to no avail. How many sensors control the engine rpms? Can anyone help?

Submitted by asemastermecha… on Thu, 12/04/2003 - 23:11

Hello Don Horton
I need more data:
How many miles on the car?
Is it a daily driver or a show car that is in storage much of the year?
Is the fuel tank full, don't trust the gauge?
Did this start after filling the fuel tank?
Can you get fuel pressure reading while it is malfunctioning?
When was the fuel filter last changed?
Have you ever had fuel system work done on the car?
What and when was the last garage service done?
Have you replaced all the relays under the bonnet?
Have a great day.

whunter
ASE Master Mechanic
Bloomfield Eurotech
45671 Woodward Avenue
Pontiac, MI 48341
Work Phone 248-334-6400 Fax 248-334-2363
asemastermechanicatjuno.com

Submitted by asemastermecha… on Thu, 12/04/2003 - 23:00

Hello Don Horton
I need more data:
How many miles on the car?
Is it a daily driver or a show car that is in storage much of the year?
Is the fuel tank full, don't trust the gauge?
Did this start after filling the fuel tank?
Can you get fuel pressure reading while it is malfunctioning?
When was the fuel filter last changed?
Have you ever had fuel system work done on the car?
What and when was the last garage service done?
Have a great day.

whunter
ASE Master Mechanic
Bloomfield Eurotech
45671 Woodward Avenue
Pontiac, MI 48341
Work Phone 248-334-6400 Fax 248-334-2363
asemastermechanicatjuno.com