I just bought a 99 mustang GT about a month ago. It has 90k miles on it. When I bought it everything was stock and it came with a K&N cold air that already had a MAF and IAT installed it in. So I added this but nothing else.
I have been doing alot of maintenance on the car lately because I noticed a slight misfire or stumble in the midrange when accelerating. I also noticed it almost sounds like the motor knocks a bit during mild acceleration. At first I thought it was just the catback (flowmaster) on the car but it definatly sounds like the motor.
I just replaced the spark plugs (NGK T55 Copper) which made it idle better (factory plug were toast btw) I also found 1 bad injector cap and replaced it. I replaced the spark plugs because on previous vehicles the midrange stumble/miss was a sign of bad plugs but the problem is still there.
Last week I drove the car on a 700 mile trip and 1 time after decelerating downhill I pushed in the clutch and it died which I found very strange. SOOO all symptoms I have seen in the past week.
Car died once after decelerating downhill off the throttle but in gear - after I pushed the clutch in to downshift and turn it had died.
- has a weird stumble/miss in the midrange - sorta like it just falls on its face for a split second while accelerating
- I hear some sort of knock that I think comes from the motor but it is not noticable unless at about 2500-3500 RPM and under mild throttle. I dont think I hear or feel it when I am WOT. There is NO noise when reving while not under a load.
The car still pulls extremely well when WOT but I want to get this squared away. I am going to clean the stock MAF and IAT and swap the factory air intake back on to see how this affects the condition.
Any other ideas what else it could be?
Thanks guys
I have been doing alot of maintenance on the car lately because I noticed a slight misfire or stumble in the midrange when accelerating. I also noticed it almost sounds like the motor knocks a bit during mild acceleration. At first I thought it was just the catback (flowmaster) on the car but it definatly sounds like the motor.
I just replaced the spark plugs (NGK T55 Copper) which made it idle better (factory plug were toast btw) I also found 1 bad injector cap and replaced it. I replaced the spark plugs because on previous vehicles the midrange stumble/miss was a sign of bad plugs but the problem is still there.
Last week I drove the car on a 700 mile trip and 1 time after decelerating downhill I pushed in the clutch and it died which I found very strange. SOOO all symptoms I have seen in the past week.
Car died once after decelerating downhill off the throttle but in gear - after I pushed the clutch in to downshift and turn it had died.
- has a weird stumble/miss in the midrange - sorta like it just falls on its face for a split second while accelerating
- I hear some sort of knock that I think comes from the motor but it is not noticable unless at about 2500-3500 RPM and under mild throttle. I dont think I hear or feel it when I am WOT. There is NO noise when reving while not under a load.
The car still pulls extremely well when WOT but I want to get this squared away. I am going to clean the stock MAF and IAT and swap the factory air intake back on to see how this affects the condition.
Any other ideas what else it could be?
Thanks guys
