New 03 GT, Engine and Electrical Questions

[Rebel03]

Hey guys, I recently bought my first mustang, an 03 auto gt with 85000 miles on it and so far LOVE it. However I have a few questions that I hope you guys can answer since this is my first stang. When I get up to around 70 mph the car vibrates(only at that speed), you can actually see this while looking at the hood. I know for a fact that the rotors do need to be replaced because I can feel the pedal pulse when braking(I usually only feel this when driving down steep grade like the mountain I live on) I had the fronts turned which seemed to help a little bit but the front end still shakes at that speed. I know this could be the drive shaft being out of balance, tires being out of balance, or the rotors being warped. Generally speaking what causes shaking like that only at a certain speed? If when I'm in park and idling I push on the gas and hold the engine right at 2000 the engine seems to vibrate like the shaft or something is out of balance but just a needle width under or over 2000 it goes away. If it were the shaft I would assume it would do it at higher rpms as well, not just RIGHT at 2000. Do you think the two are related and its the shaft? When driving at 60mph and the rpms around 2000, I cant really feel any vibration like I can when standing still.The only other engine issue I've noticed is an occasional gurgle/slurp sound from the air intake filter after revving and the rpms are dropping. Is that normal? The snorkel is removed and I have a K&N filter on it. Other than those issues the engine sounds incredible(not a single ping or tick) and runs like its new(even looks nice and clean)

Now onto electrical. Most of the time when I start the engine it starts immediately. Occasionally (this has happened on cold and warm start) it takes it about 2-3 seconds to actually start. Sound like a bad starter maybe? The other electrical problem I have is that on occasion(rarely) my driver window switch will stop working, normally when this happens it's after I've rolled the window down, driven for a while and then parked the car and wanted to roll it back up. When I hit the switch it sounds like a relay clicking under the dash. Do the power windows have relays(only see fuses in the book)?

 

[trinity_gt]

Hey guys, I recently bought my first mustang, an 03 auto gt with 85000 miles on it and so far LOVE it. However I have a few questions that I hope you guys can answer since this is my first stang. When I get up to around 70 mph the car vibrates(only at that speed), you can actually see this while looking at the hood. I know for a fact that the rotors do need to be replaced because I can feel the pedal pulse when braking(I usually only feel this when driving down steep grade like the mountain I live on) I had the fronts turned which seemed to help a little bit but the front end still shakes at that speed. I know this could be the drive shaft being out of balance, tires being out of balance, or the rotors being warped. Generally speaking what causes shaking like that only at a certain speed?

In general, warped rotors don't cause this sort of vibration. What you feel occurring at certain speeds is due to the effects of resonance and is almost certainly a tire either being out of balance or having a defect such as a shifted belt.

If when I'm in park and idling I push on the gas and hold the engine right at 2000 the engine seems to vibrate like the shaft or something is out of balance but just a needle width under or over 2000 it goes away. If it were the shaft I would assume it would do it at higher rpms as well, not just RIGHT at 2000. Do you think the two are related and its the shaft? When driving at 60mph and the rpms around 2000, I cant really feel any vibration like I can when standing still.

We readers are too isolated to judge whether or not the vibration you feel at 2K RPM is related to the vehicle vibration at speed. We can't judge the severity of the vibration: At 2K RPM, do you feel a little wiggle in the seat back or is the hood shaking? The former might be considered "normal" whereas the latter is something wrong.

The only other engine issue I've noticed is an occasional gurgle/slurp sound from the air intake filter after revving and the rpms are dropping. Is that normal? The snorkel is removed and I have a K&N filter on it. Other than those issues the engine sounds incredible(not a single ping or tick) and runs like its new(even looks nice and clean)

The factory put a silencer there for a reason. Enthusiasts like noises like that whereas the other constituency that buys the car -- suburban soccer moms -- don't. I'm going to wager anything you're hearing in the intake with the silencer removed is normal.

Now onto electrical. Most of the time when I start the engine it starts immediately. Occasionally (this has happened on cold and warm start) it takes it about 2-3 seconds to actually start. Sound like a bad starter maybe?

Not enough information. If the starter motor is rotating the engine "normally" but it's not firing right away then the starter motor sounds faultless; it is there to turn the engine and if the engine is turning normally, it's working fine. If the engine is just cranking and cranking and eventually coming to life you may have a minor issue with fuel pressure dropping after the engine has shut down. It takes a second or two for pressure to build while first cranking.

Put a fuel pressure gauge on the passenger-side fuel rail and see what the pressure does when the engine is turned off.

Having said all that, mine does this too occasionally. I don't think it's particularly rare for SOHC Mustangs to require a bit of an extended crank now and again to start. Not saying it's normal or right, just not rare.

The other electrical problem I have is that on occasion(rarely) my driver window switch will stop working, normally when this happens it's after I've rolled the window down, driven for a while and then parked the car and wanted to roll it back up. When I hit the switch it sounds like a relay clicking under the dash. Do the power windows have relays(only see fuses in the book)?

Can't offer much advice here except to suggest that clicking under the dash is most likely a relay and that you pull the door panel and check for power at the motor connector with the switch depressed.

What happens that allows you to wind it back up? If it's the passage of time it may be that a thermal protector/breaker in the system has tripped because, for example, the motor is still energized when the window is in the full down position, causing excess current draw and circuit heating.

 

[wmburns]

For the long crank issue, try key cycling on/pause/off without cranking a couple of times before cranking. Does this improve starting?

If so, suspect fuel pressure leak down.