'99 Mustang Running Very Rough With Little Horsepower

thefastdraw · October 4th, 2006, 09:11 PM

Not sure where to start. I have a '99 mustang, V6 with 120,000 miles. When I crank the car it cranks fine, but now ides rough, and bogs down when accelarated. It cuts out pretty badly while driving. I have changed ou the fuel filter, spark plugs an wires. Not sure which direction to go. Would appreciate any help.

chrish91286 · October 4th, 2006, 09:58 PM

try cleaning your IAC valve, check for vacuum leaks, it could also be the coil pack.

mdvaldosta · October 4th, 2006, 10:39 PM

IAC valve doesn't affect anything when driving, only idling. If the car stumbles on acceleration it's usually ignition related. I'd check to make sure you don't have any dead cylinders, and if you do check for fuel and fire there. It may lead back to a bad coil as was suggested.

AtlanticBlue99 · October 4th, 2006, 10:44 PM

also check for seals on the intake manifolds. i had a similar problem after changing fuel filter, air filter, spark plugs/wires and even coil pack, and i had a leak at the back of my upper intake manifold- new gasket, perfection. check for vacuum leaks if you have good cyl. and use brake cleaner and spray around the manifolds, if the idle surges, you found the leak.

thefastdraw · October 5th, 2006, 03:39 PM

Originally Posted by mdvaldosta

IAC valve doesn't affect anything when driving, only idling. If the car stumbles on acceleration it's usually ignition related. I'd check to make sure you don't have any dead cylinders, and if you do check for fuel and fire there. It may lead back to a bad coil as was suggested.

I had a scan done and it showed that #3 cylinder is dead, aslo it showed the #2 oxygen sensor was bad and the EGR flow was bad. What should i look for on the bad EGR flow?

AtlanticBlue99 · October 5th, 2006, 04:32 PM

this is bad. you have no power in the 3rd cylinder.

you have a bad oxygen sensor which tests the air/fuel ratio and is making your car run weak as well, probably very rich. egr flow goes from the passenger exhaust manifold and recirculates into a pump and into the intake manifold

Roadhawg · October 5th, 2006, 05:02 PM

Originally Posted by thefastdraw

I have changed ou the fuel filter, spark plugs an wires. Not sure which direction to go. Would appreciate any help.

The condition of the sparkplugs is one of the best overall indicators on what is happening with your engine. Whenever I remove the sparkplugs I note which cylinder they came from and thier appearance.

October 4th, 2006, 09:11 PM	#1
thefastdraw Newbie Join Date: Oct 2006 Posts: 2	'99 Mustang Running Very Rough With Little Horsepower Not sure where to start. I have a '99 mustang, V6 with 120,000 miles. When I crank the car it cranks fine, but now ides rough, and bogs down when accelarated. It cuts out pretty badly while driving. I have changed ou the fuel filter, spark plugs an wires. Not sure which direction to go. Would appreciate any help.

October 4th, 2006, 10:44 PM	#4
AtlanticBlue99 Modded Autos Site Mod 1999 Ford Mustang V6 14.79 @ 92.15 Join Date: Aug 2005 Location: Evans, GA/Athens, GA Posts: 7,249	also check for seals on the intake manifolds. i had a similar problem after changing fuel filter, air filter, spark plugs/wires and even coil pack, and i had a leak at the back of my upper intake manifold- new gasket, perfection. check for vacuum leaks if you have good cyl. and use brake cleaner and spray around the manifolds, if the idle surges, you found the leak. __________________ ModdedAutos 1999 Mustang V6 I used to list my mods here but stopped when I exceeded 255 characters.

October 5th, 2006, 04:32 PM	#6
AtlanticBlue99 Modded Autos Site Mod 1999 Ford Mustang V6 14.79 @ 92.15 Join Date: Aug 2005 Location: Evans, GA/Athens, GA Posts: 7,249	this is bad. you have no power in the 3rd cylinder. you have a bad oxygen sensor which tests the air/fuel ratio and is making your car run weak as well, probably very rich. egr flow goes from the passenger exhaust manifold and recirculates into a pump and into the intake manifold __________________ ModdedAutos 1999 Mustang V6 I used to list my mods here but stopped when I exceeded 255 characters.

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October 4th, 2006, 09:58 PM	#2
chrish91286 Regular 2003 Mustang GT Join Date: Oct 2006 Location: chesterfield, VA Posts: 248	try cleaning your IAC valve, check for vacuum leaks, it could also be the coil pack. __________________ 70mm t/b, plenum, cast intake manifold, full magnaflow exhaust, JLT cai, FRPP c springs, anti roll kit, steeda upper control arms, custom tune, subframe connectors, HID headlights, mach 1 chin spoiler

October 4th, 2006, 10:39 PM	#3
mdvaldosta Maintenance Man 2002 Mustang GT 11.47@120.58 Join Date: Aug 2005 Location: Valdosta, GA Posts: 3,945	IAC valve doesn't affect anything when driving, only idling. If the car stumbles on acceleration it's usually ignition related. I'd check to make sure you don't have any dead cylinders, and if you do check for fuel and fire there. It may lead back to a bad coil as was suggested.

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'99 Mustang Running Very Rough With Little Horsepower

'99 Mustang Running Very Rough With Little Horsepower

Re: '99 Mustang Running Very Rough With Little Horsepower