Mustang GT is giving me problems!
10-10-2010, 11:05 PM
#1
Thread Starter
Join Date: Jul 2010
Location: Texas
Posts: 6
Mustang GT is giving me problems!
I have a 1999 Mustang GT 5 speed with a pretty much bone stock 4.6L.
I started having issues with it feeling almost as if it were driving through water once it warmed up. I started running open headers, and this cleared up the issue. The problem was the cats had melted. I just put a new exhaust on there and there is an exhaust leak from the passenger side flange gasket, but I don't think this would be the issue.. just keeping my options open.
Recently, when idling, the car has started ALMOST stalling, but then recovering RPM at idle and it will smooth out for a second and repeat. If I give it gas in neutral it hangs and sputters for a fraction of a second (hard to notice, but I know my car), and then once I let the RPM fall, it ALMOST stalls again (around 200RPM) violently vibrates for a moment and smooths out to its normal 500RPM. The car also feels cut of power by quite a bit when this started as well as the car is very jumpy when I l let off the gas while driving. Say for example I would accelerate and shift to second and then need to coast so I let off the gas, it jerks back and forth versus slowly coasting. What could be causing this?
I started having issues with it feeling almost as if it were driving through water once it warmed up. I started running open headers, and this cleared up the issue. The problem was the cats had melted. I just put a new exhaust on there and there is an exhaust leak from the passenger side flange gasket, but I don't think this would be the issue.. just keeping my options open.
Recently, when idling, the car has started ALMOST stalling, but then recovering RPM at idle and it will smooth out for a second and repeat. If I give it gas in neutral it hangs and sputters for a fraction of a second (hard to notice, but I know my car), and then once I let the RPM fall, it ALMOST stalls again (around 200RPM) violently vibrates for a moment and smooths out to its normal 500RPM. The car also feels cut of power by quite a bit when this started as well as the car is very jumpy when I l let off the gas while driving. Say for example I would accelerate and shift to second and then need to coast so I let off the gas, it jerks back and forth versus slowly coasting. What could be causing this?
10-11-2010, 01:55 AM
#5
Thread Starter
Join Date: Jul 2010
Location: Texas
Posts: 6
See I ran a diagnostics on my car a minute ago because the check engine just came on and it said something about mass air malfunction. It's got the factory pipe from the throttle body to the air filter which is just a simple K&N intake. What do I need to do to take care of this?
10-11-2010, 11:00 PM
#8
5th Gear Member
Join Date: Nov 2007
Location: Maryland
Posts: 4,955
See I ran a diagnostics on my car a minute ago because the check engine just came on and it said something about mass air malfunction. It's got the factory pipe from the throttle body to the air filter which is just a simple K&N intake. What do I need to do to take care of this?
If its throwing a Mass air code its probably the mass air flow sensor... Cleaning it will do nothing if its bad.
If i were you i'd try a MAF, they are kind of expensive so best thing to do (if you can) would be to swap out one from a friends car (99-04) Idk about older ones check the part number, if it works go buy a new one, but it is most likely your MAF is its throwing a Mass Air code....
10-12-2010, 12:47 AM
#10
2nd Gear Member
Join Date: Feb 2009
Location: Portland, Oregon
Posts: 324
I have a 1999 Mustang GT 5 speed with a pretty much bone stock 4.6L.
I started having issues with it feeling almost as if it were driving through water once it warmed up. I started running open headers, and this cleared up the issue. The problem was the cats had melted. I just put a new exhaust on there and there is an exhaust leak from the passenger side flange gasket, but I don't think this would be the issue.. just keeping my options open.
Recently, when idling, the car has started ALMOST stalling, but then recovering RPM at idle and it will smooth out for a second and repeat. If I give it gas in neutral it hangs and sputters for a fraction of a second (hard to notice, but I know my car), and then once I let the RPM fall, it ALMOST stalls again (around 200RPM) violently vibrates for a moment and smooths out to its normal 500RPM. The car also feels cut of power by quite a bit when this started as well as the car is very jumpy when I l let off the gas while driving. Say for example I would accelerate and shift to second and then need to coast so I let off the gas, it jerks back and forth versus slowly coasting. What could be causing this?
I started having issues with it feeling almost as if it were driving through water once it warmed up. I started running open headers, and this cleared up the issue. The problem was the cats had melted. I just put a new exhaust on there and there is an exhaust leak from the passenger side flange gasket, but I don't think this would be the issue.. just keeping my options open.
Recently, when idling, the car has started ALMOST stalling, but then recovering RPM at idle and it will smooth out for a second and repeat. If I give it gas in neutral it hangs and sputters for a fraction of a second (hard to notice, but I know my car), and then once I let the RPM fall, it ALMOST stalls again (around 200RPM) violently vibrates for a moment and smooths out to its normal 500RPM. The car also feels cut of power by quite a bit when this started as well as the car is very jumpy when I l let off the gas while driving. Say for example I would accelerate and shift to second and then need to coast so I let off the gas, it jerks back and forth versus slowly coasting. What could be causing this?
so your saying that on the passenger side, where the header meets the mid pipe, there is a leak? if you have longtube headers, your o2 sensors are pretty much right there. i had a nasty leak on the header/mid pipe junction which caused my car to hunt for idle and gave me bad drivability issues also. i tied that to cold air reverting back through the exhaust on decel and bringing my o2 sensors below operating range.
that was really only a hypothesis on my part though, although fixing my leak (a significant pothole tear) solved my problem, it might not be your fix. if you have exhaust manifolds this may not be your problem...