99-04 Common Issues

2gtrs

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Aug 7, 2009
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I have been searching the board for answers, but unable to find any. Could anyone please tell me the common issues/defects/problems etc of the 99-04 mustangs? (Or more specifically, the '03 GTs). So far for 99-04, I've read about known issues involving the IAC, power windows failure, spark plug blowouts, and 1-2 grind/clunk on the tr-3650. If anyone has more to contribute, I would greatly appreciate it. Thanks in advance.
 
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I never have had one of those problems you listed.
My tr-3650 has seen various 4,000 rpm dumps on slicks and not even a slight whine, clunk etc...
I think some have complained about hanging rpms when slowing down. Mine hangs slightly, but not enough to annoy me.

Solid cars man.
 
Decent cars. If I had to pick a starting point, I'd go mid 2001-up. An aluminum crossover was added to the intake manifold to replace the very prone to cracking plastic one. The T45 trans was upgraded to a much tougher TR3650. The Engines were switched to Romeo, vs the Windsors in the '99-'00 Cars. Not necessarily an upgrade, but the Romeo engine is the more popular of the bunch. The '01-up also got the revised interior consol and double DIN stereo head unit and traction control button placement. Othewise, the difference are mostly cosmetic. Wheels are different in the pre-01 cars, side scoops, hoods, colour options, etc.
 
Some of the problems with my 03 gt are what you have already said. I've always drove mine pretty easy but around 25k the 3650 started "clunking" in the 2nd gear, at 80k still with stock clutch still clunks but nothing every come of it yet. Others ive experienced is the stock 6disc messing up several different ways but nothing pulling it apart could'nt fix. Just replaced window motor as mentioned, never had any problems with the IAC. Don't get me wrong, love the car, just answering your question, but overall great reliable cars with no problems other than ones mentioned. You'll completly enjoy it.
 
there OK

all in all the boys mentioned the problems but they are decent cars change the oil , use the good stuff every 3,000 & you have a car that will run up to 200,000 oh yeah get a hypo needle and grease the ball joints as there not greaseable & will dry up & go bad ..... there good cars , good brakes , & take a beating & keep on ticking :nice::nice:
 
all in all the boys mentioned the problems but they are decent cars change the oil , use the good stuff every 3,000 & you have a car that will run up to 200,000 oh yeah get a hypo needle and grease the ball joints as there not greaseable & will dry up & go bad ..... there good cars , good brakes , & take a beating & keep on ticking :nice::nice:

I can understand wanting to be meticulous about oil changes, but literally hundreds of thousands of 4.6L's on the road have had nothing but Dino oil every 8,000-10,000km and are still running strong well over the 200-300km range. Next time you're in a taxi cab take a look at the odometer reading. Most cab companies I know of won't change the oil until it starts to resemble tar. The 4.6L Modular is a much more durable engine than most give it credit for....even with so-so maintenance.

If you're going to run synthetics in it, then let them do their job and go the distance. That's what they were made for. Flushing it ever 3,000-miles is a huge waste of money! Personally, I'd concentrate more on going with a good filter, than the type of oil I was running. :shrug:
 
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Since mines got the issue, my search for a solution has revealed many others that have it also. That's is a "stumble / misfire" at cruising speed at 1800 to 2k RPM. It also comes with a slightly ruff idle.

Sounds like you're in need of a tune up. New plugs, clean out the IAC, changing the air and fuel filter might be all it needs. Could be a bad COP too, but I'd replace the cheap stuff before I went and tried to tackle any of the electrical. :)
 
Since mines got the issue, my search for a solution has revealed many others that have it also. That's is a "stumble / misfire" at cruising speed at 1800 to 2k RPM. It also comes with a slightly ruff idle.

ive had this problem too... but other than that i replaced ball joints and had the heads rethreaded, and an alternator and she has 140,000 on the clocks. i love my car its tough, handles tight, and has great power.
 
Here are a few common problems off the top of my head:
-TR3650 shift fork bent
-wheel bearing failure
-spark plug launch out of head
-all plastic style intake manifold cracking
-IAC problems
-stock shocks/struts fail way too soon
-window regulator falls apart inside door
-window motor or switch failures

In general the cars are pretty reliable and almost all the above can be easily fixed by the home mechanic.
 
The slight stumbling is usually caused by a weak COP or a bad COP spring/boot combo. Unfortunately, the only way to find a weak COP is either to use a known good one and swap them out one at a time until the problem is gone (if it's only 1 that's bad to begin with), or take it to Ford, they have a diagnostic machine just to load test the COPS, and it will show you quickly. It's a little costly, but saved me a ton of time and aggravation. Ended up being 4 weak cops, and 2 that tested good, but the springs were worn out, and not getting a good connection. Replaced the 4 bad ones, and replaced the boot/springs on the other 4, and life has been good since. No stumbling or bucking at low rpms anymore.

I'm surprised that noone's mentioned seatbelts that won't retract, that's the one thing that really ticks me off with my car.