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2000 mustang gt, bad idle, no power

1696 Views 9 Replies 8 Participants Last post by  msirach
ok i recently got a 2000 mustang gt auto:/, anyways it runs fine most of the time, but everynow and then itll have a really bad idle, like it sounds like a legit aftermarket cam, and you can put your foot on the peddle, dont matter how much but its just like its an old toyota pickup or something, really lacks power, then all of a sudden itll be fine, i have checked for vacuum leakes, cant find any (doesnt mean there isnt one) but i was thinking something with the pcv system, or EGR, the vaccuum line going to egr doesnt seem to have any vacuum on it. i have one code p0453 evap emission control pressure sensor high input, could this be related, i know a little about evaporative emissions and dont feel like it should be related, also i have a big hole in the muffler, once again dont think its related but just giving as much info as possible, any ideas?, thanks
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Well, on old 5.0 motors, the evap canister had a vacuum line that ran to the back of the intake. It didn't cause that big of a problem but that is a totally different setup. I just got my 4.6 so I want to learn as much as I can as well.
Pull your egr valve off and see if you have carbon buildup in the egr. That would be the first thing I would do.

I doubt its your Evap system that would cause this. That system has very little effect on how your engine runs, and the codes shouldn't freak your ECU out. My escort ZX2 ran great with that code for years lol.

One possibility could be your ignition system, dont rule it out. When at low RPM and high load, you demand a lot of electricity to ignite the rich fuel air mixture, and your power supply from the alternator tends to be a little less at low RPM, despite the voltage regulator. The thing that tells me to lean this way is the fact that you have no "vacuum leak" or "misfire in cylinder" codes. Try to find a way to test the ignition coils first, then check out the plugs and wires.

Good luck finding the problem! sAni_spider.gif
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thanks man ill definatly look into that
Ever replace your fuel filter?
My bet is the EGR valve, I had the same problem on my 2000 GT manual and replacing it fixed it. It might also be bad gas.
yeah thats what ive been thinking is EGR havent had much time to actually mess with it i got the car a few weeks ago and i havent really driven it more than 100 miles since i got it, i drive my 03 gt as my daily haha
EGR could do this.

If I were you, if you haven't yet.... The crappy little plastic vacuum lines ford uses get unbelievably brittle after this many years. I chased down a vacuum leak on myGT for months before finally giving in and spending 4 dollars on new vacuum HOSE (not new crappy brittle plastic) and 10 minutes replacing all of the vacuum hose on top of the engine. 4 dollars and ten minutes and the result was astounding.

Id advise everyone who even suspects a vacuum leak to spend the time replacing these crappy plastic lines, they get brittle and leak in the strangest places.

Also, vacuum leaks would result in 1) fluctuating rpms, watch tach needle, does it flutter? and 2) youre O2's would read consistently lean, if you have the ability datalog it or find someone who can and check long term fuel trim, should be close to 0 if it's +3% or more chances are vacuum leak. (along with other symptoms)
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The random bad idle on my 2000 GT was cured when I changed the IAC (idle air control). The part was about $90 from Ford. I replaced it with an Autozone part for less than $40.
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