2000 Gt Hesitating And Backfiring..

[jmcdowell]

So my wife bought a high mileage 2000 GT (169k), that ran perfect that is before I messed with it.. Ima go through the whole story just so those reading know everything..
Shortlyafter getting this car, it was realized that the filler neck was shot.. So I dropped the tank, ordered the part and replaced the fuel filter. After seeing how bad the filter was, I went ahead and replaced the fuel pump with a denso. I also decided to order some other parts and install them, and they are as follows.
• New rear shocks
• Fuel pump / sending unit combo ( 7.5 ft lbs torque spec and sequence used )
• Ground off rust spots sprayed with rust converter
Differential service
* 34 ft lbs Torque spec and sequence used
* 2.1 quarts of synthetic oil used
New gas filler neck+seal
New Infinity 6x8 door speakers
New Drivers side door lock
New Polyurethane end Links (ford blue)
New dimmer switch
New fog light bulbs
Scrubbed 1/4 of gravel dust out of trunk.
New Cold air intake
Removed and cleaned filthy gauge cluster
Attempting to restore head lights.
New key fobs

So the car is still waiting for the filler neck. It has jack stands on the rear axel. When I start the car, its all good.. When I hit the gas from idle it hesitates and sometimes goes and sometimes back fires. If I bring it u a little slow and hit it, it goes without hesitation.. I have checked the intake, there is nothing blocking it and I can't imagine its leaking past the MAF.
The tank doesn't have but 3 gallons in it, but surely that's enough..

Any ideas? My wife is going to be upset if I don't figure this out...

Thanks in advance!
J

 

[wmburns]

OK, before we get into worrying, a few questions.

Manual or automatic?

Traction control or not? If the car has traction control is it on or off?

Why are you running it so hard on axle stands?

Do you have a Ford service manual and wiring diagrams for your car? If interested in getting a copy for yourself I maybe able to help. PM if interested.

 

[jmcdowell]

Its an automatic, but I didn't take it out of park.
I am not running it hard just tapping the gasto get the rpms up to make sure its going to run right.
I don't have the service manual for this but would sure like one.

I am starting to think one of three things has happened..
I stressed the connection from the tank to the filter getting it down and putting it back in.
Or
I damaged the MAF
Or
Something was in the cold air pipes and got sucked into the throttle body. ( Shoving my inspection camera down there in a minute.)

Thanks on advance!
J

OK, before we get into worrying, a few questions.

Manual or automatic?

Traction control or not? If the car has traction control is it on or off?

Why are you running it so hard on axle stands?

Do you have a Ford service manual and wiring diagrams for your car? If interested in getting a copy for yourself I maybe able to help. PM if interested.

 

[wmburns]

For an automatic, the PCM "knows" when the transmission is in PARK or neutral. When in park the motor is reved up, the PCM limits the timing advance. This serves to limit the RPM's. To me it's perfectly normal for it to act like the reported symptom under the circumstance.

I really think the actual driving experience will be much different.

 

[jmcdowell]

So I did a little more trouble shooting…

I cleaned the MAF, that made no difference..
I reseated the sensor just behind the MAF, and that had no effect.
I did realize that the popping is coming out of the INTAKE and not the exhaust and originally thought, which from reading tells me that it’s a “misfire” condition..

I have read that misfire can happen for several reasons..
· Weak fuel pressure. ( It’s a brand new pump and I have no way to test this to date.)
· Vacuum leak. ( I am going to test this tonight.)
· Needs tune up.
o This is an interesting one, because I started to wonder.. Did changing the fuel pump, intake and the filter create a situation where the plugs are getting way more fuel and air their they are currently capable to handling due to age? I bought this basket case at 169k, I don’t know what has or has not been done to the car. I can safely state that it was neglected on many fronts. I have new plugs, but can’t locate the spark plugs. Everyone tells me that they should be in the same place as any car. However, I think they are located right next to the fuel injectors on top of the head. If everyone is saying that the 2000 shouldn’t have these types of plugs, I am wondering if the engine has been swapped for a newer one.

My next steps are as follows :
· Change the plugs with new ones set to the correct gap.
· Fill tank half way with 93 or higher octane fuel.
· Drive around, see what happens..


Any thoughts from the experts? I truly am a mustang n00b..

Thanks in advance,

J

 

[jmcdowell]

I would agree with you if the engine was getting to RPM and then acting this way, and I still concead you could be right, time will tell.. I posted a video on youtube..
is the link.. That should get you to it...
It's not getting to 1000 RPMS, hesitates, misfires, and then revs up to around 3k before I let off it.

Does that change your thoughts? Or are they still the same?

Thanks in advance!

J

For an automatic, the PCM "knows" when the transmission is in PARK or neutral. When in park the motor is reved up, the PCM limits the timing advance. This serves to limit the RPM's. To me it's perfectly normal for it to act like the reported symptom under the circumstance.

I really think the actual driving experience will be much different.

 

[wmburns]

I have new plugs, but can’t locate the spark plugs. Everyone tells me that they should be in the same place as any car. However, I think they are located right next to the fuel injectors on top of the head. If everyone is saying that the 2000 shouldn’t have these types of plugs, I am wondering if the engine has been swapped for a newer one.

From the Video, your car has a run of the mill standard SOHC 4.6. The spark plugs are located directly on top of the heads under the coil on plug (COP) units. They are near the fuel injectors.

Since you are new to SOHC 4.6, be sure to throughly CLEAN the spark plug wells before removing the spark plugs. The 4.6 is bad about accumlating dirt in the plug wells. If not cleaned, the dirt will go straight into the cylinder when the plug is removed. A "smoker" is the result.

If you are really worried about this project, then consider running a compression test while the plugs are out. This will give you a base line on the health of the motor.

IMO you would really benefit from the Ford service manual.

 

[jmcdowell]

I thought it only fair to update the thread..
I got home and started looking at changing the spark plugs.. I will have to remove the fuel rail, so I decided that could wait.. I took one off and it exploded, shooting a long spring out the end. I got it back together and all was the same as before.. (Hesitation POP!)

I got the tank back up, got the new filler gromet in, that took some research.. Couldn't remember how it went in.. After much research I decided the smaller end went into the tank.. This left sort of a tunnel effect for the filler neck.. Got the filler neck in..
Poured in a couple gallons of premium.. Pulled it out of the garage.. Hit it! Shutter POP- damnet! Took it to the gas station, put about half a tank of premium in it, and the hesitation and popping stopped. Completely...

I don't think it was getting enough fuel? There was very little in the tank..

Got back, checked diff, so far so good, no leaks.. This will be the first time ever that I did some work on a car and it just "works".

Thanks for all your help! I am sure I will be around here for a while.

 

[wmburns]

FWIIW, the fuel rail does not have to be removed to change the spark plugs. I have done the job myself on a 96 GT Mustang, 97 V8 Cougar, 2000 GT Mustang, and 2003 GT Mustang.

For the COP cars, it is necessary to remove the screw holding the COP and bend it slight sideways to remove. If it exploded while being removed either you were too rough or it was part of the walking wounded.

Autozone (Duralast) makes a replacement set of (8) COP boots that cost less than a single COP. Consider it.

Also note, it is normal for the car to run poorly after a battery disconnect. The PCM needs time to re-learn new idle trim values.