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hesitation/bucking is back

fuel filter was done probably 20 or 30k ago but it did sit for 7 months. will autozone be able to pull a code without a idiot light on? when it was sitting the battery died (damn thing was low on water, luckily it took to a top off and slow charge) so any codes that were in there are gone now.
 
I am not going to read through 7 pages, but have you checked your fuel pump?

After removing the screens, sock and replacing the sending unit, the proble I had which was just like yours, went away.

It even had a funny story that went with it.
 
I have not removed the fuel pump, but we did hook up a fuel pressure guage to the schrader valve. It was reading about 45 psi @ idle, and went up to above 54 psi when I gave it throttle. That is why I blew out the return line and replaced the FPR.:shrug:
 
how do the pumps come out in these cars? do i have to remove the tank or is there an access hole in the floorpan somewhere?

everything i know tells me there should be enough fuel in the lines to let it rev even for a second before it falls on its face. i hate electronics grrrrrr :help:
 
ill be damned.... after i used some contact cleaner on the MAF sensor and that didnt fix it - i decided to do what i should have in the first place and check the spark plugs. well, they looked so-so and my neighbor had just pulled some bosch platnium 2s out of his dodge (they had the same thread length) so i put em in and it ran 95% better. one trip to advanced auto parts and 16.00 later i had 4 new autolite double platniums and it runs just about as good as it should. hesitation is no mo. =)

yay for stupid simple fixes!!!!!
 
Scott: The fuel pressure you're getting/quoting is normal. Starting in 97, Ford changed the FPR from 1 which runs at (approx.) 31 psi to 1 which runs at 41 psi at idle. I know as I have a gauge on the Schraeder valve and did a swap from an early regulator to a late. Those no.'s are normal.

Your plugs s/b light brown/tan colour. White deposits indicate a lean conditon. Are you sure you don't have an air leak? My car has similiar symptoms, but I have 2 lean codes (0171 & 0174).

The TPS is a "wiper" type of sensor, so it can give intermittent problems.
 
I am going to keep an eye on this thread. I am having the same problem you are with an 01 cougar v6 5 speed. I cant seem to figure it out. I am going to try plugs today and tomorrow it goes to the dealership for a new alt since its under warrenty :)
Ill see what I can come up with
 
getsum111 said:
Pull up your back seat, there is a hole there where you will see the top of the pump.
Click to expand...

Hi, I've just read through this post and I hate to see you waste a lot of time.

Do you have a return style fuel system or returnless?

If return style you will look for about 40-45psi at idle and 50-55psi WOT.
Returnless will vary the pressure according to engine demand so there is no easy way to determine.
our
Back to your problem. It is probably an ignition system problem. The misfire or stuttering problem at light throttle and low rpms that clears up by high rpm and full throttle is CLASSIC symptom.

Here is how it works on the Primary side:
12v applied to the coil pack primary side (3 coils), then from the coil pack primary side directly to the PCM to three transistors, then from those three transistors directly to ground.
The computer switches a transistor on and off when it is ready to fire the coil. Any bad ground, bad transistor, corroded wires, or bad primary coil pack will cause this circuit to work poorly.
There are grounds for the pcm right on the passenger side fender. You will want to pull that off and clean it.
Possible your PCM could also have issues since it is an integral part of the ignition coil circuit.

Now the secondary side of the coil is the from the plug wire connector on one side of the coil, out the wire to one spark plug, through the plug electrode to the block, through the block to the other plug electrode into the plug and back up the wire to the coil pack. This completes the circuit.
So two plugs, two wires on every coil pack are required to be in good shape.
Now coil, plug, and plug wire resistance all play a role. If they are off then the spark will not build to the correct level.

If back on the primary side the resistance is off too much then the same thing will happen.

Generally the stuttering is caused from noise on the circuit and combined with the oversaturation of the coils at low rpm.
I don't want to explain this because it will take up too much time, but suffice it to say that the longer 12v is applied to the coil then the the more noise can be developed. At low rpm the time between ignition points is longer so the coil remains saturated (charged) the whole time until the next point to fire comes up. As the rpms get faster the time between coil firing gets shorter and the coil no longer gets as much time to oversaturate. The spark signal gets cleaner. Combine this issue with improper resistance in the secondary circuit (plugs, wires) and you will have major issues.
If there is a lot of noise on the coil circuit it can actually fire the plugs multiple times at the wrong time, hence the stuttering issue.

So what do you do?

1.) Change to correct plug wires, plugs (i.e. not some single copper core plug wire at least until you find the problem.
2.) Check the coil resistance or change the coil pack
3.) Clean all your connectors on the coil packs, on the PCM grounds.
4.) Last, swap PCMs with someone else who has the same car.
 
LUCA said:
TPS Volts: Volts should be between 0.2 and 1.4 volts at idle. At WOT volts should slowly rise to slightly less 4.8 volts.
Click to expand...

I have found the best way to check a TPS is with a scope. They get noisy, liike an old radio volume control. As you move the throttle you'll see "hash."

Al
 
Tom and Al, thanks for the responses. I've sanded the grounding spot for the pcm, and the plugs are teh correct type, app764. I've tried several different wires w/o success.

BTW, it is a return fuel system. My biggest problem is that it only does this under load, and I don't want to have to hang on to the car reading gauges while my wife runs it down the road.:laugh:

I checked the coil when this first appeared (Thanksgiving) but it tested ok. I also swapped coils w/ another CEG'r to no avail.:mad:

I will double check all connections later today.

Al, unfortunately I don't have a scope. Bummer, huh.
 
Wow, flashbacks.:laugh: Just kiddin' ya. No, IMRC stands for Intake Manifold Runner Control. It's the box that controls when your secondaries open around 3300 rpm. (ABOUT;)! ) Many people have stated that heat can ruin them, which is why the assumption that, since the bucking starts around then too, that the IMRC could be the problem.

In my instance, I think it was my Magnecor wires that were the problem. I have since bought a new set of Taylor Thundervolts. Can't yet report on them, as the car is undergoing a header install at present. :laugh: If you get the same trouble, triple check alll your ignition components.
 
Well, just replaced my fuel filter.

Is it bad if the filter drains brown liquid? lol

Checked all ignition components, nothing out of place. Whoever figures this out gets the cash pool!
 
Plugs, 6 months. Pulled and clean as can be.

Wires, don't know, probably original.

Right now I am leaning toward TPS, and they are only ~40 dollars to replace.
 
I had a coil pack go bad within 6 months. It caused a misfire in high gear. Was a Wells brand from AZ. It tested OK on the Ohm meter. Had #6 injector go out once too. It caused an intermittant miss.
 
Well, i had a terrible depressing time trying to fix my misfire and it turned out to be my Brand New premium autolite wire boot. Too bad it took me forever to see the obvious. Sorry to thread hijack but thought it could help others later.
 
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