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What's with all the stumbling/bucking/hesitation problems lately?

C

ck42

CEG'er
Joined
Jun 4, 2005
Messages
99
I've got this problem going on right now myself....and am almost to the end of my rope trying to figure it out.

Maybe it's only because I'm having this problem, but I feel like I'm seeing an increasing number of threads with the same story over and over again...and there doesn't ever seem to be a good answer for what's causing it.

Sure....there are many different things that can bring on these symptoms, but it seems that most of the threads involve someone trying one thing after another...and not getting anywhere (there ARE the exceptions, of course). I've even run across several posters who have these problems and basically state that they've given up and "just live with it".

I feel like it would be useful to try and keep as much wisdom together as possible to try and crack this nut.

Personally, I'd be interested in running a poll to see who all is having these symptoms, year car, and type of motor.....and also what they've tried so far to fix the problem.

...or am I just overreacting?
 
mattsBLK99cSVT said:
All i can say is bad fuel pumps. ...
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.... and the weather. When it gets cold, all sorts of issues show up. Some because of vacuum leaks (due to plastic hoses hardening and cracking), or the manifold gaskets or just the IAC valve taking a dump (and it usually happens when it is cold).:blackeye:
 
Good info.
In my case though (and more detailed in another thread) I've already replaced the fuel pump and the IAC and the manifold gaskets.
I've checked for leaks while I had things pulled apart, but I'm wondering if I should just bite the bullet and buy the vacuum tube harness from Bill J.
 
ck42 said:
.., but I'm wondering if I should just bite the bullet and buy the vacuum tube harness from Bill J.
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I don't think that is a good idea unless you know the vacuum tube harness is broken. While it may be considered a good maintenance thing to do, it might not be the solution to your problem. Check for leaks using the carb cleaner method. Spray while idling and if the idle changes, you found the vacuum leak.
 
Haven't gone through the 'spray it' method yet...but when I recently did the UIM/LIM cleaning, I did a thorough visual on all the lines and vacuum tested the ones I could get to. They checked out. But yea, I otherwise hate spending that much of a part only to hope that *maybe* it fixes the problem. I like finding a smoking gun.
 
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Check spark plug gap, sp wires, and wiring harness. You know how prone the 95 to 97's are to wiring harness issues.:blackeye:
 
Tony2005 said:
Check spark plug gap, sp wires, and wiring harness. You know how prone the 95 to 97's are to wiring harness issues.:blackeye:
Click to expand...

Already checked the gaps (and replaced plugs) and new wires. Wiring harness was replaced at 99Kmi. LOL!
 
I thought it was bad gas. I bought the STP injector cleaner. no improvement. I went on a long distance trip and it happened a lot, until the car just finally died (after 2000 miles of driving straight). I had the fuel pump replaced, as well as the fuel filter and had the injectors cleaned.
BUT, I had the same symptoms. The car would hesitate when I would punch the accelerator. otherwise it worked fine. NOW, IT RUNS LIKE BRAND SPANKING NEWW!!!! the mechanic said that the new FORD fuel pump seems to have a better design.
 
DeepDishSVT said:
I thought it was bad gas. I bought the STP injector cleaner. no improvement. I went on a long distance trip and it happened a lot, until the car just finally died (after 2000 miles of driving straight). I had the fuel pump replaced, as well as the fuel filter and had the injectors cleaned.
BUT, I had the same symptoms. The car would hesitate when I would punch the accelerator. otherwise it worked fine. NOW, IT RUNS LIKE BRAND SPANKING NEWW!!!! the mechanic said that the new FORD fuel pump seems to have a better design.
Click to expand...
If you still have the invoice, would you please post the Part number of the fuel pump which was used for your 2000 SVT? Thanks.
 
Yep, have a 2000 duratech. When the outside temp gets above 75F, it bucks, sputters, quits, etc. Tried plugs, wires, new ambient air temp sensor, intake manifold gaskets, fuel filter, and other things too numerous to recall. Still no luck. When the outside air temperature is below 70-75F, it runs very good, no hesitation, etc. When it gets up around 90F outside, it will hardly pull its own weight. I wish I could help you but...no luck with my own. Cat/precat doesn't make sense. Someone suggested fuel pump. I don't know.
 
Contour_dave said:
Yep, have a 2000 duratech. When the outside temp gets above 75F, it bucks, sputters, quits, etc. Tried plugs, wires, new ambient air temp sensor, intake manifold gaskets, fuel filter, and other things too numerous to recall. Still no luck. When the outside air temperature is below 70-75F, it runs very good, no hesitation, etc. When it gets up around 90F outside, ....
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Ambient temperature related? Check Intake Air Temperature Sensor. ;) You may want to check if the wiring is not up to snuff. The chart is below.

Edit: Autozone link IAT sensor
http://www.autozone.com/servlet/UiB..._us/0900823d/80/1b/ca/f8/0900823d801bcaf8.jsp

Figure 5 chart.
http://www.autozone.com/servlet/UiB..._us/0900823d/80/1b/ca/ba/0900823d801bcaba.jsp
 
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Missing on just about every cylinder, runs bad

Missing on just about every cylinder, runs bad

Just today my Contour started running extremely rough. I drove it to my customers abut 400 miles. Thought it was bad gas, but since I went to a known gas station and filled up again it did not help, so ruled that out. As long as my foot is on the gas it is running good. As soon as it goes to idle, it mises, surges very bad and then just dies. I was lucky to make it back home today.
I get 9 trouble codes, P301 P302 P304 P305 P306 P0171 P0174 P1131 P1151. Not sure what to check first?

It has been very cold here lately, so maybe that has effected something?
 
Loomster said:
Just today my Contour started running extremely rough. I drove it to my customers abut 400 miles. Thought it was bad gas, but since I went to a known gas station and filled up again it did not help, so ruled that out. As long as my foot is on the gas it is running good. As soon as it goes to idle, it mises, surges very bad and then just dies. I was lucky to make it back home today.
I get 9 trouble codes, P301 P302 P304 P305 P306 P0171 P0174 P1131 P1151. Not sure what to check first?

It has been very cold here lately, so maybe that has effected something?
Click to expand...

Massive vacuum leak. Really, really massive.

Check for broken rubber and plastic hoses (UIM). It must have a big hissing, loping sound.
 
Tony:

Just went out and started the car. Big loping. Hear a little hiss, but spraying carb cleaner didn't change anything. Maybe tomorrow I will pull it into the garage where it is warmer and check everything else.

Thanks
 
Loomster said:
... Hear a little hiss, but spraying carb cleaner didn't change anything....
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Yeah, I did not mention the carb cleaner because of your major vacuum leak. It would not have made much of a difference because the "hole" is so big that it is also sucking air in to dilute the carb cleaner "fumes". You probably have a broken hose or hose which came out or a hole in your intake. Look closely from the air filter area towards the engine to the TB and as well as to the IAC valve (and to the PCV valve). Also look at the UIM plastic tubing on top of the UIM. Most times, it is from the MAF sensor area to those items.
 
I just recently had the hose from the PCV valve to the Evap Cannister break. It's the black ribbed line that goes behind by the firewall. I had to look close to find it because of the way the hose was made.
 
ck42 said:
Good info.
In my case though (and more detailed in another thread) I've already replaced the fuel pump and the IAC and the manifold gaskets.
I've checked for leaks while I had things pulled apart, but I'm wondering if I should just bite the bullet and buy the vacuum tube harness from Bill J.
Click to expand...

No, no, NO!

Cold weather brings on vac leak issues - most often the intake manifold gaskets. The symptoms are high idle, idle/stumbling issues, and hesitation at tip-in. A severe case will cause a lean code CEL.


bucking & hesitation are typically caused by 2 things:
  1. Fuel pump & filter
  2. Plug wires - sometimes plugs
Symptoms of plug wires will be a miss at low/moderate rpm & seemingly OK running at higher rpm.

Symptoms of fuel pump will be hesitation, bucking, lack of power at higher rpms in particualar, but can happen throughout rev range. Symptoms get worse with low fuel levels and go away temporarily after the car sits overnight (pump & filter sock indicated on those last two).

That is by no means complete. Your symptoms/conditions may vary from the norm, but generally that's what you can look for.

So, if you have bucking and it doesn't get worse when you have 1/4 tank or less fuel, your problem is most likely your plug wires and/or plugs. Get Auotlite APP764 plugs (and gap them!) and a good set of wires - Motorcraft OEM from the dealer ($$) or some Autolite Professional series. Some people have had good luck recently with Taylor Thundervolt wires purchase over the internet. I have no experience with them.
 
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TourDeForce said:
and a good set of wires - Motorcraft OEM from the dealer ($$)
Click to expand...

I just ordered Motorcraft OEM wires from Advance for $73 (set). Their MSRP was $123, and Ford quoted me at $140+. I'm assuming they're all the same right? Tomorrow I'll have a part number to verify.
 
Mine ending up being fixed by replacing the O2 sensor.
Althought cleaning the IAC and putting in a new gasket helped a little.
 
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