Occasional Hesitation

[bigjad2001]

I have a 1998 Mercury Mystique with 211,000 km. I have a problem where occasionally when accelerating the car will jerk and hesitate quite noticable for about 10 seconds then it will clear itself and be fine. It is quite intermitant, I can up to a week and it won't happen. It started after I had the timing belt changed and transmission serviced at 200km. I have had it looked at three times and have done the following:

Changed the fuel filter
Cleaned the throttle body
Replaced the spark plugs and wires

It doesn't bring up a code. It is hard to diagnose because it only happens occasionally.

Any suggestions???

[bdallenjr]

i have the same questions and replaced the same parts now im told that my timing belt may have jumped a couple of teeth

[rfalke]

I've had the same problem. And you can add fuel injection maintenance to the list, nothing helped. I just paid $170 for the mechanic to tell me he can't get the problem to reoccur! So if anybody has any idea please speak up. Thanks

--ryan

[rsvasquez]

I have a 2000 Mercury Mystique and it has about 93,000 miles on it.
I've already had the timing belt changed on it too, plus the fuel filter....now it hesitates ALL THE TIME!!! I have to pull over and turn the car off so that it can reset itself and stop doing it. It mostly happens when I am on the highway, which is most of the time. After it hestitate really bad one time I took it to a transmission shop and the guy put the diagnostic machine on it and he had to replace the transmission module on it,which wasn't expensive, but it only took care of the problem for a little while. I'm afraid that it might be the timing belt like ya'll say...that costs a pretty penny to get fixed. I don't want to have to replace it again unless someone out there has another solution. Any ideas on how to fix it? This is the last time I buy a Ford! Anyone out there think it might be some kind of defect?

[flyboyutah]

I've been troubleshooting my daughters 98 with a similar problem that turned out to be (so far at least) a destroyed idler pully of the timming belt. I don't think that is what's going on with your cars, but I've learned in all my reasearch that the MOST common problem (on the 2.0 4 cyc zetec engine) is with the VCT valve. (Variable camshaft timming).
The good news is, this valve is 'powered' by oil, and it's very sensitive to dirty oil, or even using 10w 30 instead of 5w 30, and if it's not workng correctly, any time you hit 3000 rpm it begins to control the exhaust camshaft timming. If the oil isn't able to power the VCT valve, you get a hesitation.
If that's your engine, You might consider getting an engine flush done, or do it yourself, then change to the 5w 30 if you aren't using it already. Also my alldata book said to only use a certain oil filter that holds the oil inside when the engine is shut down. I guess that's suppose that's to get the oil to the engine quicker on startup.

[VinnieD34]

We have a 2000 Mystique. We got it serviced at 70,000 I believe b4 a trip from Boston to Niagra Falls. Feeling good that the car was just serviced we were on the highway when it hesitated and stalled when I needed power...almost an accident with a Tractor trailer.
Called the service hotline...they suggested we got bad gas..went and filled up after the car sat a bit it started again...hesitated until we filled up gas...thought that water in gas was problem..WRONG.
Now every time the car is below or around half a tank going up an incline the car hesitates and will stall depending on the angle of the up-grade. When around a 1/4 tank of gas it will hesitate and stall on any surface though this is intermittent. Without a 3/4 tank or better the car will not climb a hill.

Replace oil filters, oil, fuel filters, added dry gas, have done multiple fuel injector cleaners in full tanks,...only temporary inprovements..a couple of days at best...then back to the same...not cool to have to fill up every time you get down to 3/4 of a tank.

Has anyone else noted these problems associated with amount of gas in their vehicle???

Any ideas? Brought it in to the dealers service center and car would not repeat problem on test drives.

[flyboyutah]

I'm guessing they replaced the fuel pump and checked the fuel pressure, inline filters and so on. Have you ever gotten the 'check enging' light lit? If so what were the error codes?

[r.m]

I have a '99 Mystique that has the same problem with hills. I only need to keep the tank 1/4 full to keep things going. It is getting worse. It sometimes runs rough and then stalls. It gave me a check engine code: low fuel pressure. Tried changing the fuel filter. It improved for a while. Now the same old thing. Any ideas?

[Kris_durbin]

I have experienced the exact same problem everyone else here has. If anybody has found the solution to this problem, PLEASE post! My car started off hesitateing under 1/4 tank when trying to accelerate rapidly. Over the past year, it has worstened to whenever you accelerate at all. The harder you accelerate, the worse it is. If the tank becomes to low, (around 1/8 to 1/4) the car won't turn over. My mechanic stated that at high revolutions the fule pressure read at only 30 psi. The following things have been recently checked/replaced/fixed:
Fuel filter
Spark Plugs
Alternator
Air Filter
AC Compressor (different problem :-p)
Fuel Pump
Throttle Motor
etc. etc. etc.

My mechanic found a problem in a diode in my alternator and traced it to the fuel pump. After replacing the alternator and testing the fuel pump, everything checked out okay, but the problem still exists. Unlike others here, I have never changed my timing belt. After what I read, I'm almost afraid to. My car is at about 85,000. Please, please, please, please HELP!!!!!!!!!!!!!!!!!

[Kris_durbin]

Okay....after reading some of the comments here, I think I've found the fix. It sounds odd and I've spent hundreds on diagnostics, but the fix was in reality a $16.00 problem. Change your oil to 5W30 and change the oil filter to one with a Flow Back Gasket in it. This prevents the dirty oil that is already in the filter from reentering the motor after the car is shut off. Also, you need to religiously change your oil with the Contour or Mystique. (must be a female.) Now for the higher RMPs (4000 to 5000)hesitating, you need to have the runner control modual looked at. This allows the throttle to open wider to allow greater air flow into the motor. If it's malfunctioning, it does the opposite...therefore the motor gets NO air. Hope this helps everyone else and saves everyone lots of money!

[buchanan06]

I have been having the same problem with my 2000 Mercury Mystique. Mine got to the point were it hestitated and then died twice, and had to be hauled home. You couldn't even push the gas without the car bogging down. My fiance managed to drive it for a short amount of time by feathering the gas. The next day we called a mechanic. He put it on the computer diagnostic scanner, and no codes came up so he was completely puzzled. Many people thought, as well as myself, that I had gotten bad gas, needed a new fuel filter or pump, or that my transmission waas going out. Someone suggested that we clean the Mass Air Flow sensor, which we did. This has seemed to fix the problem for now. My car is running top notch for the moment-I will keep all of you notified if this solves the problem.

[buchanan06]

[quote=buchanan06]I have been having the same problem with my 2000 Mercury Mystique. Mine got to the point were it hestitated and then died twice, and had to be hauled home. You couldn't even push the gas without the car bogging down. My fiance managed to drive it for a short amount of time by feathering the gas. The next day we called a mechanic. He put it on the computer diagnostic scanner, and no codes came up so he was completely puzzled. Many people thought, as well as myself, that I had gotten bad gas, needed a new fuel filter or pump, or that my transmission waas going out. Someone suggested that we clean the Mass Air Flow sensor, which we did. This has seemed to fix the problem for now. My car is running top notch for the moment-I will keep all of you notified if this solves the problem.[/QUOTE}
Well, the Mass Air Flow sensor didn't fix the problem. Still stalls when it gets below quarter of a tank of gas! Anyone figure out the problem? Contacted Ford to suggest a recall on the Mystique, but haven't received any replies!

[greeffs]

it seems this problem is ongoing with all the 4 cylinder mystiques . i have just replaced my timing belt and fuel filter as well as all the injector cleaners and still continue to have the hesitation problem described in all the above postings.. Does anyone know the solution to this ?advise is greatly appreciated and feedback will be given

[Stevo2]

Originally Posted by greeffs

it seems this problem is ongoing with all the 4 cylinder mystiques . i have just replaced my timing belt and fuel filter as well as all the injector cleaners and still continue to have the hesitation problem described in all the above postings.. Does anyone know the solution to this ?advise is greatly appreciated and feedback will be given

Was this hesitation there before you replaced the timing belt?

How many miles on the engine?

Has the problem become progressively worse?

What year is this?

[cdavis76]

I just purchased a 1996 Mercury Mystique 2.0L 4 Cylinders from a friend who had decided he was done with all of the problems. Unlike everyone here, he had decided long ago to stop ADDRESSING those problems. The price was right and I like a challenge, so I went for it. Here's the problem, I have an absolute minimum knowledge about cars. Instead of spending another penny on the car, having already replaced the battery which was the reason it wouldn't start - this time - I've decided to see if I can't just learn about fixing cars by starting with this Mystake. I, too, am having the hesitation problem as is being discussed in this thread and haven't attempted any fixes yet as I just brought the car home yesterday. The last oil change this car received was on June 8, 2005 and it has been driven a total of 2400 miles since. My first course of action is to change the oil (using 5w30 and the filter suggested above), but any suggestions as to what I can do from there would be most appreciated. Thanks in advance!