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2.5 stalling under acceleration

A

avnut

Be Gentle I'm New Here
Joined
Aug 13, 2007
Messages
2
I have a 1998 Contour SE with 150,000 miles, it has a 2.5 V-6 and an automatic transmission.
The first symptoms of the problem started a while ago. I originally thought it was a transmission problem but now believe it to be a fuel delivery problem. I have done a lot of research mostly on this site and found little information other than the possibility of a bad idle air control valve. I haven’t had time clean the IAC. Furthermore, I am hesitant to clean the IAC because I don't know what else to look for if the IAC doesn't fix the problem. Any thoughts or suggestions would be helpful.
The problem is a stall or possibly a miss usually under acceleration. The RPM's do not drop but there is a hesitation in the cars speed and an annoying jerk.
As I said earlier the first symptoms I thought were transmission related. The only time the "jerk" occurred was after the car was up to speed when I give the car gas, usually before an up shift of the transmission.
However, the problem has become more frequent.
There is no real pattern to the jerk other than acceleration or possibly when going up a hill at a cruising speed usually between 1/8 and 1/4 throttle.
The car cranks, idles, and usually cruises at a steady speed with out a problem.
Also there are no new check engine codes. The Lean O2 2nd bank and no EGR are there, but are old codes. The Lean O2 has been a problem since the car had 35,000 miles its been to 4 different dealerships and had over $1000. spent on it and the problem still exist. This isn't a code that I am taking into consideration since it has been present for the last 115,000 miles. Also I disconnected the egr.
I will try to clean the IAC today, however I currently live in an apartment and they are strict on the parking lot policy. If the IAC doesn't cure the problem I will probably wait till next weekend and head to my parents house were I keep all my tools and there are not restrictions on auto work.
What else could the problems be? my thoughts are
1. bad Throttle Position Sensor
2. bad coil pack
3. some sort of injector problem maybe electrical
I don't think its a bad fuel pump because the car idles and cruises fine.
However, I haven’t done a fuel pressure test.
Thanks for any thoughts or past experience stories.
 
Your description sounds more like an ignition miss. Fuel problems are "softer". Ignition misfires are "sharp".

Fuel mixture may be an issue, but not likely. If you suspect a slight lean condition, run some injector cleaner through the tank. I like RedLine SI-1.

Other than that, have a good look at the plugs, plug wires, and ignition coil. I think that is where you will find your problem.
 
sounds a hell of a lot like all you need is a new spark plugs and wires, possibily a coil pack.

can you get those CEL code numbers and post them here? Might help a little bit, might not.

It doesnt sound like an IAC issue because it has to do with acceleration, the IAC really is only there to make sure there is enough air getting to the motor to idle until throttleless conditions. If its stuck closed then it wont allow idle and your motor will just shut off every time it goes to idle. It doesnt sound like a trans issue because when a transmission slipps the motor runs completely smooth, it just doesnt shift correctly, and the O/D off light flashes.
 
avnut said:
The problem is a stall or possibly a miss usually under acceleration. The RPM's do not drop but there is a hesitation in the cars speed and an annoying jerk.
As I said earlier the first symptoms I thought were transmission related. The only time the "jerk" occurred was after the car was up to speed when I give the car gas, usually before an up shift of the transmission.
However, the problem has become more frequent.
There is no real pattern to the jerk other than acceleration or possibly when going up a hill at a cruising speed usually between 1/8 and 1/4 throttle.
The car cranks, idles, and usually cruises at a steady speed with out a problem.
Also there are no new check engine codes. The Lean O2 2nd bank and no EGR are there, but are old codes. The Lean O2 has been a problem since the car had 35,000 miles its been to 4 different dealerships and had over $1000. spent on it and the problem still exist. This isn't a code that I am taking into consideration since it has been present for the last 115,000 miles. Also I disconnected the egr.
I will try to clean the IAC today, however I currently live in an apartment and they are strict on the parking lot policy. If the IAC doesn't cure the problem I will probably wait till next weekend and head to my parents house were I keep all my tools and there are not restrictions on auto work.
What else could the problems be? my thoughts are
1. bad Throttle Position Sensor
2. bad coil pack
3. some sort of injector problem maybe electrical
I don't think its a bad fuel pump because the car idles and cruises fine.
However, I haven’t done a fuel pressure test.
Thanks for any thoughts or past experience stories.
Click to expand...


1.) I don't believe this will end up being your problem, however a cleaning of the EGR passages in the Throttle Body probably wouldn't be a bad idea...even if you have the EGR blocked off (which is how I read your post).
2) Highly doubtful. There are very few reports of Coil Packs causing this type of problem in the past. This is one of the few electrical components I believe Ford got right on the first try as it is a derivitive of the SHO coil pack and has been around for awhile in different models along the Ford line-up.
3.) A good injector cleaning is a good idea with a high mileage engine. Surely they have not been removed and if you have not run any sort of injector cleaner through the fuel system... it couldn't hurt too bad to do so.


Suggestions:

1) Clean the MAF sensor with a reputable brand of electronics cleaner. I don't recommend removing the actual sensor from the tubular housing it resides in, but giving it a thorough spray and dry and repeat cleaning until no "dirty residue" follows your cleaning.
2.) As suggested above, I would do a general tune-up using the Autolite Double 'Plats' as your replacement plugs. Autolite or Factory Ford replacement wires will be the most widespread suggested replacement wire to use for Daily Driver applications.
3) A good general cleaning of the Upper Intake Manifold and Lower Intake Manifold is recommended (by myself and most others on this site) using a good dousing of Berryman's B-12 and a SOFT TOOTHBRUSH to loosen the built-up carbon deposits in the manifolds. This will no-doubt give you better throttle response/ power/ and mileage per-fill-up which will be beneficial in maintaining the drivability of your 'Contique'.
4.) The lean O2 code can be found in the logic code of trouble shooting due to bad Upper Intake Manifold (UIM) Flow, as well as bad Lower intake manifold (LIM) flow characteristics. By not having the EGR connected you can expect (due to measuring of the EGR flow being incorrect when shut off) the O2 bank's' (all),,, mixture to be incorrect. Because the O2's function of reading "burn times" or "sweeps" will be miscalculated, the EGR will show an incorrect amount of recirculated gasses to be entering the intake system...and will start the whole cycle over again.

I am not saying this is "the root of all your evil", however, this is someplace to look. Generally we (as a website ) have found that most problems, emissions related, come to be something more simple than not.

If there are any others than above, or perhaps more to add, please chime in to help.
 
I replaced the plugs at 100000 with a cheap set of autolite. Around 130000 I had a constant miss at all ranges of the throttle. A computer test showed number 4 miss fire. I replace first the number 4 cylinder wire and the miss disappeared. I then replaced the rest of the wires, autolite was the brand of wires. At 135000 I had another small miss only slightly noticeable in gear at idle. The miss was more of a nuisance than a problem, it didn't even affect the gas mileage. However, I replaced the plugs with the better grade autolite plugs. The miss was still there but went away shortly afterwards probably around 135500.

I don't really want to spend the $45. on the plug wires but I will try to find a salvage yard to buy some from to see if that fixes the problems. I will also replace the plugs with the motorcraft recommended plugs.
 
Did you fix it? If not, consider transmission mounts! I have a similar problem, done a lot, now thinking what I perceive as a miss or engine problem is back and forth movement of the engine at a certain load and speed...

Mike
 
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