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Hesitation when accelerating


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thepoores
New User

Apr 19, 2010, 9:33 AM

Post #1 of 6 (3327 views)
Hesitation when accelerating Sign In

2001 Ford Mustang
6-cyl
automatic trans
approx 79,000 miles

A few months ago, my wife's car started hesitating when she mashes the accelerator. It seems to only do it after it's warmed up a bit and mostly when it is up to speed. In other words, it doesn't do it when she first takes off. If she's doing 40 mph (for example) and then goes up a hill (or accelerates for other reasons) it will hesitate/lurch/sputter. It seems to idle fine. Check engine light does not come on. Also, I've hooked it to a code reader and there were no errors.

I have replaced the fuel filter, plugs and wires, and ran injector cleaner in the fuel system. Didn't help.

I appreciate any advice on how to fix this!
-Roger


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 19, 2010, 9:56 AM

Post #2 of 6 (3322 views)
Re: Hesitation when accelerating Sign In

Guesses - ideas + question:

Does this seem more like an engine issue or is it possibly staying locked in overdrive? At about 40 with little load the trans would normally lock to OD. If it stayed there with request for power it would fumble.

Basically I'm asking does it downshift properly in your opinion?

T



thepoores
New User

Apr 19, 2010, 10:39 AM

Post #3 of 6 (3318 views)
Re: Hesitation when accelerating Sign In

Good question. I believe it has an OD override button so I'll take it for test drive tonight with OD off and let you know what I find out.

BTW--forgot to mention that mpg has gone down too since this started.


thepoores
New User

Apr 23, 2010, 6:51 PM

Post #4 of 6 (3298 views)
Re: Hesitation when accelerating Sign In

Finally got a chance to take it for a test drive. Took it out of OD and it still does it. It definitely has to be warmed up before it happens.....that's the one thing I'm sure of. Any other thoughts?


Sidom
Veteran / Moderator
Sidom profile image

Apr 23, 2010, 8:07 PM

Post #5 of 6 (3296 views)
Re: Hesitation when accelerating Sign In

Get a can of mass air flow cleaner and clean the MAF. If you aren't familiar with where the wire is inside it may be better to get some tamperproof torx bits, remove the 4 screws and take the sensor out of the housing as opposed to just removing the assembly and cleaning the wire....



If this helps the way it runs you may really want to consider replacing the sensor. I've never been able to get these back to total fuel control by cleaning. I've seen cleaning cure drivability problems but the fuel trims never come back to an acceptable level....


(This post was edited by Sidom on Apr 23, 2010, 8:08 PM)


thepoores
New User

Apr 25, 2010, 10:13 AM

Post #6 of 6 (3278 views)
Re: Hesitation when accelerating Sign In

Okay, I bought the MAF cleaner and cleaned the MAF. I didn't take the sensor completely out but I did take the assembly out of the air filter housing. So I was able to see and spray the sensor wires. I also sprayed the connectors for good measure.

This did not seem to help though. I guess that doesn't mean the sensor isn't bad but they are $130 and I'd hate to buy a new one and that not be the problem. I have the Hayes manual for this car and will try my hand at checking the sensor with a multimeter.

Any other thoughts? Thanks for the suggestions so far.






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