Engine hesitates with accelerator push...

[Jake's Dad]

My 97 5.0 is acting a little funny. It starts and idles just fine (usually idles somewhere between 500 and 1000 rpm), but when you give it gas it sorta hesitates - and then "catches" up with itself - for lack of a better term. I end up just punching the accelerator to get it past the hesitation. This happens at all speeds. The engine never stalls, and the CEL is not on. All new plugs and wires done late summer.

Any ideas??

Thank you.

Jake's Dad

 

[Alec]

Do a check of your throttle cable and throttle body operation. Also check your MAS if you haven't lately. How is acceleration otherwise? Any knocking/pinging? Could be a fuel delivery problem.

 

[ChuckyD]

TPS?

 

[Jake's Dad]

Hi Alec-

There is no pinging - and I have yet to clean the MAF. I will clean up the MAF this weekend, but it could be something else. The fuel filter wa changed out this past summer.

ChuckyD-

I dont know what "TPS" means....

Thanks!

JD

 

[ChuckyD]

Throttle Position Sensor

 

[Jake's Dad]

Ahhh yes, you may be onto something there. Ill check into that possibility as well.

JD

 

[V8-X]

Sounds kind of familiar to my problem. So the hesitation is through all driving speeds? Does it seem to have a loss of power? Meaning it doesn't pick up speed as quick as it used to. Has the engine/exhaust tone changed? Any change in gas mileage? How many miles on the X?

 

[irtySanchez]

Originally posted by V8-X
Sounds kind of familiar to my problem. So the hesitation is through all driving speeds? Does it seem to have a loss of power? Meaning it doesn't pick up speed as quick as it used to. Has the engine/exhaust tone changed? Any change in gas mileage? How many miles on the X?

Hey! I have a hesitation problem also, and my exhaust tone has changed to a deep vibrating hum when I am stopped. What was the peoblem you are having?

 

[Jake's Dad]

I have not noticed any change in the noise level with the exhaust. I have about 79,000 miles on it. The hesitation happens at all speeds and is very annoying!!

JD

 

[V8-X]

I haven't been able to diagnose my problem yet. I have had the X into 5 different shops (2 Ford dealers & 3 independent shops), not one can seem to find a problem. I've replaced many parts, no luck. Finally I have a Ford Dealer that may be able to pull a 5.0 X off their lot to test side by side to my X. Hopefully they'll be able to find something. The following thread was posted by myself, regarding the problem I have.

Dead Link Removed

This next thread was posted by DarkFox1, who also has a 5.0 X that seems to have a similar problem as mine.

Dead Link Removed

Check both these threads and see if anything sounds familiar. So far DarkFox1 is the only person that I've found that has a similar problem. Neither of us have had luck finding what is causing the problem. We're both lost on where to go next, since all shops state that our X's are running perfectly. I'll keep you posted with the results that the Ford Dealer finds if they are able to perform the comparison test. No CEL is a bad thing, since nobody can seem to diagnose a problem without it. Good luck, and I hope it's not the same issue as DarkFox1 and myself.

 

[Alec]

irtysanchez:

Your problem is that you need a new IAC.

 

[V8-X]

It could be the IAC, but why/how? I've replaced my IAC, no luck.

 

[irtySanchez]

Originally posted by Alec
irtysanchez:

Your problem is that you need a new IAC.

I am not doubting you, but why do you say that?

Thanks!

 

[Alec]

from the moaning that you mention at idle.

 

[Jason_25]

Jake's Dad: Definitely clean the MAF with electrical contact cleaner. It will leave almost no residue on the filament wires and you can pick it up at most any auto parts store. If you can figure out how to remove the IAT on your V8 (I haven't) clean that too.

 

[V8-X]

I see now, mine does have a loud moan at idle, but unfortunately this is not my problem

Already replaced the IAC, and Ford double checked to insure this was functioning properly.

 

[ChuckyD]

so whats the verdict Jake's Dad?

 

[Jake's Dad]

Hey Gang -

Sorry for the late post. Well I cleaned the the MAF. It looked pretty darn clean when I got it off. I took the liberty of cleaning it anyway while it was off. I used rubbing alcohol. Anyway - it is having the same exact problem. I had the negative terminal off for a good 2 hours.

I did get a clue though. My problem is a hesitation from a dead stop, or when Im at a constant speed and give it a little gas to go faster. When I push the accelerator at these times - there is a strange slow tick, or popping that is coming from someplace behind the engine. Almost sounds like when you hold a PCV valve between two fingers, and shake it up and down like. That sound from the little ball in there.

What a bummer.

I dont think it's the TPS, only because the problem soesn't happen on the same place where my foot moves the accelerator. It depends on the initial push on the accelerator from a coasting fixed speed, or from a stop.

UHG!!!!!



JD

 

[Jake's Dad]

Hey V8-X - I almost forgot

A special shout out to you for all of your help.

One question for you - do you use an aftermarket filter?? What about DarkFox1???

JD

 

[V8-X]

Jake's Dad - I do have a K&N drop in filter on my X. This is the only Mod. I have on the X currently. I noticed a slight increase in MPG & power when first installed. This was 6-7 months prior to this problem starting. I did clean then I swapped out the air filter to insure this wasn't the cause of my problem, and it wasn't. I believe DarkFox1 has a K&N drop in, but I am not absolutely sure.

Jake's Dad, it sounds like the same problem I am currently experiencing. The sound from the back of the engine sounding like the PCV being shaken. Sluggish & slow when trying to accelerate from a stop, cruising speed or from a steady speed. Mine though, usually is dependent on the RPM's & MPH. At certain RPM's or MPH's, the problem is worse than others.