Engine miss at idle / vibration while accel

[dustincayton4895]

1997 Ford Taurus GL 110,00 miles
Recent Trans Flush/Filter
New Ball Joints
New Driver CV axle
PASS CV EASILY COMES UNKNUCKLED

***01/28*** I've cleaned the throttle plate it's spotless... I assumed the throttle butterfly was stuck slightly open but it was closed but i cleaned anyway.

So I'm assuming an IAC can still work but not work properly? I did all the tests everyone keeps saying to do with the IAC.

As with the slight miss at idle what should I do with that.
I checked Plugs they all look good, I ohm tested all the wires they read good and look great. I water tested the wires as well in the dark and got no jumps... could my coil pack be intermittently missing? If so how come my CEL has never came on for a mis?

Engine at Idle has a slight miss that you can feel.
Engine Idles at 900 and perodically pulses from 600-900 give or take a hundred rpms

Normal Warm idle is 900 in neutral and around 650 in drive

Car seems to have lost power and shutters when accelerating gas mileage has gone down quite a bit as well...
(Fixed with new CV axle 1/26)

Was getting 300ish to the tank now im lucky to get 250 at the most

Need this car to last so any good and detailed information will help

[behlinla]

Idle should be roughly the same speed in park and in gear. You might need a new IAC.

Hesitation and shuddering could be a misfire problem (such as weak ignition), so I suggest you read our misfire topic: How to Understand and Diagnose Misfires

[dustincayton4895]

I understand how to check and diagnose a misfire... I do not have any codes logged into car... It always idles at 900 when in park or neutral, the only time I feel a "miss" is when it is idling its not noticeable unless you know what your looking for imo

[dustincayton4895]

ttt

[behlinla]

Originally Posted by dustincayton4895

Normal Warm idle is 900 in neutral and around 650 in drive

Speed should be pretty much the same in and out of gear. It's probably an IAC or a vacuum leak. Unplug the IAC with the engine running and see what happens.

[dustincayton4895]

I used brake cleaner/propane etc to spray all over the engine around intake/vacuum lines etc and failed to find a vacuum leak. I did fix the vibration while accelerating with a new passenger side CV axle. But today i noticed that every once in a while the car will idle itself at 900 and then drop down to 600ish but immediately go back up to 900. It's starting to bother me that I cant figure this out. I pulled IAC while running and car staled and would not start back up while unplugged but starts right up when plugged in.

[Breeves002]

Replace the IAC.

Clean the throttle plate as well.


Sent from AutoGuide.com App

[dustincayton4895]

Originally Posted by Breeves002

Replace the IAC.

Clean the throttle plate as well.

I've cleaned the throttle plate it's spotless... I assumed the throttle butterfly was stuck slightly open but it was closed but i cleaned anyway.

So I'm assuming an IAC can still work but not work properly? I did all the tests everyone keeps saying to do with the IAC.

As with the slight miss at idle what should I do with that.
I checked Plugs they all look good, I ohm tested all the wires they read good and look great. I water tested the wires as well in the dark and got no jumps... could my coil pack be intermittently missing? If so how come my CEL has never came on for a mis?

[behlinla]

Originally Posted by dustincayton4895

So I'm assuming an IAC can still work but not work properly? I did all the tests everyone keeps saying to do with the IAC.

Yes, they can stick intermittently. Cleaning them only works part of the time so they have to be replaced if they still are not working properly.

I water tested the wires as well in the dark and got no jumps... could my coil pack be intermittently missing? If so how come my CEL has never came on for a mis?

The CEL requires a certain threshold for a misfire code to set. If you have a slight or intermittent misfire it won't always set a CEL right away. Doing a spark test on the coil is easy enough to do and will rule out the coil as being bad (see video in misfire thread).

[dustincayton4895]

Originally Posted by behlinla

Yes, they can stick intermittently. Cleaning them only works part of the time so they have to be replaced if they still are not working properly.



The CEL requires a certain threshold for a misfire code to set. If you have a slight or intermittent misfire it won't always set a CEL right away. Doing a spark test on the coil is easy enough to do and will rule out the coil as being bad (see video in misfire thread).

Today after work I decided I would plug up my HEI tester to all my wires and check the output of the coil... Well While doing so I noticed that one of the back cylinders the spark plug was loose!!!!!! WTF so I checked all the wires and they are all good and coil checked out good I torqued down all the plugs and viola!!!!! Idle I now at around 800ish but doesnt have the miss feeling. Is this idle still too high? Maybe I'll get my power back now that I have all 6 cylinders again