[aiwasoundsystem]

Heya guys, got a new one stumping me. When I am driving down a level or slightly inclined up road, if I take my foot off the gas and put it back on to maintain speed it maintains RPMs for a moment and then drops about 200-400 rpms and randomly starts a vibration that shakes my whole car. This happens both in and out of Cruise and only in Overdrive. I can purposely make it happen as I did in the following video.

The CEL is for insufficient flow in the EGR. My question is could the EGR cause this and if not where should I be looking or testing?

This started randomly about a month ago, and once the vibration is going if I keep trying to maintain through the vibrations the RPMs start surging and the car will finally downshift. To make the issue go away all I have to do is take my foot off the gas for a moment as you can see in the video.

Also, I never noticed before but when the shuddering/vibration start the RPMs jump.

I couldn't get the youtube tags to work so here's the link.

http://www.youtube.com/watch?v=0kP2QSaItQA

 

[aiwasoundsystem]

Here's what I've done recently to correct the issue:

Replaced PCV hose as the bend was collapsed with a hole in it.

MAF sensor cleaning.

Front Sway bar link replacement of both links (I know one was bad)

Had all motor mounts checked.

Replaced Tensioner arm in accessory area due to it being damaged. I also replaced serpentine belt and water pump at the same time.

Oil changes and all other scheduled maintenance have been done on time.

I really need some help here guys, this is my daily driver and I'm stumped as to the cause of this one.

 

[aiwasoundsystem]

Can anyone help me with this, it is really starting to become a concern for me.

 

[sleepyboy]

When you say motor mounts checked what do you mean? They can look good and still be bad. The passenger side one is notorious for looking ok but being bad. You don't see it till you get it off and look at the under side of it.

 

[Fucus-minded]

do you have an a/f gauge? is the car leaning out during this?

 

[aiwasoundsystem]

When you say motor mounts checked what do you mean? They can look good and still be bad. The passenger side one is notorious for looking ok but being bad. You don't see it till you get it off and look at the under side of it.

Did the hold the brake and gun the engine test. Also, had a mechanic I trust check them out. But, I can inspect them individually. I've had the Passenger one off before, could you tell me what I'm looking for on it so I can check it?

do you have an a/f gauge? is the car leaning out during this?

By a/f guage do you mean an air/fuel guage? If so then no, I don't have one. I can swing in Autozone tomorrow and see if this is something I can use. Also, thinking of getting a fuel pressure guage and checking that also.

Thanks for the help guys I'll get back to you with the results of what I find this week.

 

[sailor]

To answer the first question, Yes - I've seen EGR issues cause 'driveability" issues B4, and not just on a Focus.

Occasional "bucking" at steady light throttle, not responding "normally" to slight throttle changes are some of the symptoms similar to yours I've seen before...

So fixing a "known" issue might solve your problem...

Luck!

 

[alz focus]

FYI, no shrader valve on these cars to read fuel pressure.

 

[aiwasoundsystem]

To answer the first question, Yes - I've seen EGR issues cause 'driveability" issues B4, and not just on a Focus.

Occasional "bucking" at steady light throttle, not responding "normally" to slight throttle changes are some of the symptoms similar to yours I've seen before...

So fixing a "known" issue might solve your problem...

Luck!

I'm going to replace it tomorrow, doesn't look like I'll have any issues. Will test and let you know

FYI, no shrader valve on these cars to read fuel pressure.

Last pressure guage I used, on another car, just mounted in place of the fuel filter. I'm sure there is some point I can attach the guage in-line if I can't use the filter's spot. Gonna try the EGR first though.