Shaky Idle

[03hothemi]

Originally Posted by mopar_man

Here's one check for the head gasket without tool requirements: let the engine cool to stone cold. Remove the radiator cap and start the car. See any bubbles in the coolant? Besides doing the pressure check, you might want to borrow a compression tester. You sure have pulled up a dandy problem here. It'll be interesting to see what it finally ends up being.

The bubble test you mention above is exactly the reason I didn't/haven't up until now suspected a head gasket problem.

[03hothemi]

I haven't had a chance to put the new plugs in...but is it a possibility that during the stint of time that the cooling fan did not work, that if the pop-off valve on the AC compressor went off and released freon multiple times, that the freon is low on the low side and the ac compressor doesn't like it? Just a blind shot in the dark because I notice the rough idle when the AC compressor is kicked in. I won't say that it isn't there when the AC compressor is not on, but it is very evident in that I can see the hood shaking when the AC compressor is on.

The car will idle steadily at 700-750 RPM all of the time, so I don't think it's the IAC (I've cleaned it anyway) or an injector problem(would notice that more on takeoff).

How about EGR issues? I kow my old Fords would darn near die if the EGR valve went bad.

[quicksilverdon]

Originally Posted by 03hothemi

How about EGR issues? I kow my old Fords would darn near die if the EGR valve went bad.

EGR went away after '02, but the PCV valve is a possibility.

[03hothemi]

Well, I checked and cleaned the PCV valve, but for 4 bucks, its probably worth replacing, huh?

[03hothemi]

Took a while...but I finally got back to working on the car. Been way too busy at work the last couple of weeks.

I went ahead and changed the plugs, wires and PCV valve. I installed Champion Platinums, Borg Warner wires, and and oreilly's brand PCV valve. I went ahead and gave her an oil change and air filter while I was in there. All of this is now new, complete and right, and there was NO change in the idle.

I did notice that the upper and lower motor mounts were completely shot, so I am off to oreilly's to pick those up too. When I got the mounts off to inspect, both of them fell apart in my hands. Maybe that's it? Not sure...we'll see in a bit. How hard is it to change out the center mount on the drivers side? I'm starting to think that at only 52k I'm gonna have to replace the timing belt, so maybe I'll do it then.

On edit: It seems that the motor mounts being bad were not the cause of the shake. New upper and lower mounts have been installed, and the shake is still there.

Please keep in mind that the idle is not erratic, and it is not missing erratically. It is a constant shake that disappears off of idle. This is really starting to frustrate the heck out of me...

[irishman331]

I was really hoping to see you fix this because my son's '05 does exactly what yours does. I have replaced the lower mount, PCV, plugs (although I used Bosch quad tip), wires, air filter, checked the same as you for vacuum leaks, etc.
His also does not miss, it's just a rough idle and it gets much worse with the A/C on. One thing in common maybe is that I noticed the A/C cycles a lot and I'm thinking it could have had a leak somewhere along the way and possibly is low on juice.
Like yours, his has no other driveability problems whatsoever. Gets 23 combined, acceleration is probably as good as the 2.4 Non turbo gets. However, his actually will die if let alone to idle with the A/C on but it takes a few minutes.
Now one thing I noticed is that with or w/o the A/C on, if I decel fast, for instance if it's in gear and I were to hold the brake and raise the throttle, then let off suddenly, it wants to die.
Other than that, as soon as I see yours get fixed, maybe I'll know the answer to his.

[03hothemi]

The only difference between yours and mine it seems would be that yours tends to die. Mine never has.

As soon as I get the front end rebuilt on my Ram, and get her back on the road, I'm gonna tear into the PT to see if the timing belt needs to be replaced. Other than that, I have no codes or other diagnostic tools to work with. Maybe its an injector imbalance or catalytic converter starting to clog...hmmmmmmm...what a pain.

[fljohnboy]

Seems like this has been quite a problem for many on here. I'm thinking has anyone ever gone to the dealer and addressed this problem? I have a 2005 GT I bought about a month ago with 61k miles and have the same problem. I replaced the wires and plugs and that did nothing. It does idle smoother with the a/c off. I notice that rpm doesn't drop at all with the a/c on or off so it's not an idle too slow thing. I'm thinking of taking the accessory belt and running the car for just a moment and see if there's something in that area that could be causing the problem. Anyone have any ideas to this?

[Hooligan]

fljohnboy, the problem as I see it, is that people ask questions about problems, find the answers and they never return to tell what the outcome is!!! It certainly doesn't help the ones that tried to help as well as those that may have the same problem.

[fljohnboy]

Originally Posted by Hooligan

fljohnboy, the problem as I see it, is that people ask questions about problems, find the answers and they never return to tell what the outcome is!!! It certainly doesn't help the ones that tried to help as well as those that may have the same problem.

Yep, totally agree. I've been on different forums with different cars over the years and that's the way it seems to be.