Rough Idle, hesitation

[PTEuclid]

2005 PT Limited...4 cly, automatiic...

Hicup in gear at idle....rougher w/ac....seems to be after about 10 seconds at stop...Seems to be intermintent......but mostly semi rough when it occurs...will repeat about 5 seconds between occurnances....when it happens..(If bad wires or plugs would this not be constant)...??? Puting into netrual does't seem to effect the stumble...
When giving gas after stumble or rough idle the Pt will take off without any stumble and will wind up to at least 4500+ rpm without any problem..
85,000 miles on PT...
hesitation after idle at stop...
new plugs at 75,000, with oil and oil filter change, and new air filter....at time of service complete running ok.....(Serviced at a Local Goodyear site) prior to this service ok with no problems....after about 2,000 miles starting to run rough.....
pcv working seems to be working ok......
use for courier service about 200 miles per day.....1000 miles per week mostly highspeed interstate...
gas mileage still good at about 26.5 ..........
no codes indicated by turning key on with odometer pressed...shows all but error codes...
no check engine light on....
slight stumble at about 50 mph on gear slection ......
Hot or cold weather doesn't seem to effect this condition...
any sugestions on what may be the problem would be a help to me...
thanks. PTEuclid.....

[CREWZIN]

You didn't say anything about changing the spark plug wires (unless I missed it). They are a sore (weak) point in the ignition system. Race & Street sells some excellent Crane wires. Here's a link...

PT Cruiser Crane Fire Wires: Race and Street

[fritz_t_coyote]

Originally Posted by PTEuclid

no codes indicated by turning key on with odometer pressed...shows all but error codes...

The 'key on, odometer button pressed' trick still does the dashboard test/display, but has not been a reliable way to get the codes since at least Model Year 2002.

Here is a more reliable way to get the Codes to display:
To get the codes, move the key from Run to Off to Run to Off to Run within five seconds.
It does not always work the first time.
(Run is JUST before Start).
The code will show up in the odometer - thank your lucky stars for this, since the codes used to get blinked on the engine light.
Alan Borgolotto noted that “if you do it too quickly it doesnt work (got to wait to see the odometer light up” and that if you have no codes, the odometer will say “done.”

Chrysler PT Cruiser computer codes

And as a shoot from the hips guess: Plug Wires.

[satellite66]

I was thinking maybe when they changed the plugs they messed up an o ring on the intake and you might have a small vacumn leak?

[PTEuclid]

Used WD 40 around the intake manifold with no change in the idle so I think the gaskets are ok...Thanks for the tip....

[PTEuclid]

Tried multipule time with your suggestion but got nothing on the codes...Thanks for the tip...

[PTEuclid]

No I didn't have the wires changed so I think I'll order from Crane as suggested..Thanks for the Info....

[littleblueGT]

You may want to check out Bosch Premium plug wires as they come with heat shields, and a life time warrenty. They cost the same as the OEM plug wires. You may want to consider cleaning the throttle body if you have that many miles on it.

[PTEuclid]

Thanks for all the help from PT Cruiser Forum..
I Changed the wires to Beldon from Napa (Premium Set) about $40.00 and changed the plugs (Champion 7570) which were changed at about 75000 miles, the wires were not changed at the time of plug replacement..Plugs were gaped at about .044 and I changed the new to .040...Old plugs did not look to bad....My new mileage is now at 87,000....Looked at throttle plate and it had some discoloration around the edges...This will be my next project...(now getting to fussy) This is a 2005 "B" engine and had no EGR tube at the back of the intake manifold....easy change following photos in other forum...dont't forget the antiseze, dielectric goop and torque to spec..Now the PT runs fine w/the AC on at idle...Did not change the intake manifold gaskets as they seem to be in good shape..I did buy a set from NAPA but did not use...The set from NAPA are blue and what is on the PT is orange...Didn't even check to see if they would fit...Just oiled up the ones on the manifold and put the manifold back on...You guys know your stuff...This all took about one and a half (1.5) hours with two beers to complete...No beer about an hour...Thanks again...Will check forums for the throttle body cleaning help...
PTEuclid (Gary).....

[strangelove]

What is the torque spec for spark plugs?