Engine pluse

[flalmondgt]

My PT with the AC on driving at highway speeds seems to pluse or slight jerk while driving. I put in new platitum plugs and changed to Crane spark plug wires. I was wondering if anyone has noticed this on there PT's. Does anyone have any suggestions on what it may be ? I hate to take it to DM they want too much to just check it out. Thank You FLSILVERPT

[Sci-Fi]

Might want to read this thread:

New PCM Flash for 5-Speed

and there was a TSB issued that may pertain to your situation:

Bulletin Number: 1802701 Component: Engine - Some vehicles may exhibit moderate to severe high way speed 45-60 mph vehicle surge. **TT PT 2001 and 2002

[BraytonAK]

I would think the shuddering feeling while your A/C is on is normal. Unless your PT is like mine and has a faulty A/C Compressor right from the factory. It's swell. And I did get the usual shuddering feeling when the compressor cycled off and on during that first and only moment that it functioned. haha

(That's what I don't like about A/C... It causes your car to feel like it's leeping forward or driving on Velcro.) I guess when my .5 Star dealer gets my compressor and console trim piece in stock I can have them Flash the computer, too.

[flalmondgt]

Thanks for the information on the TSB computer flash, I went to my 5star dealer and they knew about it. I had them flash the computer and it really did help, they said it would help out a little because of the lean condition at those speeds. I could really tell an improvement driving with the AC on, I do not know if it will change the MPG any but hope it will improve it. Has anyone had this done yet and did you notice any change in anything. Thanks for your help fellow PTENTHUSIASTS.

[dev]

Have a similar jerk at highway speeds.
Had the dealer flash TSB done. It did not fix jerk.
Am begining to think about plugs and wires.
Flalmondgt... you never said if new plugs and
wires fixed your problem or not?

[Overtake]

Even when I had my Lincoln Navigator with a V8, I'd feel that ever so slight jerk, whenever the a/c would kick in!

[Ali N I]

The AC compressor does not 'run' all the time, it has an electronic actuated clutch in it, as it locks up it will suck power from your engine inducing the 'pulse' The lower your throttle setting the more you will notice it.
It will happen, there is no true fix.

[MiniHemi]

FLalmondgt I was just wondering why your using platnium plugs and wires. I mean Platnium plugs hurt the performance but last longer from what i hear on here. So why use hi performance wires with them wouldnt that make them the same or less as your stock plugs and wires?

-Cory

[Mrspastor7]

Who else has this engine pulse/shimmey sensation?
If it's a characteristic, then I can settle but it's disconcerting.
Help!