Lump in idle Revisited

My 01 PT Cruiser had a very lumpy idle when the air was running. Thanks to
postings in response to my post I discovered the following.

The high speed fan did not come on when the air was running. This caused
Freon to escape the system reducing pressure in the system causing the
compressor to turn on and off rapidly.

I put in a new fan assembly and the fan works as designed now. Had a shop
re-pressure the system. Much better but not perfect. [May have a small leak,
perhaps in the evaporator].

Then I learned that Chrysler had changed the plug gap recommendation from
..05 to .04. During this regap procedure I discovered that the hose holder
mount had been placed between the intake manifold sections instead of on top
of the end section. With both issues corrected the lumps are purged from the
idle. Thanks for all the suggestions.

Richard

 

I think I have been telling you this from the beginning.

Glenn

 

Hi...

Accidentally discovered something interesting about the lump in
mine (94 lhs) today, and curious what might be causing it.

Was idling in the driveway today (full auto) when neighbour stopped to
talk. Rolled down the window. After a couple of minutes, cool air in
my face became unpleasant, so I pushed the AC button (to off).
A second or two later the engine rpm's dropped suddenly to about
500, then slowly came back.

Interesting, so tried it several times, same result. Seems the
engine slows when the compressor dis-engages.

Any thoughts?

Take care.

Ken

 

Ken, the program in the PCM is designed to raise the idle when the a/c turns
on and then lowers it when the compressor cycles off. This is normal.

Glenn Beasley
Chrysler Tech

 

Glenn, although the new fan assembly cured the lack of high speed fan out of
the assembly, it is strange that the old assembly did go into high speed
when I bypassed the high speed relay.

I know that Chrysler changed the spark gap recommendation for the normal
fuel injected enginein the Cruiser from .05 to .04, do you know if they did
this for other motors as well, and do you know the reason?

To anyone thinking of doing the fan assemble themselves in the Cruiser, I
can report that it is not so hard, takes about an hour the first time.

Richard

 

how about it's suppose to do that