Lump in idle Revisited

Jul 16, 2007 5 Replies
R

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


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M

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

Glenn

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K

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

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M

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

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R

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

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