surge confusion.... please help

super51fan

New Member
Jul 28, 2010
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Indianapolis
Like i said several days ago. Have you unplugged the connector to ISC. Did the surging stop. If so why does the the ecu want to change Idle. I guess he does not want to do that. I don't know why?
 
Oct 11, 2005
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Thousand Oaks, CA
The ecu changes target idle speed very slowly. The surge is not from the ECU rapidly modulating the ISCV.

You can get a feel for how slow it is by driving with a cold engine on the freeway until it warms up, then pulling to stop. The idle speed will be initially high since the ECU has only the cold idle speed data in memory, then it will slowly ramp down to the usual 650rpm over many seconds, it is not fast at all.
 

suprunner

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Jun 22, 2011
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south dakota
super51fan;1964406 said:
Like i said several days ago. Have you unplugged the connector to ISC. Did the surging stop. If so why does the the ecu want to change Idle. I guess he does not want to do that. I don't know why?


(hunting this problem myself...) When I unplug my ISC, the surging continues... I'm not sure I'm able to keep up with what this should mean...


Thanks,

Greg