Dodge RamCharger Central banner
1 - 15 of 15 Posts

·
Registered
Joined
·
406 Posts
Discussion Starter · #1 ·
Having a hard time finding any info in my manual about adjusting the ISC for cold start only?  When I start my 89' idle goes to almost 3K, but curb idle is fine and I live in a warm area.  Can I back off the ISC a little  for cold starts and not affect curb idle?  Tried a search but didn't see anything.  Thanks in advance
 

·
Registered
Joined
·
2,365 Posts
while it could be the ISC, to flare that high usually is a vacuum leak, bad CTS or bad air temp sesnsor in throttle body
 

·
Registered
Joined
·
406 Posts
Discussion Starter · #3 ·
Hmm...It runs beautifully the rest of the time.  Does that eliminate any of those possibilities?
 

·
Registered
Joined
·
13,500 Posts
that electric thing has a certain lenght of throw , or stroke to it . follow the instructions ( here somewhere ) and adjust it , but what jersey is sayin is its hard to believe it goes from 3 k all the way down to normal 700 or so idle speed . you must unplug the 2 wire temp sensor BEFORE adjusting ( 2 wire not the 1 wire sender for dash )
 

·
Super Moderator
Joined
·
14,330 Posts
Check codes, check for vacuum leaks as mentioned, and follow procedure:
 

Attachments

·
Registered
Joined
·
406 Posts
Discussion Starter · #7 ·
So, it seems the RPMs are where they should be.  Just seems a little high for the climate I live in.  Kind of a scene to start it up and have it go so high with Magnaflow dumped in the land of prius.
 

·
Registered
Joined
·
13,500 Posts
so slow it down some , no harm done ... does it drop if you "goose it" ? try changing the engine temp sensor ( 2 wire sensor not 1 wire temp sender )
 

·
Registered
Joined
·
406 Posts
Discussion Starter · #9 ·
Sorry, that was my original question...Does the ISC just perform "choke" function or does it change warm, curb idle if adjusted?
 

·
Super Moderator
Joined
·
14,330 Posts
The choke equivalence is inputs to the computer from the coolant temp sensor and throttle body temp sensor.
 

·
Registered
Joined
·
13,500 Posts
yep it changes the throttle stop when it warms , it "knows" its warm when the inputs listed tell the puter , so , miss-adjustment ( 1 time only when newly installed type thing ) or failing sensors can cause it to "stick" like a choke, or respond later than it should . My '91 throttle body will idle fast for a little when started in COLD weather , goosed it will return to a slower idle . It will also idle up some if working the power steering alot at idle , the puter knows the idle speed got below set rpm's and triggers the idle air motor to " correct" the rpm's .
 

·
Registered
Joined
·
27 Posts
sorry,  I know this is an older post. 90 TBI 5.9  I have viewed my ISC is working when key is turned to on,  Have not put a tach on it but have zero complaints about idle working, warm, cold or A/C on...  only have a condition  where my idle will climb or hang for about 2 seconds after you tap throttle. comes back to nice idle but there is this little rev 1st???  I can see the ISC is slow to come back to idle position, even when fully warmed up. Does or could this mean the ISC is out of adjustment? Have not located any vacuum leaks so far but that does not mean there isnt one. thoughts?
 

·
Super Moderator
Joined
·
14,330 Posts
legit said:
sorry, I know this is an older post. 90 TBI 5.9 I have viewed my ISC is working when key is turned to on, Have not put a tach on it but have zero complaints about idle working, warm, cold or A/C on... only have a condition where my idle will climb or hang for about 2 seconds after you tap throttle. comes back to nice idle but there is this little rev 1st??? I can see the ISC is slow to come back to idle position, even when fully warmed up. Does or could this mean the ISC is out of adjustment? Have not located any vacuum leaks so far but that does not mean there isnt one. thoughts?
If you look a few posts up from here, did you set the idle procedure? Second, check for error codes. Lastly, you should start your own thread with this information.
 

·
Registered
Joined
·
1,637 Posts
Brand new vehicles also do that, hanging high rpms for a few seconds  that is
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top