[blixdevil]

I haven't been able to figure out why my Daytona has such erratic idle patterns. Most times it's fine but then I'll pull up to a light and it will be idling at 2200 for no apparent reason. Sometimes it will come back down, sometimes not. Then maybe at the next light it will be fine. Sometimes when I start it in the morning idle comes down to 900, sometimes it will shoot up to 2200 within a minute. Sometimes it's more like 1500 or 1600. It does seem to be happening more now that it's warm outside, but I'm not sure if it is a coincidence or not. There are no fault codes or anything. only other observance that I can think of is that it only gets 23mpg.

thanks!

 

[the_rabbit1]

IAC or O2 would be my first things to check

 

[blixdevil]

I replaced the O2 sensor a few months back, and the profile just doesn't seem to match the IAC. I mean it's obviously not stuck; there wouldn't be any mode of failure that I can think of that would make it have a mind of its own other than a intermittent connection, but all the connections appear to be ok.

I did find one problem though - in my infinite wisdumb I must have timed it with the coolant sensor connected. When I checked time it was fine when connected but then it jumped down to 4 degrees when I disconnected it! I'll take it out for a drive today to see how it did.

 

[Viper9087]

I replaced the O2 sensor a few months back, and the profile just doesn't seem to match the IAC. I mean it's obviously not stuck; there wouldn't be any mode of failure that I can think of that would make it have a mind of its own other than a intermittent connection, but all the connections appear to be ok.

I did find one problem though - in my infinite wisdumb I must have timed it with the coolant sensor connected. When I checked time it was fine when connected but then it jumped down to 4 degrees when I disconnected it! I'll take it out for a drive today to see how it did.

try changing the IAC motor, if they go out of adjustment or get clogged the computer constantly opens & closes it trying to reach the specified idle, unable to do so..

your coolant temp sensor when unplugged makes the computer go into timing adjust mode and attempts lowers the idle to 700rpm so this is normal.

another cause could be your throttle position sensor, or a vacuum leak

 

[shelbymonster]

and can be cam timing out one tooth