I've been having a rough idle issue. At first I figured it was the cc503, but I hooked a scanner up to it and my iac counts stayed between 10 and 15. Sometimes when I pull up to a light it acts like it's gonna die. Also if I drive to town and put the car in park it will idle at 1200, it's set to idle at 800. If I shut the car off and immediatly re start it it will idle at 800. Please help. I think my Iac may be faulty. Also my map is reading 14 to 15" of vacuum. It fluxuates between 14 and 15.

 

anyone? i could use some help. i would really like to get this fixed.

 

Who tuned it?

How does the IAC counts respond when "it acts like its gonna die"? .....when its idling at 1,200RPM? Have you verified the throttle is not sticking slightly open when its idling at 1,200rpm? What is the TPS voltage at these various idle values?

Vacuum seems OK for the cam. Just to clarify.... "MAP" isn't vacuum. To get the vacuum, you would have to subtract MAP from the BAR reading. It just happens that if you are at sea level (30"HG barometer) a 15"Hg MAP reading would equal 15"HG vacuum.

 

ion tuned it. my manual vac guage reads between 14 and 15 inches of mercury. it actually fluxuates quickly between the two. im sure my valves are adjusted correctly because i have zero miss at 5500 plus rpm wot pull. i think it may be my map seal. im gonna try that tomorrow. i have checked every other vac line. even the injector seals which are new. i used the right stuff on my egr delete plates so i highly doubt that i have a leak there. i now believe my iac counts are so low because of a vac leak, it doesnt need to open more because its getting air from where the leak is...

 

A 1" Hg fluctuation is not significant, unless it follows a distinct pattern, indicating its a misfire or a misadjusted valve on a specific cylinder. A misadjusted valve it going to be a lot more noticable at idle than it is at 5500rpm. Or maybe its a drippy injector, or bad compression on one cylinder. These things are often more noticable at idle.

Again, since you have a scanner, how does the PCM's IAC counts react when it feels like its going to stall? Does the PCM increase the counts to try and prevent the stall? How does the IAC counts react to the 1200rpm idle? Does the PCM pull down the IAC counts to try and bring the idle down? Do the counts bottom out at "0" under the 1200rpm idle condition? If the PCM is using the IAC counts to try and control the problem, and the system isn't responding, the IAC valve is suspect.

 

i have access to a scanner, ill hook it up again today. i doubt its a compression issue, its a brand new short block. i should have mentioned that to begin with. it has not even 700 miles on it. another reason why i dont think that its a mis adjusted valve is it didnt do it at first. im going to check my map seal and hook the scanner back up and i will post after that. thanks for your help.