Idle question 93 camaro 383

[stroked93camaro]

Just bought this car, so im learning as I go. The motor is fully built and when i start it it idles around 750 -850 then after it runs for a few mins it revs to 1200 and then idles back down to around 900 and thats where it runs. why does it do this. Im assuming its in the tune. Someone teach me on this.

Thanks

[Madman337]

To do a proper diagnostic you need as much info as you can give such as "what do you mean by built?" ect so post up everything you know about the car.
Think of it like this. You walk in to the doctors office and say "Doc my head hurts whats wrong?" At this point he will be guessing something like "maybe its a tumor (cue Arnolds voice there) but maybe its not"
There is nothing wrong with asking questions and I myself look forward to hearing the answers because I have a 93 too and they are a different animal than most you will hear about on here but dont count that against the good people here because they are very knowledgeable and will help you if they can but you need to give as much info as you can.
BTW please post up pics of your 93 ok :)

[stroked93camaro]

Ill post up some pics soon, As far as the motor goes it is a 383, forged eagle crank ,h beam rods,11.1 keith black forged pistons,cnc trick flow heads 185cc ,xfi 260/270 dur. 560/555-113 lsa comp cam, long tube headers that have been dumped,fireball ignition system.
Hope this can help.

[stroked93camaro]

Anyone?

[bobdec]

Idle speed is controlled by air flow into the intake. Normally two paths the TB blades s/b opened a crack, but the majority of air should be supplied from the IAC valve that is controlled by the ECM (tune). The IAC feeds the LT1 intake idle air runners and they distribute air equally to all cylinders, while the TB blades just feed the front cylinders first. An incorrect balance between TB blades and tune can cause incorrect idle RPM, rough idle, split BLM's (fueling) and hesitation coming off idle. Madman is asking as a lot of idle problems on modded setups are caused by TB blade adjustments, TPS sensor voltage levels, and corresponding IAC settings and readings from the ECM. Also to consider are vacuum leaks, EGR problems, etc. What's your intake setup, cam specs, valve train, is TB stock or aftermarket & what size TB. Is air, EGR deleted, and was ECM tuned for all the mods. Do you have data logs or scanned data when it's running fast, MAP, IAC counts, TPS voltage, left/right LT BLM's, coolant temp in ECM, also what injectors are you running would help isolate the problem.