Vacuum leak?

93SVT

93SVT

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Truck is back on the road....again....finally. Weather is warming up so obviously the AC is getting used. I am noticing at idle when the AC cycles (dont know if that is proper terminology) the idle surges/truck lunges a bit. I have an old stupid cold air intake filter and that thing starts hissing real loud like it sucking in a lot more air when this change in idle occurs.

Any particular areas or specific things to check for vacuum leaks? I used to remember way back in the day people would spray (something) along vacuum lines to where you can detect leaks in tubing, is that a thing? If so what do you spray to find the leaks when it sucks in a leaking tube?
 
I would check the voltage at the battery when the AC kicks on. Do you have an electric fan that also comes on when the AC does?
 
Brake clean or starting fluid will work for finding vacuum leaks, if there is a leak the idle will increase, but the smoke detection is a safer way for testing.
 
FMOS Racing said:
The hissing is the IAC opening wider trying to catch up with the idle.
Click to expand...
I'll check voltage at battery but any guesses what would could cause the IAC doing that or are you just saying that's a symptom of the overall issue?

Sent from my Pixel 7 Pro using Tapatalk
 
93SVT said:
I'll check voltage at battery but any guesses what would could cause the IAC doing that or are you just saying that's a symptom of the overall issue?

Sent from my Pixel 7 Pro using Tapatalk
Click to expand...
That's just the IAC doing it's job.

If the battery has been disconnected or run down I would just drive it a while. Sometimes they wake up in a brave new world and need some time to figure things out.
 
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