Checked with "smoke' for vacuum leak? What about oil use,fouled plugs
You're an experience mechanic, so you probably already used some sort of fake smoke to check for a vacuum leak under the hood.If the leak was downstream of the air sensor, it would run lean,and would take a lot more RPMs to keep from stalling.
Does it use any oil? If it has developed blowby it might decrease the vacuum.Maybe you could pull a few plugs and see if they are oiled up?
Luck,
Charlie
PS I'm new-4 weeks-to Suburbans/Chevey trucks,so take everything I say with a huge dose of salt.
In the past folks would use WD40 spray or even starter fluid to check for a vacuum leak under the hood.If it was pulled in,the RPMs would change-usually increase.Always struck me as a bit dangerous(the ether/heptane in the starter fluid)
You're an experience mechanic, so you probably already used some sort of fake smoke to check for a vacuum leak under the hood.If the leak was downstream of the air sensor, it would run lean,and would take a lot more RPMs to keep from stalling.
Does it use any oil? If it has developed blowby it might decrease the vacuum.Maybe you could pull a few plugs and see if they are oiled up?
Luck,
Charlie
PS I'm new-4 weeks-to Suburbans/Chevey trucks,so take everything I say with a huge dose of salt.
In the past folks would use WD40 spray or even starter fluid to check for a vacuum leak under the hood.If it was pulled in,the RPMs would change-usually increase.Always struck me as a bit dangerous(the ether/heptane in the starter fluid)
