My car makes a deep “voom” sound whenever I start the engine. It usually takes 10 - 15 seconds for the sound, but it always happens. The only thing I can think of is it may be coming from the antilock breaks mechanism. Could it be anything serious? The car still runs well for a 1998 Civic. Never had a major problem with the car except when the security system went up several years ago.
No I am not going with the ABS self test. Myself deep “vrooms” on Hondas point to the exhaust system,perhaps EGR tubing,something exhaust related.
A look under the hood at inital start-up may help pinpoint the failure,you may need to trace the exhaust back to the rear.
There is a high pressure pump that pressurizes the ABS system on start-up. That could be what you’re hearing. I suggest you have someone start the engine while you listen to and observe the ABS unit. You may find the noise is the ABS pump, or you may discover the noise is coming from elsewhere.