Thread: Whistling at 3k RPM likely vacuum leak

About 2 months ago I suddenly started getting a whistle when holding the engine rpm between 2,500 and 3,000 RPM while in drive. I have checked and replaced all other small vacuum leaks I had by redoing the vacuum lines and getting a brand new north star throttlebody gasket as well as resealing my adapter. The whistling sounds like it is coming from the driver's side of the engine bay. I have gone through three cans of carb cleaner and can't locate the leak.

Since my car started with the whistling sound my engine also stalls whenever I crank it. I have to keep the throttle slightly open for the engine to start. I have been getting terrible fuel economy of about 15 highway and 10 city. Oil and transmission fluid levels are fine. Has anybody dealt with a similar situation? I am open to suggestions as I am all out of ideas.

Swap back to a stock throttle body??

Are you even getting a lean code?

No lean code. Looking at my aerofoce my long term fuel trim tends to go to 11.xx to 13.xx while driving then climbs back down to match single digits.

Would it be possible that a pin hole leak either on the egr tubes or manifolds could cause this vacuum leak/whistle? My car does have 204,000 plus miles.

Bump!

try leaving it in 1 st gear and run it up to the rpm's that whistle. maybe its just wind?

It is consistent with RPM. Also my fuel economy is horrendous getting about 9-10 mpg. Still can't figure out the location of the leak. I can vaguely hear a puft puft at idle around the area where the egr is. I have sprayed the crap out of that area with carb cleaner and found no leak that way. THinking my next shot in the dark is to delete the egr and see what that does.

Since the whistle started out of the blue one feezing cold sunday morning as my car stalled (since then it stalls every single time I crank it) my guess is that something gave out. Redid all the vacuum lines after that and the noise is still there. With the high miles maybe a seal gave out in the egr?

id think a egr code or lean bank one code would have popped up by now.

egr tubes have been known to crack for no reason. and stalling can be vac leak related for sure. maybe worth deleting it to see if it stops.

Oddly enough no check engine light. I need will check the Aeroforce to see if there are any pending codes stored. I will deleter the egr this week (after I get my inspection done) to see how it responds. I am 90% sure that my vacuum leak is from that corner of the engine bay.

UPDATE! Had the engine smoked to uncover vacuum leaks or blown gaskets. The engine is sealed up tight. The mechanic mentioned that the engine is tight as a newly rebuilt engine. So now I am 99% sure it all along has been the Idle Air Control. Wiring is fine and ran the engine at idle while sputtering the IAC plunger kept opening and closing erratically. Makes sense that it made an induction whistles as it is opening and closing when it is not supposed to. Also when there is extra load from the AC or alternator load from the headlights or radio the car starts trying to stall again. I will swap it out tomorrow and report back. Looking forward to having a properly running engine again and finally be able to tune it.

Confirmed the Whistle was from the IAC not properly closing at throttle. The old IAC fell apart when I was trying to install a new one. Next I noticed that the faulty IAC was an incorrect one! It did not even seal properly and someone installed it with RTV to get it to seal. The car runns great. Need to reset the fuel trims and my fuel economy, but today my fuel economy went from 10 MPG (broken, incortrect IAC) to 19MPG mixed city highway.

nice find.

There ya go..