DIY: Intake boot replacement. No more whistle while accelerating

I had to loosen the hose clamps A LOT and rub some soap around the openings of the boot. Maybe there is something better to use? Just make sure it dries before you start the engine.

Originally Posted by J1Productions

Im having a really hard time getting the lower intake boot back on, more so then getting it off, any advice?

If you have correct boots & With DISA out.. Prepare lower boot by Siliconing boot and throttle body so it will slip on. I used pool silicon I have for "O" rings.

Before starting Install/wiggle the spacer that connects the two intake boots together on lower boot. Sorta snaps in. Easy with silicon and not connected.

With the O ring clamp screw facing straight up, make sure "lower Boot lip tag" is between and on top of grooves (they stick up) that are on top of the throttle body, push/wiggle in, Check with mirror or with fingers that the large boot is correct. Find lip grooves before installing around one O'clock on top of throttle body about two inches apart.

Slip small boot hose on with clamp.. Tighten large boot screw with long flat blade screwdriver with handle coming down from cabin filter area. Again with fingers & inspection mirror check fitting. Tighten clamp on small tubing hose I had clamp screw facing toward DISA hole. Check again clamps and tighten again.

Hope you have checked, DISA gasket, pin, vanes and did DISA vacuum check by placing finger on hole. See DIY. Take your time with "Boots out". Feel/check the hose that comes from CVV to bottom of dip stick for breaks or plugged up. Squeeze lightly. Check bottom of Coolant & power steering resorvoir for leaks. Be carefull of "F" splitter on first intake now is the time to follow/inspect vacuum lines to ICV from "F" spliter.

When installing Airbox boot end, do not tighten clamp to lower boot spacer until you have manuevered boot around so it fits MAF correctly, and fully open. Clean you MAF....Not a bad idea either.. Worked for me CRC Mass Air Flow sensor cleaner..

Thanks alot for the quick response! Unfortunately I have no way of driving to autozone to purchase throttle cleaner and Maf cleaner, But I did still clean the throttle body with a rag. Could you link me to the DISA diy?

Originally Posted by SchatzieII

If you have correct boots & With DISA out.. Prepare lower boot by Siliconing boot and throttle body so it will slip on. I used pool silicon I have for "O" rings.

Before starting Install/wiggle the spacer that connects the two intake boots together on lower boot. Sorta snaps in. Easy with silicon and not connected.

With the O ring clamp screw facing straight up, make sure "lower Boot lip tag" is between and on top of grooves (they stick up) that are on top of the throttle body, push/wiggle in, Check with mirror or with fingers that the large boot is correct. Find lip grooves before installing around one O'clock on top of throttle body about two inches apart.

Slip small boot hose on with clamp.. Tighten large boot screw with long flat blade screwdriver with handle coming down from cabin filter area. Again with fingers & inspection mirror check fitting. Tighten clamp on small tubing hose I had clamp screw facing toward DISA hole. Check again clamps and tighten again.

Hope you have checked, DISA gasket, pin, vanes and did DISA vacuum check by placing finger on hole. See DIY. Take your time with "Boots out". Feel/check the hose that comes from CVV to bottom of dip stick for breaks or plugged up. Squeeze lightly. Check bottom of Coolant & power steering resorvoir for leaks. Be carefull of "F" splitter on first intake now is the time to follow/inspect vacuum lines to ICV from "F" spliter.

When installing Airbox boot end, do not tighten clamp to lower boot spacer until you have manuevered boot around so it fits MAF correctly, and fully open. Clean you MAF....Not a bad idea either.. Worked for me CRC Mass Air Flow sensor cleaner..

If you are just getting car going again you can do DISA and MAF when you have time but if DISA is out give it a good inspection.. Use light oil instead of silicon to put back in. Put sock in lower boot. This is a mechanical check only. If still in: Disconnect electrical wire to DISA. A Clip on plug to push in is on the rear of plug toward engine. Lift up. Careful not to drop bolts. Towel good idea under work area. Remove DISA with Torx 30 wrench. You will hear a little click as you break seat of the bolts. Remember pressure when you reinstall. Pull straight out and then tilt DISA toward firewall to fully remove. Ask yourself, did DISA come straight out easily or with a pull. Easy means "O" ring gasket needs replacing. My "O" ring was below groove. Get one on EBAY.
Inspect DISA valve vanes/flap for signs of wiggling/flapping. Should be firm. Check large pin at end that it is fully seated and does not stick outward or have any signs of cracks. I was reluctant to pull pin just looked. Any problem here, it is junk. Pin can be sucked into intake can destroy engine. I have read where you can pull pin out and flap for emergency use of your car awaiting new DISA. Now close Flap and release, does it feel smooth and fully open when released? A very slight bump may be felt when closing when first moved. Close Flap fully and look for a small hole by the diapham. With vane fully closed put finger on hole. Release flap. Flap should open slightly 1/2 " and hold, staying closed. Release finger over hole and Vane should snap fully open. Reinstall with new gasket allowing Torx screws to pull DISA in slowly. I used masking tape on bottom DISA screws to hold to TorX socket. Pull out sock install first boot. If DISA goes in with no pressure order a gasket.

Originally Posted by tbear325

I have a whistle at the beginning of acceleration but it disappears when you give it more gas. Lower boot is new and no codes. Any ideas?

Mine is the same. I tested it, at its at all RPM's. When I give about 10-20% throttle it will whistle. But not if I do more or less than that. It can be annoying though as the 20% throttle is my most common spot. Is this the intake boot or maybe something else?

No idea. DISA is new as are the lower boots and most of the vacuum hoses. No codes so I have no idea where to look.

Just wanted to say thanks to the OP. The clamps were a pain to access but worth it because it fixed the whistling problem! Thanks again.

Thank you for this DIY. This Helped fix my idle and got rid of the "turbo whistle..." I have a 99 E46 328i. My intake boot was very badly cracked, i'm surprised something worse didn't happen. I mean you can see through the hole.

This has been a probably for me for the past 40k miles, I've just overlooked it many times. Now that it's fixed, it seems as though my throttle response has increased. But on the other hand, my MPG dropped from 26 to 24. I have only driven close to 20 miles since the replacement.

I was thinking, this may be the MAF adjusting to the change? Does this sound remotely correct?

Thanks for the writeup! I definitely had to remove the cabin filter and the heat shield next to the brake booster. Also had to unclip the booster vacuum hose and fuel vapor return line from the manifold. The clamp holding the lower tube to the throttle body was easy to get with a 2' screwdriver from under the car. At least, it's easy if you _have_ a 2' screwdriver. The clamp holding the smaller branch of the lower tube was a mother to get at, ultimately requiring a 1/4" ratchet and a 2" extension and extensive contortions.

I was concerned that after all this work I'd still have my whistle, because unlike most of you, I did not have a SES light or any rough running. My whistle occurred at random times, throttle openings and RPMs. Happily, I found cracks thru each accordion fold of the small tube!! It just started pouring rain, so I'll get back out and finish up when the waether improves...

Taking a break. This has to be the hugest pain in the neck job I have ever encountered. The screws for the lower boot clamps were in absolutely the worst position possible. Also three of my fingers are taped together because of a tendon injury, so maybe I shouldn't have attempted this. Oh well, it's done, now I just have to put it back together.

Also, the vacuum hose on the f connector for the fuel filter was so brittle it just fell apart, so now ill have to fix that...

Originally Posted by urbankyleboy

ahhh i just did this and let me tell you it was a huge PITA!!! the bands in step #11 were facing to where i couldnt get at them! i ended up using a ratchet that would fit over the screw.

I agree to the second power, then squared!

Please forgive, if this was answered earlier, as I just found this thread and it's just after 6 a.m., but I'm heading out to pull a few things off, so I can hopefully put my car back together having been screwing with this p.i.t.a for most of yesterday.

Questions, is there a one piece intake bellows now available? I see in the diagram, linked here, that the lower hose has been discontinued. Or am I to assume, that I just order a new one as if my car were a June of 06 car?

Just finished! 6hrs. What a complete pain!!!!!!!

I did the temporary patch on all the cracks with super glue, then heard the crunching of the super glue as I try to reinstall the the bellows, so I took some silicone and smeared it in the ribs at the bends and around other areas. Not the cleanest looking but difinately airtight now!

What codes are you showing?

I'm getting po491/492...

Took it to my indy he says needs new air pump/vac lines... going to drop it off on friday to have him do a smoke test?

I am dealing with RPM fluctuations at idle on my 325i 5MT 2001. I also have the whistle...

Looking for guidance... thank you!

My car has 168,000 miles and is a 2001 E46 ZHP 330i.
I have had a crazy whistle from my engine ever since I took it to the auto mechanic for an air leak I gave up on. My engine runs great. But gas mileage is very poor and I get a LOUD whistle until the engine is completely warm. It whistles at idle, when accelerating and maintaining speed. I just did this "Intake Boot" write-up DIY today. Used a factory boot. All went very smooth as I read this FANTASTIC write-up before proceeding. The whistle is still there. I see many references to possible pulley/tensioner being the source of the whistle. Are these parts expensive? I consider myself really good at DIY, but no master as I need to do research before I take on any task beyond brakes & oil. Would it make sense to just replace these parts, anyways? I plan to keep my car as long as possible... My goal is 1,000,000 miles. Any feedback is appreciated.

Where to buy both lower and upper tube for a 2001 325i sedan??????????????

Originally Posted by Rezist09

Where to buy both lower and upper tube for a 2001 325i sedan??????????????

Sponsor sites on here. Take a look at the top of the page. I needed 13 parts total just for this diy and a couple other random things. Some sponsors didn't have the parts I needed and ordering from different websites pretty much came to the same amount I paid to get it the next day from my dealership.



Thanks for the write-up ///M=Power.

I finished this yesterday. The lower intake boot's clamps were pointing towards the back of the car, at an aggravating angle. I don't have a flexible socket extension (like these: http://www.ebay.com/itm/350679813836 - which would have helped out a lot!), so I removed a bracket that was holding 2 lines, which is located to the right of the lower intake boot. Doing that made the job easier.

I also removed the throttle body and cleaned it. Mine looked pristine on the outside, but the inner part was dirty as hell. I'm not sure how just spraying tb cleaner from the outside (even with the flap open) like I've seen people do in most dyi videos would get it as clean as removing it. You'll also need to replace its gasket if you do.

My icv gasket was black as night on the inside, but was still rubbery, no cracks, not hard so I just cleaned it thoroughly. The icv slid back on easy afterwards. So, just clean it out unless you want to blow $20 on a small rubber piece.

And don't be an idiot like me and forget you have the black plastic firewall piece on a table behind you after you've put everything back. You'll never get it after you put your boots on.....believe me I tried swearing up a storm before giving up and taking the new boots completely off just to slide that piece back in.

Thanks for the DIY, helped me out today while I was replacing the lower boot, cracked with 136k km's on it. The screws on the lower end of the intake were turned upside down, which made it such a PITA to get at. When I installed the new ones, I made sure to keep the clamp screw on the top of the tube.

nice writeup man, i also had this high rev whistling sound, but when i checked lower and upper intake boot was in good condition. what else could add up for this whistle?
sounds like my car had turbo in it :p

Great thread and DIY

Replaced my boots last night while doing my CCV and DISA. Well worth the extra $30. Make sure you align the hose clamps to where you can get to them. The idiot who had worked on the car before me pointed them in the worst direction ever.