Replacement of Air Intake Lower Rubber Boot

[pina4greg]

I recently replaced the Lower Rubber Air intake boot of our Z3. Had read and researched a bit and can confirm that it is a relatively easy job other than the location of the hose clamp screws. They must have been the original ones from our 2000 2.0 litre as the would have been easier to access from underneath.
I actually purchased the boot from a supplier in Latvia. And when it was taking too long to arrive i ordered from the US and of course just after the second order the first arrived so i had two. They are not a very good design as the bend in the hose arm is very kinked and would be better having been redesigned to go straight to the upper connection. see photos. The original piece was quite perished after all these years. Car was starting to idle a bit rough and also there was a high pitched whistle when accelerating from a start. Had to use a wobble tool to bend around and onto the screw heads. Have placed them in an easier location for the next time. But if its not replaced for another 15 years then it would be fine. I did not try to remove the vacuum hose from the upper boot as it was not cracked and i thought that if i tried to pry it off the older rubber would have been damaged and i did not order that part. In hind sight it would have been better to replace both.

 

[GazHyde]

That's a great write up - thank you!

I've done a few of these and they can be infuriating to seat and then tighten up. The newer less pliable rubber doesn't tend to help either.

Good work

 

[t-tony]

A 1/4" drive socket set which includes a flexible drive are invaluable, also I have a Bosch IXO screw driver which is fantastic kit for these jobs, saves on the knuckles no end.


Tony.

 

[miller1098]

Flexible drive.........my favourite tool to use in the whole toolbox

 

[Gjewing]

Z3 - called Ziggy - Had an erratic idling and uneven running issue and the EML and ASL warning lights started to come on intermittently. My mechanic had a look and the computer diagnosis said that the Throttle Position Sensor was faulty. Apparently on this 2.0 version the sensor is in the throttle box which would need changing at around 800 euros. Then he spotted a leak in the lower air intake boot and tried to seal this with silicon - which lasted a couple of days. So I ordered a genuine BMW lower air intake boot and fitted it myself. Upper intake boot looked OK so did not change that. After fitting the lower boot she sounded great so went for a spin and she drove beautifully for 10 miles but then started to get blowy and lumpy again and the EML and ASC lights came on. Managed to limp home. On arrival she sounded OK on tick over and the EML and ASC lights went out. Checked all the clip tightening and all seemed fine - I am confused and would appreciate any help from the forum.

 

[colb]

If after checking all the intake rubbers joints are tight and sealed the next check would be to smoke test it, that will reveal any air leaks you may have right across the engine and vaccum system. If you find any leaks then replace the offending hose/pipe and tighten the clips.
If you have diagnostics code reader that can view fuel trims live data have a look to see if they are reading high. If high thats a pointer to the exhaust sensors picking up more air in the exhaust than the Maf has reported going in, hence the car thinks its running lean and will put more fuel in at the injectors to correct what it sees as a lean mixture. Will keep doing that until it is adding 20% more fuel then gives up and sets the EML. Your mpg will be reduced if its seeing unreported air getting into the system as it tries to compensate by adding fuel.

 

[Gjewing]

I have fitted the lower air intake boot on the Z3 and checked all the joints and everything sounded great but after a short spin of 5 miles the same problem occurred. EML and ASC lights came on, engine kept stalling or running lumpy. We managed to get her to limp home and, again, on idle she sounded fab. My code reader said that there was a fault with the throttle position sensor. Previously my french mechanic had the same fault come up on his reader. The other code that came up in the diagnostics was issues with rich/lean mixture. My french mechanic says that if I order a throttle position sensor it has to be programmed for my Z3 - can anyone comment on both the need for a throttle position sensor and whether it requires programming? Cheers!

 

[Gjewing]

Apparently, the Throttle Position Sensor on the version of the Z3 is in the main throttle assembly which is expensive to buy and fit I believe.

 

[bear2020]

Mine had split in exactly the same place. I found the easiest way to get the bottom air intake on was to apply a tiny amount of silicone spray and it slid on with no problems and a ratchet screwdriver meant it was easy to tighten the jubilee clips up

 

[bear2020]

Z3 - called Ziggy - Had an erratic idling and uneven running issue and the EML and ASL warning lights started to come on intermittently. My mechanic had a look and the computer diagnosis said that the Throttle Position Sensor was faulty. Apparently on this 2.0 version the sensor is in the throttle box which would need changing at around 800 euros. Then he spotted a leak in the lower air intake boot and tried to seal this with silicon - which lasted a couple of days. So I ordered a genuine BMW lower air intake boot and fitted it myself. Upper intake boot looked OK so did not change that. After fitting the lower boot she sounded great so went for a spin and she drove beautifully for 10 miles but then started to get blowy and lumpy again and the EML and ASC lights came on. Managed to limp home. On arrival she sounded OK on tick over and the EML and ASC lights went out. Checked all the clip tightening and all seemed fine - I am confused and would appreciate any help from the forum.

Is there any gaps around the upper intake and the MAF? If it is not seated correctly it will leave a gap and run rough. I looked at a friends mates one and noticed a 5mm gap around the MAF once I took everything off and reseated the MAF in the upper cleared the codes & lights it ran fine and has done so for the past few months. Sometimes it is the simple things we fail to see that cause the problems. Might be worth checking that

 

[Gjewing]

Thanks Bear2020 - MAF meaning Main Air Filter? - checked this and all looked sound. I have never fitted a lower air intake boot before and the lower jubilee clip is difficult to check especially underneath so used a small mirror to see if it was sound - looks OK from my untrained eye and certainly does not move suggesting it’s tight.

 

[bear2020]

Thanks Bear2020 - MAF meaning Main Air Filter? - checked this and all looked sound. I have never fitted a lower air intake boot before and the lower jubilee clip is difficult to check especially underneath so used a small mirror to see if it was sound - looks OK from my untrained eye and certainly does not move suggesting it’s tight.

MAF Mass Air Flow sensor its the bit that fits inside the air filter and the upper intake hose with the electrical connection. It will run rough if there are any gaps. If you unplug it the car will drop the revs and try to stall.
The bottom air intake has a tag on it that locates on the throttle body so it is quite hard to put it on wrong

 

[Gjewing]

Thanks - just watched a YouTube video on how to clean the MAF - looks easy enough but would a WD40 or equivalent be good enough - on the video the guy uses a special MAF cleaning spray?

 

[Gjewing]

MAF Mass Air Flow sensor its the bit that fits inside the air filter and the upper intake hose with the electrical connection. It will run rough if there are any gaps. If you unplug it the car will drop the revs and try to stall.
The bottom air intake has a tag on it that locates on the throttle body so it is quite hard to put it on wrong

Thanks - just watched a YouTube video on how to clean the MAF - looks easy enough but would a WD40 or equivalent be good enough - on the video the guy uses a special MAF cleaning spray?

 

[bear2020]

Thanks - just watched a YouTube video on how to clean the MAF - looks easy enough but would a WD40 or equivalent be good enough - on the video the guy uses a special MAF cleaning spray?

I personally wouldn't use WD40 as it leaves a residue and why normally you would use something like isopropyl as it will evaporate. In the past with air induction kits I have had on other car I've had numerous problems with kits that use spray oil to attract the dust play up when it gets to the MAF. I only use non oiled panel filters in any car. I have used 10k to clean MAF,s and isopropyl (which is cheaper)

 

[Varptr]

Great article, thanks. I’m about to replace both hoses on my 2001 3.0. I have a split in the same part as well. Both hoses bought from Amazon.