Intake air temp showed up as 203F. Normal?

[RickHaleParker]

Do you have a pic I can go by so I make sure I'm unhooking the right part(s)?

This is what Jimmy 57 is talking about.

There is a mechanical thermostat in the Air intake hose that switches over to warm air pulled around the exhaust when it is cold. It might be stick on warmed air intake.

[gnalan]

Thank you for that video. I will check from inside the air box and see if I can see if it's stuck open.

Can the two vacuum lines going to the airbox be removed without it causing any problems, and just cap it off at the intake manifold? Or maybe just cap off the vacuum line that goes to that thermostat at the airbox? I know that won't help if it's already stuck open, but maybe it might help after I get the heat flap shut so it'll stay shut. JB Weld, possibly?

[gnalan]

I pulled the fresh air scoop that feeds into the air box, and it is stuck open letting the hot air into to intake rather than the cool air from the scoop. This was with the engine off, though. I haven't checked it with vacuum to see if the flap will open the fresh air side and close the hot air side, but from the readings in VIDA, before I checked the flap, the temp just kept climbing. I'm going to assume either the thermostat isn't working correctly to open the flap, or I'm not pulling enough vacuum (possibly a bad vacuum line causing a leak?).

I see the two vacuum lines running from the air box, one to the intake manifold and the other to the thermostat that opens/closes the flap. Couldn't I just run a vacuum line from the intake manifold straight to the thermostat to see if the flap changes position? If that does work, would it keep the fresh air side open at all times while driving, and idling, or would it be variable based on the vacuum the intake is pulling?

(This is a non turbo car, just to be clear, so there wouldn't be any boost pressure from the intake manifold.)

[jonesg]

Do you have an actual problem that has symptoms like poor running, poor mileage?

[EngineeringBloke]

You should be able to detach each of the vacuum lines in turn, and check the vacuum on them with a vacuum gauge borrowed from an auto parts store.

You could try switching the two hoses connected to the air box, to see if that changes the flap position.

MAFs and MAPs

FYI. Pete's description earlier is not correct:

On turbo‘d P2’s the IAT is not built into the MAF. It is on the outlet side of the intercooler, just before the air goes into the intake plenum (pipe). It is also referred to (on turbo’d cars) as the MAP sensor or BPS (Boost Pressure Sensor).

For turbo engines, the MAP unit on the pipe from the intercooler to the throttle and intake manifold is a Manifold Absolute Pressure sensor and measures only pressure and not temperature.
https://www.denso-am.eu/products/automo ... they-work/

MAF units measure air mass. To do so, they determine a rate of cooling of a heated element which is maintained at a fixed temperature. This takes a measured flow of electrical power. It is also necessary to measure the temperature of the air at the MAF, as cooler air will look like a higher rate of air flow (as well as having a higher density and so greater air mass). Therefore there is an IAT in the MAF.

On my 06 turbo S60, the MAF has a visible temperature sensor (the termistor, a small cylinder with wires at each end) on the front of the MAF, plus a thermal plate that is hidden within an air channel (preventing contamination, according to Bosch). Before I understood this, I was only cleaning the IAT part, and missing the internal plate.

In the following picture, you can see the IAT on the top of the MAF, and the two openings for the air flow to the internal plate sensor:
https://www.autohausaz.com/pn/16934636- ... gLxffD_BwE

Bosch has a video that shows the S shaped duct that the air follows to get to the MAF plate. Diagram is 30 seconds into the video on this page:
https://www.boschautoparts.com/en/auto/ ... ow-sensors

Given your concern that the IAT may be reading high, I am not sure if contaminants on the visible thermistor would result in higher or lower readings but it would be worth cleaning, use MAF cleaner only as the sensor can be damaged by many other cleaners!

[jimmy57]

My favored method of defeating those doors when they stick is to use a drywall screw through a drilled hole on the flap run into the housing to hold it to cold air position. It is reversible. The drilled hole is to avoid the drywall screw cracking the door once it screws all the way down but he screw has not drawn the door against the stop.
I have fixed these when there was complaint of low power. 100F air makes for a better running car than does 225F+ air. heated already high temp ambient air can fail MAF sensors.

[gnalan]

My favored method of defeating those doors when they stick is to use a drywall screw through a drilled hole on the flap run into the housing to hold it to cold air position. It is reversible.

Do you have pictures showing how to do this, or a link to a video? This sounds a lot easier than what I was thinking of doing in my head.

The reversible part would also be helpful, so I still have the option of heating the air during the winter, assuming that's needed.

Has anyone done a fix like this, even through winter, and had any problems with the way the car runs? I saw something about the butterfly icing up, which doesn't sound like much fun if/when you need to stop in a hurry and the engine wants to stay running where it's at. Popping it into neutral would help stop the car, but it wouldn't do much for an iced in place butterfly.

[gnalan]

Do you have an actual problem that has symptoms like poor running, poor mileage?

Misfiring like crazy after the car is up to temp, and barely drivable through town now. I got 135 miles out of 7/8ths of a tank of gas on my last fill up, but I did/do have a fuel leak I either have fixed now or still need to fix.