Below Nav Bar Ad Module

**Tonestar** · 05-02-20, 05:30 PM

Originally posted by disco stu View Post

Hey all. So I'm down to the fiddly things to get everything sorted for this engine to go back in. Want to clean the maf sensor. 3.5l v6 petrol engine

Looking at it, I can't see where the actual air flow sensors are, just the zener diode looking temp sensor. So I'm wondering about dismantling it all to give it all a proper clean, but nervous about damaging something. There are the screws on the electrical connector, plus the tabs holding the large black square cover on top. I've taken that cover off but doesn't actually give me access to the internals. Electrical connector has a lot of resistance to being pulled out, so didn't want to force that.

Can you dismantle these for a full clean? Would appreciate a few hints of anyone knows

Note: I'm aware of maf cleaner spray etc etc

Thanks in advance

Stu

Don't dismantle it, the MAF sensor was not designed as a fixable part but to either be replaced or cleaned with a cleaner spray. The best way to do a clean is to use the spray as it is a chemical solvent for what needs to be cleaned. Always ensure you clean the MAF sensor every time you replace the air filter, which should be at every service interval at least.

**disco stu** · 05-02-20, 07:00 PM

Cheers. Finally figured out it was Doppler or similar, so I figured it wasn't with trying to clean to the level I was intending

And as an addition to the maf cleaner vs electronics cleaner argument that seems to be ongoing in many forums-compare the msds of some and you will see no difference....except price

**stumagoo** · 05-02-20, 07:32 PM

the MAF in our wagons has a thermo resistor or similar in it.... the ecu heats it to a set level and the more airflow over it the more it is cooled (or the more power it requires to be heated to its set level) this is what gives us our airflow measurement --- add to that they are a partial sample unit (notice the plastic framework behind the honeycomb) the air folw is basically measured in its segment and then multiplied by the ecu to allow for the total airflow. This is where pod filter adapters can stuff us up. most have a base plate with a round spigot --- if you look through this reduces the area of air flow onto the sensor. basically more of the air is being pushed into the sampled segment than the others. The ECU does not know this but sees more air and adds fuel accordingly

**disco stu** · 05-02-20, 08:09 PM

You sure I that one Stu? (Genuine question, not arguing with you)

I thought it was in one of the workshop manuals that I read that the wedge in the centre disrupts the flow, causing vortices further back and those vortices are what is read by some means or another (you can tell where my memory is at moment) to get the airflow. I thought where I read that also said that the little thing we see when looking in was temp sensor to allow correction for density based on temperature

I could be off with this, I'll try and see where I found that info if I get time

**stumagoo** · 06-02-20, 08:55 AM

there is a temp sensor and a barometer in there as well our units have 4 or 5 sensors involved - but as for the partial sample thing --- yeah certain -- the framework may not be completely for that but the honey comb is to smooth out air flow so not sure why they would want to create a vortex.... as for the segment thing --- I did a heap of ressearch trying to figure out issue when I started my tuning - when I first started I had a cheap round pod adapter on and I could not stop running rich ---- until I monitored the AFM readouts via evoscan and found I was getting 1/3 higher readings with it on than when I had it off - I went to a properly shapped one and the air flow was corrected

**disco stu** · 06-02-20, 06:10 PM

Sorry, should have been clearer. I meant are you sure that it measures air flow only based on cooling of the heated wire

Interesting about the pod filter. I'm sure that would leave some people scratching around for ages trying to find the issue as it's not immediately obvious

**stumagoo** · 06-02-20, 07:52 PM

yep that is how most this style work their is other sorts but they not as common and the older sorts which use a flap or similar that operates a variable resistor

Mass flow sensor - Wikipedia

https://en.wikipedia.org/wiki/Mass_flow_sensor

**disco stu** · 06-02-20, 08:27 PM

I've started looking through and can't find the place I found the info, but now now remember more details at least

Karman Vortex sensor was what (I think) I worked out it was

**erad** · 06-02-20, 09:22 PM

The airflow meter on my NL had some aluminium honeycomb mesh in the sides of the opening. I can only assume that this was to generate some turbulence at low airflows, because the readings that the heated wire would get would otherwise be very difficult at low airflow (low revs). With the many backfires I had in my NL, the honeycomb pieces used to get loosened and as the air filter box lid lifted during backfires, eventually I lost one piece of the honeycomb. The other piece had been flattened by the filter box lid coming back down on it so I panel-beated the mesh with a 2" nail to get it roughly back into shape. The missing piece I replace with a small piece of aluminium sheet, drilled in an attempt to simulate the losses caused by the honeycomb. Since most of my running with the NL was on LPG, and the mixer was a fairly crude old design, the airflow meter was therefore not used when on gas so minor differences didn't matter that much.

**disco stu** · 08-02-20, 06:16 AM

The backfires really make a mess of a that honeycomb

Below Nav Bar Ad Module

Dismantle MAF sensor?

Dismantle MAF sensor?

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Matched content