Quick Throttle Body and MAF sensor clean.

[spunagain]

Hi All

I had noticed the odd time, particularly when the engine was cool that the idle speed was quite low and when disengaging the clutch at highish engine speeds the engine would occasionally stall.

Reading threads it looked like the throttle body may be to blame.  Talking to Hilly (He of the Audi V8 esprit), he has come across the same symptoms with a VW he had where the carbon build up actually blocked the airflow.

So I thought I would have a go and clean the Mass Air Flow (MAF) sensor while I was at it.

First of all tools:

• Torch to see with,
• 10mm socket with a 2 inch extension bar to remove the throttle body,
• Crosshead scredriver for removing the MAF sensor,
• Flat blade screwdriver to remove the jubilee clip holding the air pipe onto the throttle body.
• Kitchen roll for cleaning
• Carb cleaner to clean the throttle body
• Autosolve for cleaning the MAF

So with the cross head screwdriver remove the 2 screws holding in the MAF sensor and pull it out.Lift the Tab to relase the connector and take somewhere with a bench or kitchen table.  My view with the MAF is not to touch the sensor elements at all, so I simply gave the the larger sensor (I suspect the temperature sensor) a good dousing with Autolsolve and filled up the void you can in the picture below containing the other 2 airflow sensors with Autosolve and let them soak while I went back to look at the throttle body.

Autosolve is an electrical component cleaner which is used to clean excess flux and crud of circuit boards and seems to be a safe choice for the delicate MAF sensor. To be honest looking at the photo's now the MAF was not dirty at all.

Back to the throttle body. Simple loosen the jubilee clip and pull off the rubber pipe to the left of the throttle body, then undo the 4 bolts holding it down and put them somewhere safe.  You could undo the other hoses connected to the throttle body and clean it somewhere warm, but I was lazy and simply pulled it away from the inlet pipe and cleaned it in situ.  It was horrid, zooming on the photo below, the carbon build up is thick enough to have started to flake off in places. 

I cleaned this down with the kitchen roll and carb cleaner. I cleaned top and bottom, inlet and outlet, the outled being the nastiest. Nice and clean below:

Euew!

Then simply bolted the TB back on being careful not to dislodge the seal and refitted the inlet pipe and nipped up the jubilee clip.

 

Then back to the MAF. I emptied out the autosolve and let it dry for a few minutes. To be honest I can't see much difference, but no harm in a quick bath.

Finally I simply screwed it back in position and clipped on the connector.

Then a test drive, hey presto no more stalling!

It was a very quick and easy fix that I suspect that anyone can try!

 

 

[Bibs]

Good work, great write up

[Danelaw]

Yes, nice write-up Phil. It looks like your car is around 6 years old, but just out of interest do you know how many miles worth of grime accumulation this represents? 

[spunagain]

Yup: 36000 miles, of which 26k are using either Radium or BOE air filter setups.

[Brendonian]

That's interesting. I had similar problems, which were solved just by unplugging and re-connecting the MAF sensor and the throttle body connector.

It's just possible that your fix was actually just a result of improving the electrical connections, but it certainly can't hurt to have it all nice and clean inside too!

[spunagain]

That's a good point, next time I am under the boot lid I will give the connectors a quick squirt of autosolve as preventive maintenance. Did not think to did it at the time.

[CaptainSlow]

Resurrecting this old thread. By the end of last season my car started to act funny when cold. Randomly died, no issues to restart and ran just fine when hot. Just had it in for it's annual service and the workshop had cleaned the throttle body which was "pretty dirty". Time will tell if it solved the problem but the rationale I was given makes sense. Build-up of oil and dirt blocks the airflow (just as stated earlier in this post). For reference, my car (Evora S, MY12) has close to 80 000 km on the clock now (49 700 miles).