DIY: Air System Cleanup, Throttle Body Service & Cleaning of Sensors

[juadjee]

Dear Brothers,

I've been wanting to do this for a while and I recently got some new tools so I'm well equipped for the job. So here's another DIY.

The aim was to do:

1. Air System Cleanup (including the air cleaner housing, stock intake pipe and the MAF sensor)
2. To do a throttle service (including the throttle body itself and particularly the IACV and the sensors attached since I was facing some unstable idling)
3. To clean all the sensors I could find
4. Degreasing Engine and doing a major cleanup of the engine bay area (you'll see why this is on my agenda) This part has been posted on Page 4 of this thread

So here goes...

1. Air System Cleanup

Here are my tools...

The air system... Dirty as it gets..

Disassembling the air cleaner housing and intake pipe, you can see the bolts are undone and i'm ready to detach it from the throttle body...

Disconnected from the throttle body, the CNG Venturi (if I'm correct) has a lot of gunk on it..

Okay, the air system is out and i took it home for the cleaning...

You can see the oily deposits here..

The housing is dirty from outside and inside..

And from beneath..

The stock intake pipe is detached and this thing on top of it, i don't know what it is exactly but it looks like it would be some kind of catalytic filter or something of that sort.. well I checked it and it was empty from inside..

Oily dirt is deposited on either side..

So we take it for a wash..

After a nice long wash with surf..

The intake pipe is CLEAN..

Nicely clean..

And here it is, looking lovely after the cleanup..

Here is the full housing, with the intake pipe attached.. I did spray it with some Formula1 dash spray cause washing it with the surf left it dry and that grey-ish plastic colour I hate..

All set and put back in..

If only the whole of my engine bay could look like that.. Sigh.. one day..

[Samialvi]

Awsome DIY!!! have been thinking of doing this all with my VTi 2000...
Keep the pics coming

[tayyabbaig]

plz keep the pics coming... its making me more encouraging to do it with my vti. Especially the Idle thing, clieating TB, IACV and sensores.

[tayyabbaig]

Thread subscribed.

[juadjee]

2. Throttle Body Service

First, disconnect all attached sensors by unplugging their harnesses.. These will include the MAF sensor (placed on the air intake pipe), the MAP sensor (placed on top of the throttle body - also in this image), TPS or throttle position sensor (placed behind the throttle body) and the IACV sensor (this is placed underneath the throttle body in A/T version of this civic)

Then you take out the intake pipe.. disconnect it from the one end connected to the throttle body and the other one to the air cleaner housing

Here is a view with the intake pipe disconnected

Now a challenge in removing the throttle body was to remove these two cables that are attached to the fly on the throttle body

Here you see the first one is detached

The CNG venturi removed.. to detach this, I had to unscrew two screws which fastened it to the throttle body..

This is the second cable, removing it was a bit of a challenge, I had to unscrew the metal plate which was attached to the throttle body as well.. it came out after I did that..

Both cables are now disconnected

A shot of the dirty and gunky throttle body.. if you notice the top two corners are unscrewed, there was a bolt on one and a nut on the other.. I then went on to unscrew the two at the bottom..

and here you can see the throttle body disconnected from the intake manifold.. However there are still two water pipes connected at the bottom of the throttle body, had to disconnect those before I could take it out..

These are the pipes below that had to be disconnected.. and water poured out when i did that..

At LAST! Success! The bad boy is out.. and ready for its cleanup..

Very dirty..

This is the bottom of the throttle body, this solenoid you can see attached with a lot of screws is where the IACV is and that plastic thing sticking out is the IACV sensor..

I stuffed the inlet manifold, just in case. To avoid anything from going inside while the throttle body was removed overnight.

Here's the advantage of working with a pair of gloves, automotive dirt is so greasy, its a hassle to get off - and for safety too, i recommend using gloves.

Getting all the things ready to clean up the throttle - a tub, all my tools, petrol, WD40 and a tooth brush is what will be used

The next three pictures are for before-after purposes..

AFTER removing all the sensors attached to it (these were the MAP, TPS and IACV sensors) start to clean up..

Wash it generously with petrol..

Use a toothbrush to clean in the groves also and clean the throttle body inside out a couple of times..

And you will see a lot of unwanted matter left behind.. and cleaned off of your machine..

I tried to open up the IACV but the screws on it were so tight and they are so old that trying to open them were just effing the heads up..

So I just poured in petrol and WD40 from the inside of the throttle body into the IACV and cleaned it up that way..

After the cleanup.. the screws and nuts getting some WD40 on them..

Installed all the sensors back on to the throttle..

And here is a serviced, clean throttle body..

THE TROPHY

[juadjee]

Part Three - Cleaning the sensors is very small, and I have very few pictures.

3. Cleaning the Sensors

Here's a little helpful piece I found which tells me where all the sensors are located in my model..

Removed the MAP sensor from the throttle body..

This is the Idle Air Control Valve Sensor.. The most critical one i reckon..

Here are the MAP Sensor (right) and on the left is what I had mentioned as the MAF sensor but is actually the Air Temperature sensor as correctly highlighted by Xulfiqar

Cleaning the sensors with some petrol...

And here, cleaning the TPS and IACV sensors..

[Xulfiqar]

What you are reffering to as MAF is the intake air temp sensor, the hollow plastic thing on top of the air inlet pipe what you refer to as catalytic filter is the resonator plenum tube.

anyways - it wouldve been wise to remove and clean the idle air screw and passages - as they get loaded up with gunk and dirt from the crankcase vent. Your choice of WD40 will not cut through varnish like carb cleaner. and to clean the ISC motor - its best to clean up with carb cleaner and load it up with engine oil then empty- that way it frees up to react fast.

The other stupid thing that happens to Hondas in Pakistan is that the throttle body heater pipes which are tack welded to the breather pipe - get corroded due to rust and block inside (because we use tap water in the cooling system and love to open the cap every chance we get) - they are tack welded to keep the breather pipe temperature high so oil mist cannot settle into oil drops again - thats what gets the throttle body oily.

This is also very high point in the cooling system, thats why I never advocate to open the rad cap every now and then - this pipes empty themselves when you check the level and boil over causing corrosion and eventually leak - The best way is to park on a slope facing upwards and check radiator coolant if you need to check through the cap - otherwise the overflow bottle is perfect to check coolant. - Its a quirky design but you have to live with it.

[Xulfiqar]

The venturi's bore is quite small.. Doesnt it choke

[VCheng]

Great DIY, but WHAT CAR MODEL IS IT, or did I miss it?

[Xulfiqar]

its a Honda Civic 1.6 VTi MY 2000 I believe from eyeballing the distributor connector

[Navqam]

Great work juadjee. I'm impressed, really...! Keep the pics and info coming. And do share the performance of engine afterwards.

[irfansiddique]

very nicely done.

[juadjee]

What you are reffering to as MAF is the intake air temp sensor, the hollow plastic thing on top of the air inlet pipe what you refer to as catalytic filter is the resonator plenum tube.

anyways - it wouldve been wise to remove and clean the idle air screw and passages - as they get loaded up with gunk and dirt from the crankcase vent. Your choice of WD40 will not cut through varnish like carb cleaner. and to clean the ISC motor - its best to clean up with carb cleaner and load it up with engine oil then empty- that way it frees up to react fast.

The other stupid thing that happens to Hondas in Pakistan is that the throttle body heater pipes which are tack welded to the breather pipe - get corroded due to rust and block inside (because we use tap water in the cooling system and love to open the cap every chance we get) - they are tack welded to keep the breather pipe temperature high so oil mist cannot settle into oil drops again - thats what gets the throttle body oily.

This is also very high point in the cooling system, thats why I never advocate to open the rad cap every now and then - this pipes empty themselves when you check the level and boil over causing corrosion and eventually leak - The best way is to park on a slope facing upwards and check radiator coolant if you need to check through the cap - otherwise the overflow bottle is perfect to check coolant. - Its a quirky design but you have to live with it.

Thanks for your detailed and advising reply.. You are correct, that is in fact the Air Temperature sensor.. What is the function of the resonator plenum tube?

On the carb cleaner issue, yes I did want to use that NASA carb cleaner spray but well - I didn't get a chance to get it, so I just did it with petrol.. I really tried to access the actual IACV area cause that is basically why I opened the throttle body up, but the screw heads were so messed up.. I didn't want to eff them up further.. I did however make sure I poured in a lot of fluid through the holes inside the throttle body and also turned the magnetic tip that opens and closes the valve (and connects to the sensor) a lot of times with WD40 inside and I could actually feel its movement becoming free.. This is, well the best I could do.. as much as i'd like to rip open the IACV and clean the ***** out of it.. I will keep your carb cleaner + engine oil technique in mind for next time!

That is very good information for me! And yes, the tack welded pipes had corroded in this case and I had to unblock them.. IMO they are very poorly designed because they were full of rust.. so much so that they were chipping off, Honda should've just used plastic here..

Thanks for the tip on checking the radiator water after parking on an incline.. I am having issues with my cooling system and i need your help here..

First off, whenever I open the radiator cap, there is always a high pressure gas release - air builds up inside and this happens even when the car is cold..

second, the water never remains full in the radiator, i pour water on a running engine and it gives off a lot of tiny bubbles also when its filled up..

and third, my radiator won't be full but my reserve/overflow bottle fills up more than i had put in it.. basically water transfers there..

I know this is not good and will cause problems especially since my car has had a history of heat-ups.. let me know what I can do for this..

Thanks..

[juadjee]

The venturi's bore is quite small.. Doesnt it choke

The car runs quite well on CNG, I haven't faced any choking issues yet..

[juadjee]

Great DIY, but WHAT CAR MODEL IS IT, or did I miss it?

Thank you Mr. Cheng, this is a Civic VTi 2000 model as pointed out by Xulfiqar..

[juadjee]

Samialvi, tayyabbaig, Navqam and Irfansiddique: Thanks a lot you guys..

[juadjee]

Here are some pictures from the re-installation I did this morning after having worked on it last night.. Enjoy..

These are the two nuts and two bolts that fastened the throttle to the intake manifold

With the nuts and bolts tightened..

Look for the harnesses for each sensor

And attach them

To the relevant sensors

Harnesses for the IACV sensor and the TPS sensor are both connected

This was also very dirty, so i quickly cleaned it with WD40

Venturi placed back on to the throttle and the screws tightened

Attaching the one end of the intake pipe to the air cleaner housing

Attached

Attaching the other end of the pipe to the throttle body..

Re-connect the air pipe from the head to the intake pipe

This is after reconnecting the MAP and Air Temp Sensors

All done

[Xulfiqar]

the resonator acts a silencer for your intake roar and also as a reserve - when you let off the throttle pedal (as air has got weight it moving in a stream will not stop abruptly when it meets a closed throttle blade suddenly it will tend to compress and look for places to expand (plenum chamber), and get sucked in the next time you step on the throttle. The resonator box behind the main air filter box is also of the same function.

If your coolant is transferring to your overflow tank but not back - you have tiny air leaks - that allow in air when the system depressurizes and creates vacuum (which I believe in this case is the little coolant pipes you just cleaned out) - have them made in copper A/C tubing soldered together

The vacuum I talked about is the function that opens up the tiny hat valve on the radiator cap and allows coolant to flow into the radiator from the overflow.

The pressure you are seeing is mostly because of the air thats getting trapped in because of these vacuum leaks - search very carefully for leaks that may seem slow or just trickling - mostly found at - the stupid tiny pipes, hose flanges, and the metal pipe going from the Tstat to the coolant pump.

You also should know that this design needs to be air purged when you fill coolant - there must be a bleed nipple on one of the flanges

[nomicool]

Wow...interesting diy...not many diy's impress me...but this one did!

[memad]

the resonator acts a silencer for your intake roar and also as a reserve - when you let off the throttle pedal (as air has got weight it moving in a stream will not stop abruptly when it meets a closed throttle blade suddenly it will tend to compress and look for places to expand (plenum chamber), and get sucked in the next time you step on the throttle. The resonator box behind the main air filter box is also of the same function.

What happens in cars which do not have resonator. Do the air passage recieves reverse pressure.

Why there is a delay in rpm build up in efi cars as compared to carby ones, upon increasing the throttle.