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I have a 2006 accord sedan ex I-4 automatic with 81k miles.

1) I pulled the MAF sensor out and was trying to figure out where to spray the CRC maf cleaner. All I saw on the sensor was a small opening where some electonics were so I sprayed inside. Nothing black came out on the paper towel sitting below. It seems it was very clean. Am I doing something wrong? I put it back and test drove the car and no change in performance.


2) Next, I pulled the intake tubing off the throttle body opening and proceeded to clean it. I did NOT spray the CRC throttle body cleaner into the bore and butterfly (plate). Since I have a drive by wire system, I simply pushed with my finger onto the upper portion of the butterfly and held it open while I took a rag soaked in CRC cleaner and cleaned it with my other finger inside the rag. Some black carbon deposits were present on the white cloth. Test drove the car and noticed a very slight increase in performance.

Still, I have a very slight vibration at idle when stopped and foot on the brake and in drive. Vibration definately increases as outside temperatures become colder. I was hoping it would stop after these two cleanings.

All responses appreciated.
 

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elvis:

1) You did this MAF sensor cleaning correctly. You usually will NOT see black residue from a MAF cleaning.

2) You may need to do this throttle body cleaning again, as if there is any residue on the butterfly valve itself it won't seat 100% properly. I had to do it twice on my 240sx, and was still getting residue and what not on my white cloth during the second cleaning....

The spray will get to more areas than a soaked rag wrapped around your finger ever will. I would suggest spraying as well....you may end up using half a can- but so be it. Your fingers are simply too "fat" to get every spot that the spray can hit.

Like you, I did notice an increase in performance. In both my Accord and 240sx, it idled better. I hope another cleaning helps you.

(BTW, you should end your post with "Thank you, thank you very much." The King would have wanted it that way....)
 

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Discussion Starter · #3 ·
elvis:

1) You did this MAF sensor cleaning correctly. You usually will NOT see black residue from a MAF cleaning.

2) You may need to do this throttle body cleaning again, as if there is any residue on the butterfly valve itself it won't seat 100% properly. I had to do it twice on my 240sx, and was still getting residue and what not on my white cloth during the second cleaning....

The spray will get to more areas than a soaked rag wrapped around your finger ever will. I would suggest spraying as well....you may end up using half a can- but so be it. Your fingers are simply too "fat" to get every spot that the spray can hit.

Like you, I did notice an increase in performance. In both my Accord and 240sx, it idled better. I hope another cleaning helps you.

(BTW, you should end your post with "Thank you, thank you very much." The King would have wanted it that way....)


I went ahead and sprayed the butterfly pretty good and wiped up with a cloth. Test drove the car and did not see a change. I've been chasing this slight idle vibration for a while now. There has to be a scientific explanation for this slight vibration at idle with foot on brake and in drive. By the way like I explained in another post all motor mounts are new oem installed by Honda foreman. This is strange.


"Thank you very much"
 

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I previously used to spray clean the throttle body with CRC. It helped marginally if any with rough idle, low idle rpm and persistent mild-moderate but noticeable idle hunting between 625 and 700rpm with the AC On. The idle would be steady and around 700 with AC Off. And as soon as the AC kicks-in, the idle drops to 600 and then compensates to 700 but drops again to 625 and compensates to 700 - the cycle goes on and on and on until the AC goes Off.

This idle problem has been bugging me for a while now. Today, I got a chance to remove the throttle body completely. I removed the negative battery terminal before I started working. After removing the throttle body, I cleaned it with CRC, toothbrush and cloth. The amount of carbon that came with this method is simply unbelievable. There is a lot of carbon build-up around the area where the 'plate' approximates with the opening in the throttle body. It all came out clean (not as new though). I also took this opportunity to remove the Air Temperature Sensor and cleaned it with dry cloth. The sensor tip was black and after cleaning it, it turned into its original light yellowish color. Next was cleaning the intake manifold opening (the opening onto which the throttle body connects). It was sticky, gummy, blacky, sootie and what not. Sprayed it with CRC and promptly cleaned it with a cloth. CRC cleaned it very well because the deposits were sticky but not bone-hard dry (CRC dries very quickly and so it doesn't penetrate into the bone-hard dry carbon deposits). Did that multiple times until the interior looked kind of whitish. Let it air-dry. Went back to the throttle body. Removed the MAP Sensor. Looked into the sensor hole on the throttle body. It was clean. Looked at the opening in the sensor itself - it was clean too. The major part was cleaning the throttle body opening and the 'plate' that moves in that opening. They are all black and the carbon was sticky at some places and bone-hard dry at other places. CRC, toothbrush and cloth were able to clean the sticky carbon deposits but not the bone-hard dry carbon deposits. I had to use my finger nail to remove them. A wire brush or steel wool will be handy I'm sure. Let everything air-dry. I put back everything. Connected the negative battery terminal. I followed the Coolant replacement instructions as opposed to adding new coolant instructions, since some air might have entered the system when the throttle body was removed. Did the ECM/PCM idle learn procedure. The car now idles at 800 with AC Off and a shade higher at 825-850 with AC On. As soon as the AC kicks-in, the idle goes from 800 to 780 and then compensates quickly to 825 and stays there. Once the AC kicks-off, the idle goes down marginally to 800 and settles there and the cycles go on and on. Checked the specs with the service manual and it is 850 for my model. I couldn't be happier. The difference in idle is significant. It is smoother, quieter and I had to check on my tachometer a couple of times to realise that my engine is running. I was able to make my cigarette stand vertical (on the cigarette's filter) on the intake manifold cover with the engine running. The cigarette fell-off (and I caught it) when the radiator fan came on. That's how smooth the engine has become now. Coming to on-road performance - there is a mild and noticeable improvement in acceleration. I highly recommend this to you all.

Some observations along with assumptions:

When the throttle body was removed, I could barely see light coming in from around the border of the 'plate' of throttle body. The car's idling wasn't nice and clean as per my personal preference and my experience with the other two 7 gen V6 Accords that we have in our family. So, I'm now assuming that Honda is making their cars with sensors with a huge range of 'normal' limits. This huge range will, over a period of time, lead to a mild-moderate and noticeable drop in overall performance. This means, when it throws a check engine light, the system is way out of order. After this experience, I've decided to cut down Honda's maintenance limits to nearly half except for Timing Belt. But the bigger question is why is Honda doing this. I don't know. But most likely, it has something to do with ownership costs and may be to earn some bragging rights that their cars are reliable and work for years with little maintenance. Well, if we can cut down on our trips to mechanics and do our own maintenance works, we can use that money on increasing the frequency of service intervals and keep the car close to the condition it was in when it rolled out rather than keeping the car close to the lower limit of 'normal'. My next project is to clean the intake manifold and EGR passages. Can't wait for that.

BTW, I changed the internal transmission filter today with three drains and fills. I realized that my phone battery was dead only after I started this DIY. I'm very sorry that I couldn't keep my promise to post a DIY project for the transmission filter. Will I change the filter again? Yes, in the next 20-25K miles. The very first drain was blackish. The second drain was brownish. The third drain was pinkish to brownish. I am happy that the fluid in my transmission now will be more pinkish and barely brownish. Is there any change in the transmission performance - smoother shifting - yes. Peace of Mind - OH YES.

Sorry for this long post. I thought the OP will benefit from this first hand experience of throttle body cleaning. Thank you for going through this long post.
 

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Hmm seeing my future here...should I just connect the egr barb on the block to a catch can somewhere in the engine bay so theres no chance of random oil effing up the TB?

EDIT: took an unusual amount of googling, but I'm referring to the PCV overflow breather tube that connects to the intake pipe ahead of the TB. I noticed when removing my SRI that there was quite a trail of oily residue going on.
 
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