Hey Guys,

I've got a few engine codes on my newly acquired 98 Accord EX, with approximately 167,000 miles.

I've got the P0401 (EGR Recirculation flow insufficient detected) as well as P0505 (idle control system malfunction). I've found an incredible amount of information about the EGR problem on this website. I'll eithercomplete the fix myself or take it to the dealer.

As far as the IAC problem, this is where I am now. I've only driven the car a few hundred miles, but there was one occasion where I put the car in park, and the idle started fluctuating (bouncing), leading me to this IAC issue

My questions are as follows:

How often does cleaning the valve actually solve problems?

Will the $102 Advance Auto Parts replacement valve solve my problem (elminate check engine light and idle fluctuation)?

How did you guys unscrew the IAC to remove it? Just a mini screw driver? I am having a hell of a time getting to the screws with something good enough to put some torque on them.

Thanks!

 

I just cleaned mine on saturday, so it's fresh in my mind.

To actually remove the sensor, it's a 5-point bit, not a Torx or anything, so I left it in there. To take the valve off youll need to loosen the 10mm bolts holding it to the manifold. And a good spray with carb cleaner, a nylon brush and a q-tip should clean it out pretty good. But, the problem probably lies in the port on the manifold itself. To find the bolts youll probably need a mechanics mirror (similar to a dentist mirror), but it may not even be accesible without taking the whole manifold off. I found the latter to be the easiest since the manifold is push farther back than the 95 I used to have.

I took the whole upper half of the manifold off over the weekend to thoroughly clean it.

Before:







After:







In the last picture, the IACV port is the slotted one on the bottom of the picture (side of the manifold if rotated correctly)

 

Oh wow, great pictures. Thank you!

I guess taking the whole thing apart and cleaning everything is going to be the best thing to do. You've inspired me. Is there anything I should watch out for when taking anything apart? Anything that might surprise me later on?

Did you do this for any particular reason, other than just to clean it? Do you have a check engine light or any sort of problem with the way your engine is running?

 

My engine had a slight surging idle, but nothing to worry about. When the car was started the idle also liked to dip down to 250 and then back up again, almost stalling. I'm driving to Florida from Minnesota on Friday so I wanted everything to be in top shape and I may have slight OCD, so I cleaned it haha.

Things to take note of:

- One of the vacuum hoses on the IAC is difficult to put back on and the manifold has to be angled a funny way to do it, it took me a while to get it back on and tight.

- Drain the coolant out of the radiator all the way to make sure there is no coolant sitting in the manifold (I don't even think there a coolant feed line going to the manifold, but I did what the book told me to.

- Take pictures of all sides of the manifold before you start just in case you forget where something connects to.

Here's every thing you have to unplug/disconnect:
- Ground wire (drivers side)
- Mounting bracket thing (drivers side)
- air intake piping (passegner side)
- IACV (blue connector, passenger side)
- Air temp sending unit (I think, driver side of manifold) (white connector)
- Manifold Absolute Pressure sensor (map) (gray connector, passenger side)
- 2 vacuum lines from top of manifold
- vacuum line under throttle body (you can see the nipple in the pic)
- vacuum line #9 from part #5
- metal vacuum bracket from fuel rail (I found it easiest to remove the tube from the bracket on the valve cover side of the bracket)
- PCV tube on manifold


Wow, that's a lot of stuff. If you decide to do it, good luck! I'd set aside a full day to do it, but it should only take 3-4 hours to remove, clean, and install it again.

 

What did you use to clean this, only throttle body cleaner or other? Very impressive cleaning job.

regards

 

I used CRC Thottle Body/Carb Cleaner

All I did was wipe it, spray it down, wipe it again, spray it, scrub it with a nylon brush, spray it, scrubs the stubborn spots with a brass wire brush and sprayed it down again.

 

Yeah... I guess, initially, I didn't know there was so much involved. I will have to find some special motivation somewhere to tackle this one. I'm going to try and get rid of my EGR check engine light first, as the IAC issue almost seems like it was a fluke. Hmmm...

 

Only bad thing is... you have to take the manifold off to clean the other end of the EGR. You can take the EGR valve off and clean those ports fairly easily. It has a gasket on it though, which I forgot about and tore, but a little RTV Silicone sealed it right up.

 

So you're saying that if Ireally want to do things right, I need to take the manifold off. I'm starting to get it!

So once off, I should clean everything for the sake of the IAC issue, and do the EGR cleaning according to the Honda TSB? Then everything wll be perfect?

When I bought the car, the check engine light was on, and the code was for the EGR valve. The seller of the car put on a new EGR valve for me, just to make me happy, but as is often the case, the problem was not fixed. Then I found this site and found out all about the EGR issues. After driving my new car for a few hundred miles and scanning codes again, I came up with a couple more codes, including the IAC issue. Ihave also gotten codes for the evap canister and that code that apparently means by cat is bad. Makes me wonder if this car will ever be driven again without a check engine light on. Its too bad, because the car runs and drives incredibly well...

 

EVAP codes usually mean that you didnt tighten the gas cap 3 clicks, I've gotten that before too. If it's persistent, it acutally may be the EVAP canister haha.

And don't worry, the previous owner of my car (bought in April) said the CEL has been on for 7 years. Runs and drives great, especially after cleaning the manifold.

As far as doing things right, if you don't want to tackle cleaning the manifold yet, then don't do something youre not comfortable doing. You may as well just remove the EGR valve, clean out the ports with carb cleaner the best you can (you can see the rectangular opening on the right travel to the intake manifold). If you destroy the gasket, buy a new one or just make one with the RTV.