Engine hunting after Rbc installation

[Vtequila]

This problem has probably been reported several times but looking for
a better view on the problem I've got and the solution to get the hunting/revving straight.

After fitting the Rbc and 70mm tb I was finally able, after 2 months not driven, to start the
engine again but it started revving from 1k to 2k rpm. Here is a video I made for example :

[youtube]http://www.youtube.com/watch?v=y3Woe4gyEkA&feature=player_embedded[/youtube]

I have read multiple topics that it's probably the Idle Air Control Valve but before I fitted the tb to the Rbc I thought I cleaned it well.

Would like to add that I looped the stock water bypass (stock way) hoses like instructed in the Karcept rbc installation manual, not sure if thats the right way for the DC5 too.

http://www.karcepts.com/index_files/instructions/KIM01%20Installation%20Instructions.pdf

So for now, it's a puzzle to me where to find this leak or faulty installtion of the Rbc intake with 70mm throttle body.

 

[davidpingu]

When you cleaned the IACV did you take it apart properly so you could turn the valve? I made the mistake of not cleaning it that way and this is what it was for me. If you strip it properly so as you can feel how smooth the valve spins you'd be able to rule that out.

Once thats done if it doesn't sort it, get some brake cleaner and spray around all the areas there may be a leak. It is flammable so better to do it when the engine is cold.

One question is does it hunt immediately from starting cold or does it run fine for a minute or two and then start?

 

[davidpingu]

Just noticed your temp guage is reading half warm. If its only doing this as the engine warms then its definately the IACV, clean it properly and it should fix it. :xyes:

 

[Vtequila]

I didnt know the IACV could actually spin, maybe I did cleaned it only for half of it is but I think that I should check it again yes, just to make sure the IACV gives this problem or not. The temp guage could be at half because I also had to refill the radiator so maybe that was the cause.

 

[davidpingu]

I only mention the temp gauge as I notice the car was warming when you recorded it in your video.

When I had the valve problem I could start it from cold and it would be fine for 2 - 3 minutes. As soon as the revs start to drop towards the normal idle speed thats when it would start hunting. THis is the point the car starts to use the IACV once butterfly fully closes in the TB.

Yes strip the IACV right down. Theres a plastic piece with two screws that nobody has a head for but you can remove them using mole grips. When the plastic part comes away it will reveal a spindle. When you turn the spindle it should feel smooth. If theres any resistance that is what will be the cause.

I cleaned mine out with carb cleaner while continually spinning the valve and once it was 95% there I gave it a little squirt of PTFE based spray (WD40 type stuff) and you could feel the difference by hand.

 

[Vtequila]

Yes, thats what mine also did. The first 2 minutes it was normally but when the rev dropped to 1k rpm it started hunting.

I dont believe I cleaned it like you just told. Tomorrow I will take off the IACV and clean it like it should be done and hopefully the problem will be solved.
Is it possible to removed the IACV without having the tb off ?

 

[davidpingu]

I don't think so mate but if you've already had it off it should be a 2 minute job to get it back off. Just tie the water hose up with a cable tie so it doesn't leak and when it all goes back together warm the engine with the rad cap off for a couple minutes to expel any trapped air.

Ideally when you remove those two weird screws I mentioned about, you'd replace them with a different type. I didn't have any that would fit so ended up putting them back in the same way I got them out which was with mole grips.

Very naughty of Honda to attempt making this inaccessible. Its an expensive part to replace and yet its a very simply cleaning procedure.

 

[Vtequila]

Have been able to get the IACV off the tb and it seemed it was totally stuck! I could not even twist it with my fingers so used some carb cleaner to loosen it up and cleaned it properly from the inside, than I lubed it up with WD40 to keep it smooth for as long as it lasts. Now I understand why my engine was surging al the time from 1k rpm to 2k, back and forth.

 

[davidpingu]

Glad it seems you've found the fault. You'll have to confirm once it's back on that the hunting has gone. Bet you'll be glad to finally drive the car again on your new mods

 

[Vtequila]

I can report that the engine is fine now The hunting/surging have disappeared and cleaning the IACV have seemed to solve the problem (see video 1st post). So happy now!

Glad it wasnt something else, I am using thermal gaskets from Tegiwa and they seem to do their job.

 

[davidpingu]

Great! Now go enjoy your rbc

 

[Vtequila]

Yes! Still need a re-map though

 

[C&S Evo7]

It's a really common problem if they stand around for any length of time, I think fuel dries it out , I have also thought sometimes as the engine breather goes back into the intake it's possible oil contaminants can help it get stuck, when the car is in regular use its ok but after a while of standing around can get sticky

 

[donkeykong]

Luckily never had that, my car is standing still a lot, mostly a week and drive a bit. When the spring comes put on some new tires and enjoy it more haha