New to Forums / Question about IACV routing

[axle]

Hey CB7tuner.com , I have been lurking around this forum for a little bit of time. I first off want to thank everyone that has put up good information here which has helped me out a lot over my time of owning my cb7 .

Now onto the problem; a little background on the car. It has a H22a swap in it with a Euro R IM, attached is an S2k Throttle body connected to it. The engine is turbocharged. I have been troubleshooting a common idle problem where it fluctuates from roughly 800rpm to 1500 rpm. I found a great piece here going through the troubleshooting for it.

What I have already done, was take off the IACV, and cleaned it out. Made sure that coolant can flow through it also. After reattaching it upon first start up the car ran great and the fluctuations were barely noticeable. It bounced maybe at most from 800rpm to 1000rpm. The next day I started her up again and the fluctuations were back. My next move was to check the FITV and see if that is the issue. Well, it appears that the FITV is blocked off. I then was wondering where the coolant line from the IACV was going to. Following the lower IACV coolant line it is connected to the lower / closer part of the Thermostat housing to the engine. This is where I am wondering if it is ok. I read that blocking off the FITV it will only increase the time it takes to warm up the engine in a cold climate (In Connecticut, I would say it is a cold climate now). If this is wrong info please correct me.

Did you spray out the iacv with carb cleaner to clean any carbon on the screen & out of it?
Did you tighten the plate inside the fitv?
Did you plug the air boost valve to the intake pipe?
Have you checked for any vacuum leaks?
Have you tried re-adjusting the idle screw?
Did you bleed your coolant system for air bubbles?

IACV - check
FITV - non-existent
Air boost valve - not sure where to find it on the IM, however checked all lines from the IM and lines are connected with no leaks. Will be going over these again though.
Checking for vacuum leaks - yes, but will again double check this too. On a side note, I am not losing any boost pressure when running the car. Not that it is the best way to tell, but the boost gauge is not spiking or dipping once I am in boost.
Idle Screw - have not attempted yet
Coolant system bleed - Did this first with a cold engine, then realized that the engine needs to be at temp for coolant to run through the entire engine, so did it again when it was at temp.

The big thing that I notice while the idle Fluctuates is that my Wideband goes from a 12.6 to as high as a 16.0 then dips under 11.5 and up again to 15.5. I am also thinking that the ECU might be the issue, but want to get the mechanical side of troubleshooting finished before I look at the ECU as the problem. I have to double check, but I believe it is either a p72 or p28, it is running a Hondata S100.

Any feedback or help or direction is extremely appreciated. Thanks everyone

[1990exr]

Do you have a p13 to throw on it just to check the idle? Are there any codes/check engine light?

[axle]

Do you have a p13 to throw on it just to check the idle? Are there any codes/check engine light?

Unfortunately I do not have an extra p13 to throw on it. No Check engine light, nor any codes thrown.

Although, definitely helpful looks like we were on the same wave length there.

[1990exr]

Or it could be the IACV as well, or sensors that affect it's operation, what does it idle at when warm? Is there an air gap screw in that throttle body to adjust the idle? has the idle been set previously and then started acting up?

[deevergote]

It's difficult to diagnose an engine that's so heavily modified. I'm guessing you weren't the one to install or boost it?

I'm not able to offer much assistance here, as you've already done everything that I've experienced myself. Playing with the idle screw on the throttle body is the only thing left, right? That always seems to fix things on my H22... though our setups are VERY different.


By the way, thank you for a near perfect first post. You described your engine, explained the problem, explained what you have done, showed that you've searched for answers already, and mentioned things that you think it may be. If everyone posted like that, this site would be 100x better than it already is!
Good luck!

[axle]

Or it could be the IACV as well, or sensors that affect it's operation, what does it idle at when warm? Is there an air gap screw in that throttle body to adjust the idle? has the idle been set previously and then started acting up?

From first starting up the car it idles perfect. About the time when the temp gauge starts to rise (I believe about when the car is at operational temp) the idle then starts to do its jump around. Not every time, but once in a while a stab at the throttle will stop the fluctuation. I am going to check for screw to adjust idle, but unless it has somehow vibrated out of position it has not been messed with. I might need to check the sensors also.

It is possible it might be the IACV itself, but I don't have a second one to put on to diagnose that or the sensors it is attached too. Might have to make a JY run to find one and see it if changes anything.

It's difficult to diagnose an engine that's so heavily modified. I'm guessing you weren't the one to install or boost it?

I'm not able to offer much assistance here, as you've already done everything that I've experienced myself. Playing with the idle screw on the throttle body is the only thing left, right? That always seems to fix things on my H22... though our setups are VERY different.


By the way, thank you for a near perfect first post. You described your engine, explained the problem, explained what you have done, showed that you've searched for answers already, and mentioned things that you think it may be. If everyone posted like that, this site would be 100x better than it already is!
Good luck!

I am just about to hit that idle screw now to see if it helps. I picked the car up just about the time it was 95% complete. I had to throw on an oil feed and return lines from the turbo, intercooler piping, and ECU with a tune after it was all put together. There is still much to be desired to finish this swap and make it perfect. Future plans include a built bottom end, but that is neither here nor there a matter for this thread.

Thanks for the Kudos Deevergote Been a member of different forums over the years. Most recently Clubeg6. I miss my bubble, but looking back at it, I should have gotten an Accord back then instead of the Civic hatch.

[deevergote]

I don't think it would cause the problem, but a boosted stock bottom end can give out quickly. Broken ringlands are very common when boosting any stock block H or F engine. Your symptoms don't seem to indicate any issues inside the engine, but doing a compression test might be worth a shot.

[axle]

I don't think it would cause the problem, but a boosted stock bottom end can give out quickly. Broken ringlands are very common when boosting any stock block H or F engine. Your symptoms don't seem to indicate any issues inside the engine, but doing a compression test might be worth a shot.

I never thought to do a compression or leakdown test over this issue. When I get a chance I will.

I understand that the ringlands are the Archille's Heel of the H22 especially for a boost application. That is the whole reason in my future plans is to beef up a bottom end and replace the current bottom end I have. The big question is how much am I going to throw into the bottom end. I am still debating over MAhle pistons and rings for the FRM sleeves or doing a full Sleeve job and go with a different set of pistons and rings... that is getting off topic though. We can discuss that at another thread and another time.

Going to take a few pics of the IM, hopefully my camera on my phone will do a good job so you can see what it looks like.

[1990exr]

That is completely opposite for most fluctuating idle problems I've hear of and helped people with when the engine is on cold idle it is in closed loop using minimal sensors to regulate your air fuel ratio and a set fuel map is usually when it happends. When the engine hits it warm idle is when it starts using differant intelligent fuel maps and all sensors one of which I know for sure to be the o2 sensor. If the O2 sensor were gone it should throw a code though unless the ecu has it disabled.

[dj_ender]

The surging idle is either air in the coolant system, or you have a vacuum leak. Did you bleed the coolant this way? From the sounds of it you didn't, and FYI, you CAN bleed the coolant on a cold engine.



BE SURE TO HAVE THE HEATER IN THE HOT POSITION.

[axle]

That is completely opposite for most fluctuating idle problems I've hear of and helped people with when the engine is on cold idle it is in closed loop using minimal sensors to regulate your air fuel ratio and a set fuel map is usually when it happends. When the engine hits it warm idle is when it starts using differant intelligent fuel maps and all sensors one of which I know for sure to be the o2 sensor. If the O2 sensor were gone it should throw a code though unless the ecu has it disabled.

It might be possible that the tuner disabled the oem O2 sensor and just working off the Wideband O2 sensor... I'll have to get a hold of the tuner to find out. I don't have the Hondata software anymore (long story) so I can not just go into it and check .

Going to do a couple more things tomorrow to it and see if it helps. If not I am going to have to check with my tuner and see if he knows anything he did with the tune that might cause this. Maybe he might find the issue when he plugs in...

[axle]

The surging idle is either air in the coolant system, or you have a vacuum leak. Did you bleed the coolant this way? From the sounds of it you didn't, and FYI, you CAN bleed the coolant on a cold engine.



BE SURE TO HAVE THE HEATER IN THE HOT POSITION.

Ah, Eric the Car Guy. Love that guy and his website. Yeah, I bled it the way he showed. I did it first when the car was cold, but I had an inkling that it may not have worked because it was cold, so I did it once warmed up.

I actually would not have known about his site if it wasn't for this Forum

[axle]

Just got a new/used IACV from my buddy that owns a junkyard. Cleaned it out and tested the electrics on it. Installed it on the car and so far so good. After three start ups and warm ups the fluctuations have not reared its ugly head.

Thanks everyone for input and helping out. I appreciate it.