fast idle thermo valve

[prNonVtec4u]

i just used a thick manila folder(traced FITV, cut, and place between FITV & manifold) and it's worked flawlessly since b4 i even did the swap

[d112crzy]

Now that I think about it, removing the coolant lines/blocking the FITV off might provide some gains.

My reasoning is that the coolants heat is transfered to the throttle body, which in turn heats up the air entering the throttle body, to an extent of course. It's not enough to feel, but I'm sure it does lower intake air temps just a bit.

**just rambling random shit that popped into my head.

[DRzCB72nr]

u still need warm air going into the combustion chamber so that it helps evaporate the fuel. isnt that why theres coolant lines in the TB? or am i wrong

[d112crzy]

The air is plenty warm. Go ahead and touch your intake manifold right near the head if you dont believe me.(after running the car a while)

[bcjammerx]

I doubt it would heat the air that much.

I've placed a restrictor plate on my IACV and I now have LOW cold start idle...like it will damn near die.

Without the restrictor plate the cold idle is still a little low...hmmm I guess my FITV might be messed up.

once the car is warmed up it idles right.

I'm still fabbing that restrictor plate btw...hope to get the bugs worked out...once I actually do more work on it that is.

[Gettin_faster91]

I blocked mine off just the other day due to idle problems after my h23 intake install. Autozone sells a nice roll of rubber gasket for about 6 bucks. Just cut it to fit your application and block off whatever you want. Worked out fantastic for me. I was also able to trace out other gaskets and cut them out with a razor blade, Saved a ton of money it just takes a steady hand and some time.

[prNonVtec4u]

i tried rubber myself and thankfully something made me wanna check things over and found out the damn thing was just about to rip right through ...

and about blocking the IACV... i don't really recommend it since it's not even a main common failure(at least as much FITV) i personally tried it myself and the car would B-A-R-E-L-Y idle, had to take it right back off...

[johnl]

I've placed a restrictor plate on my IACV and I now have LOW cold start idle...like it will damn near die.

Without the restrictor plate the cold idle is still a little low...hmmm I guess my FITV might be messed up.

once the car is warmed up it idles right.

This problem does suggest that the FITV is not working properly.

If the FITV isn't working, then the IACV should kick in to lift the cold idle to the correct warm idle speed, though with a restrictor it's ability to do so will be less than without the restrictor. How large is the hole in the restrictor?

With both the FITV and the IACV blanked off on my f22A9 engine, I have warm idle set at 800, and cold idle is around about 400ish. Even at this rpm the idle is fairly stable and relatively smooth (i.e. only a bit rough), but only after I fitted new spark plugs. At any rate I just push the throttle pedal a little to keep the cold idle up a bit until I get underway (about 5 seconds and I'm off), and it doesn't take very long for the idle to rise and smooth right out (though it isn't exactly snowing around here).

[johnl]

u still need warm air going into the combustion chamber so that it helps evaporate the fuel. isnt that why theres coolant lines in the TB? or am i wrong

The throttle body, IACV, and FITV have coolant lines fitted to alleviate possibility of these components icing up in sub zero temperatures. If it's not very cold then there's no harm in bypassing the coolant lines to these components.

The amount of heat that the intake air will pick up from these components will I think be very small (particularly from the IACV and FITV), and have little if any noticable affect on intake air temp (general heating of the plenum / manifold from heat soak and ambient engine bay temp will be far greater).

For maximum performance you generally want the coolest intake air temps you can reasonably get, unless the engine is carburetted with a poor manifold design (in which case you need a heated manifold to adequately atomise the fuel and prevent it from 'wetting' the cool manifold walls). Fuel exiting an injector at very high psi (compared with the pressure differential in the carby venturi relative atmospheric) through a tiny orifice will be very well atomised, and not in significant contact with cold manifolding since the injectors are so close to the (heated) ports.

[johnl]

i tried rubber myself and thankfully something made me wanna check things over and found out the damn thing was just about to rip right through ...

That's why you should use metal shim. It's not hard to cut up a drink can with scissors...

and about blocking the IACV... i don't really recommend it since it's not even a main common failure(at least as much FITV) i personally tried it myself and the car would B-A-R-E-L-Y idle, had to take it right back off...

That will be because you didn't adjust the idle higher with the idle screw after you blanked the IACV off. The fact that the idle dropped way low when you blanked off the IACV is indicative of the base idle being set too low in the first place. With the IACV blanked off, if you adjust the idle air bypass screw but can't get a correct idle speed then the bypass port is blocked up with crap (which might explain your low base idle in the first place).

Even when the IACV is working as Honda intended, it creates problems with gear shifting (more or less irrelevant for automatic cars). It would be OK if all it did was adjust idle for auxilliary load, but it does other things that are a pain in the arse.

I am willing to contemplate that the problems I've had with my IACV (related to gear shifting) could be due to the IACV not working entirely correctly, but I doubt it because it it did everything it was supposed to do with idle compensation perfectly. I've also driven a manual Civic that suffered the same reluctance to drop rpm when shifting gears.

[bcjammerx]

I was starting with small holes and was going to work my way up. I was also going to look into only increasing one holes size...again...more reasons why I haven't fiddled with it.

...I think they are right now set at 1/16 of an inch on both holes HA HA super small!!!

I was at 1/8 and it didn't do anything to the idle at all.

Sine the holes are so small I figure the IACV may be trying to compensate but really can't, also I figured this would sorta render it useless...but it does idle right when warm and it doesn't drop the rpms between shifts like it does when the IACV is unplugged. Also, when in gear and rolling...light throttle changes do not jar the car around as it woud when I unplugged the IACV...so it's doing something.

Currently it is ideling up to 1100-1200 now that is is super cold...but this has only been the past two days...when it snowed and iced. Normally it will try to die then kick up to 400-600 then back down...etc. If I leave the throttle alone it will usually try to idle VERY low...maybe 300-400...to low for me, I worry about oil pressure...but it's when I come to a stop...it dips down to 0 then kicks up...repeats. BUt...usually it behaves once it's warm...I'de say it behaves when warm mostly...90% of the time.

I am going to alter the block plate some more before I attempt to diagnose that since...it idles just fine without the plate.

[johnl]

I was starting with small holes and was going to work my way up. I was also going to look into only increasing one holes size...again...more reasons why I haven't fiddled with it.

...I think they are right now set at 1/16 of an inch on both holes HA HA super small!!!

So you have one 1/16" restrictor hole at the IACV inlet, and another 1/16" hole at the outlet? It's only necesary to have one small hole (with a larger one at the other port), and it doesn't really matter at which port that is. For the air to pass through two equally sized restrictive holes will create more restriction than through just one (but not by all that much), so in effect two 1/16" holes in series will act like one hole of slightly smaller size.

At any rate, 1/16" is probably too small to allow proper idle speed compensation (especially with two holes that size through which the air has to pass). On my CB7 the single small hole (when I was using a restrcitor plate) was 3.5mm (a bit over 1/8"). You're probably as close to damnit to having the IACV completely blanked off.

I was at 1/8 and it didn't do anything to the idle at all.

The idea behind the restrictor is that it doesn't affect idle speed compensation (with auxilliary loads), but does reduce the undesirable affect of the IACV keeping rpm too high during shifts.

Sine the holes are so small I figure the IACV may be trying to compensate but really can't, also I figured this would sorta render it useless...but it does idle right when warm

As I said above, the IACV is effectively very close to having a blanking plate. If the idle rpm are OK when warm, then the base idle is either set correctly or nearly correctly, so the IACV isn't having to adjust warm idle or only having to do so to a small degree (which your small restrictor holes may be just large enough to allow). When cold the holes are too small to allow the IACV to raise idle speed to 'normal', i.e. to the same speed as correct warm idle.

and it doesn't drop the rpms between shifts like it does when the IACV is unplugged.

This is why I've replaced the restrictor plate with a blanking plate, i.e. when blanked the IACV can't interfere with gear shifts at all, whereas even with the restrictor plate it still can to some smaller degree. I am a little suprised that with such a small restriction in the plate that the difference in rpm dropping between having the IACV connected and disconnected isn't almost the same.

Also, when in gear and rolling...light throttle changes do not jar the car around as it woud when I unplugged the IACV...so it's doing something.

This is why unplugging the IACV isn't a feasable proposition, it's just too harsh and irritating. Blanking the IACV will do everything that disconnecting the IACV will do, except make the on / off throttle and light throttle behaviour harsh (or throw a CEL).

Currently it is ideling up to 1100-1200 now that is is super cold...but this has only been the past two days...when it snowed and iced. Normally it will try to die then kick up to 400-600 then back down...etc. If I leave the throttle alone it will usually try to idle VERY low...maybe 300-400...to low for me, I worry about oil pressure...but it's when I come to a stop...it dips down to 0 then kicks up...repeats. BUt...usually it behaves once it's warm...I'de say it behaves when warm mostly...90% of the time.

Sounds more like the FITV misbehaving to me.

Low oil presure at very low idle isn't a problem. So long as you have oil flow you're OK. I wouldn't be concerned unless the OP idiot light comes on at low idle.

I am going to alter the block plate some more before I attempt to diagnose that since...it idles just fine without the plate.

FWIW, my advice is to try a proper IACV blanking plate (i.e. no air holes at all) with the idle raised to about 800rpm with the idle adjusting screw. I'd also either blank off the FITV or ensure that it's operating correctly. I'd then reset the ECU and see how it all goes. With the IACV blanked, the only issue is idle drop when auxilliary loads exist.

If you blank the FITV as well as the IACV you will have a very low cold idle (which may or may not be a real problem for you, I don't find it to be a problem for me), but if you keep the FITV operable and ensure that it's good then it should anly affect cold idle, i.e. rasing it for the first few minutes of operation, which sounds like it would suit you better.

[CB7Man]

I took my FITV apart and cleaned the seals, screwed it back together, dialed it in over the next week.
Works flawlessly now for a month so far