brians356

Following the manual procedure as described in this how-to:

https://honda-tech.com/how-tos/a/hon...-timing-374867

I jumpered the service check connector, started the engine, checked timing at idle. It was at ~12-degs (mark to right of the RED 16-deg mark.) Then I rotated the distributor, RED 16-deg. mark now centered on the pointer at idle.

Stopped the engine, removed service check jumper. Started the engine, checked timing, it had reverted back to ~12 degs. ;-(

Stopped engine, jumpered service check again, checked timing - bingo, it's back to 16-deg (RED) again.

Stopped, un-jumpered, check again - back the 12 degs again.

So why doesn't the timing change "stick" when the jumper is removed?

Brian

TomCat39

Did you let the car warm up to operating temperature (radiator fan comes on at least twice) before doing your ignition timing?

If the car is cold it does several things differently called running in open loop.

mk378

In normal operation (test jumper not installed), the ECU varies the timing intentionally to run optimally under various conditions.

This is why you have to install the jumper to tell it to temporarily stop doing that. Then you can see the true mechanical "base" timing without interference from the computer.

brians356

Yes, engine quite hot, and fan intermittently operating.

brians356

Thanks! Makes sense now.

A related question: Idle speed is ~830 rpm. This is higher than specified '92 VX idle of 600 (+- 50) rpm, and higher than the base ignition timing is supposed to be set against (16 BTDC @600 rpm.) So I would like to set the idle speed lower. The procedure as I understand it for '92 (engine hot, stopped) :

1. Disconnect the 2P connecter from the IAC valve
2. Start engine, rev to 1000 rpm, then allow to idle
3. Adjust idle screw to 370 - 470 rpm
4. Stop engine
5. Reconnect the IAC valve 2P connector
6. Remove BACK UP (7.5A) fuse for 10 seconds, to reset ECM
7. Start engine, check idle speed is now 550 - 650 rpm

I got as far as Step 1, cannot get the 2P connector loose from IAC valve. ;-( What's the secret to the connectors latch?

Relic1

the latch can be a pain on that one, it's an awkward position to get to and if it hasn't been removed in a while it can be stuck.
Easiest way I found was the pull out the two bolts holding the IACV to the rear of the intake manifold, then you can move it around and see what's going on with the clip.

brians356

Yes, I thought about removing it, too. But it would help to simply know if I must depress the connector's lever, or lift it, to release it.

09chaplak

I'm pretty sure it's push in the middle...

09chaplak

https://honda-tech.com/forums/honda-.../#post48795245
https://honda-tech.com/forums/acura-...valve-1575913/

brians356

Naw, figured it out. There's a similar connector, but white colored, on one of the TB runners. The lever has a fulcrum under its middle. The end of the lever has a couple of grip bars molded into it. When you press that end down hard enough, the other end (towards the wires) pivots up, and comes off a small retainer tab. Teeter-totter design. You can wedge a thin screwdriver blade under the lifting end, to encourage it to clear the retainer - if you have clear access. ;-(.

I read the article about cleaning the IAC valve. I removed the valve to gaim access to the connector, and did not find a rubber gasket as such, there seems to be a seal recessed around the two screened air holes in the IAC body. The IAC to TB was solid metal on metal. Am I missing something?

TomCat39

Also be aware, the car's tachometer is not accurate for setting idle.

It's advised to use an external tachometer. I personally bought an inexpensive laser tachometer that you put the silver tape on the crank pulley and aim at that to get your RPM readings.

As for the IACV, there is a rubber figure 8 seal Part#14. Please see the parts diagram for the 92 VX:

brians356

Absolutely. First thing I did was buy an EZ-Tach from WalMart, cordless inductive, $45, clamp it on a plug wire. Only downside is it says 600 rpm is the bottom of the range, but I haven't tried it lower yet. With IACV disconnected, I need 370 - 470 range. I might have to dead reckon, trial and error. Will take longer but should work.

PS Yes, I saw the figure 8 seal, semi-recessed and intact, but I might replace it, as it's nearly flush with the mating surface, could leak a tiny bit of air.

TomCat39

I would suspect there is no might have to replace it about it.

If the surface of the seal is flat and not round, and when you take it out it's even remotely stiff, it's old and needs to be replaced. The original seal does not have any flat surfaces to it and it very pliable and flexible rubber.

brians356

Thanks, it is flat and no longer pliable. Doesn't make sense to adjust idle and timing if it's questionable. I'll replace it, and clean the IACV while it's out.

brians356

Bummer. My FLAPS will sell me the whole IACV for $209, but cannot sell me the figure-8 "gasket" alone.

So ... where do I find obscure gaskets for a '92 Civic VX?

brians356

Found it, at Majestic Honda (where else?) Still, locally - at the Honda dealer, or a particular FLAPS chain?

brians356

Update: I ordered 1. IACV gasket, 2. IACV filter (screen), and 3. Valve cover gasket (spare) from local Honda dealer, parts available for pickup at 7:30 am Saturday.

I've had the IACV off and on the TB twice now, and have not noticed any change in idle speed, smoothness, or off-idle activity. My hunch is the old seal is still holding, but it's cheap enough insurance to put a new seal and screen in there. And, if my idle speed does change at all, I will know why. While it's off, I will clean it internally as best I can.

Thanks for all the help!

TomCat39

Offtopic - Like the Porsche 356 in your Road and Track avatar pic.

brians356

Update 2:

With new gasket and filter screen in hand, I pulled the IACV off to the bench. Try as I might, the old screen wouldn't budge. I tried a drop of Kroil around the rim, no go. Rather than destroy the screen getting it out, and not knowing exactly lay directly behind it, I chose to leave it, and clean the carbon out of the screen with TB cleaner.

The new gasket would not stay in place by itself, so it was tricky to get the valve body back in place with the gasket in position, but I managed. It was satisfying to feel the slight compression of the new rubber while tightening the bolts.

Next, I set the idle with IACV disconnected to 430 rpm, using my new EZ-Tach on a plug wire. After connecting the IACV, and resetting the ECU, the idle settled at 610 rpm, close to middle range. Then, with proper idle speed, I readjusted the timing with service pins jumpered, as expected it was a bit too advanced since, previously, idle speed speed had been high.

I'm very satisfied with the outcome. The engine idles lower and smoother, has more pickup, and I expect to see an increase in fuel economy.