Tricking HCAC codes into going away?

Any update on the HCAC and the CEL?

BTW, Did you use one of the "Direct fit" aftermarket cats for gen 1 with one cat? I am wondering how well the direct fit gen 2 with 2 cats fit. I mean, I expect some welding is going to be needed, but the thieves took the HCAC assembly and the resonator, so I might as well replace both cats.

 

I just installed the gen2 cat in my gen1. Of course I had to fabricate all the back tubing as you get just the front two cats.
I'm going to tackle the HCAC codes..

 

Awesome. Keep us posted about HCAC.

 

Well so far I can't get the code to show up on this car. I know my blue one, it showed up right away. It opens the valve when cold, and then closes it when its warmed up, I think the code showed when it warmed up. So it is not so easy to make it notice it isn't working, and so far, I have not gotten the code on the green one.

btw, to pass smog, you can just warm up the car, clear all the codes, then drive it around until its 'ready', then have it smogged, it will not throw the code until it cold again.

 

So I got the P1436 with the hose plugged up. I had removed the vacuum canister from the exhaust, and plugged it into the hose,
and the P1436 cleared. As one might expect, the sensor is only measuring the air flow in/out of the canister and not doing checking anything with the actual exhaust. So if one attaches a vacuum cannister to the hose, it should not trigger the code.
Coming up with one now..you can buy just the cannister from Toyota for $200. I think $2 max $20 is more appropriate.
I turbocharger waste gate control looks about the same, I have some of those around here.
Or something else more common, thinking of a syringe in a big size or a epoxy dispensor that already has a spring in it..

 

Finally got it. Took about 4 tries..but the final solution that worked used a pop-up sprinkler and a balloon.

Hose connected via a drip irrigation fitting on the threaded side of the sprinkler. Gutted the sprinkler inside,
and kept just the spring and the spring seat, and then covered the top with a balloon (cut off necked down part),
and secured with a zip tie. When the car turns on the valve, it sucks down the ballon and compresses the spring,
and then when it off it returns. Over time the balloon might tear, so might need a heavier duty one than a party balloon. I bought some 'water balloons' in the past but could not find them, they are heavy duty balloons.

So now just tuck the contraption under the hood.

 

Good Work. I am guessing that attaching pretty much any vacuum actuator to the vac hose would do the trick.

 

What I learned was it has to have a volume that is similiar to the oem unit.

 

Now that's some inventiveness right there.

 

Has anyone tried a vacuum advance unit from an older vehicle distributor. It works off manifold vacuum and has adjustable spring tension.

 

Makes sense. I got the cheapest actuator I could find off ebay, which was a used CC actuator from a Honda Goldwing. We'll see if that works.

 

can anybody link a cheap vacuum actuator that'll work to clear the P1436 code. I plugged up the hose near the catalytic converter P1437 disappeared but replaced with P1436 I really don't like seeing the CEL Light on

 

So the Goldwing Actuator has worked great: no check engine lights anymore.

Search eBay for "goldwing cruise actuator gl1500" and you should currently find a bunch, starting at $7.25 shipped.

To install in the engine compartment, see the photo I am posting and pull that hose off and put it on the actuator. That rigid line goes down and connects to the flex hose at the cat.

VAC_Hose by Soren Lorensen posted Jan 3, 2022 at 10:11 PM

 

I've been following this thread trying to piece the information together. I ordered the suggested valve, a summary of what you did would be much appreciated. The previous owner replaced the stolen CAT, but I don't see a valve anywhere on it (they managed to pass the smog test, I got to deal with the code now).

 

Soren,
I'm fighting the same problem you seem to have conquered - stolen cat replaced with a Gen2 ebay cat assembly. $85 delivered. Was impressed on how well that part fit and the fact that there were no O2 codes. Apparently the aftermarket cat is doing a reasonable job.

For the remaining P1437 and P1436 codes, I tried a beefy Borg Warner choke pull off from a carb. No dice. So would like to move to the Goldwing solution. In addition to the actuator device/assembly there is apparently a separate vacuum canister that works with the cruise control. From reading your post, it sounds like you used the actuator only and did not use the vacuum canister. Could you please confirm. Also, could you comment on how a cc actuator might operate differently than a choke pull off diaphram.

I thank you in advance.
Larry

 

Most likely you don't see a valve because its not there. Unless the previous owner replaced the whole cat assembly with a genuine OEM Toyota one, in which case, you wouldn't have any code issues.

What to do: Pull the hose with the red arrow in the pics above off the rigid line that goes back and down toward the cat, and put it on the barbed end of the Goldwing actuator (you may have to pull a piece of old hose with a braided exterior off first). Done. lay the actuator assembly in that gap to the left of the engine, close the hood, drink a beer.

 

Yes, Actuator only and not vacuum canister.

I know nothing about the choke diaphragm you tried, but Nimblemotors hypothesized that the actuator "has to have a volume that is similar to the oem unit" to trick the sensor into believing that the line is connected to the original type of HCAC actuator. I suspect the unit you tried may have been too large.