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Old 07-28-2012, 10:54 PM   #1 (permalink)
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Vac hose diagram for '89 corolla LE

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CAUTION Do not repair or modify your car unless you know what you are doing and if you are unsure then ask a back yard mechanic. ToyoyaNation.com and/or Vachoseblows is not liable for any loss or damages due to mods or advice that was given in this thread or elswhere.
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i just did a head gasket on 89 corolla LE. i tried to find a vacuum hose diagram before I started this job as the 4AF carb has alot of vacuum hoses. I tried a haynes manual but the hose diagram was the size of a postage stamp - a maze of hoses that all went to the same place. I found the Toyota vac hose sticker that was glued on the underneath of the hood - at first I thought my eyes were blurry, so I peeled the sticker off and scanned it and enlarged the pic. Still to no avail, as later on I discovered that this vac hose diagram had errors as you can see below. Most of the pic is OK except for the big jumble of hoses just above the last "A" in the word CANADA

If you look at the TVSV the connectors are marked J M K L N which agrees with a pic of a TVSV later on in this thread. Notice that most of these vac diagram stickers develop wrinkles and I also learned not to clean the sticker because some of the ink came off as you can see. The bottom of the sticker says "----air conditioner, power steering". This particular car did not have an airconditioner and the ACV was found attached to power steering pump. ACV means air control valve - a generic term. The dashed lines - - - representing vac hoses seem to be for models with the air conditioner option. The VSV at the top of the vac sticker which operates an "actuator" device, has the dashed lines and that device does not exist on the corolla with no air conditioner. There was a vacuum cap on the metal pipe that is probably for the VSV and actuator device. It's function might be to turn on the air conditioner when the engine is warm enough - yes another TVSV controlled device.

I would like to say that during my head gasket repair job I discovered that the 4A-F is very well engineered. The engine head is a marvel of engineering. Solid lifters that don't need adjusting, a single timing belt that drives two geared cams, and the water pump is driven by it's own belt. No wonder why these cars last!! To top it all off, the engine is non-interference so if you break a timing belt then no damage is done.

Since I had never done a 4A-F before, I postponed the head gasket job until I had all vac hoses figured out . This took 2 days of hard work with pencil, paper and eraser. i finally obtained a remarkably clear diagram of all vac hoses - all 24 feet of them! I wish to put this diagram up on this thread. i have not scanned the diagram yet as my comp blew up (running in safe mode right now) I will in due time put this diagram up.

Btw if you have any questions related to the 89 corolla fire away.

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Old 07-29-2012, 02:11 AM   #2 (permalink)
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So here is the long awaited vac hose diagram ( 1 hour later)




The various parts are numbered for easy reference. Please join in here if you know anythng about these parts and what they do. I will start at part number (1) and attempt to give an explanation of it. If I make a mistake then please jump in and make me look stupid.

(1) Choke breaker also called a choke unloader. The choke plate is actuated by a dual diaphram vac pot that opens with applied vacuum through check valve (21). It's job is to prevent a flooded engine. The secondary diaphram is operated by the TVSV (12) which opens as the engine warms up. This action results in a gradual opening of the choke plate.

(2) The AAP Auxiliary accelerator pump. This thing is prone to leaking and should be disconnected by inserting a golf tee into the hose that goes to the AAP port. Once the engine warms up, the AAP is no longer needed. A malfunctioning TVSV and/or APP could make the car fail emissions test and why pay the oil companies every time you step on the gas pedal??

A bit of a break here. The hard part of following the vac hoses on the toyota are all the miles of vac pipes (small metal tubes) that are absolutely indeciperable by a casual glance. Tubes that ran around the entire engine when they only had to travel a foot or so got me puzzled These maze of metal tubes prevented the removal of the intake manifold among other things. i made a decision early on to not put the tubes back in. i bought some good quality 5/32 ID vac hose (made by goodyear). i used 24 feet of hose but now anyone can tell what is connected to what.

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Old 07-29-2012, 08:17 PM   #3 (permalink)
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Another choke related part is vac pot (7) . This is a single diaphram pot that opens the choke plate completely from vacuum applied via port "b" of the TVSV. It's job is to prevent the automatic choke from being applied when the engine is warm to hot.

One thing i found out is that the car still starts fine if this pot is disconected. i would recommend to leave it hooked up though as it might be there to prevent a flooded engine under certain operating conditions. A TVSV that is stuck will pretty much disable pot (7) You will notice that the vac hose going to pot(7) also goes to the EGR vac pot through check valve (19). If your car has failed an emissions test for Nox then verify that pot(7) is recieving a vacuum (and can hold a vacuum) when the engine is warm. if there is no vacuum to pot (7) then the TVSV is stuck. It might seem that the TVSV applies vacuum to the EGR vac pot -do not be mislead - the check valve (19) will not allow vacuum from the TVSV to reach the EGR pot. never connect check valve (19) backwards as the engine might not run. When the engine is cold the TVSV supplies atmosperic air to the check valve (19) thus leaking out the vacuum supplied by the EGR modulator. When engine is hot the TVSV applies vacuum to check valve (19) thus sealing off the flow through the check valve so the vacuum in the EGR pot is maintained.

(3) Distributor vacuum advance. A dual diaphram vac pot that advances spark timing with applied vacuum. The primary diaphram is connected to what looks like "ported" vacuum at "c" on the carb. I have used the letters a, b, c, d for the connectors on the rear of the carb. These connectors are very close together so care must be taken so as to get the right hose to the right connector. I wish i had a pic of this area of the carb to show those conectors. The secondary diaphram is connected to manifold vacuum. Check valve (20) maintains vacuum on the secondary diaphram even when manifold vacuum is low. The check valve (20) is bypassed by the BVSV (15)
when the engine warms up. It looks like the secondary diaphram applies a bit more spark advance when the engine is cold at low manifold vacuum because of vacuum retained by the check valve. This might improve acceleration when engine is cold.

(4) EGR modulator.. The EGR modulator senses the exhaust gas pressure and modifies the vacuum from connectors "b" and "c" of the carb. The modified vaccum is fed to the EGR pot (6) This regulates the amount of exhaust gases that are fed back into the intake manifold. The hose that goes from the exhaust connector (at base of EGR pot) to the bottom of the EGR mod is not shown.

(6) EGR valve ,, A single diapram vac pot that actuates an EGR valve. A stuck TVSV will disable this valve and wont pass an emissions test for Nox, If that happens just remove the hose that goes from check valve (19) to the EGR (6) and put a vac cap on the EGR connector Take er back thru the emisions test and get a pass

..do you know the feelin when you type for an hour and hit the wrong key POOF where did it go there is no UNDO. From now on i type using WORD then paste it in

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Old 07-30-2012, 08:14 PM   #4 (permalink)
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(5) I accidently erased number 5. Connector “d” on the carb is where number 5 should be. It goes to the charcoal canister

(7) Already discussed

(8) Here is a part that is pretty much useless. It is a single diaphragm vac pot that controls engine RPM when you turn the steering wheel.

The related parts are VSV (9), vac pot (8), VTV (17), ACV (10) . These parts can be removed and a vac cap put on the carb where the VTV hose used to go.
Car owners have complained about a mysterious power steering fluid leak. This can be caused by a defective ACV valve. The linkage from pot (8) should be removed as well to restore the idle back to normal RPM. I have not actually removed the linkage but I think it is doable. Im not recommending the parts be removed just indicating they can be.

(9), (10) Already discussed

(11) A single diaphragm vac pot that is mounted on the firewall about center of vehicle. It gets vacuum from connector “c” of the TVSV . This vacuum contolled switch has normally closed switch contacts (with the engine off)and will open with applied vacuum. The ECU will not switch into closed loop mode if the vac hose to this switch is disconnected.

(12)TVSV

This part is extremely unreliable but the car will still run fine without it. Mine was stuck in the “cold” position and so I had to disconnect the AAP (Connector "N" in the pic) as already discussed. The EGR was also disabled by the stuck TVSV but I know how to get around the emissions test on that one – already discussed. The TVSV controls 5 devices. The AAP and vac pots (6), (7) and vac pots (1), (11). Pot (11) is a vacuum controlled switch required for closed loop operation. The most important device it controls is EGR pot (6) and AAP is a close 2nd

(13) Vacuum connector threaded into the intake manifold near cylinder #1. If your #1 spark plug is black then chances are good that the AAP diaphragm has ruptured and gas is being sucked into this vac connector. The gas from the leaking AAP goes to cylinder #1

(14) The EBCV looks like the robot from a star trek episode that was set to sterilize anything it did not like. When the robot discovered that Dr. Jackson Roykirk was actually cap James T Kirk then the robot says error error must sterilize and Scotty beamed it out of the enterprise in the nick of time.



(15) Already discussed

(16) goes to cruise comtrol

(17) already discussed

(18) check valve. operation not known

Well that is about it for now. You don't see too many vac diagrams on the net huh? Don't worry this thread is all you need - heh

Last edited by vachoseblows; 12-10-2012 at 03:04 PM.
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Old 08-04-2012, 03:13 AM   #5 (permalink)
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The EBCV deserves some attention.


The pic shows current and an air flow graph. The valve looks to be fully open at .6 ampere. The left hand side of the graph is measured in litres per minute so I think the graph is for a Tercel EBCV - yes there are differences so don't get too excited. The tiny mosquito breath air flow into the air bleed jets on an 89 corolla LE, surely could not be measured in litres per minute, more like pico litres per century.

I have finally determined that EBCV operates in duty cycle mode at a frequency of about 100 HZ (cycles per second)

In general the EBCV is a device that controls fuel mixture and is part of a computer operated closed loop system. To make matters more complex, the EBCV is different for a Tercel and different again for an SR5 corolla. There may be even more variations of the EBCV, as these devices seem to vary in design and application from one model to the next.

There seems to be no defintive explanation of how the EBCV operates in the 89 corolla LE. There are tidbits all over the internet that give some insight.
example: http://www.autozone.com/autozone/rep...00c15280047f7d


The HAC (high altitude compensator)
is built into the EBCV on the 4AF corolla. Having an EBCV and a HAC in the same device causes confusion when trying to trouble-shoot the device. There is also an electrical connector to the top of the EBCV (two wires) that is controlled by the computer which operates the valve.

From the following site http://newgrn.rlftest.com/lingo.aspx?pcid=785&Ch=E
Quote:
The Electronic Bleed Control Valve, or EBCV, is a pulsed air control valve used by Toyota to adjust the fuel mixture in closed loop by increasing or decreasing the amount of air being drawn through the carburetor air correction jets.
Another tasty tidbit from this site:http://www.underhoodservice.com/issu...ontentid=39836

Quote:
On the road test, I also found that the EBCV valve was fixed at 66%; the PCM was trying as hard as it could to lean out this carburetor,
That is interesting - the mechanic says the EBCV is maxed out at 66% What does he mean?- he means 66% duty cycle. He is measuring the duty cycle with a DWELL meter (I think) so it looks like he's already converted from the DWELL scale to the duty cycle scale . The mechanic also says that the 02 sensor read 900mv when under a rich condition.

Quote:
The O2 sensor gave me a constant rich reading of 900 mV, but back at the shop the response and calibration tests proved the sensor was able to function properly

A good site that explains 02 sensors. An 02 sensor output of 450 mv is considered to be optimum air/fuel mix http://www.autodiagnosticsandpublish...or-testing.htm

The O2 voltage swings up and down due to response of the feedback system.

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Old 08-06-2012, 02:54 PM   #6 (permalink)
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Im going to sidetrack a bit here ......

Here is a video of an 02 sensor readout with a digital voltmeter. A scope is one of the better ways though.
Well sorry folks the owner of that video does not want his vid to be used. but I did like his background music though from Tom Petty. Here is another you tube video - a splendid example of some one who is trying to get better gas mileage by fooling the O2 sensor.


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Old 08-07-2012, 07:50 PM   #7 (permalink)
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Here goes I hope this is correct but it is better than a guess.

The HAC device is a kind of booster valve. The weak force of the bellows is not enough to move a mechanical port switching valve reliably nor far enough because the movement of an atmospheric bellows is very slow. Manifold vacuum assists in moving a HAC valve. The bellows operates a valve that allows manifold vacuum to operate a port switching valve by means of a diaphram. So there are two valves in the HAC device. The switching port allows atmospheric air to enter the carbs air jets at high altitude only. There are 3 air jets in the carb which are used to lean the fuel mixture.

The HAC device switch port needs to be in parallel with the EBCV switch port because the HAC's switch port is closed under normal low altitude conditions. I found another vac hose sticker from Need info (sticker under the hood) of 1988 Toyota Corolla FX
Where I found this pic



This vac hose sticker shows the EBCV and HAC as two separate devices. Notice that two of the EBCV and HAC switch ports are in parallel as can be seen from the vac tees connecting the two devices. This sticker is way easier to follow despite the wrinkles and gives some important clues. Testing indicates that the "S" connector on the EBCV feeds air into the idle jet and the "M" connector feeds air into the primary jet. These two jets are also fed by the HAC. The HAC feeds the secondary jet thru it's own port which is the only port not controlled the by the EBCV.

Notice that manifold vacuum is used only by the HAC not the EBCV, which proves that manifold vacuum is not applied to the carb jets. The HAC and EBCV switch ports allow atmospheric air to enter the carb's air bleed jets due to a small vacuum that originates from the jets.

Refer to the hand drawn vac hose diagram at the top of this thread. In the pic it says EBCV (14) there are 3 connectors in a row and one connector below. I forgot to mark the connectors, so lets say that from left to right the top row will be "a", "b", "c" and the lower will be "d". The "d" connector goes to manifold vac through a check valve (18)

The hose from connector "a" of the EBCV goes to the primary fuel jet and the hose from connector "b" goes to the secondary fuel jet. When the car is idling, removing connector "c" will stall the motor because the idle circuit draws air - not fuel. If you put your thumb over the open hose the vac can not be felt as it is very minute. Here is what happens if you try to drive an 88 corolla (same EBCV as the 89) with the vac hose from the "a" connector removed

From this link Issues after installing new carb

Quote:
First problem is during acceleration. Under 3k rpm the car accelerates very unevenly and sometimes not at all. It seems to run best in that rpm range when I only give it the smallest gas possible, anymore than that and it doesn't work. I feel like it may be too rich... When I give it gas and quickly back off the accelerator it seems to recover. After 3k rpm the car runs like normal and if i dump fuel long enough the car will switch gears and accelerate hard.
The above poster thought that the car was accelerating poorly due to a rich condition when in fact it was due to a lean condition.

Testing revealed that plugging off the PCV valve made a huge difference in O2 sensor output volts at idle. With the PCV as is I measured a steady .050 volts at idle - thats right 50 millivolts. When I plugged off the PCV valve, the volts jumped up to a steady .6 volts or so. The variability of the PVC makes accurate testing of the O2 sensor impossible unless plugged off. At least the O2 sensor works well - the slightest hint of oxygen smashes the volts down real quick.

I tried to see if I could get the car to run at less than .050 volts at idle. I removed the hose going to connector "C" of the EBCV and quickly put my thumb over the hose so the car would not stall. I very carefully released my thumb pressure from the hose and sure enough the o2 sensor volts started dropping. When it hit about .025 volts the engine stalled. Strange thing is the EBCV is supposed to work even at idle but I could not get a response from it. (Found out what was wrong later in this thread) Many car web sites report this same thing about the EBCV that it does not work. I wonder what goes wrong with it.

I tested the EBCV itself by putting batt voltage thru a small test light to the EBCV electrical connector > there was a click noise and the engine stalled so I know the EBCV idle switch port is working but the ECU simply is not sending it anything. I found out later that even though this test worked, the EBCV idle switch port would not actuate with the signal that the ECU was sending it.

Last edited by vachoseblows; 01-14-2013 at 12:33 PM. Reason: spell mistakes and grammer etc
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Old 08-13-2012, 12:04 AM   #8 (permalink)
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More searching the net about the EBCV has turned up nothing other than the EBCV does not work. It seems Tercel had notorious carb and EBCV problems. I cant understand why there is no definitive info on the EBCV. This device is a critical part of the feedback system on the 4A-F engine. Most people disconnect the EBCV cause they dont understand what is wrong with it. That is my problem as well - More testing is needed.

I probed the electrical connector of the EBCV and was able to measure a voltage (not connected to EBCV) One side of the connector is grounded back at the ECU - lkely thru a NPN transistor open collector. The other is fed from the + batt supply.

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Old 08-13-2012, 01:55 PM   #9 (permalink)
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I got + supply volts at one of the connector pins The other pin goes to the ECU. I attached the test light to that pin of the connector and other lead of the test light to + batt and reconnected it to the EBCV (made sure the connector itself was good).. Started the engine (made sure vac sw (11) was open (vacuum applied to vac sw.)and plugged off the PCV which will give a readout on the O2 sensor anywhere from .6 to.8 volts. I was hoping the test light would glow in response to the ECU turning on, but nothing.

Don't know why this 4A-F won't go into closed loop at idle (Later Note: I found out later that the EBCV itself was not working properly etc)

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Old 08-14-2012, 03:17 AM   #10 (permalink)
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I wanted to know which sensors are needed by the ECU to switch it into closed loop mode. I found this web site about a Toyota powered Chevy Nova that describes various sensors.

http://business.highbeam.com/138076/...tor-age-garage

Quote:
REPAIR ORDER

VEHICLE: 1986 Chevy Nova POWERTRAIN: 1.6L 2-bbl., feedback-carbureted 5-spd. M/T MILEAGE: 89,000 SYMPTOM: Stalls only in cool damp weather while in neutral or in gear. Stalling decreases as engine warms and it won't stall under power.

We guess the saying: "You never truly appreciate what you have until it's taken away from you" is true. At least, that's how we felt when an FBC, Toyota-powered Nova rolled into our service bay. In case you don't know, the Nova's Toyota 4A engine has computer controls, but it lacks self-diagnostics. This Nova had been to its normal repair shop on numerous occasions for its stalling, but the shop could never duplicate the problem. Now it was our turn to dust off our carburetor knowledge and remedy this malady.

System overview

This FBC system was quite simple. The carburetor is set up to run richer than the desired 14.7:1 air/fuel ratio. This sets a predetermined limit of rich operation. Therefore, the ECM commands air to be bled into the carburetor's main metering system and its primary bore. Thus, a leaner operating condition is easily obtained. The system's main inputs to the ECM are an oxygen sensor, a vacuum switch, a throttle position (TP) switch, and the distributor. The ECM's output consists of a ground signal sent to the electric air bleed control valve (EBCV). The EBCV is energized (grounded) by the ECM when a leaner fuel mixture is desired. …
Here are some pics of the Nova Carb - 4A LC

http://store03.prostores.com/servlet...,-Chevy/Detail

Notice the above article mentions a "throttle position switch" as one of the inputs to the ECU (they call it an ECM same thing) Well it turns out that the 4A-F also has a throttle position switch. The 4A-F that i worked on had a defective TP switch and it's plunger was stuck in a retracted position. The ECU would still go into closed loop mode with this defective switch, so I left it as i found it. There does not seem to be any issues with the TP switch in the retracted position.

At idle, the throttle position switch contacts are open. The ECU uses the switch signal and an RPM signal to energize the primary fuel cut solenoid. According to the autozone site, the RPM must be around 2300 for this to happen. http://www.autozone.com/autozone/rep...00c1528006f22e. The primary solenoid is energized during deaceleration. This evidently protects the catalytic convertor from overheating due to a rich condition. (I can't see it though)

With the throttle switch wire disconnected there is a fluctuation at around 2300 RPM so evidently the ECU is turning the solenoid on and off. (I have not performed this test so i can't explain it any better)

That explains why there are two wires going to this solenoid, one wire is positive battery and the other is switched by the ECU. When the solenoid is energized, the fuel to the primary jet is reduced. There are not one but two fuel cut solenoids on the 4A-F. The secondary fuel cut solenoid seems to be an anti dieseling solenoid here is a site that talks about it . . 4A-F problems at 2200rpm

There is not much information on the secondary fuel cut solenoid so i don' t really know what it does. The above thread says this solenoid is simply powered by the ignition switch on or off and that makes sense because there is only one wire going to it. It is not known if another device controls this solenoid in some way. Still looking . . . . Here is a good PDF on fuel cut solenoids

http://www.tomco-inc.com/Tech_Tips/ttt11.pdf

On the 4A-F, RPM of greater than about 1100 and vacuum switch (open contacts) are the only two inputs needed for closed loop operation (The throttle position switch is not an input for closed loop operation). There are a total of 3 temp sensors on the 4A-F engine. One operates the temperature guage, another operates the radiator fan and one more at the back of the manifold, close to the carb, operates the CMH (Cold Mixture Heater). According to autozone, the CMH was only on the 4A-F

http://www.autozone.com/autozone/rep...06f1c8#hd1-1-2

None of the 3 temp sensors are used for closed loop operation. Why did not someone just say that ??

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Old 08-15-2012, 12:19 AM   #11 (permalink)
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PAY DIRT

Meet the guy who invented the EBCV!!!!!

http://www.patentgenius.com/patent/4766868.html

Let me clear that up. The patent speaks about a feedback system that uses an EBCV device. Found out there are quite a few patents like this. Here is one from Bendix that was done with operational amplifiers. ................. http://www.patentgenius.com/image/4300507-2.html


To sidetrack a little bit - I found out later that an EBCV on a Toyota Tercel is way different from the EBCV on a 89 corolla LE. The tercel EBCV injects air directly into the intake manifold while the 89 corolla EBCV injects air into the fuel jets. There seem to be more issues with the Tercel EBCV, the most annoying complaint being lack of power and hesitation.

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Old 08-15-2012, 12:22 AM   #12 (permalink)
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So I've done some more testing on the 89 corolla LE carburetor feedback system. My main goal to verify that the ECU and all other feedback device are in control of the air fuel mixture. I have an analog O2 voltmeter and an analog ampmeter. I connected the O2 voltmeter directly to the O2 sensor and left it plugged in to the wiring harness. This voltmeter has 40 megohm input resistance so it won't load down the O2 sensor. I started the engine and let it warm up. After about 4 minutes the O2 meter started reading a voltage but it ws all over the place. I thought it was loose connections. After about an hour of this torment Itried plugging off the PCV valve which I did and sure enough the O2 volts were nice and steady. The PCV is a real torment if you want to measure the O2 volts - unplug the PCV from the valve cover and put a thick piece of tape over the end of it to seal of that horrid good for nothing vaccum leak!!!!

That being done, I was somewhat satisifed but I could not get the EBCV to operate at idle. It seems that one of the inputs to the ECU is an RPM signal and the closed loop mode seems to switch in at about 1000RPM which is about idle RPM. So you can't have your cake and eat it too. I don't like that - a computer deciding for me when it will turn on and when it won't. So I upped the idle to about 1100 RPM and finally got a signal to the EBCV. I had connected the analog ampmeter in series with one of the wires going to the EBCV and attached an audio device across the two wires going to the EBCV (4 ohm speaker in series with a 1 microfarad capacitor) so that I could hear if the ECU was sending it a duty cycle signal - yep a nice bzzzz in the speaker - duty cycle, not linear!!!

Even so, with about .3 amperes flowing (at an unknown duty cycle) through the EBCV, the carb would not lean out - there was no air coming through the EBCV port to the idle jet of the carb. I thught I came this far and still this EBCV remains as mysterious as ever. I'm trying to look at this objectively . . . Could it be the filters inside the EBCV ? Maybe, but I don't want to take the EBCV apart just yet as it is very expensive to replace. Another test was done with full battery power through the EBCV limited to about 1 ampere by a small tungsten light bulb in series with the EBCV. The car stalled when the power was applied so I know the EBCV works and the filters are not plugged. So why can't the ECU send it enough power?

Next day . . .

Last edited by vachoseblows; 12-04-2012 at 07:32 PM.
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Old 08-15-2012, 09:17 PM   #13 (permalink)
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You got to think of everything when you work with these feedback carbs. A previous test determined the EBCV switch ports were isolated from each other. I thought that maybe the idle switch port had something wrong with it. The clue to that was a previous test at 2000 RPM where I removed the plug to the EBCV for 2 seconds and plug it back in, the engine RPM dropped momentarily. That proved the primary switch port in the EBCV worked. At 2000 RPM fuel is coming out of the primary jet.

So I thought what if I swap the idle connector "c" with the primary connector "a" of the EBCV? I know the primary air port works so the swap should allow the good port to control the idle jet.

I set the idle to 1100 RPM, plugged the PCV and sure enough the system went into fuel control at idle. I could hear the change in duty-cycle of the speaker and could see variations on the O2 voltmeter. So all along it had been a defective EBCV and a ratty PCV that screwed with the precious O2 volts and a strange RPM setpoint in the ECU. A whole bunch of stuff that was all happening at the same time - a real headache.

I'am now considering an EBCV from a Tercel - a lot less complicated, just one big honkin valve that allows air around the carb to control air/fuel ratio. Even with the fact that many Tercel owners complained about hesitation and poor acceleration - at least these Tercel EBCV worked - maybe a bit hyperactively but I think with some back yard engineering the Tercel EBCV is the way to go. Could this thread become the Tercel to Corolla EBCV swap ? we will see. . .

Last edited by vachoseblows; 12-10-2012 at 03:40 PM.
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Old 12-04-2012, 08:19 PM   #14 (permalink)
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If i decide to convert to a Tercel EBCV, I will use the manifold connector that goes to the PCV and throw away that usless PVC (You will see my PCV mod in another thread )

Then I would design my own feedback system with an option of manual control. I want a dash mouned control that I can dial and watch the O2 volts. I already know how to extract the O2 volts and amplify it.

I think the ultimate would be a fuel mileage meter along with the ability to control air/fuel ratio. Dial the air/fuel control until the fuel mileage peaks????.

Last edited by vachoseblows; 12-09-2012 at 05:31 PM.
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