cruise throttle surge

[1995 toad]

but the port from the intake doesn't seal off the vacuum?
please explain, this. more details.

the port in the egr that comes from the intake manifold does not seal when the egr is closed. so it has a vacuum leak through the egr (where exactly is this LEAK)

the 1995 had 2 systems used, early and late seen here,, part ID 50 is missing it is early 95. (what I call the quad port)

https://fixkick.com/EGR-Gen2a.html

it idle and not moving the car, 0mph there is no vacuum ever past the VSV valve.
hose 16 is ported vacuum "P" at idle The TV in the TB is closed and there is no vacuum to the hose 16.
the nose 20 is dead until the car move faster than 0mph
then opens and ported vacuum lands at modulator 8. (using cat back pressure to see engine load)
if the cat is not missing or hose 13  gone, then part 8 , sends vacuum to EGR MAIN #5 opens, and opens based on CAT back pressures, (then at WOT, the vsv closes)
hose 13 is exhaust back pressure bark tube,  #4 exhaust only Putt Putt Tube. this does the modulation.


early:



if any of  this fails DTC 51 happens. (if you just unplug hose 23 and put screw or golf tee in the end , EGR main stays closed and stays that way for ever. code 51 full time.

the vacuum that leaking is coming from the metal line that leads to the intake. when the egr valve is closed the vacuum leaks out of the valve. the exhaust port side is sealed from the intake side of the port.

so line 14  steel tube rusted and leaks ? what ever leaks needs only to be replaced. (use vacuum hand pump tool to find leaks is best)


for example, golf tee the end of 23 and put too at 16 hose end.
then with vacuum pump hand tool , pump it so you pull say 10 inches of vacuum, the stop and it must old holds at say 10, and proves no leaks present.
if it did leak DOWN make sure vsv #1 above is not leaking .  it is closed, at all times car not moving. (the problem on this car key must be on, or  at idle to test the lines)
if it is ok then we check both sets of lines from 16 one by one to 23, one must be leaking.

let me explain the problem testing on this car,  VSV valves are tricky in susuki land
with key off,  the valves are not in there natural state , closed,  when you key on ALL VSVs in the car go to the natural state.
the being EGR off, no vacuum flows, (lines) EVAV VSV closed. 


vsv= vacuum solenoid valve. (#1)


see facts here
https://fixkick.com/sensors/vsv.html


the full FSM vsv test is linked on that page above.
to test the VSV on car, key must be on,  ECU is on. CEL lamp in cluster in dash glows, keyon engine off. or just  idle the engine.

the vsv coil is about 35 ohms. the VSV is easy to bench test with 12vdc power pack or battery, and hand vacuum pump. as the FSM shows.


FSM = factory(real) service manual , not flying spaghetti monster.(as some say )

vacuum leaks are not always easy to find,  so  many things can leak. (here)
the famous quote by  “Nature abhors a vacuum.”

― Aristotle

no Astronauts then ; the man was earth bound, so is true .   We fight this problem here on earth.  (1bad of atmosphere wants inside the engine)



that EGR valve above is  Twsv  three way vsv.
has  2 nipples and 3 modes.
when driving say 45mph (not 0 and not wot) (wot = wide open throttle)
then the 2 main port nipples pass vacuum from the plenum 16 hose to 19 pipe. and al the way to MAIN #5
when at say idle, the vacuum at 16 hose is blocked dead at the VSV nipple, this is closed VSV but at the same time the down stream hose 19 is vented, to the atmosphere to that filter seen on the top of the VSV, this prevents EGR MAIN #5 from going vacuum locked.

when key off, vsv is in vent mode.
when key is on vsv is closed. or cranking, too.
when idling vsv is closed.
when at wot , the vsv vent modes.
when going over 0 mph , vacuum flows from end to end, if the TB  port P 16 is open this is ported vacuum and only has vacuum with foot pressing throttle some.


as you can see it is a tricky beast how EGR actually works ,just on the vacuum side,  and then the MOD valve,. now that is even more magic, (Houdini like)

The mod valve, adjusts vacuum to main5,  using CAT back pressure, this back pressure  is engine load. (crude but works, until it don't)


if you defeat the EGR
1: MPH DROPS
2: EXHUAST VALVES RUN WAY HOTTER AND LAST LESS long
3: the engine may ping under huge loads. (may)
4: the CAT is three way, and if EGR is dead the NOX part fails soon.

if the car has no cat all this above, is just a waste of time,  the EGR is already dead, or worst,  worse means the MOD valve acts wrong, causing bad things, to happen.
Now the MOD, note how it vents air, if hand tested. (see RED path?) That means all hoses and pipes really must be individually hand tested for leaks.
The MOD has  very good B diaphragm ,(silicon rubber VG ) and never fails,(cracks)  but the RED path does fail. only needs to  be cleaned. the filter can pack in dirt, easy.

here is my mod cheat sheet,   many folks use this to pass smog in calif. (seen on all toyota's same years , same valve and same PAIN)

its not 14 
the line that sends the exhaust to the intake manifold from the egr does not seal at the egr when the egr is closed and sending no exhaust to the intake.
it should seal I would think.