egr vsv any one??????

[deeznutts77]

i think i need the egr and evap vsv's. i get egr flow malfunction p0400 code and have done "all" egr cleaning things. now the only thing i can think is these two switches.
96 16v 4wd

[jtgh]

did you clean the TB ,port, the one that is hidden behind the butteryfly valve ?
most miss this port.

is car stock.
all origional parts.
or is cat missing or rodded out.etc,

the vacuum lines can be tested for live vacuum by power on the VSV valve.
there are lots of tests if yous has a unique problem.

EGR-repair-methods

see last photo, can you do that with a tie wrap as show?

can you stall engine by opening the main EGR valve.

stall test.
can you.

stall test, clean whole path , miss nothing. on exhaust path.

if all that is ok then we test the activtion paths (rarely fails)

let us know,

[deeznutts77]

yup all of the above is been done yes all stock cept header put new cat con on still 0400code and reves up and down when warmed up. im ready to fully insuer this and drive it into a tree

[jtgh]

nooooooooooooooooooooooo,

lets work it.

ok , is p0400 the only code (DTC)?

did you know there are other places for it to clog.

you said yes, but did the stall test stall engine or nearly so,, ,tell how it sounded and behaved.

if sure, the hidden rear exh path thru head from exh. man, rear all the way to the EGR is clean and free and the EGR is clean and metal pipe (mostly clean it is huge)
and TB special small port is free and car stalls then...............

you are special. yours is the 2% P0400 EGR Hell.

first the EGR diaphram must be tested , a mityvac or clone tool for doing that is best.
second best is steal vacuum off engine.

start carl attach EGR main diaphragm nipple directly hand tool.
first pull 10inchs vacuum (no more) and see how long it takes to leak down.
look at diapharm with mirror see if it drops after you stop pumping.
if id drops ,the diaphram is bad ( pinch hose so your are sure the hand tool is not the leaker,see.)
now start car , and the hand tool can now stall engine. start car , pump hand tool , stall.
The FSM says 8 inches, will fully deflect EGR, and thus a stall.
release and EGR closes cars starts.

I am going to test both ends against the middle.

now start car, make sure vacuum To EGR vsv varies with RPM. (manif. side)
a vacuum gauge is best but you can feel it , and rev. and feel somemore and not increases of vacuum. This is called PORTED vacuum.
if the nipple on the manifold is clogged, then EGR is dead.

next is the VSV test.

see that electrical connector, on its side.
it can be connected to a 12vdc source (it is just a 12v coil in side)
apply 12v to the coil .
now this gets tricky as the VSV is default open.
[ fyi, there are 21 steps in the FSM for P0400 ] ouch.

basically make sure you can gate vacuum thru the VSV with 12vdc power source.
12vdc to the coil , should cause the valve to close. (it does on 95's)

if the valve opens and closes and passes vacuum thur the vsv , it is good.

next the 3nd to the lasts tests.
the modulator vavle , called the Pressure transducer.
It has 3 nipples.

P, Q and bottom, do not remove the lid , loosing P/Q orientations.
it has a filter inside so make the base with P next to P then pull lid.

The bottom tube goes to the MAIN egr.
this nipple on the EGR main must have its oriface clean. it is 1/16" diameter .
when the car is running feel this port with finger, it MUST pulsate, if not it is clogged up.
clean this port.
than a larger tube connects to this nipple up to the PQ mod valve.
OK .
This is the FSM verbatum instructions on this PW mod valve( aka transducer)

1: connect vacuum pump to the tube "p" and plug tube "Q" with your finger (or?)
2 Blow into tube "A" (bottom) and while applying vacuumto the tube "P" at the same time.
3: Stop blowing in to tube 'A". ( ask favorite Politician for this , or IRS agent.) LOL
4: you should be able to obtain vacuum on the vacuum pump, gage when performing step 2 and the gage should read zero in step 3.
5: if this fails, bad Mod valve.

There are other live tests to do , but are very difficult to do.
on a 96, the VSS speed sensor must be clicking (moving ) for EGR to activate.
which makes the last tests very risky.

rules.
HOt engine.
not WOT, not IDLE.
rearwheels turning. (spec. mph ranges)
RPM range.
Basically HOt Cruising is when EGR opens.


i do have the exact rules , as published by GM. for the tracker at hand.

sorry your EGR is a "SUPER PITA"

cheers.

[deeznutts77]

i think its the egr sensor over the egr itself, it has two vacuum hoses on it.

[jtgh]

this is a 1.6L engine , right ,not 1.8L?


that is the modulator valve. P and Q on top. see it.

it is a exhaust to vacuum modulator.
it regulates the vacuum to the EGR main valve.

see the mitchell test here.
P0400 Exhaust Gas Recirculation (EGR) Low Flow

nothing better for live test.
even shows the vacuum readings.

this is a copy of the public library mitchell , you mUST walk in to read it.
nothing better , free.

never pull top of mod valve , with out first marking P or Q at base unit. as approp.

P0400 Exhaust Gas Recirculation (EGR) Low Flow

1 page, has everything, or at least how to get everything you need.

not even the map sensor can be bad, but is rare.
shows test for it too.

[jtgh]

is this clean , in side where red arrow points?

see this point,
it takes a 90 degree towards the TB.

it needs to be fully clean at the hidden port restriction.
all 96-98 are very funny about this point, no restrictions.


cheers.

[deeznutts77]

yup 1.6 and not the mod thing theres and electric sensor to the left of that and i did the hole and tube first or second. ill do some reading andc what happens

[jtgh]

that link shows EVERY thing.

in cluding the live tests.

not to mention all 96+ cars with OBD2 , one can see the Freeze frame data.
this shows which of the 2 tests are failing, and I have the full spec. on the 2 tests.

in my hands.

one can do a full test, and see if the system is operational (go , no go)
if it is no go, fix it.
if it is go, and fails then the system has a restriction.

that is how you find the hard ones.

[jtgh]

is p0400 the only code throwing ? important question 1: