Please help cold start/emmisions jtgh?

[DJB1981]

Hi,

I'm in the U.K and having real trouble sorting my spi 8valve auto vit (1992) Sorry in advance for the long post but im getting desperate

I bought the car months ago as a non runner to replace my rusted tired Vitara as a non-runner, It was a easy fix it was the dreaded ECU problem so i got a refurbished one (plus my old one as spare). First problem was previous owner had tried fixing it and managed to mess timing up and really flood engine bad!!! (did'nt usea injector seal)

I have managed to get car running fine when warm but to start it i have to pull fuel relay run it till it stalls then plug relay back in and try again eventually it will run terrible (100 -300rpm) till it warms up. When i took it for its test the emmisions was over 10 (limit is 3.5) i managed a pass by disconnecting map sensor (passed at 0.8) which did not make any difference to engine performance even though it in limp home mode.

I have no way to check emmisions but assume its connected to cold start problem. Also i do have a slight exhaust blow were exhaust meets manifold (below 02 sensor) And dont know what to try next so far i have changed -

Manifold, full exhaust, filter, plugs, leads, rotor, TPS, Injector, Map sensor (also tested) IAC not tried adjusting?, ATS, WTS, EGR MOD and the bits were the egr pipes go in (blue and brown plug thingy controls vacuum for choke? seems to be working)

As you can see i'm all out of ideas all bits are from my old vit which was a runner , i have not yet changed egr cannister?

Sorry 4 the long post on a side not nice forum just found it so i have some serious reading to do

[jtgh]

if map is good and it idles low:
the IAC is bad, clocked , dirty, etc. (or EGR)

your cat is good , if you passed smog in limp home. wow, hot cat she is.

you need to fix the IAC so that cold start is 1200 rpm then drops to 800 when hot.

Egr stuck open with carbon will destroy any idle speed. check it visually and make sure
you cant blow air thur it.

if you think that EVAP canistor is bad ,just pinch the hose for now.

you can block the egr tiny vacuum line too , just to test and elimanate that as a faulty circuit ( the upstream EGR vsv can go bad and make you crazy , but this is rare)


Keep in mind your IAC has two modes.
cold start mechanical wax expanding warm up high idle.
then when car enters close loop , the ECU modulates the second part of that IAC.

your tactics are brillant ! pully FP relay , kills injection and then you unflood.
very good trick.

on this 8v engine, if the IAC clogs, you engine has almost no air supply.
because the fuel injected is FIXED (based on coolant temperature) the mixture
goes way rich and floods the engine.

If it were mine, Id make sure EGR is closed like a rock.
then if it wont start and idle correctly jump all over the IAC.

if both my ideas are wrong,then maybe the Fuel pressure regulator is stuck wide open
and producing huge Fuel pump pressures. there is a pressure port on the left banjo of the fuel filter , front of tank.

lets fix this puppy.

happy holidays, jerry

PS: sounds like your cam timing is correct and ignition too, right? no slipped belts, < very bad symptom wise.

[DJB1981]

Many thanks for the suggestions Not got much time to play due to time of year Happy holidays to you too

So far i did the EGR test by pushing the EGR diaphram (once i managed to start the car) this causes the engine to stumble and die, What do i need to do close the egr like a rock? I pressume first step is to block pipe that runs from cannister to inlet manifold (done that)

Other thing i found by reading the manual is under the IAC and above the EGR is the air valve (remove 3 screws to access it) this is permanantly closed ie not allowing air to bypass when cold but i cant see how you replace this?

Once again many thanks i will update this post once i have had another play problem is once engine is warm it runs fine so i have to wait for it to go cold again, Also spent the morning looking through your website which is a excellent resource only wish i had found it sooner

[jtgh]

sorry but like a rock is
EGR off, look at seat inside, make sure it is fully closed. No carbon chucks allowed.
blow air thru it, then if sure it is sealed, then test spring for proper tension.
blowing air from exh. side to intake side of valve.
if spring seems strong and holding, the valve shut,
then put back on , make sure gasket is sealing .
and plug the input tube (temporarally ) to the main EGR diaphragm.
these steps insure it is sealing,


at start:
Canister (EVAP) is off
EGR is off .
PVC is tiny oriface and very small . (not major player in Air during start, unless someone drilled it out, seen that too)
remainder of air supplies during start:
IAC (major player) ( has 5mm hex key for adjustment on my 91)
Throttle plate butteryfly valve, is held open with the Dashpot fast idle diaphragm.


but it has a spring in it that opens the Idle with no vacuum !

mine is closed for hot and cold running.
but cranking, that's another story.!

see next post on cold start fresh air.


Its all about Air.

Happy Christmas eve to all , and CHEERS !

[jtgh]

conditions 40d, F. sea level + 450ft

I ran a test for you. (Cold Start FRESH AIR TEST)
here is how it functions on a good 8v sidekick and tracker.

During cranking the Dashpot diaphragm holds the throttle open during cranking.
there is an adjustement screw shaft to the bell crank, of TB.

the IAC has only a tiny leak of air when Ignition is off .
during cranking and coil unplugged , the IAC pulsed like a drummer , with lots of air flowing, Lots ! 50 /50 duty cycle it seemed like. open , closed, open,repeat 5 times a second approx.
Easy test , I used a clean test tubing to use while sucking. (dont inhale)
if this bothers you , buy a flow meter..... Page 6E92 in FSM.

while engine is cold and sitting the Dash pot is holding the throttle open
about a 1/4 inch (6mm?) (guessing here, more later)
if this isnt happening , then the spring inside is busted or someone buggered that fast idle adjustment. (says dont touch in FSM)

now we know why?, it is calibrated to the fixed Fuel map for cold start in the ECUs perminant memory. aka: cold start fuel map.

I will try to measure the gap , running, and post that.
the 6mm , will try to get a very accurate measurement using screw thread diameters.
that way everyone could just buy the screw and gap it using that,
simple huh?


if all the above checks out , then open up the IAC screw for more air. 5mm hex Allen key.

if IAC doesnt pulse hard during cranking, the IAC is stuck (clean it) or coil is open, 2 wires broken to ECU and last ECU bad.
measure coil, if 11-14 ohms its ok
if coil good ohms, then apply 12v to coil in IAC, then suck tube at TB air tube input to IAC. with power to coil the IAC must open
wide open and let tons of air in. (flow = much)
do not apply 12v to this coil more than 1 min. and then rest 1min. to avoid over heating the coil (it is modulated).
Notice all tests on car, cool huh?

None of this is in the book,save coil test and voltage test.(scope is better)

with a mechanics stethoscope one can listen to the IAC while running or cranking. click , click, real fast.

more later... on the Dash Pot gap. (factory setting)

[jtgh]

that valve you inspected in the base of TB.
it is called an Air valve in the fsm.
Says, open when cold and closed when hot.
cold is below 60d C. 140f
hot is above 60d C. 158f
that is all it says on this cold start and cold run air valve.
so there are 3 major players, for AIR.
1. Dash pot
2. IAC(isc)
3. TB base air valve.


next the dashpot gap on mine.
luckly there are 3 tests on car to check them.

[jtgh]

last data:
that air gap on the dashpot , high idle diaphragm.
my 8v is, #25 drill bit (USA) or 0.149 inches or 3.79mm. (measured with 20" hg on nipple) a 9/64" inch drill would work but is hard to find.

any 1-60 drill bit set has this #25 bit.

i used a vacuumtool to pull in diaphragm.

a 4mm screw is to big. so is #8 american screw.

any way , that's me gap.
Cheers !

[DJB1981]

Many thanks once again i will try all you suggestions as soon as i get chance (might have to sneak off christmas day lol). Also as i said the TB air valve is stuck not letting air in so i left the screws loose so i could let a bit of air in and tried the cold start, Fired up straight away at about 1000 rpm letting more air in raised rpm putting it back to factory killed engine. Im aware this may not be the main reason its not starting but i like to think we narrowed it down and its definately not getting air.

Only thing worrying me is i dont think the air cold start problem would make the emmisions go sky high untill the map sensor is unplugged? unless there is also a problem with the EGR setup

Thanks cant wait t have a look but its dark outside and i dont have a drive nether mind a garage

[jtgh]

that TB air valve MUST be open to start , up to water temp. 158dF it must be closed hot.
it is a major supplier of air .
Plus you just proved the AIR supply is wrong, (remember ECU has canned fuel tables)
you may have 2 problems. tis possible.

once engine is hot , its a whole different game of Cricket !
the Map sensor is the primary device here. HOT.
The ECT says I am hot , so lets try to enter closed loop. (thinks the ECU)
what is happening is your car fails to enter closed loop.
causes are manifold.

randomly:
TPS is jumping around like a mexican jumping bean.
MAP is bad ( not likely )
EGR leaking. (inspection)

OXYgen sensor , flat lined (dead) . or exhaust manifold cracked or that broken Collector tip gasket , letting in air. No air leaks from exhaust valve all the way to end of CAT.
any air leak will make OXY say LEAN way lean and the ECU throws extra of gas to the engine.
if the ECU THINKS oxy is crazy it will go to rich + retarded timing.
if the ECU thinks OXY is good, but it is telling a lie , Lean,then again,more gas.


you need to fix this fast, it will render the OXY useless.
Also i do have a slight exhaust blow


the reason is the exhaust pressure varies , especially on a 4 jug.
it even varies to negative pressure. ( cause by complex action of bouncing gas pulses)
some pulses are additive and soom subtract.
no matter, no leaks allows.

HAPPY cheer, to you.
my radiator just blew a tube (top right corner) RATS !

[jtgh]

i update my nostart page again, to include the flooded no start , path.

nostart

holidays cheer to all,

off to Drinking and Kissing cute women.