dustrider

thanks a lot scuba
I cant get the idle above 1000, even at cold start unless I disconect the vacuum line to the idle control pod , then it goes to 1500
it goes to 1,000 at cold start then drops to 750 within 5 seconds or less
the dealer said the comp was #1-140,#2 -150, #3-180, #4- 190
I havent checked the compression myself
it doesnt get hot or use a drop of coolant on stop & go or climbing the mountain every day
only uses about 1/8 quart oil or less in 6,000 miles

when I replaced the plugs wires and valve cover seals last week the intake valves were too tight to get a feeler guage in the ex got a .004 in , I didnt do a real thorough job just a quick check because I was doing it after work ( 6hrs driving/8 hrs at jobsite)

has a very slight rough idle at random sometimes its real smooth
power is OK , could be better
goes up the mountain (4000 feet in 10 miles) at 55 mph

the local mechanic said dont adjust the valves or it might suck a valve at this point and also believes a valve job may cause the bottom end to blow

I just keep thinking the valve issue is separate from the low idle at cold start...am I crazy ?....yes , but thats a separate issue too

if I could get the idle to stay up then maybe it wouldnt stall before it warms up

James Woods

iTrader: (1)

The leak down test Scuba refers to is different from a normal compression test, the compression test just tells you the compression of each cylinder, a leak down will tell you where the compression is being lost as if it leaks past the cylinder rings or a valve.

dustrider

9 days until my first observation of " no help here" and utterence of my desperation whining, and until the first response to my post
is a little more than 2 hrs

but 10 days until the first useful response is better than nothing I guess

Thank you to all who responded

dustrider

yes thank you

I just figure a number like 140 down from 190 means repair is immenent, a leakdown test wouldnt be of much use would it ?

if it was 140 due to rings wouldnt it smoke, use oil or have excess blowby ?

a leakdown test if it was 170 or 180 might tell me if its valves or piston rings , but such low oil consumption has me not too worried about rings
correct me if Im wrong ?

dustrider

the factory manual gives an IAC test
says jump terminals te1 and e1 at the underhood DLC test terminal with the SST 09843-18020 ( special service tool) and the idle should go up to between 1250 and 1500
says if it does not , check IAC wiring and ECM

when I jump it with a wire the idle goes down to about 600 and it surges

since I have a new IAC then is it either the wiring or the $1100 ECM at fault ?

is that SST 09843-18020 just a jumper wire ?
or is there a resistor in it ?

dustrider

https://www.yotatech.com/forums/f116...k-like-131131/

i see it is just a jumper wire
so according to the manual my idle air control is not recieving commands because of a wiring fault or the $1100 OEM toyota ECM ??

so when the motor is cold there is no idle increase
would that cause cold stalling ?

dustrider

no codes so far zero codes

until this morning !
finally got a code during the cold start episode

PO402 excess egr flow
manual says
egr stuck open
or
VSV valve open malfunction
or
short in egr gas temp sensor circuit
or
ECM

cleared the code with the OBDII and drove 2 miles and it didnt return

I always thought from the start it acts like a slow to return EGR
one of the first things I checked
the EGR valve itself checked out ok

VSV operates vac to egr switching when revved and shuts when back to idle

jumping the terminal kicks up idle now with the motor warm
before when it was cold it made the idle go down

dustrider

found I can get a Toyota remanufactured ECM for $550

i wonder if it is worth a try and what are the odds that the ECM is causing the trouble

dustrider

However
ran through the diagnostic "tree" for IAC circuit everything checked out that it ended at replace ECM

everything is pointing to the ECM onboard computer as the perpetrator

even the recent EGR code may have been caused by the ECM computer

except that I did not chase the AC idle up circuit

my AC recently burned out the clutch so I removed the belt
I wonder if that could have anything to do with it
.

dustrider

I am pretty sure the demon was the ECM (or ECU same thing )
I got home and let it cool with a fan in 35 degree wind for about three hours until the block was cold to the touch and installed the Toyota Reman ECM
It started quicker and the idle went up to 1250 and stayed up like it is supposed to. Took off down the road and pulled over where it would normally stall and it did not stall
Ran smoother to the next stumble stop tests with no stumble no stall. Ran it up to Normal operating temp and noticed that the idle is very smooth now. I also noticed that it is smoother coming to stops now as before it had a slight stumble like an EGR delay stumble . No more EGR stumble at stops when warm either
I believe the computer was not sending a voltage signal to the EGR VSV which caused the stumble because there was no computer controlled EGR cutoff and at the same time, no voltage or wrong voltage to the IAC valve from the computer to trim idle speed, two combined factors which made it stall when cold

thanks you all for the help

dustrider

Ooops !
not that anyone around here seems to care but I guess I like talking to myself so....
the battle continues

I went to sleep last night optimistically thinking I had it licked
but my pragmatic side was nagging at my pessimistic side waiting for that stone cold start in the morning
sure enough cold stall came back

went to another toyletoda dealer to get a third opinion
he let me tell the whole story and concurred with the two others that it is valve condition
he agreed with my opinion why . I think that although the leaky valves would not make all motors stall, the nature of the toyodor engine control system will not compensate for it when the motor is stone cold . It will only meter out enough for a small amount of compression loss at cold valve condition

I think someone mentioned somewhere that the spongecake buildup on the valves will somehow absorb the fuel or something like that, not sure what the theory is
it would require more fuel at cold start and the toyoter system will not provide it
next thing to try will be valve job

the stupid motor has shim and bucket and is a PITA to adjust
a valve adjustment might help but i am not sure why the mechanics are saying it cant be done, when I ask the just shrug and say theyve never considered it but the manual tells how
maybe they know that enough shim cannot be removed to get the valves seated or some such

seems like a shame to pull the head when it runs fine

kball

that sucks, hope you get it figured out.

scuba

Just pull the camshafts to do the valves. No big deal.

dustrider

here I am 59 years old been doing all my own wrenching and tech work since I was 15 on high mileage rigs and this is the first I have even heard a hint of anything like this.

maybe it is a smog emissions thing to make sure the environmentally friendly toyota will not pollute the planet and kill us all with excess fuel at cold start up

I asked the service writer why it didnt do it after I plugged in the new computer and he said he knew a mechanic who had this happen and he had a way to clear the computer each morning with a switch and it wouldnt stall, that somehow the computer senses whats up and shuts off the fuel instead of sending more ( hence the excess EGR code )
,....said he had a switch to a wire that just cleared the computer and not the clock and radio

suppose I may be able to test that theory by clearing the computer at cold start by disconnecting the battery cable ?

?

dustrider

you know I thought that, you mean adjust the valves , right ?
shim and bucket
install thinner shim to let the valve close
valves get tuliped from overrevving on high compression engines
previous owner probably like revving

I do it on my motorcycle , usually just need checked because I am a low revver
I got a riding buddy who is a successful MC mechanic with his own shop and when nobodys looking he sands the shims down instead of using up the overpriced new ones
shim and bucket valve adjustment on a motorcycle is almost $1,000

cant understand why 3 mechanics said the 2.7 valves are not adjustable

rworegon

dustrider, are all your vacuum hoses in good shape? I'm wondering if a hose may have a slight leak and/or disconnected and combined with the cold start, the ECM cannot fully compensate until the engine is warmed up. This theory seems to tie into the resetting computer so it goes into a base startup default mode before relearning new fuel trim settings, etc. My 0.02....

rworegon

Joe Cool mechanic: "Oh, I've never done that job before (or it's a pain to do) so, sorry customer, they can't be adjusted (but they are "shimmable" and I won't tell you that".

They just might need to review this:
http://www.ncttora.com/fsm/2003/Repa...alcle/insp.pdf

dustrider

hey thanks
yep , when confronted they all say its done one time by the machine shop when the send out the head with the cams on it

I do have that manual someone gave me
one concern I do have is that if the valve is sticky then when prying down on the bucket with the SST (special screwdriver tool ) the valve could go down with the spring and hit the piston and bend the stem, or even let the keepers pop out
so it may be a lot safer to just remove the cams

waddya think ?

maybe the dealers had too many tragedys doing it that way so they just say no and never thought of removing the cams like I do on the motorcycle

dustrider

yes i cant find any leaks
however, good point, they are pretty old and it wouldnt hurt to replace them all
whatever the problem is it is more extreme in nature than a minor vacuum leak and involves computer control feedback response from the computer sensing a mechanical problem evidently

thanks
the complete story of troubleshooting the entire engine control system is on this thread if you are into reading the complete novel legnth version, its one of the first things I did

rworegon

Yeah, I read the entire thread before responding above. I know on my 3.4, it had a rather small split that was barely noticeable on one hose and it would idle like a diesel truck. Sometimes the tube from the air cleaner to the engine will get a small crack too. Unmetered air can wreck havoc on the ECM as you well know.


Vacuum entered my reasoning when you mentioned on 11-21-11: "I cant get the idle above 1000, even at cold start unless I disconect the vacuum line to the idle control pod, then it goes to 1500".

At least the CEL shines the light on the EGR system. I'll keep checking in as I'm interested in the final fix.