1990 Honda Civic will not start. Was ECU issue

We got the repalcement ECU ihn and it works fine in my Civic,
but the other Civic will not start. Cranks great, getting fuel
into the throttle body, and has spark, but does not even try
to fire.
Tigger over in the Toyota group suggested that I check the
PGM relay, and the solder di look dull and crystallised.
So I removed the old solder and resoldered, then used a mil spec
silicone "conformal" spray to protect it. I have since
tested that in my Civic.
The one big difference between the cars is that the non
running Civic blows air back through the throttle body.
This apears to happen once per revolution.
Tuesday afternoon, after some repairs to her CPU, I was able to
start the engine, but got a PA sensor error. I removed and continued
repairing the ECU and Thursday afternoon, I tested it again.
Thiat time the engine tried to start but died after a second or
so. When I cranked it againm, I heard a sound that I had never
heard before. I now know it to be the air coming back
through the throttle body.
I am afraid the T-belt has really jumped and the engine is badly
out of time. My wife has gone to visit her mom, abnout 100 miles away.
so I don't have my car for comparison.
Can I use a timing light to rough check timing?
I have trid to use a long wodden dowel to find TDC in #1, but even
with all the spark plugs out, I just can't turn the flywheel by hand>
A hint to everyone with a 1990~1994 Honda. Itmight be well worth your
while to check your ECU for corrosion. I have taled to several local
Civic owners who have had bizare errors on their ECU and I have
checked
2 and found the electrolytic capacitors has signs of leakageone of the
47uF/35V and the 220uF/35V show seriuos corrosion. Since I up to my
bellybutton in engine problems I was not willing to replace their
capacitors at this time. With a good work station, controlled temp
soldering iron, antistatic solder sucker it should take less then an
hour to change
all 6 electrolytics caps. Given that a rebuilt ECU will run $150 and
up,
it could save you some real money.
While her ECU appears to have been wet, there is no sign that water
has
been in the floor pan, the noise reduciton carpet shows no sign of
mildew,
their is no interior rust etc. I am beging to suspect that the prior
owner got ripped off for a repair and somebody swtiched a flooded unit
for a good one. Either that, or someone pulled a midnight switch. How
many different key patttterns does A Honda Civic have anyway?

Terry

 

Sounds like it. Put the front up on jackstands, remove the left front
wheel, and find a socket big enough for the bolt on the crankshaft
pulley. Turn it with that. This will be a two person operation but one
can be a wife who doesn't want to get her hands dirty.

Remove the rocker cover, watch for #1 cyl exhaust open & close, then
#1 intake open & close. That's to make sure you're turning in the
right direction. Then get a flashlight and look down the sparkplug
hole for the piston. When you're close, clean off the face of the
pulley and look for the timing marks.

 

Removed all four spark plugs, then the valve cover. Then ran the
starter to
verify engine direction of rotation. Then insered an 18" 3/8" wood
dowel.
With the plugs out, and the car jacekd up (and braced with several
4X4,
gravel driveway and jackstands are a bad idea) then rotated the crank
with
a T handle driver. At TDC #1 the distributor is pointing (roughly) in
the
proper direction, pointing where #1 plug wire would be if the cap was
in
place.
The valves behave like I would think correct. After TDC, with the
rotar
pointing at #1, as I rotated, on the next upward stroke the exhaust
valve
opens, then closes just before TDC, on the downward stroke, the intake
valve opens and near the bottom of cyl movement, intake closes, then
neither opens until after then next TDC would should be the power
stroke.

It started to sprinkle, so I covered up the valve train with plastic
wrap
and will check it all again Sunday afternoon. I will also get my wife
to check
the T-belt teeth, a quick look shows the belt to be in great shap, no
obvious
missing teeth, no cracks, no oil. I will also check compression if I
can find
a gauge long enough to go down to the spark plug hole. I thought that
with the valve cover off, I would have access to the spark plug base,
no go. They are
at the bottom of individual tubes, and my compression gauge is
designed
to work with "standard" heads, where the spark plus hole is easy to
get at.

I would think that even if I had blown/leaky intake valve the engine
should still at least attempt to start. Do pieces of intake valves
ever "break off"?

Terry

 

blowback through the throttle is common if the timing's off.

re: you valve question, sometimes the head drops off the valve, but
that's real rare on a honda and usually results on the head & piston
being irreparably damaged. and you'd hear the mangled metal noises.
often the engine will run on the 3 "good" pistons until the valve head
breaks through to another cylinder or the broken piston crown sucks all
the oil out of the motor leaving it to sieze. something like that.
it's ugly any way you slice it.

re: timing, i wouldn't bother trying to find out how close the current
timing is to book with all that stick-in-the-hole business. the timing
marks on the crank and cam are way more accurate. just start again by
slacking the belt off completely, aligning crank to tdc, then the cam,
then seating the belt properly. make sure the belt is nice & tight per
the book spec, then crank by hand to be sure it turns ok and ends up
with the timing marks back in alignment after 2 full revs - remember the
crank turns twice for every turn of the cam. then you can try start it
again. if that doesn't work, try a compression test. if you've dropped
a valve, you'll get zero compression on that piston, but as i say,
engines with a dropped valve often run.

another possibility for blowback is a burnt valve, where part of the
valve has been eroded away. again, this will show in a compression
test. and these engines also run.