I hope someone can help me figure out this issue with my 89 accord lxi sedan
timing. It knocks in hot weather and I want to retard the vac advance a
little more. The timing is supposed to be 15+/-2 btdc with hoses on. The
most I can retard it is about 16-17 degrees, barely in range. with vac
hoses disconnected and plugged it is supposed to be 4btdc, but at the proper
vac advance, I am at TDC. Does anyone know how to back off the vac advance
without affecting the plugged (no-vac) advance?
Actually, I am getting a funny feeling. Pinging isn't a normal thing in '89
Hondas (or at least we don't hear a lot about it), so I'm wondering what is
going on. You shouldn't have to mess with the advance.
Did it always do this or did it start after some work was done (or maybe the
car is fairly new to you and the history is unknown)? Is the temperature
guage reading normal - whatever it reads in cool weather? Finally, to ensure
the problem is detonation (which is affected by timing) and not pre-ignition
from hot spots (which is not affected by timing), you can run the tank down
fairly low and refill with premium. If the knocking is the same with premium
timing changes won't affect it and you will have to pursue decarbonizing. Of
course, if the engine is running hot in hot weather that is the place to
Good thinking, Mike... another thing to keep in mind when adjusting the timing
is that the vacuum increases with RPM, and thus advances the timing further.
It's important that the engine be at the specified idle when checking and
adjusting the timing - on your car, depending on the exact engine, it should
probably be around 700-800 rpm.
Mike / Matt:
Thanks for responding. History. Bought used in 1994 with 55k miles. I had
a good garage do the 60k service at 72k. I had a schlock garage do the 120k
service at 140k. I assumed that they did the coolant. They did not. It
went acid and killed the cooling system. I replaced the radiator, thermostat,
water pump, and hoses and flushed the rusty water as well as I could, but too
late. I cracked the head at 186k. Got a rebuilt head and new pistons and
cylinders installed. A radiator cap that could not suction from the overflow
led to coolant loss and a blown head gasket at 212k. I replaced the head
gasket myself and blew out about 2 quarts of rusty crap from the block in the
process. Very little carbon on the head (especailly number 1 and 2 where the
gasket blew). The temp gage stays low even when blowing head gaskets. Now
at 218k it runs great, but it knocks as always going up hills in the heat.
High octane gas does quiet the knocks. To hit Matt's question, I checked the
timing at about 800-850 rpm. It bogs a little when I check the no-vac
advance. If I set it any more advanced than the maximum retard I can get, it
knocks worse. Most of the time it runs fine. It just knocks briefly if I do
jack-rabbit shifting or knocks pulling grades in dry heat.
Incidentally, I am replacing they front crank seal tomorrow. Why did I not
do that with the new head gasket? A mechanic convinced me that hondas never
leak from the crank seal even when they are bad. I replaced the water pump
seal and oil pump seal so I think it must be the crank seal, so it's back
under the hood for me. The timing thing still confuses me.
Michael Pardee wrote:
Only other thing I can think of, is if the ignitor/stator assembly (inside the
distributor) is loose, or the air gap between the stator and reluctor (the
components that provide the actual timing signal) is too small and is thus
triggering the timing too soon...
I can't find an actual spec for the air gap, but there's a diagram of it here,
to give you an idea of what you're looking at:
If the stator is loose or out of place, it could also be affecting the timing.
There's a brief bit on checking and adusting it here as well:
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