Problem shutting puter down to check timing.

[91Caprice9c1]

Erroneous readings... I like that idea. Gene, how old's that timing light? Is there a groove in the crank pulley where you are taking your measurement?

You could go through an amount of work by marking the back of the t-belt pulley to line up with the mark on the oil pump, and get your reading that way (if you have an advance timing light) but then your light could still be off.

When it comes down to it though, if it's running good and you aren't pinging I don't think the numbers really matter other than for the sake of curiosity.

-MechanicMatt

[Gene H]

My timing light is a Sears model 161.213400 linear Xenon flash tube. It has inductive pickup and connections wires to the battery for power. It's about 20 years old but on excellent shape. Always stored in the original box. When I looked for the model number on the box, I noticed that it says " for 12 volt electronic and conventional systems, 4,6 and 8 cylinders" Nothing about 3 cylinders. Just the same, even if my timing light is not capable of reading 3 cyl engines, My engine should stumble before i reach the end of the adjustment slot.
I'm using the standard groove in the pulley. I have it marked with white chalk so it's easy to see. When I crank the motor manually, that groove lines up with 0 when the #1 piston is at TDC. FYI: last night I pulled the distributor to check if the small drive pin was deformed or broken. It wasn't. As long as I had the bolts out I rotated the distributor top toward the firewall while running the motor. It started to stumble when the screw hole was just beyond the housing boss. So, there is a limit to my madness. I will keep checking other things.

[sas95]

I was the guy (or one of the guys) talking about altitude effects on timing. I had thought that you could/should add to your 5-degree base timing when driving at altitude, but I was mistaken. I'm pretty confident now that ECM/PCM takes care of timing at alltitude. I'm in Albuquerque at 5500 feet elevation. I'll explain.

My Metro is a '95 1.0L 5-speed. I bought the car used early in 2007. It was using oil, compression on the center clyinder was much less than the outside cylinders, and the check engine light was on with EGR malfunction. I replaced the engine myself with a JDM engine. (The EGR passage in the original engine was completely blocked off with carbon.)

The timing was sensetive. With stock 5-degree base ignition timing acceleration was sluggish. If I advanced the base timing to 10 degreest, I got better response. However, at a later date I suspected the exhaust system (especially catalytic converter) was clogged from lots of oil consumption by the original engine, so I replaced the entire exhaust system with stock replacement components. With advanced base timing of 10 degrees, the engine now pinged when I put the engine under load. I immediately changed the timing back to 5 degrees. The car runs great now. The engine had not been breathing right with a clogged exhaust.

If all other checks recommended by MechanicMatt don't fix your problem, you might try a new catalytic converter.

[Gene H]

sas95, Your Metro story matches mine to the "T" except my motor had a broken rod cap #2 cyl. Your exhaust theory is interesting except, I don't have a CAT. My muffler blew a big hole in it the day after I advanced the timing to full, so I'm basically running with open exhaust. My pipe from just under the engine to the muffler is new. Hmm, I wonder if that non dented, old dual wall elbow pipe from the manifold to my new pipe is collapsed inside!! I'll need to check that out. I haven't had much time to mess with the car this past week. Been busy with the 91 metro that I picked up. With a cold engine and dry test, the compression on that 91 motor turned out to be 190,180,190, SWEET!!! I have a spare motor.

[DOCTORBILL]

I have one of those Old, Old, Old Sears Timing lights !

It gets power from the battery and the signal from a spark plug wire.

It cannot work incorrectly!

All it does is fire the Xenon Lamp when the spark plug wire gets the spark....

So you hook it up to the Number One Cylinder spark plug and it fires when it gets
the voltage spike.

Maybe newer Timing Lights have some electronics that "Interpret" the signal,
but not those old ones like Sears sold.

Were you talking about timing meters that were used to read the breaker point gaps?

I've got one of those, too! Haven't used it in many many years.....

They have scales for 4, 6 and 8 cylinders.... You probably use the 6 cylinder scale
for a 3 cylinder engine and multiply or divide by 2....but then metro engines done
have distributor breaker points like the old cars had.

Before computers were made that sent the signal to the coil, we had the old
breaker points that one had to gap on the distributor.

Now it is all magnets and electronic ignition.....super dooper pooper scooper high falootin electronic wizardry....

Old guys like me remember that stuff.

When engines were simple things and you could repair them without requiring
unfathomable manuals and sophisticated electronic gobbledegook...

When you could get at the spark plugs without requiring engine disassembly.

When the engine compartments had room to see the engine and the cement
underneath the car.

When you dropped a screw, it fell thru to the floor - didn't get caught in some
hideously expensive sensor and short it out unbeknownst to you.

Of course the cars polluted and smoked and got 15 mpg and wore out at 80,000 miles -
no Check Engine Lights....
.....now such as they are illegal - and probably are in India or Pakistan or China!

DoctorBill

[sas95]

Originally Posted by Gene H

My muffler blew a big hole in it the day after I advanced the timing to full, so I'm basically running with open exhaust. My pipe from just under the engine to the muffler is new.

Did you keep the resonator (the can upstream of the muffler)? If not, that might affect engine breathing a bit, but mostly at low rpms with engine under load.

[Gene H]

DOCTORBILL, I hear ya about the days before computers in cars. I agree with you 100% on those points. Well, I used a timing "light" not a timing meter. You statement agrees with the info I got from an X mechanic that I work with. My timing light should only react to the impulse it senses in the No 1 spark wire. By the way, I do have a "relic" timing "meter". It's been so long that I don't even remember how to use it.
sas95, I discarded the resonator when I installed the 1 3/4" OD exhaust pipe. I backed the timing off of the full advance a little bit last Thursday (approx 5 deg.) The car seems to pull up a hill a little bit stronger since then.
The car is running good at these settings. The mileage is back up near 50mpg. No pinging. I'll keep tinkering with it. If I come up with a something I'll report back.
Thanks guys, for your help.