Additionally, does advancing timing increase horsepower? Optimum timing from a fixed locked ignition advance occurs at only one engine speed. The engine speed operating range affects where the timing is the best. Increasing the timing advance raises the high-end power, reducing the low-end.
Decreasing the timing advance raises low-end power, reducing the high-end. Advance timing , and response increases , easier to start, more power torque off idle. Some engines use the vacuum advance to advance timing at idle.
This allows the engine to be able to start without kicking back against the starter since the base timing is actually retarded slightly. How do you know if your timing is too advanced? Symptoms of incorrect ignition timing are poor fuel economy, sluggish acceleration, hard starting, backfiring, or "pinging" or "spark knock". Too little spark advance will cause low power, bad gas mileage, backfiring, and poor performance.
Too much advance will cause hard starting and pre-ignition. What does advancing and retarding timing do? Every car i own pings on this crap and these are cars with knock sensors.
I ended up switching to 90E10 which behaves perfectly. I am also aware that any Ethanol based fuel, Over time, will drop its octane rating, IF it sits too long in a high humidity, high condensation environment. And who knows how the stations keep their in ground tanks. So does that change the answer for anyone? Found it quite entertaining and educational. As a note: both my manual and hood sticker say 6 degrees at rpm. Also of note: When i moved the base timing from 6 to 10 the idle rpm increased to rpm.
I have since adjusted back down to base until my own analysis is completed. I am not that concerned about killing the engine. Also of note in my case: Remembering that the vacuum advance again for my car for the distributor comes from above the throttle plate, there is essentially no vacuum at idle, hence the base timing.
If you are a one of those drivers who are using only your big toe to push the gas pedal to get the best mpg out of your car, then at best you are barely opening the throttle plate and barely advancing the distributor. Hence i can see where if you started at a higher base timing say 8 degrees and drove with your big toe, you would become more like the driver who started with 5 degrees and drove with the entire foot, that is, there is a tendency to advance the distributor more due to higher vacuum being applied.
Thus getting the right average optimum ATDC pressures. So the base timing may also be relative to the type of driver you are. On the cars with the ECU controlled advance, doesn't the ECU try to keep the timing at or near to 20 degrees cant remember where i read that. Hence the reason you have to jumper the connector to set the base timing at 5.
Once the ECU is allowed to kick in, then it can add to the base whatever advance it needs based on the type of driver your are, load, heavy foot passer, hills etc. And I assume the base is set that way as the ECU has a limited range that it can advance or retard the timing.
If you mess with the Base too much then you are straying away from the parameters that the ECU has to make adjustments, with the end result of damage to your engine, crappy mileage, rough idles, etc.
It seems to me that on an ECU controlled timed engine the point is almost moot. The ECU will always try to adjust to its pre-programmed timing settings under normal driving conditions. One may also ask, will car start if timing is off? Just like your heart, if the engine jumps time, it will run poorly or fail.
If a timing belt fails, your car will not start. Ignition timing retarding causes the spark plug to fire later in the compression stroke. The effects of retarding ignition timing include reducing engine detonation, which is combustion inside the cylinders after the spark plug fires.
This is also known as engine knocking. It would not smell rich. Advance timing, and response increases, easier to start, more power torque off idle. Some engines use the vacuum advance to advance timing at idle. This allows the engine to be able to start without kicking back against the starter since the base timing is actually retarded slightly.
Usually timing is at 5 degrees before top dead center, but sometimes there will be a vacuum diaphragm to retard the timing at idle for emissions control purposes. For the common firing order 1, 8, 4, 3, 6, 5, 7, 2 , cylinder set 1, 4, 6, 7 is one polarity. Cylinder set 8, 3, 5, 2 is a different polarity. One polarity has a greater ignition shift than the other.
Either set can be set up to the hot polarity. For the same timing, cylinder-to-cylinder, spark plug readings may be different between the two sets without proper fuel system adjustments. Some teams stagger one of the two magnetos, reversing the polarity from that magneto, to achieve both a positive and negative polarity in each cylinder for more consistency.
Advertisement Bob Szabo is an engineer as well as writer and publisher for racecarbook. Jennifer Szabo is the owner and developer of airdensityonline. Jennifer is also the owner and developer of the ProCalc fuel injection tuning program. Components: All About Timing Chains. Components: Intake Manifolds for the Modern Age.
Magazine Current Issue Past Issues. Connect with us. Advertise Subscribe Contact Us. Compound Turbo 5. By Bob Szabo. Ignition Timing Control — Closed loop Timing in more recent ignition systems is computer controlled according to a closed loop ignition timing function.
Mixture enrichment is common for racing alcohol fuels. More enrichment of alcohol fuels usually needs more ignition timing. Less ignition timing is needed for higher power ignition systems.
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