Good Timing
 

No, not "at the right place at the right time", but spark timing instead :p

I performed a full-advance over the summer and didn't have much of a problem with detonation (but a decent bump in FE) and improved low-RPM efficiency.

Now, loads are bit higher (likely due to the colder weather, and the varied resistance from a variety of operating sources -- rolling, viscous, wind, etc.) I hear pinging quite often these days -- so what to do?

- Retard the timing a bit
- Wait for colder weather
- Change the Oil, it's due
- Run 89 Octane (at 10-cents more/gallon, it would only be about $1 every 2-weeks)

The latter has been on my mind -- is the FE bump worth a buck or 2? ...Or is there option "E"?

RH77

Don't know what your choices are there, but here in South Dakota, we typically have three choices at the pump.

1. 87 octane "May contain up to 10% Ethanol" Currently $2.18 per gal.
2. 85 octane Regular Unleaded. Currently $2.28 per gal.
   About 10 cents more than 10% Ethanol.
   Must still contain some Ethanol, because ethanol replaced MTB.
3. 89 octane Premium Unleaded. Currently $?.?? per gal. (will check tonight)
   About 20 cents more than Regular Unleaded.
   Also must still contain some Ethanol, since ethanol replaced MTB.

With gas prices low, my % drop in FE with 87 octane is less than the % price difference from Regular Unleaded. I've never tried timing adjustments based on the octane difference between the two.

Apologies for my forgetfulness in regional octane offerings.

We have 87, 89, and 91-92. I'm thinking about a mid-grade octane boost to prevent the pre-ignition. High-octane variants are generally 20-25 cents more/gallon (and may be cost ineffective). I have a couple of weeks before I fill up, so maybe I'll give mid-grade a try and see what happens...

-Rick

How much of an FE bump did you see from advancing the timing? If the percentage is less than the percentage difference between regular and mid-grade, you're better off retarding the timing back to stock specs and running regular.

And if the oil change is actually due, do it either way!

-soD

How much FE bump did you realize?

This timing thing seems to be a YMMV thing. For example, I have two Tempos, identical engines, one has a/t and the other 5-speed. I advanced the timing 6 degrees over stock on the a/t Tempo with no detonation issues at all. But, for that matter, I haven't detected an FE change either. And it might be my imagination, but I thought low end responsiveness was better. So, I tried bumping the timing up 4 degrees on the 5-speed. It pinged. So I've backed it off to +2 degrees. Who knows why such a difference in timing requirements? Could be wrong timing marks?

Could be the MT is a bit more carboned-up or has stronger compression due to less cylinder/ring/valve wear than the A/T?

FE Bump...

Taking 3-tank averages before and after:

Stock Timing = 33.16 MPG
Full Advance = 39.29 MPG

There was some added technique mixed in there, but it has to be statistically significant. The Butt-O-meter noticed some added power in the lower revs...

The oil change and ATF drain/fill should happen this weekend. I wanted to wait for the ATF fluid to arrive first. Only one synth brand is approved for the Honda slushbox.

Weird about the Tempo, Frank. Are the ECUs setup differently (don't know the years, but does it electronically tweak the timing)?

I don't really know the marks, I just cranked the distributor into a full-advance position. Other Honda folks have done this on a variety of engine designations for the horsepower boost. I just noticed the pinging more lately.

-Rick

You got a nice FE bump but I haven't seen anything.

AFAIK they have the same engine management systems.

Yes, compression is something to look at. I shall try a compression test.

So, how much grille block is too much?

It was relatively warm today (45F). With a double grille block (block the A/C rad up front, and a cardboard piece sandwiched in front of the coolant radiator). Driving in-town or on the highway, the fans kick on and temps rise and level to 210F reported (likely 195-200F at the thermostat).

It's the most aggressive grille block I've tried. Warmups are much quicker and efficient IATs are available sooner. I filled with a higher octane fuel for the higher temps and the knock. Hopefully, the Winter temps will allow normal operation.

Any advice? Pull the power to the fans, pull the cardboard? Wait for the cold?

-Rick

Stop Stop Stop STOP.

Don't re-adjust your timing... instead, do the following:

1. Seafoam your engine. If it has more than 50,000 miles on it, this is one of the essential things to do. Follow the instructions explicitly.
2. Change to a colder range plug. One range colder could stop the detonation on it's own.
3. An often over-looked quickie, good for a slight boost in economy and power (not even noticeable) is indexing your spark plugs. Mark them where the electrode's open side is. When you put them in, place that mark as close to the intake port as possible. Voila, you're done.

Do those things in that order, and pinging should stop. If it does not, you need to consider cooler intake charge, or faster intake velocity. (Get both... cut a big hole in the bottom of your intake box.)

SeaFoam is one of my favorite products, and I firmly believe that it works as well as anyone has said. Unless they said it added a turbo and intercooler for them.. or something. Then they're full of it. :D

You could also try running the thinnest oil that your climate will allow... or running thinner oil in the summer. Also check/clean your PCV system... the oil getting sprayed into your intake stream causes detonation.

I too am a huge SeaFoam fan. Every car I touch gets the vacuum suction treatment, etc -- usually twice a year. The replacement plugs are cooler and gapped to spec. I also have a PCV catch setup. So far, it's performing well at 140K miles.

As far as Intake Air goes, FE is optimal at 100-110F. Under high loads lately, the pinging is very noticeable -- so I filled to a mid-grade mix. The airflow is slower after the warm-air tube to the airbox. This was added later (when the Weather turned colder). I just changed the oil and trans fluid (synth ATF), so that should help. The pinging started after a dead battery cleared the ECU's memory. I may need to "re-train" the ignition system with the ECU bypass method.

I'll have some time to test it this week. It's getting a bit warmer before the next cold snap. Time will tell...

RH77

Jeez... leave out the important stuff...

Drive for an oil change with OE timing settings, then re-adjust it back to what you have it at now... What's happening (for reference) is that the ECU is assuming the timing is at a factory setting, and it's trying to over-compensate, thus the pinging. Your timing is now further advanced than you think it is, after the electronic advance takes place.

Once you've done about 1k miles, you can slowly adjust the timing in 1-2* increments until you're max advanced... adjust each 1000 or so miles. This will manually train the ECU to under-correct the spark curves, allowing your timing to be run as optimal for your RPM range, instead of a broader RPM range.


I'm not positive, but if your car is anything like my Honda, I can just insert a jumper into a specific connector under my hood, and stop the electronic advance from taking place... this is how the service tech sets the initial timing, and how you reset it to whatever you want... on my car.

ECM's aren't stupid.. but they're better at being stupid than humans are.

RH77: I had the timing on my 89 Honda advanced. However, what I noticed was starting about mid September the pinging went up dramatically. I know that here in California they adjust the fuel blend for smog reasons and the consequence on my car is that I had to back off the timing. You could go to a higher octane rating, but my expectation is that the mileage gain will be lost if you look at the costs.

Forgot about that... EPA reg suggests fuel blending in at least the winter months... perhaps you should try changing gas stations? Maybe get something that doesn't use ethanol, or uses very little of it.

It's E10 everywhere here now instead of MTBE for Winter (mandated). But change stations [gasp] never! My QuikTrip station around the corner and Pump 13 have been there for me since I started hypermiling (and is one of the cheapest places in the Metro) :o Mostly for consistency in filling, but it's also a Tier-1 fuel.

I'll be headed to a work visit in town, then to the airport for a trip to DC, so we'll see what the SGII comes up with tomorrow evening.

Odd though, Ethanol has a higher octane rating, so it shouldn't ping -- in theory...

-Rick

FWIW, based on what I've read it seems that advanced timing is only needed if the ratio of gearing/displacement given some power output isn't optimal. The lower the air&fuel to cylinder volume ratio, which corresponds to lower torque, the farther apart in the cylinder pockets of air/fuel can be, and the sooner ignition needs to start to get all the air/fuel burning up around TDC. W/ pockets that may be farther away, retarded ignition may not result in everything igniting until after TDC. W/ proper gearing and greater torque, the mixture is more or less homogeneous, and in this case even/consistent ignition of the whole mass in the cylinder is much more likely.