Scangauge Suggestions

[JonnyG]

Hey guys, it's been a while. I ended up getting a Scangauge II for Christmas and I've been having a lot of fun with it in the past 6 weeks
The only problem I have is that it's been so darn cold and snowy that it's been hard to boost fuel economy. I also installed snow tires this winter
Because of these harsh conditions, I don't know how much I'm improving by using the Scangauge. So my question is: How do you guys use the Scangauge to improve driving technique? All I've been doing is using the instant MPG to adjust my right foot at cruising speed, and using LOD to keep the AT from downshifting. Thoughts? Ideas?

[moonmonkey]

jonny use the instant and the average mpg, i use the instant and try to keep it higher than the average the whole trip,i play a game every day going to and coming from work, trying to get to work with 60+ mpg showing on the average ,,its tuff, to do (for me) i also moniter the intake air temps because of my grill block, lod is ok but i dont use it much, using the gauge i,ve learned what my car likes for mpg,,,great device also love scanning mine and friends cars for trouble codes, i also use the tach to shift around 2000 rpm ,,my echo has none.

[puddleglum]

In winter, monitoring engine temp is important and the SG temp guage is much more accurate than most dash guages. If you engine isn't warmed up fully, you'll burn more fuel. If you aren't using a grill block, I suggest you put one in. I have found that I use several of the gauges for short periods to find out certain things. Eg. GPH to find out the difference in fuel used at a light in gear vs neutral, or how much more fuel is burnt cold vs warm. That sort of thing. I like IGN better than LOD and try to keep it as high as possible.

[MetroMPG]

For most people, winter is less of a "how do I improve fuel economy" situation than a "how do I keep the MPG decrease as small as possible!"

I like moonmonkey's advice: use it as a game gauge. Record your trip consumption if you drive a regular route, and challenge yourself to match or beat it each time.

[jfitzpat]

Originally Posted by puddleglum

In winter, monitoring engine temp is important and the SG temp guage is much more accurate than most dash guages. If you engine isn't warmed up fully, you'll burn more fuel.

I'm not sure that I like this suggestion. The big problems in winter efficiency are fuel blends, road conditions, and dense intake air.

That last one is killer for a couple of reasons, first, denser air means more fuel required to reach stoichiometric ratio, and the vehicle needs to burn at stoich to get the exhaust temps nec. for the cat to operate for emissions. Second, as any small plane pilot can tell you, peak performance soars, so you are throttling back more for the same performance. Throttling back creates vacuum, which means you are operating less efficiently.

A warmer engine can offset this a bit, but the efficiency change is not that great. The much bigger impact is rather or not the ECU has decided you are warm enough to run closed loop. If you are driving open loop in winter, the vehicle is generally pig rich, wasting fuel, and operating with less efficient emissions control.

This is why we are so focussed on more durable sensors and faster wideband measurement. So vehicles can get closed loop faster, and stay closed loop under greater loads.

From all the measurements I've seen, it would be better to make your driving decision based on rather or not the ECU is reporting closed loop operation yet, not a fixed temperature in, say, engine coolant. The problem with the later is that it will generally result in some needless idling, and, because of the extra fuel needed to achieve stoich, idling is more costly (efficiency wise) in winter.

-jjf

[MetroMPG]

Of course, the ScanGauge will also show open/closed loop conditions.

And the best solution to the problem of poor cold temp engine efficiency (particularly after a cold soak) is to use a block or coolant heater.

[jfitzpat]

Originally Posted by MetroMPG

Of course, the ScanGauge will also show open/closed loop conditions.

My point was that it is better to directly monitor the ECU's decision, rather than inferring it from the commonly available temps, like ECT, which will not have a fixed value correlation - not that any particular scan tool can or can not get a PID.

Originally Posted by MetroMPG

And the best solution to the problem of poor cold temp engine efficiency (particularly after a cold soak) is to use a block or coolant heater.

Again, I'd have to disagree a bit. The two primary problems in a 'cold soak' (sorry, I have to put it in quotes because the term, though popular, is a bit of a technical misnomer) are oil viscosity and oil seperation. The later is often forgotten, but unless you are using actic grade oil, which has it's own special concerns, any wax and tar that seperates out doesn't easily mix back in or get cleared.

Block heaters are a decent *preventive measure*, but once an engine has been subjected to protracted cold the steps that can get the engine started are not nec. all the steps you want to take to prevent excessive wear and tear and permanent (at least short of rebuild or factory reman) top efficiency loss.

-jjf

[MetroMPG]

Originally Posted by jfitzpat

The two primary problems in a 'cold soak' are oil viscosity and oil seperation.

Do the problems exist in both synthetic and mineral oils? I don't know enough about the separation issue, but synthetics seem to have resolved the viscosity problem for cold weather/cold start performance.

[jfitzpat]

Originally Posted by MetroMPG

Do the problems exist in both synthetic and mineral oils? I don't know enough about the separation issue, but synthetics seem to have resolved the viscosity problem for cold weather/cold start performance.

No, but still sort of...

Sorry! Engineers never answer in clear yes/no.

Synthetics contain no paraffin, so they don't need pour point depressants. So, they don't have the separation problems. Also, they tend to have dramatically lower pour points, period. That is, they stay liquid at much lower temps than conventional petroleum motor oils.

But there are some downsides. For example, although the oil itself doesn't tend to break down into individual components, lots of the crud it can be carrying does. And since the synthetic oil doesn't thicken with temp, you can get something called 'thermal collection'. Basically, if it is cold enough, the gunk can fuse into bigger, nastier hunks of gunk.

If you use synthetic to greatly extend intervals between changes, this can be a real concern on some engines. In that case, the obvious answer is use synthetic for the low temp viscosity, but still do regular oil changes to keep the system clear of excess gunk.

If it wasn't clear above, I'm not really disagreeing with your basic point. I'm just stressing that prevention is a lot easier on engines than recovery.

I'm also thinking about my daughter. Having a car sit outside in the coldest part of winter in Minn. undriven for 4-5 weeks is a very real possibility. A jump and a block heater may get it started, but I've already changed out one cyl and would prefer not to do another any time soon - so I lean towards over cautious.

-jjf

[puddleglum]

Originally Posted by jfitzpat

I'm not sure that I like this suggestion. The big problems in winter efficiency are fuel blends, road conditions, and dense intake air.

That last one is killer for a couple of reasons, first, denser air means more fuel required to reach stoichiometric ratio, and the vehicle needs to burn at stoich to get the exhaust temps nec. for the cat to operate for emissions. Second, as any small plane pilot can tell you, peak performance soars, so you are throttling back more for the same performance. Throttling back creates vacuum, which means you are operating less efficiently.

A warmer engine can offset this a bit, but the efficiency change is not that great. The much bigger impact is rather or not the ECU has decided you are warm enough to run closed loop. If you are driving open loop in winter, the vehicle is generally pig rich, wasting fuel, and operating with less efficient emissions control.

This is why we are so focussed on more durable sensors and faster wideband measurement. So vehicles can get closed loop faster, and stay closed loop under greater loads.

From all the measurements I've seen, it would be better to make your driving decision based on rather or not the ECU is reporting closed loop operation yet, not a fixed temperature in, say, engine coolant. The problem with the later is that it will generally result in some needless idling, and, because of the extra fuel needed to achieve stoich, idling is more costly (efficiency wise) in winter.

-jjf

I appreciate what you are saying, and agree with you, in this and your other posts today. But, my intent was not to suggest that we should wait till the coolant is warm before driving, just that we should use whatever means available to get the engine/drivetrain up to temp. and use the SG to monitor it. this thread was about what guages to use in winter. Most new cars with heated O2 sensors will drop into closed loop very quickly, long before the engine is warm, so the Cl Lp guage doesn't seem of much value to me. I never warm up anyway, just start and go and drive gently. A warm air intake is the only way I know of to help offset the effect of denser winter air and they are difficult to implement effectively and come with thier own set of complications. I have used the intake air temp guage in the past to evaluate the effectiveness of a WAI but I see no other use for it otherwise. I know from my SG that cold intake air hurts FE, as does a cold engine, drivetrain, and bad roads. I live in "the great white north" afterall.
Thanks for your comments about oil. I too am a strong believer in synthetic oil.