P&Ging the 1NZ-FE 1.5L engine

Discussion in 'Toyota' started by SentraSE-R, Apr 13, 2009.

  1. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    Good to know I’m not shorting myself mileage for calculation purposes. 5 miles might not seem like much but might just be the difference when reaching for a 55 mpg tank.

    In the Yaris, when I push in the clutch to shift the RPM’s rev. You can not let off the gas and clutch to shift as in most manual transmission vehicles, at least not like all the older ones I have ever driven. What I do for normal shifting is let off the gas for a second then push in the clutch and shift. It keeps the RPM’s from revving and makes for a smoother shift. For FASing I let off the gas for a little longer, most times I see the 99999 before clutching and engine off. I will replace LOD with the tachometer tonight and make sure it is idling at that point.
     
  2. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    Drive by wire throttle?
     
  3. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    Yup, I think that is what they called it. Annoying to first get used to. There were many stalls or high revs starting from lights when I first got it. Lots of folks mention it after they first get their manual Yaris. Now it comes second nature and it is just how I drive.

    I have a modified 1994 Cherokee 5-speed and it always takes a few shifts to get used to the Yaris after driving it. Conversely, the first couple shifts in the Cherokee are always a surprise. I let off on the gas quick before clutching and my head bounces off the steering wheel!

    :eek:
     
  4. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    I noticed that difference between my '95 and the '02 Elantra I drive now. It feels as though the car is trying to emulate a flywheel to help rev match better. The '95 dropped RPM much more quickly.
     
  5. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    There is good news tonight, this morning actually. Beat my old record commutes by 3 mpg both ways. According to the SG, 57.something mpg FROM work and 56.6 mpg TO work this morning. I did make a lot of costly errors and figure it will take a few weeks to get a good P&G routine down. 60 mpg is 185% to combined EPA for my Yaris and I can see that happening within the next few weeks. Does it make me a pessimist for not shooting for 65 mpg and 200% to combined EPA from the get go?

    Error example: On the way home I was stuck at 54.2 trip mpg for about 10 pulses in a 45 mph psl zone. Deltas were 48 to 40 mph, I tried a few to 35 mph but under 40 mph the pulse starts in 4th gear and negates the glide gain. Trying to keep it in 5th for the pulse from 35 mph takes a long time to even get to 40 mph and is not the answer. Going to 50 or 51 mph didn’t seem to improve the length of the glide all that much. Maybe at 55 mph or over it would make a difference but that is 10 above the psl and out of the equation. At the end of this section I went below 54 trip mpg for a few before hitting a nice long coast section. The coasts were short (15 to 20 seconds) unless I try a 15 mph delta but then to get back to speed takes that much longer also. I am thinking that this particular section, which is gently rolling 15’ to 40’ hills pretty close together is not suited for gliding. My glide ends up being the same time as the pulse or even less. With DWL I can always hold my own or even gain one or two trip mpg here. In the past I remember doing a FAS from 50 mph down to 20 mph in this section and that seemed to work alright. But, chances of not meeting traffic for that long are few and far between and when someone does come up behind me they are going 55+ mph and I need to accelerate fairly rapidly.

    On the busier sections of the 45 psl I kept the delta to a maximum of 8 mph and I seemed to not impede traffic while still gaining a little after each pulse. This is a flat section so the glides were really nice. Do you think if I called the President he would OK using stimulus money to flatten out the nasty sections of my commute route? Or better yet make it all downhill, both ways! :D

    I replaced the LOD gauge with RPM to make sure I was at idle speed before keying off. My old technique of waiting for 99999 (DFCO) to engage before FASing might have been garbage. The injectors are off but the rpm’s are at cruising speed. It took about the same amount of time to wait for idle as to wait for DFCO. Thoughts as to which might be better or are they both accomplishing the same goal of engine idle before FAS? I am thinking that before DFCO engages, the engine uses more gas at high RPM’s before shutting down. Letting off the gas the RPM’s drop to idle using less gas. I’m no engineer but I bet someone slept at one of those hotels that make you smarter last night. :rolleyes:

    I think that is enough rambling for now.
     
  6. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Woody, were you able to shorten up your keying event after waiting for idle RPM? That's the real goal here. Less angular momentum means less time waiting for the engine to get to a state where it can't diesel back to life.
     
  7. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    I can not say if it was shorter. I will keep more of an eye out for key timing. I was concentrating on traffic and that next glide last night more than key time.
     
  8. SentraSE-R

    SentraSE-R Pishtaco

    Woody,

    I agree with your analysis of DFCO v. neutral rpm drop. You'll glide farther avoiding DFCO, and probably use less gasoline.
     
  9. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    Clutch in at the same time as foot off the gas versus foot off gas, wait a second (for DFCO) then clutch. Keying off is very fast with clutch in and off gas, hands down winner. Only had to re-key off once last night on the way home using this technique. Old habits die hard and because I shift gears using the delay, there were a few glides that started using the second technique. I found myself almost needing to hold the key off for longer than needed. But, a very short cycle with the key is all it was taking. I would still get an initial increase in revs but with 2 or 3 cycles of the SG, idle rpm’s were reached. Seemed to work as I had an incredible (for me anyway) 61.2 mpg, 30 mile commute FROM work. SG hit just over 62 mpg right before the long uphill to home, I don’t ever recall seeing it even hit 60 mpg before.

    Next big hurdle? Finding the perfect pulse rate. With just a few select glides, 83 LOD was working well. I am now thinking, with more glide time than pulse time, it might be more like 73 LOD. Also timing the pulses and glides to the terrain. It does me no good to be at top pulse speed, ready for a glide, right at the bottom of a hill. But being a moron, I had to find this out a couple times for myself before realizing that it was, in fact, as stupid as it sounds. :rolleyes:

    I am thinking the correct way to look at P&G is: If the engine is on I am using it to accelerate, all other times it is off. Unless climbing a hill of course. I should no longer DWL in many of the spots I previously did, if it is flat or downhill EOC period. Correct thinking?

    Thanks for the support and help! I’ll get this right soon. :woot: :flag: :D

    Oh, can the mods block Voodoo and Drummerboy from seeing this thread!?!?! I tried telling them that there was nothing to see here but I don’t think they believed me. If they ever get a hold of even a fraction of this information my chances of beating their automatic Yarii mpg are vaporized! :eek:
     
  10. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    Nice improvement, Woody!! :thumbs_up:

    A little secret here -- P&G in an Automatic isn't nearly as effective. ;)

    Another secret -- you've still got some room for improvement that would likely shock you. :D
     
  11. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler


    That is actually the thing I am looking forward to the most. From what little I have learned so far I can see many, many places for major improvements. It will just take time and experiment, experiment, experiment then practice, practice, practice. I never would have imagined me here a year ago when I was a die hard left lane’r setting the pace and cursing folks who drive like I drive now. Going from MPH to MPG, what a concept.
     
  12. SentraSE-R

    SentraSE-R Pishtaco

    Woody,

    We've created a monster - you. You won't have to worry about Drummerboy and Voodoo until they trade in their AT cars for MTs. They'll struggle to get into the low 50s, while your new target is the high 60s.
     
  13. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    Well, I hope to be a nice monster and only give them a hard time for beating my mileage until I can consistently pass them. I’m not counting Voodoo out… yet. He’s posting some great numbers AND getting better! No more tips for me from him!

    On to happier subjects (until I crush their mileage that is)… I had 2 days of fantastic numbers last week. I see my first issue as needing to be more fluid in accelerating and then transition to glide. Popping the clutch to accelerate is pretty smooth and consistent. I am finding that after I clutch and start the engine if I give it some gas for a few seconds then let up I can get the better acceleration thing going quicker than just slow acceleration alone. Without this I’m posting low impg while pulsing and therefore am pulsing slower while losing more trip mpg than necessary. Might just be my current technique is causing this or I am imagining the whole thing. Give me a few weeks to practice and we’ll see.

    Well, there is another first issue also. I have to learn my commute in a different way now. There are places where a glide is not working, long slow uphill sections. I have to be at target speed (psl as opposed to glide speed) when I hit these spots and DWL until the next glide.

    I have been gliding right up until I hit an incline, rather than accelerating to the incline to gain momentum. Actually not right to it but close enough to only gain a couple mph before starting up. I lose more trip mpg going up the hill but gain more by a further glide to it making it a gain for the segment over my past technique. I am going slower at the top and can not glide until I crest but overall it seems to be gaining trip mpg for me. Should I try and accelerate up the hill to start a downhill glide earlier? Or maybe accelerate close to the top to gain momentum? It seems to me I would lose more energy doing that than I would gain by the extended coast. Thoughts or experiences?
     
  14. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I adjust depending on the conditions. I can estimate the minimum speed I need to tackle the upcoming hill. Then I start a pulse wherever needed to start the hill at that speed.
     
  15. aaronl

    aaronl Alternative transportation advocate

    I'm just about to buy a 2000 Echo with a manual transmission. One of the factors in the decision was the 1NZ-FE engine, which seems particularly robust and efficient. I'm hoping to come back to this thread and figure out pulse and glide in a few months, but for the moment I'm going to have my hands full with the manual transmission. When I'm ready, I'd love to take Sentra SE-R up on his clinic offer, since he seems to have this engine figured out.
     
  16. SentraSE-R

    SentraSE-R Pishtaco

    I'll be glad to offer what assistance I can, Aaron.

    I'm on my cross-country trip for the month of July. Had a tank fill issue, as my fill-up in Reno was way off - 37.8 mpg, 7 mpg worse than any other tank in my Scion. But the next fill-up in Ely NV made up for it - 50.8 mpg! I coasted from the summit above Ely most of the way into town, and got 58 mpg over 40 miles. Had another long glide from Truckee down to Reno - 40 miles at 73 mpg, and the first 28 miles at 80 mpg.
     
  17. SentraSE-R

    SentraSE-R Pishtaco

    Three more tanks today driving from Beaver UT to Albuquerque NM. As expected, my mileage is dropping because of the new conditions I'm encountering. I let my GPS route me the most direct route, which avoided the Interstates until I had to drive I-40 from Gallup to Albuquerque. My overall mileage on the Scion is now 46.25 mpg. It was 46.5 mpg before I started this trip. I was expecting it to drop about 10-15%, down to 40-44 mpg. I'm very pleased it's barely dropping at all. I actually look forward to construction delays, as the traffic travels at a sane speed, and I can P&G in the gap between me and the car/truck in front of me.

    I thought the Interstate would clobber my mileage, as it's a 75 mph PSL, and I was driving a steady 58 mph (60 indicated). But my mileage was holding at 45.6 mpg. I tucked in 2 seconds behind a truck who was going 65 mph, and watched my mileage climb steadily up to 46.9 mpg before I broke away. These boxes really benefit from having a big wind deflector in front of them! My Sentra doesn't show any net mileage gain from following big rigs, but the xB does.

    I had one impossible tank fill-up. I drove from Beaver UT to Cameron AZ, 224.8 miles, and only took 3.7 gallons to fill the tank. That's 61.2 mpg. Actually, the automatic shutoff didn't shut off, and spilled about .3 gallon on the ground. But even if I counted the spilled fuel, that's still 56.6 mpg.

    When I filled up in Albuquerque, I noticed the gas was 10% ethanol, so my next fill-up should suffer, especially since it's going to include driving in the morning rush hour across town
     
  18. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    That is great considering you are driving in the mountains! Were there many long glides or were the up and down closer together? You’ll be back on the flatlands in NM and able to gain some mileage I hope.
     
  19. SentraSE-R

    SentraSE-R Pishtaco

    There were a couple of 40 mile downhills where I got great mileage, but also lots of small hills. I prefer hills, because it's easier to see the mileage improve quickly. Flat land is just tedious to me. I paid a shop to get the cruise control working on the Scion (I'd misconnected the VSS wire), and I used cruise control today. It brought today's mileage down to below 40 mpg, with the AC working most of the time.
     
  20. WoodyWoodchuck

    WoodyWoodchuck Sophomore Hypermiler

    Findings from last week. Deltas less than 10 mph result in minimal mpg increases. I did have an interesting few mile segment using a delta of 5 mph that resulted in a pretty good gain. I could not reproduce it and am thinking there was a tail wind that helped get the results. Even a slight tail wind really helps the Yaris while a slight head wind does just the opposite!

    I tried with accelerations of 85+ LOD (as you would expect horrible results), 83 LOD (good results as long as the pulses were short in duration), 73 LOD (took too long to reach target speed and ate up any gains from the pulse) and ~60 LOD (most promising).

    I ended up using the impg gauge to accelerate. Keeping this less than 15 mpg from my current trip mpg has produced the best results. Just about impossible when I get around the 60 mpg mark as the general impg acceleration is 40 impg for over 40 mph and 30 to 35 impg for accelerating under 39 mph in 5th. The LOD and TPS values will vary, depending on current speed I think. The LOD values while accelerating do end up being less than 70 for most pulses though with many 50’s and low 60’s. It takes a painstakingly long time to reach glide speed but the trip mpg loss in very minimal this way. For example accelerating very slowly I will lose .5 trip mpg while a faster acceleration will cost me 1.0 mpg. I now use the LOD gauge to tell if the engine is really off or not.

    For the initial acceleration after the pulse, I give the accelerator some pressure for a second or two then let off. I get much better initial acceleration and higher impg readings while pulsing than if I had not done this. I can cut down on pulse time doing this, at least it feels like I am and the trip mpg seems to stay higher.

    I am still not at the gliding more than engine on stage, possibly just my commuting terrain accounts for this. All those long gradual uphill highway sections are impossible to P&G up (for me at this stage anyway). Another reason could be the very slow acceleration rate.

    All in all a positive week! I am learning, although much slower than I can stand. I see many places where I can improve; I just need the discipline to do it.
     

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