Care to lend a hand?
 

I drive an '88 Buick LeSabre with the 3800 V6, automatic tranny, and FWD.

I do nearly all the work on it to keep it running (in a driveway - when it rains, I cover what I can with tarps and suck it up), and I'll be doing whatever mods I decide to do myself as well. I change the oil regularly (between 5k and 10k miles) and use "older vehicle" oil. I'd use synthetic but I feel like the benefit would be less than the cost difference, which in turn allows me to buy more gas... Oh, and I normally keep my tires properly inflated but come winter time I let that slide a little because the extra traction is WAY more important to me than a slightly improved FE.

There isn't much I can do to better my driving - I can't coast in neutral, not habitually, anyway (engine stalls out if I do it too much, rather not push the tranny too hard else I have to fix it), the majority, or what feels like the majority, of my driving is highway, and I drive between 55 and 60 mph (the speed limit is 65, 90% of people do 70 or higher) on cruise control, I never use the AC (plus, it's $80 minimum parts alone to fix it lol), unfortunately because I drive an old car and want to keep it running and don't have a coolant/oil thermometer (not one that I have access to, anyway) I always drive with the heat on, often on high, I accelerate as slowly as I think drivers around me can live with, I brake gently and well in advance of stops, I otherwise try to conserve my momentum as best I can while not driving in a manner that would piss me off if I was following, and I'm otherwise a very observant driver.

I probably do more subconsciously, but I'd like any suggestions. I'd draft, but everyone drives faster than me and I prefer to be lazy and slow, and safe(r).

Mostly, I'm interested in mechanical mods that won't anger my poor old engine and tranny, and won't turn my classic car of the era into an ugly clown car. Sooooo, yeah, there are limits, but I am very keen on anything that saves me some cash and doesn't make my lazy commute much more difficult (just a thumb on the wheel and open eyes for over 60 straight miles). Remember, I have an OBD-I connection that's damn near impossible to find a reader for, and thus monitoring my engine block's temperature (rather, in my case, doing whatever I can to keep it from overheating) is very important to me. Being forced to replace a transmission for a FWD vehicle without a lift in a driveway by myself is what I do *not* want to have to do any sooner than I have to already.

Right, so if you skipped all that, find me a few mods that don't involve making my engine hotter than its regular cruising temp. I checked out a few on the site but I'd rather just listen to your unbiased replies before narrowing anything down.

Thanks :)

(edit: if someone notices that I didn't use an acronym, please correct me, I'm too lazy to learn them by myself :))

Welcome! The Lesabre is a nice car, even if yours is a beater, and that generation of Lesabre still looks cool to this day (IMO). The 3800 has a reputation as a robust, long lived, and efficient engine. Can you post a picture of your car?

I would definitely add a temp gauge to the car. They're not expensive. JC Whitney sells a gauge with sender for $32. I'm sure you could get into one for under $20 if you spend more time looking than I did (and I only spent 90 seconds on it). This would allow you to feel more comfortable with your car's condition, as well as not sweating your butt off in the summer.

There's probably a lot of aftermarket support for the 3800, and you may be able to upgrade the fuel injection, ignition, and maybe even the computer. I don't know how much there is to gain by doing so, but you may be able to do it cheaply with junkyard parts from newer vehicles.

I don't know if it would be difficult (probably would) but if your car revs high while cruising you could change the differential ratio. At least you can do that when the weather is nice.

You probably don't need a scanner to pull codes, but I wouldn't be surprised if you could find one to give you sensor data. However, you can probably get much of your data using DIY methods and contraptions, using gauges, meters, and LEDs that tap the sensor's wire.

In my sig, there's a link for a fuel rate meter; in the linked thread, there are links to similar/better ideas. You may be able to pull a DIC (Drivers Information Center, the factory-installed MPG gauge) from a similar car in a junkyard.

Most real improvements that people get are from driving techniques, not car modifications. Unfortunately, it sounds like you're already doing almost everything you can, and can't do most of the useful modifications. The usual things that would help are ruled out by various conditions you posted...

- No coasting rules out Pulse & Glide and downhill coasting. My 1987 FWD Cadillac's transmission took over 200,000 miles of awful abuse without ever complaining but that's no assurance that yours will survive thoughtful and careful usage of neutral. However, in my experience, the fear of the 'N' is mostly superstition; some vehicles won't cool the transmission sufficiently in 'N' but other than that it's no problem as long as you rev-match when putting it back in 'D'.

- No drafting -- well, would it bother you to draft tractor trailers at a lengthy 3 second following distance? Most people follow much closer than 3 seconds, but results posted by members here show that 1.5 to 3 seconds is the most effective drafting distance. It's not hard to find tractor trailers driving at your speed.

- You already conserve your momentum and limit your top speed.

- You can't do any grille blocking or install a warm-air intake because of your fear of overheating.

- You can'd do aerodynamic modifications because you need to look respectable when you arrive (and your car doesn't leave much room for improvement without making it look bad). You might be able to experiment with an extended air dam. You might be able to remove the hood ornament (that would be a shame) and replace the likely wire-spoke hubcaps with interesting smoothies but they'd probably look too out of place on your car.

Increased tire pressure may be a worthwhile experiment. You sound like you're decided on your tire pressures without having experimented and actually tested to see how it affects traction. Your car is probably pretty light with relatively large tires, so you may not be able to safely run maximum pressure in the summer, but it's almost certainly necessary to run the car's recommended pressure in the winter. Running less than that is just begging for a blowout on the highway, even at 55 to 60mph.

your best mechanical mods are get some feedback from the car and tire pressure those are the easiest ways to make an improvement.

Tire pressure is a good one.

That transmission already coasts automatically as soon as you lift your foot. One of the best out there for that - lift off the gas and it immediately releases and drops to idle. On the highway, don't let it downshift when climbing a hill - turn off the cruise and use your foot, allowing the speed to drop slightly as needed.

Just keep it rolling - standing starts are killers. Drive as if your brakes have failed. (but use them when approaching a light that's about to go green, so you can roll through without stopping)

A friend of mine with a 2002 Regal has done 40 mpg on highway trips, by simply driving a little slower, smoothly, and with higher tire pressure.

Do you have a Scangauge? You should buy one. It includes a temperature readout, and the feedback it gives you WILL pay for itself in gas savings. I saved over $500 last year.

It's an 88 so SG isn't an option.

Does the transmission really go into neutral or does it just have a torque converter that allows for the input shaft to stall lower than output speed more than others?

Lots of people think that automatics go into neutral when you lift off the gas, but I have yet to see credible documentation or hard data that convinces me. With the torque converter unlocked lots of cars will allow the engine to simmer down some, but most won't go to idle.

Pale, you have my respect as someone who does a lot with hard data and credible documentation, and as someone who produces real results. Do you have anything to back that statement up?

Sorry about the scangauge thing. I didn't read the year model closely enough. :(

Driving with my friend in his Buick, scangauge and tachometer equipped. As soon as you let off the gas, the rpm drops down below 1,000. It may not be exactly the same as idle, but aside from the technical details it's pretty darn close.

In contrast, my Honda Odyssey will stubbornly hold it in gear when you let up. It gives you massive engine braking unless you manually shift into neutral. The two vehicles behave very differently.

In addition to higher RPM than idle, it also does some engine braking. It's not the massive amount you get from a foreign automatic or any manual, but it's still some. I'm not confident that it would produce good results, though I can't say for sure that it won't.

What was the speed where you observed the behavior in your friend's Buick?

Doing it in my truck with RPM at ~800 uses about twice as much fuel as putting it in neutral and reduces the distance I can go before having to apply power again. I don't feel the engine braking but the distance is far shorter. I'll have to gather some hard data the next time I drive.

Interesting. I believe you. You have more time in that truck that I do in the buick, for sure. We were driving around town, so somewhere in the 30-40 mph range. He just traded the buick for an Odyssey last week, so I can't do any further research with it. I'll defer to your experience.

I'll definitely try to gather some hard data. This comes up often and nobody ever manages to bring any hard data to the table...

sounds like you're are limited to what you can do. but, here's the same motor, similar driving, different car...

https://www.gassavers.org/garage/viewgaslog/775

Harbor Freight has a trio gauge set (oil pressure, water temperature and amps) for under $20. I have a set of them on my '88 Escort and they're accurate.

add a vacume gauge if you keep it reading as high as possible you will see better milage.

Wouldn't high vacuum indicate a lot of pumping loss?

Correct. I like to accelerate at around 12 psi MAP, or very low vacuum. It's somewhere around 75% throttle. Low rpm, of course. Then I glide, glide, glide.

If you're aiming for steady speed, then high vacuum is good, as it correlates to high instant mpg.

Yup, granny accelerating really doesn't help FE. Marvin liked enough throttle to take him to about 2500rpm and keep him there until up to speed. BUT having said that, still drive as if your brakes have failed, accelerate briskly but no more than required at any instant in time, if the traffic is speeding up slowly, that might be a kind of spurt and coast regime. It's not smooth, but it works.

"Jackrabbit" starts killing FE is something of a myth, going too fast kills FE because you have to brake. If you've read the road ahead and are sure that the speed you're aiming for is appropriate, then you're just wasting gas not to be at that speed.

Wile-E is proving something of a tribulation with this at the moment, especially when cold the transmission is changing too early and he's pinging a little as it slogs. This is partially due to having to be gentle with the pedal due to winter conditions. I'm wanting to pull to at least 2500 but he's changing at 1500 and struggling :rolleyes: ... I guess I should stay out of OD until he's warm.

Don't go getting shift points and acceleration rate involved...we were just talking about throttle. Once you attach shift points to throttle (as in an automatic), the game changes entirely.

Now that I have my SG I'm finding that my auto GMC surprises me. I have been watching the instant MPG readout and I thought it would squarely confirm what I've observed in my manual VW with tank-average MPG experiments.

In the VW it definitely saves gas to use the tallest gear possible and lay on the gas. I learned that by experimenting for tanks of gas at a time. I drove it with the SG for a few days and didn't notice anything to raise any doubts.

In the GMC with the torque-beast V8 and 4 speed automatic, my strategy (which has been pretty successful) has been to lay on the throttle as much as possible within the confines of keeping RPM low and gears high. However, the SG is reporting interesting information about higher RPM and power -- if I let it kick down a gear or two and rev up to 2500, 3000, or more...I get one hell of a lot of acceleration without paying much more loss of MPG. I might lose 20% to 60% of my MPG but it seems like I gain more speed. As the RPM and speed climbs, the MPG stays steady or even improves. The downside is that my glide starts sooner and therefore ends sooner (unless I pulse higher). I'm not sure just how much of this is due to OBDII lag, but when I can get a steady baseline MPG average going again, I'm going to experiment with it.

I could post a picture eventually - right now I just have a picture of a beflowered door handle. Within a few days of owning it I let someone sit on the hood and the trunk and they had something metallic and scratchy, so I have a few rusty scratches on my hood, but I like to think that they add to the car's "character", like a scar or something.

Aftermarket parts (at least newer technology) are a great idea, and those jobs are relatively simple and cheap :)

The engine is great to drive - just basing this off of how it sounds like it's revving, it likes cruising between 55 and 65. I feel like there's a greater delay between my accelerator and an increase in revs than other, newer vehicles (98 f-150 triton, 00 taurus, 96 cavalier, 05 focus), but other than having to learn how to adapt my driving to this I don't know if it helps ya'll.

I'll look into scanners again.

How would I read the output of the DIC?

I've tried coasting in neutral (both engine off and on, different tests), and the engine always either ends up stalling or doesn't turn back on if I do it as often as it benefits me. I can and sometimes do cruise in neutral, but only on short trips along paths that I already know well. I wonder if my issues with neutral stem from a less-than-effective fuel pump or some other blockage (I'm not so great on diagnosing problems yet).

Since I posted, I retried drafting, but with a different (06 cavalier) car, and noticed lower rpms at the suggested distance, and I think I'll give it a another try in my car. I won't be sure if the increased FE will offset my annoyance at having to adjust to the trailer's speed changes until I install the fuel rate monitor (or one of the similar/better ideas).

I could probably block the grill in the winter, at least. And what's an air dam? The area beneath the grill and bumper?

My car still has every external badge (really surprising considering the condition I bought it in), which is why I haven't sold my original wire hubcaps for something cheaper, lighter, and less of a ***** to get on and off (my dad ground down a socket to fit the lock on my hubcaps - it works, but I haven't spent the time to mark exactly how it fits on each hubcap, so I have to figure it out each time I want to take off a tire. I understand that every little bit of decreased drag helps, but I agree that it would be a shame to take off the hood ornament.

When I wasn't concerned with traction (I've driven at least 50 miles through nearly every major winter storm in the northeast in the past two years, foolhardy, but successful each time) I keep the tires inflated and check them at least every two weeks (usually before I notice anything visually). My new tires are properly inflated and I plan to keep them so :)

I have noticed that my car seems to decelerate faster when I shift it into neutral than when I just drop off the gas, and the rpm (I'm doing this purely via sound btw, no tach) sound about the same. I'm not sure which saves more fuel, but a guess that's based purely on my experience (not noticing an especially different FE when I originally tested, but my methods could have been better) tells me that if the engine is on, the difference between neutral and my foot off the pedal is very small.

Pale - I make mistakes like that all the time. It's best when they're minor, inconsequential and someone notices :)

About the torque converter - my auto experience is based purely on this car (not a bad car to learn on, thus far), my dad's only really taught me things as I've needed to know them. I can double flare brake line (as well as other repairs), but I have just the faintest idea of what the idea of a torque converter (something that converts torque, and I'm assuming it has to do with shifting between drive and neutral) is, and no idea of what it looks like. :)

Actually, I do have one of those combination sets of three sensors, but what's holding me up from installing it are: where to put the gauges (more an excuse to procrastinate, but I also don't want to slam my knee on them), the fact that they're not electric, and it's cold outside right now :)

[quote=roadwarrior]"Jackrabbit" starts killing FE is something of a myth, going too fast kills FE because you have to brake. If you've read the road ahead and are sure that the speed you're aiming for is appropriate, then you're just wasting gas not to be at that speed. [quote]

Isn't there a point where aerodynamic drag cancels out the benefit of speed (more miles per time) because the drag increases to a point where the engine is fighting it more than other frictions? And could you elaborate just a bit more on the jackrabbit starts? I assume that people who jackrabbit probably burn more fuel because they overshoot their cruising speed and have to brake harder than otherwise, or because they spin out their tires.

Thanks everyone! I got a lot more responses than I expected.

Also, I sort of live out of my car so I bet I'd get better gas mileage if I packaged my stuff better and took it out whenever I could. But then again a lot of my stuff is stuff that would make me really happy to have if I ended up stranded somewhere (either no other place to sleep or repairs that I couldn't do with the tools I have in the car and I can't get cell signal to call roadside assistance) - and while the roads I drive are usually major, I usually travel them when there's as little traffic on them as possible (late at night/early morning).

What does acetone do to improve gas mileage? I read the gas log of the car that someone posted, and the driver mentions acetone...

If you can find one that's compatible and manage to get it installed, it will just display the information.

https://www.gassavers.org/showthread.php?t=4258
https://www.fuelly.com/attachments/fo...cbb1a6c596.jpg
https://www.fuelly.com/attachments/fo...bb84bc3e07.jpg

Don't make a habit of coasting in neutral with the engine off. That can destroy an automatic transmission, which requires the engine to run its oil pump.

If it was something like that, it would probably also stall when in Park or stopped.

Yes, that's what the air dam is. It's usually a plastic piece hanging down, either as an extension of the bumper or separate.

Here's a separate one:
https://www.instructables.com/files/d...S1L.MEDIUM.jpg

Here's an integrated one that's been extended by adding a second one from a junkyard:
https://www.fuelly.com/attachments/fo...f986348f8f.jpg
(That's user Jay2theRescue's truck.)

:eek: That is not normal. I wonder if it could be related to your stalling in neutral. It should coast further and decelerate less when in neutral unless your engine is idling very fast. What speed did you try it at? I can imagine at 30mph the engine could continue to power the car at idle.

That's an easy one. It fits between the engine and transmission, where a clutch would be, and does approximately the same job as a clutch. The TC is essentially two fans blowing oil at eachother. When you come to a stop while in D, it doesn't need to disengage like a clutch; the engine side keeps spinning and the transmission side stops. The transmission remains in gear and the oil in the TC gets thrashed/sheared while it waits (that sounds bad but it's fine).

The TC allows the engine RPM to not match the transmission RPM; the engine can go slower if it's not applying power or it can go faster if it is applying lots of power. Modern TCs can lock and are called Torque Converter Clutches; when locked, they cease to allow any slippage and act just like a fully engaged clutch. Locking on modern TCCs is controlled electronically by the computer.

Here's what a TC/TCC looks like:
https://racetransmissions.com/store/i...rProductG3.jpg

There's a nice disassembled view at:
https://www.tciauto.com/Products/Tech..._explained.asp

Aerodynamic drag increases as a square of speed rather than directly proportional, so at 50mph you might have about 4x as much aerodynamic drag as you do at 25mph.

Someone else should post about the transition from Laminar to Planar (did I get the terms right?) airflow, because I don't know anything about it except that it happens at a different speed for each car (between 50 and 70mph on average) and reduces drag at that speed.

It's pretty unlikely that weight reduction will help your car. Big, torquey, tall-geared American cars generally don't produce any results from weight reduction. If it would help, it would have to be a lot; your car probably weighs 3500 lbs or more; taking 100 pounds out will never make a difference.

Gas additives like acetone are generally credited with changing how the gas burns so it will burn more efficiently. I'm skeptical of most but open-minded. However, I'm also fearful of damaging stuff by putting various abnormal chemicals into my fuel.

No more cruising in neutral, engine off. Thanks! :)

Other than after I've been cruising in neutral, my car has never stalled.

I bet my idling does drive the car a bit, especially downhill at about 30 mph. I haven't made a practice of shifting into neutral at highway speeds - guess I'll have to retest that one.

Good logic about the weight reduction. I suppose that my gf's cavalier would have a much more noticeable effect if I started carrying around 100 pounds for a tank of gas, then retested without.

I figured that most fuel additives wouldn't do much to increase FE, except in very specific situations, or except for expensive fuel additives. Otherwise, why would it not already be added to fuel?

Thanks so far, everyone!

the idea of the higher vacuum is for cruise only. The idea is the higher the vacuum indicates less throttle. There will always be pumping losses especially in an older engine But i've seen 32mpg in my mom's 87 Buick Lesabre driving with a light foot.

Don't forget to rev-match before putting it back in D. This is more difficult without a tachometer but you can at least guess.

Possibly. Most people reporting success are taking 10% or more weight off of small Japanese cars. 100 pounds is at most 5% of the Cavalier.

I have noticed a big difference in my Civic, but nothing measurable in the Odyssey. (2300 lb vs 4300 lb)

A quick google search shows about 2700 lb for the cavalier.

What engine does the Cavalier have? That 2.2OHV is what I would call the little brother to the 3800. It has plenty of torque down low for in town driving and don't see 100 pounds making a measureable difference in that case either.