ways to give car better fuel economy!!!

[DJShyn3]

hello

i want to know how can I make my checy caprice 1991 sedan a better fuel economy car?
What i mean bythat is, what parts can I replace on the car that will give it a good fuel economy? Please let me know with any tips, suggestions on this.

Thanks

[consultIII]

retard igniton timing 2 degrees. you will gain 2mpg but loose a small amount of power.

[96capricemgr]

Make sure tires are inflated properly which may actually mean over the spec in the doorjamb. Try running a couple more pounds and watch the tire wear, if the centers wear more than the pressure is too high, if the sides wear pressure is too low

Make sure the alignment is good.

a full tuneup, cap rotor plugs and wires never hurt either.

After that a light foot is best.

[j cAT]

Originally Posted by DJShyn3

hello

i want to know how can I make my checy caprice 1991 sedan a better fuel economy car?
What i mean bythat is, what parts can I replace on the car that will give it a good fuel economy? Please let me know with any tips, suggestions on this.

Thanks

If you follow the proper maintanence intervals on servicing your vehicle you should get the maximum MPG ..

some other items that can help, but not much is overinflation of tires, clean the vehicle out of un needed stuff, use synthetic fluids in the engine tranny , don't operate with low fuel this causes more gas evaporation, replace the air filter often especially the paper filters, use the correct themostat , oil should be 5-30wt...check for any vacuum leaks every 6 months and replace any vacuum lines that are cracked hard brittle .. and make sure the idle is correct ...

[DJShyn3]

Originally Posted by j cAT

If you follow the proper maintanence intervals on servicing your vehicle you should get the maximum MPG ..

some other items that can help, but not much is overinflation of tires, clean the vehicle out of un needed stuff, use synthetic fluids in the engine tranny , don't operate with low fuel this causes more gas evaporation, replace the air filter often especially the paper filters, use the correct themostat , oil should be 5-30wt...check for any vacuum leaks every 6 months and replace any vacuum lines that are cracked hard brittle .. and make sure the idle is correct ...

Thanks everyone and keep it coming loving it, will follow it all

[Blue Bowtie]

Don't worry about keeping the fuel tank full. It is best to maintain between 1/4 and 1/2 full for best mileage and longest service. Since your TBI uses an exposed fuel pump in the tank it is important to maintain about 1/4 tank to aid in pump cooling and longest pump life. Carrying more than 1/2 tank is just extra weight, like carrying around a trunk and/or back seat full of junk.

Make sure the EVAP system is fully functional. The EVAP canister will trap all volatiles which try to evaporate from the fuel tank and return them to the fuel system at light cruise to extend mileage. Without EVAP, almost 10% of the fuel volume can evaporate and be lost in less than a week in warmer weather. That's like filling your tank then pumping another two gallons onto the ground just for kicks.

Install a camshaft with a shorter duration and tighter ramps to maximize dynamic compression at lower RPMs and low throttle openings. This, in conjunction with tighter combustion chambers, can increase burn efficiency tremendously.

Maintain the EGR system so that the ECM can advance spark as much as possible. Retarding spark is a waste of fuel.

If you are adept, you can reprogram the ECM to enable the factory-provided Highway Fuel and Spark Modes. This allows mixtures up to 17:1 in cruise mode and low LV8 (light loading) total spark advance up to 50º BTDC. This can increase mileage tremendously, but will increase NOx emissions, so it is doubly important to have a functioning EGR system to counteract that.

Install narrower, taller tires to reduce drag and rolling resistance.

Avoid short trips which don't allow the engine to reach full operating temperature, or group these trips together to spend as much driving time as possible at full temperature.

[silicon212]

Originally Posted by consultIII

retard igniton timing 2 degrees. you will gain 2mpg but loose a small amount of power.

I really hope you're joking! If not, you need to learn some more about how cars work!

[consultIII]

Originally Posted by silicon212

I really hope you're joking! If not, you need to learn some more about how cars work!

I definitly wouldn't say I know it all but I have 6years dealership experience plus 2 years motive power training; what about you?

Our master tech (who is the best tech I've ever seen) would adjust the timing with the factory scan tool to apease customers who would complain that there gas guzzlers weren't getting fuel mileage that matched epa ratings (another story). Alot of car making is about comprimise to give the best of both worlds hence different variables; ignition timing being one of them.

just as over advanced timing increases power (but burns exhaust valves) this minor adjustment did help mileage. Didn't believe it until I seen it either. Some Nissans models did list a allowable timing adjustment spec believe 2.5 +/- from ideal. We are talking 2 degrees; a small amount.

please tell me why this isn't possible
thanks for being so insulting (your an advisor?? maybe you should review your own sites guidelines)

[96capricemgr]

I have yet to meet a dealer tech who actually had any comprehension of how everything worked, and I have known some good techs that had no rework and consistently top production for years on end..

ENTHUSIASTS often better understand how things actually function.

[j cAT]

Originally Posted by silicon212

I really hope you're joking! If not, you need to learn some more about how cars work!

retarding the timing if it really is retarded can reduce detonation...so these so called dealer techs rather than say replace an EGR valve that is defective take it upon themselves to cheaply retard the timing ....the service manager is very happy !

with no detonation the MPG will improve..

[consultIII]

Originally Posted by 96capricemgr

I have yet to meet a dealer tech who actually had any comprehension of how everything worked, and I have known some good techs that had no rework and consistently top production for years on end..

ENTHUSIASTS often better understand how things actually function.

I know, all dealers techs are stupid. I personally got into the trade because I am too dumb to do anything else.


Here is you chance to explain it all to me...but use small words that I can understand.

I have no problem with someone challenging my post; but explain your theory as to why it is so. If I were to say your post about inflating tires properly is so overly obvious; adds nothing informative to the forum. Give me reasonable explaination as to why I am wrong I am more than open to it.

I was an enthusiast before I got into the trade and thought I was pretty smart. I realized I wasn't as smart as I thought when I started doing it for real. If all the licensed tech stopped posting on this forum; this site would something significant.

[silicon212]

Originally Posted by consultIII

I definitly wouldn't say I know it all but I have 6years dealership experience plus 2 years motive power training; what about you?

Our master tech (who is the best tech I've ever seen) would adjust the timing with the factory scan tool to apease customers who would complain that there gas guzzlers weren't getting fuel mileage that matched epa ratings (another story). Alot of car making is about comprimise to give the best of both worlds hence different variables; ignition timing being one of them.

just as over advanced timing increases power (but burns exhaust valves) this minor adjustment did help mileage. Didn't believe it until I seen it either. Some Nissans models did list a allowable timing adjustment spec believe 2.5 +/- from ideal. We are talking 2 degrees; a small amount.

please tell me why this isn't possible
thanks for being so insulting (your an advisor?? maybe you should review your own sites guidelines)

OK, I will qualify what I said. First, the car in question is a 1991, which means it does not have OBDII where you can go in and change certain things. On these cars, the computer controls timing and the static ignition timing (via the distributor) is set to 0 - direct TDC. A matter of a couple of degrees on these engines can make a substantial difference in power output. As 96 stated above, if you have to retard timing to get better economy, it's because something is causing detonation (faulty EGR valve, dirty fuel injectors, carbon buildup in the combustion chamber, etc). Retarding the timing is, AT BEST, a band-aid that does not resolve the original problem. Just because you see increase on a Nissan does not mean that will happen on a 4,000lb car with an underpowered 5 liter V8. To claim 2MPG gain by retarding timing 2 degrees is absurd at best! Heck, while we're at it, put magnets on the fuel lines and a Tornado in the air box! In other words, it's snake oil and retarding timing on these engines reduces power, and can make them run hot.

The best way to increase economy is, as 96 stated, to make sure the tires are properly inflated and I go by what's on the tire, not what's on the door jamb (which is often less in order to make the car ride softer, see the 1999 Ford Explorer / Firestone Tire debacle), make sure the car is properly in tune, front end is aligned properly (so you're not dragging the tires sideways) and put aside the 'lead foot'.

[j cAT]

Originally Posted by silicon212

OK, I will qualify what I said. First, the car in question is a 1991, which means it does not have OBDII where you can go in and change certain things. On these cars, the computer controls timing and the static ignition timing (via the distributor) is set to 0 - direct TDC. A matter of a couple of degrees on these engines can make a substantial difference in power output. As 96 stated above, if you have to retard timing to get better economy, it's because something is causing detonation (faulty EGR valve, dirty fuel injectors, carbon buildup in the combustion chamber, etc). Retarding the timing is, AT BEST, a band-aid that does not resolve the original problem. Just because you see increase on a Nissan does not mean that will happen on a 4,000lb car with an underpowered 5 liter V8. To claim 2MPG gain by retarding timing 2 degrees is absurd at best! Heck, while we're at it, put magnets on the fuel lines and a Tornado in the air box! In other words, it's snake oil and retarding timing on these engines reduces power, and can make them run hot.

The best way to increase economy is, as 96 stated, to make sure the tires are properly inflated and I go by what's on the tire, not what's on the door jamb (which is often less in order to make the car ride softer, see the 1999 Ford Explorer / Firestone Tire debacle), make sure the car is properly in tune, front end is aligned properly (so you're not dragging the tires sideways) and put aside the 'lead foot'.

thank you for that detailed explaination .....I agree with it all...

when you have to live with incorrect repairs made , you understand what the ofter effects are , better than the tech watching , the vehicle go out the dealership door..


also these vehicles have been tested and the timing has been set, by OEM engineering for the best MPG.. with not being very smart, just having common sense one would trust these settings as the best / correct ones.

[Blue Bowtie]

All good information.

Not to beat a dead horse, but to clarify, many early OBD systems used programming and sensors which controlled ignition advance and monitored for detonation. When these systems detected detonation they would retard timing in large steps instead of a couple degrees at a time. Further, they would only slowly attempt to bring the timing back up before detecting detonation and "learning" a reasonable timing advance. However, unlike fuel system trims, this "learned" data was not retained in NV memory, and would repeat at every engine start.

As stated above, in these case, retarding the base timing setting might actually help the mileage by avoiding these large "step" retards by the ECM. As stated further, this method is only a "band aid" for masking a more involved problem(s).

It is possible to reprogram the earlier GM ECMs to reduce the retard steps to less than 1 degree at a time and gain real control, but unfortunately there is a finite number of retard steps available and all timing retard has to be accomplished in that number of steps to prevent serious engine damage if detonation occurs. I've done quite a few older ECM reprograms and PROM burns on pre-OBDII systems and have toyed with the advance tables and retard steps. EVERY engine is different and every program is custom and highly influenced by the modifications.

Both ideas may be valid, but repairing the root cause is the better solution. The often hated EGR system actually has some performance and mileage benefits. The misunderstood EVAP system can improve mileage measurably. Even the EFE systems which always seem to get in the way have benefits.

If you want to get into reprogramming, take a close look at the HFSM programming I mentioned above. That can make for some significant mileage improvements at the risk of higher NOx creation. It only takes a few dollars in hardware to get set up to burn PROMs for these older systems and there is a lot of help available in the WWW for GM systems.

Even the later ECMs and PCMs can be flashed/strobed with new data and parameters, but the hardware is more expensive and the risks are a bit higher. If you have a 1993 or later, that will be your option.

[j cAT]

[quote=consultIII;6115468]I know, all dealers techs are stupid.

[quote]

Dealerships are not stupid they full well know how to do this repair work properly...they also have all the info kept in a lock box..this is so other repair shops are at a disadvantage....that is until these internets began...this also is how GM began its tremendous fall ...free info and forums like this !

face it dealerships are not operating on goodwill...scaming customers whenever they can is to help them get some easy cash...short cuts all help the tech as well as the profit line ....If you want to be employee of the month you must play the game their way or the hywy..

my state has small auto repair shops asking the legislature to pass a bill to force GM and the other manufactures to open up that lock box so that all this secret repair info is available to all so as to level the repair playing field...I hope this passes...then the dealerships will not be able to scam ..