Take a look at #28 in the "Check Engine Light" conference. I had the "check engine" light come on in a new 98 Honda Civic Hatchback and the dealer told me to stick to gasoline with detergent additives. He specified Chevron, Exxon, or Texaco, and that's all I have used ever since. I always used 87 octane, both before and after the light incident.
Hey, this thread is back on topic once again. Just wondering how dificult it is to come up with a DIY octane rating test kit? Sure there are random check by the government to keep the gas stations honest, but being able to check octane on the spot sure would help a lot more.
Is there anything like certain gasoline brands being different than others in terms of .. certain brands being tuned for cleaner emissions while certain brands being optimized for smoother and better performance within the same octane level. Is there a significant difference between Amoco, Mobil and Texaco in this respect (comparing 87 octane )?
I began posting to this topic when I noticed my '99 Silverado truck developed a slight engine ping. It remained even as I switched grades up to mid, finally premium.
I took the truck to the dealer. They checked it out and said they heard the ping, but didn't know what to do about it, because of computer engine controls. The owners manual also states that a small amount of it is normal, that you don't have to step up to a higher grade to eliminate it. They updated my engine calibration parameters, and gave it back to me. There was no noticeable improvement after this initial eprom update.
I then modified my coolant thermostat to open at a 13 degree lower temperature. This made a noticeable improvement in drivability to me, although some stated it was in my head. I began checking fuel mileage after the thermostat mod.
When I noticed a jump in fuel mileage, I took a pause to access the possibilities. My previous best was highway 17.6 mpg, in-town city driving was averaging 14.6 mpg. The in-town mileage had improved to 17.1, with some highway speeds mixed in.
My next tank improved to 18.6, all highway, but still improving on my best highway tank before the mod.
Then my next tank was 17.2, lots of highway miles, but also hauling cargo quite a bit.
Finally brings me back to my most recent tank, 16.2 , all city, some highway speeds, empty cargo bed most of the time.
All of the tanks since the thermostat mod have been run on regular grade octane, 85 here in the altitude of Colorado.
Conclusions: My fuel mileage seems to have improved. While I cannot prove the gain came from the thermostat mod, I can't rule out some benefit either. There are other seasonal variables that could apply, and perhaps my driving habits varied, or my engine completed its break-in wear. So I'm not saying my fuel mileage improved because of the mod, but my fuel mileage does seem improved.
What about the ping? Well after the thermostat mod, the ping seemed eliminated at first, but when I reduced gasoline grades, I could notice it again slightly, intermittently, but I had to listen very carefully.
And then just this week, I became aware of another engine calibration software update from GM that stated it was to address various drivability concerns including hesitation (didn't have), and spark knock (did have). I took the truck in on Tuesday, and they re-flashed the eprom with the update. As of today, I have driven 150 miles. I thought I heard it crackle a tick driving out of the dealer lot onto the street. But I'm not sure, because I haven't heard it since.
So for whatever reason, or combination of reasons, it seems like it's gone, and I am able to run on regular 85 grade octane with good drivability, and no audible knock. My '99 Silverado truck, while delivered with a few flaws, is just about perfect now, and getting very good fuel mileage while letting me haul cargo with supreme comfort. I'm very happy with it.
Thanks for the "final report" Quadrunner. Improved fuel economy near-elimination of detonation while reducing octane to 85 is surely a success. The 13*F coolant temp reduction seems to get most of the credit .... although it seems you will always wonder how much effect the eprom upgrade had. If your curiosity gets the best of you and you decide to increase the thermostat setting .... let us know! Thanks.
On the showroom floor at the dealer is a 1939 Chevrolet sedan. It is beautifully restored, yet the interior is spartan. Still, it has a coolant temperature gauge that reads full scale to 218 degrees F. The full scale reading on my '99 is 292 degrees. The stock running temperature for the '99 is closer to what was an overheating engine temp on the '39. It makes you wonder just how much of that heat is for the benefit of the engine, and how much is for the emissions factor?
By the way, the eprom update would not have been necessary if the '99 engine used a conventional camshaft driven distributor. You could just manually adjust the static spark timing. But the engine computer reads crankshaft position from a sensor, then refers to a spark map table to set the timing. So the owner cannot make any adjustments. Because my preference would have been to adjust the spark timing to cure the ping. But now you have to depend on the manufacturer to have an eprom update. Even the dealership cannot adjust otherwise.
I would not have found it necessary to begin experimenting with the thermostat, except you can't adjust the spark timing. But after I did modify the thermostat, the main thing I noticed was just a more subtle sense of calmness about the engine. Seems quieter too. Even felt like it ran slightly stronger. But to give the thermostat mod credit for reducing the ping, well I just believe the ignition timing is the variable with more influence. But I prefer the way the engine feels subjectively, at 191 degrees to the otherwise 204 degrees.
quadrunner500, regardless of which factor(s) is responsible for the improvement, the most important thing is that you're happy now with your truck's performance, whereas before you had concerns.
My peppy Hyundai Accent runs fine on economy 87. Once in while, I treat it plus. Premium gas burns too quickly for the Hyundai Accent which in turn lower the overall mileage.
I usually run 87 Octane in my Jeep Cherokee. I recently hit the mountains and that sucker knocked so much that the squirrels headed for cover. After traveling around for the day and scaring every creature in the mountains, I headed to the flat lands and tanked up on some 93 Octane. I cruised on up the mountain again to my cabin and the knocking was eliminated as best as I could tell. Of course my MPG seemed to have dropped. Anyway, my power was better with the higher octane and the Squirrels can rest in peace!! Once I returned home I went back to my cheapie gas. OH HOW I MISS THE GAS WARS OF 1998!!
Granted, I do NOT use it at high altitude, and it is highway driving, but with my 1998 Escort ZX2 (2.0L 130 HP engine), the car seemed less powerful (if quieter) when running on high octane gas.
Installing a K&N air filter made the car more powerful though, if a bit noisier.
Ford reccomends 87 octane for my 95 T-Bird, but I know enough to never take a manufacturer at face value. I usually run 89 in it, but occasionally will put 92 or 93 in it just for the heck of it. I have a mothballed 78 Grand Marquis that had a serious knock problem on low grade gas. Some 92 octane would work, but I usually ran 93 in it, till I moved to Abilene, where for some reason 93 is unavailable.
If the manufacturer recommends against a higher octane gas, that should mean that there will be no performance difference if you decide to use it.
Your car was obviously tuned to 87 octane gas. If you use a higher octane, the gasoline will not burn thoroughly, and it can quickly begin leaving harmful deposits. I would follow the owners manual, the guys who wrote it are your best guide.
That being said, if you happen to fill up with a high octane, just to test it, let us know how it feels. I've done so in 2 newer cars, and could barely tell the difference between 87 and 94 octane.
I have another one for you guys. I have a 1985 F250 300ci 4.9ltr strait six that has the computer completely disabled. In fact it has a 78 distributor and coil and an 83 carb. The original carb was a feedback design and the current one is not. The exhaust system has been changed from 2in to 2 1/4in to a turbo muffler (w/o cat). The EGR and air pump is also removed.
Here's the problem; I have bought new intake/exhaust manifolds and have blued them to the head and to each other. No problems there, great fit up. I have followed the required torque specs and procedures. All new bolts, nuts, washers and gaskets. Loose fit up on the hotbox bolts torqued the head bolts in three stages to 11-13 ftlbs and followed up with the hotbox bolts to 22 ftlbs. Warmed up the engine to operating temps and retorqued to specs. The gaskets on the hotbox will last for one or two weeks and start to leak on the side with one bolt. It has a three bolt patern (triangle design basically). I have tried different gasket designs with no real difference in the problem.
I suspect three areas, 1. Unable to automaticly adjust the timing to compensate for cold engine operation during warmup. (timing advance/retard)
2. Excessive backpressure caused by a two pass muffler combined with the timings inability to compensate for cold engine operation.
3. Uneven heat distribution to and in the hotbox. This maybe (along with #1 & #2 above) causing the cast iron manifolds to heat unevenly allowing the gasket to leak (flame from ignition is carried into the intake/exhaust (hotbox) area).
I put this here because of the discussions posted earlier about knock sensors and the effects of advancing and retarding the timing to compensate for engine knocks and pings. I currently experience pinging at speeds in excess of 65 mph. I contribute the to the inability of the engine to advance the timing any further due its current settings. I have found the engine operates best with the points set at 44-48 degrees and the distributor set at 6 degrees before TDC.
I know that last post of mine would be better off in another topic but no one had given up any wisdom there. So I put it here cuz it seemed like there were some good gear heads here. Rick
Hoho, for information about such a specific setup, I recommend trying to find the address for Professor Overdrive. Perhaps Summitracing.com has an email box for him?
I have never heard of Profeesor Overdrive but it sounds like just the place I need to go. Right on. thanks going there now. BTW gas tank at 3/4, report to follow.
Although there was no clear place to submit a question to them I did send an Email to the webmaster asking for the link to ask such a question. In the mean time here is two addy's for Summit Racing an Professor Overdrive.
If you periodically purchase aftermarket equipment, their catalog is ultra cool. You do pay for a subscription. However, the centerfolds are ultra cool. I had subscribed for 3 years, and have all the centerfold cars in a pile. It would be neat to plaster a finished garage with them someday.
The catalogs are where Professor Overdrive answers tech questions. I also have a pile of those answers, and periodically go through them for knowledge. I recall many a people specifying specific setups, and asking what they did wrong. He many times will pinpoint the problem. Of course, many of the setups are race setups, which may be most familiar to him. However, this column of the catalog, like Edmund's, is a great way to slowly pick up good quality car smarts
That easily means that he answers questions from readers. I hope I get him to reveiw my problem from within the web. If not I'll write him. Man, it (the problem)has been a thorn in my side for awhile. I don't want to give up the truck and I don't have the extra scratch for another one.
I kinda have the same thing with posters of dragsters from yesteryear along with the guy required ball caps. My wife insists that I keep them out there. Too dirty with all the red dust so I got them in ziplock bags. (kinda defeats the purpose though) I have been thinking about giving them to a couple of parts stores around here b/c they have helped me help others for a long time now.
Had good luck with "Rol" brand gaskets in the past. They have a Website. Its the brand used by Shadetree Mechanics Sam and Dave. I know they probably get paid by Rol, but I was very pleased with them when used on my 7.3L Ford Diesel.
I have the above and it has been driving me nuts for well over a year. I took it in to the GM dealer and was told that the only thing they could find wrong was a bad oxygen sensor and they replaced it for almost $300!!! To me that is highway robbery. I took it home and noticed that everything was fine until I filled it up with 87 octane and the knocking was back and worse than ever. I suffered through a week until I needed to refill and put in 93 octane and now the knocking is all but gone. My questions are: 1)Did I just waste $300? 2)Are there any other possible reasons for the knock besides octane? The dealer has suggested a fuel system service and cooling system "power flush". I am hesitant of taking their advice because I just "power flushed" the coolant a year ago, and I regularly add fuel system additive (TL3 or STP). Any thoughts or advice are greatly appreciated. In addition, this car has always been taken car of well while in my possession (3 yrs)with regular basic maintenance (oil, trans fluid, coolant, etc) and it has only 68k miles. Don't know if that helps. Thanks.
Well, if the vehicle was running hot, that could make it knock. Did they indicate that it is common for this car to build up gunk in the cooling system? If you just flushed it, how could it be so bad? That is my question for them.
My next question is: Do the fuel system cleaners you use keep the valvetrain clean? Also, is carbon-buildup in the cylinder common for this engine? Is your travel mostly city or highway? A lifetime of stop-and-go traffic can leave deposits everywhere, no matter what cleaners you use, because only the heat that a good long drive causes can keep the engine clean.
Most obviously, can the computerized timing of this car be adjusted? Since high octane seems to cure the problem, I would think that altering the timing could do the same.
I need to change the timing belt soon anyhow. I asked them if that could be the culprit and they said no. I guess if there is a problem with the timing belt I would know quickly (i.e. breaking). Right??? The car doesn't get enough highway miles, so I will start driving it a little more on extended drives. The TL3 says it cleans intake valves. I am going to go ahead and flush it one more time with Prestone Super Radiator Cleaner to see if that helps. Any other thoughts? Thanks.
Guitarzan: I tried both 89 and 92 octane in the Concorde and the results are that it runs the same except for the 92 octane. It seemed to ping and knock a little on heavy acceleration. It was enough to make me decide to stick with the 87 octane the manufacturer reccommends.
I used to fill 92 octane in my 98 concorde lxi. Once i just decided to try 87 octane and found that the car drove better. Have been using 87 octance since. Moreover .. I have noticed that Amoco works better for me than any other brand. I just get the feeling that the engine is a bit smoother.
Yeah I get the same feeling. I am going to stay with what works. Since I work in a refinery here and we make gas for the other refinery when they are down for maintenance or just need our help I am not really sure what is considered the best gas to buy. I know what we make and what they make as far as quality goes. It all depends, I guess, on how clean the storage vessels are at the other refinery or at the independent stations throughout the island. Luckily the temperature doesn't change much around here so condensation is not too much of a concern.
I bought 1986 Dodge Caravan with 103,000 miles 3 years ago. It had 4 cyl.Mitsubishi engine and I noticed heavy knocking - I tried 93 octane and it really helped. Since then only 93 - and I have never ever had engine problems - changing fuel and air filters regularly - no tunes up - I am at 150,350 miles now. I know I have to put new distributor cap and rotor at least, but it just goes and goes. And it's a carburetor engine. Here is my point - High octane is much cleaner - and that's what important on the long run. I am sure I gonna hit 200,000 miles, but I need new new CV boots, brakes, tires etc. Now I use only 93 or 92 octane for my brand new Civic - engine runs quieter (19,000 miles)than of those of my friends. Sign me up for that eXXon clean stuff. Andrey2
I've just bought Acura TL 3.2 those engine requires 91 or higher octane gas. My dealer recommended to fill first 3-4 tanks by 89 gas. It supposed to do something good for engine break-in. Did anybody hear that?
Andrey, high miles many times contribute to higher compression in an engine, and thus necessitate higher octane. Believe it or not, an engine that requires '87 octane could actually get dirtier if using a high octane.
Your Civic requires '87, right? Try a tank of '87. You probably won't notice any difference in power or smoothness. That should tell you that '87 is fine to use, and there is no benefit of higher octane. (I've owned an Integra and an Acura CL, which has an Accord engine.) When your Civic has 80k+ miles, it may start pinging, and necessitate the high octane.
To reduce carbon buildup throughout the life of the engine, try to do extended highway drives of 30+ miles on a weekly basis. That darn stop-and-go does the most long term dirtying of the cylinders. Maxim, see if you can get an explanation of this. I've never heard it, nor read it in Acura materials. Also, try asking another dealer about this.
Most American cars of recent vintage (less than 15 years old)need only 87 octane aka REGULAR. If you own a euro car, chances are the compression ratio is higher than 8.5 and will require something a little higher. Volvos for instance require premium due to the 9.5 compression ratio. Although if you live in a cold climate, the carbon build-up within the engine will be less and one could use a lower octane for a while. The HONDA line should only require regular gasoline but you may want to put a bottle of Chevron Techron about every oil change interval, say 3000 to 5000 miles. This should keep the Honda running very nice. Your engine will thank you.
All octanes have the same amount of detergent. There is no difference between 87 octane and 93 octane gas in terms of cleaness or the amount of detergent that they have.
Also using 93 octane is waste of money because your car's computer is not adjusted to differentiate or see the difference between 87 octane and 93 octane. even though you use 93, your car thinks that you are using 87. Plus higher octane will cause carbon built up in combustion chamber in long run.
Actually, some grades of premium contain more detergent to move from "keep clean" to "clean-up" potency. It will say more additive if grade does have it at the point of sale (the stuff is too expensive not to tout it at point of sale).
Octane creep-up is common in old cars, gitarzan is correct. A booster additive like Techron will often help. Beware, some aftermarket additives are crap...just mineral spirits with a bit of old-technology cleaners maybe.
"EPA minimum" gasoline only has enough additive to keep injectors clean...you can get combustion chamber buildups with these Polybuteneamine based products added to the gas. Major oil co's. (Chevron, Texaco, Shell, Amoco are some) likely use Polybuteneamine chemisty additives that do not permit carbon build-up/octane creep. Engine sensitivity to carbon build-up is also big factor...insensitive engines might be fine with cheap gas. Even some "big" gas brands at retail do not use good detergents in my opinion. Price is a good clue, not marketing.
I'd almost bet a day's pay the Caravan discussed above used cheap gas a lot...
Octane/supreme fuel use is commonly misunderstood.
Life has no free lunch...cheap gas can have problems.
Disclaimer: I have a Chemical Engineering background & work for major oil co. The informed opinions above is my own and is correct. Be careful in Edmund's Townhalls, these are *great* & fun forums, but some opinions are not at all informed but are offered authoritatively anyway. Caveat emptor.
In all the new v6 engines for Maxima's, Camry's, Accord's Premium unleaded gas is required. Is it neccesary to use premium all the time, some of the time, not at all, all the time? Will it hurt these new 24 valve v6 engines to put regular gas in it?
A week ago I finally traded-in my 86'Caravan which served me very well ( I'm still sure that a 93 gas was main contributor to that engine long life) for '95 318 ti. Now let me quote the manual where it refers to "Fuel specifications". "... At least 89 AKI or 95 RON. Because these engines are equipped with predetonation detectors (knock sensors) they automatically adapt for operation with fuels of various specifications etc.... The higher-octane fuels will provide increased performance and fuel economy, while the use of gasoline with a lower octane rating will have an inverse effect".
So, they're saying it's up to you, you don't have to buy premium, but if you want 100% output from your car - you better use premium.
I'm a firm believer in getting what you pay for but have second thoughts when it comes to gasoline.
Does anyone have any facts supporting brand name fuels, such as Chevron, being better than generic brand fuel? I live in Northern California where gas prices are unreasonably high, $1.60 for brand name 87 octane.
I've heard ethanol and some other "fillers" can leave valve deposits. Is this true? I've also heard MTBE (added to Ca. gas) has harmful effects. Any thoughts?
I work with a person who always puts 93 octane gold super premium into it. They bought it low mileage rental several years ago. They say that the motor will last longer using super premium. Can this be so?
Honda claims loss of 5 HP if 87 octane is used (instead of premium). What difference does it make. Will it affect the mpg also? Please answer in LAYMAN's TERMS ONLY. Thanks ps: I have been using 91 oct and getting 25mpg (40mile commute 50/50 city/Hwy).
Comments
Is there a significant difference between Amoco, Mobil and Texaco in this respect (comparing 87 octane )?
I took the truck to the dealer. They checked it out and said they heard the ping, but didn't know what to do about it, because of computer engine controls. The owners manual also states that a small amount of it is normal, that you don't have to step up to a higher grade to eliminate it. They updated my engine calibration parameters, and gave it back to me. There was no noticeable improvement after this initial eprom update.
I then modified my coolant thermostat to open at a 13 degree lower temperature. This made a noticeable improvement in drivability to me, although some stated it was in my head. I began checking fuel mileage after the thermostat mod.
When I noticed a jump in fuel mileage, I took a pause to access the possibilities. My previous best was highway 17.6 mpg, in-town city driving was averaging 14.6 mpg. The in-town mileage had improved to 17.1, with some highway speeds mixed in.
My next tank improved to 18.6, all highway, but still improving on my best highway tank before the mod.
Then my next tank was 17.2, lots of highway miles, but also hauling cargo quite a bit.
Finally brings me back to my most recent tank, 16.2 , all city, some highway speeds, empty cargo bed most of the time.
All of the tanks since the thermostat mod have been run on regular grade octane, 85 here in the altitude of Colorado.
Conclusions: My fuel mileage seems to have improved. While I cannot prove the gain came from the thermostat mod, I can't rule out some benefit either. There are other seasonal variables that could apply, and perhaps my driving habits varied, or my engine completed its break-in wear. So I'm not saying my fuel mileage improved because of the mod, but my fuel mileage does seem improved.
What about the ping? Well after the thermostat mod, the ping seemed eliminated at first, but when I reduced gasoline grades, I could notice it again slightly, intermittently, but I had to listen very carefully.
And then just this week, I became aware of another engine calibration software update from GM that stated it was to address various drivability concerns including hesitation (didn't have), and spark knock (did have). I took the truck in on Tuesday, and they re-flashed the eprom with the update. As of today, I have driven 150 miles. I thought I heard it crackle a tick driving out of the dealer lot onto the street. But I'm not sure, because I haven't heard it since.
So for whatever reason, or combination of reasons, it seems like it's gone, and I am able to run on regular 85 grade octane with good drivability, and no audible knock. My '99 Silverado truck, while delivered with a few flaws, is just about perfect now, and getting very good fuel mileage while letting me haul cargo with supreme comfort. I'm very happy with it.
By the way, the eprom update would not have been necessary if the '99 engine used a conventional camshaft driven distributor. You could just manually adjust the static spark timing. But the engine computer reads crankshaft position from a sensor, then refers to a spark map table to set the timing. So the owner cannot make any adjustments. Because my preference would have been to adjust the spark timing to cure the ping. But now you have to depend on the manufacturer to have an eprom update. Even the dealership cannot adjust otherwise.
I would not have found it necessary to begin experimenting with the thermostat, except you can't adjust the spark timing. But after I did modify the thermostat, the main thing I noticed was just a more subtle sense of calmness about the engine. Seems quieter too. Even felt like it ran slightly stronger. But to give the thermostat mod credit for reducing the ping, well I just believe the ignition timing is the variable with more influence. But I prefer the way the engine feels subjectively, at 191 degrees to the otherwise 204 degrees.
Installing a K&N air filter made the car more powerful though, if a bit noisier.
If the manufacturer recommends against a higher octane gas, that should mean that there will be no performance difference if you decide to use it.
Your car was obviously tuned to 87 octane gas. If you use a higher octane, the gasoline will not burn thoroughly, and it can quickly begin leaving harmful deposits. I would follow the owners manual, the guys who wrote it are your best guide.
That being said, if you happen to fill up with a high octane, just to test it, let us know how it feels. I've done so in 2 newer cars, and could barely tell the difference between 87 and 94 octane.
guitarzan
Community Leader/Vans Conference
I have another one for you guys. I have a 1985 F250 300ci 4.9ltr strait six that has the computer completely disabled. In fact it has a 78 distributor and coil and an 83 carb. The original carb was a feedback design and the current one is not. The exhaust system has been changed from 2in to 2 1/4in to a turbo muffler (w/o cat). The EGR and air pump is also removed.
Here's the problem;
I have bought new intake/exhaust manifolds and have blued them to the head and to each other. No
problems there, great fit up. I have followed the
required torque specs and procedures. All new
bolts, nuts, washers and gaskets. Loose fit up on
the hotbox bolts torqued the head bolts in three
stages to 11-13 ftlbs and followed up with the
hotbox bolts to 22 ftlbs. Warmed up the engine to
operating temps and retorqued to specs. The
gaskets on the hotbox will last for one or two weeks and start to leak on the side with one bolt. It has a three bolt patern (triangle design basically). I have tried different gasket designs with no real difference in the problem.
I suspect three areas,
1. Unable to automaticly adjust the timing to compensate for cold engine operation during warmup. (timing advance/retard)
2. Excessive backpressure caused by a two pass muffler combined with the timings inability to compensate for cold engine operation.
3. Uneven heat distribution to and in the hotbox. This maybe (along with #1 & #2 above) causing the cast iron manifolds to heat unevenly allowing the gasket to leak (flame from ignition is carried into the intake/exhaust (hotbox) area).
I put this here because of the discussions posted earlier about knock sensors and the effects of advancing and retarding the timing to compensate for engine knocks and pings. I currently experience pinging at speeds in excess of 65 mph. I contribute the to the inability of the engine to advance the timing any further due its current settings. I have found the engine operates best with the points set at 44-48 degrees and the distributor set at 6 degrees before TDC.
HoHo
guitarzan
Community Leader/Vans Conference
BTW gas tank at 3/4, report to follow.
Although there was no clear place to submit a question to them I did send an Email to the webmaster asking for the link to ask such a question. In the mean time here is two addy's for Summit Racing an Professor Overdrive.
Thanks Gman, Good info, Cool site.
Professor Overdrive;
http://www.summitracing.com/techzone/profov15.htm
Summit Racing home page;
http://www.summitracing.com/index.htm
HoHo
The catalogs are where Professor Overdrive answers tech questions. I also have a pile of those answers, and periodically go through them for knowledge. I recall many a people specifying specific setups, and asking what they did wrong. He many times will pinpoint the problem. Of course, many of the setups are race setups, which may be most familiar to him. However, this column of the catalog, like Edmund's, is a great way to slowly pick up good quality car smarts
guitarzan
Community Leader/Vans Conference
I kinda have the same thing with posters of dragsters from yesteryear along with the guy required ball caps. My wife insists that I keep them out there. Too dirty with all the red dust so I got them in ziplock bags. (kinda defeats the purpose though) I have been thinking about giving them to a couple of parts stores around here b/c they have helped me help others for a long time now.
LSC
cooling system "power flush". I am hesitant of taking their advice because I just "power flushed" the coolant a year ago, and I regularly add fuel system additive (TL3 or STP). Any thoughts or advice are greatly appreciated. In addition, this car has always been taken car of well while in my possession (3 yrs)with regular basic maintenance (oil, trans fluid, coolant, etc) and it has only 68k miles. Don't know if that helps. Thanks.
My next question is: Do the fuel system cleaners you use keep the valvetrain clean? Also, is carbon-buildup in the cylinder common for this engine? Is your travel mostly city or highway? A lifetime of stop-and-go traffic can leave deposits everywhere, no matter what cleaners you use, because only the heat that a good long drive causes can keep the engine clean.
Most obviously, can the computerized timing of this car be adjusted? Since high octane seems to cure the problem, I would think that altering the timing could do the same.
guitarzan
Community Leader/Vans Conference
The car doesn't get enough highway miles, so I will start driving it a little more on extended drives. The TL3 says it cleans intake valves.
I am going to go ahead and flush it one more time with Prestone Super Radiator Cleaner to see if that helps. Any other thoughts? Thanks.
I tried both 89 and 92 octane in the Concorde and the results are that it runs the same except for the 92 octane. It seemed to ping and knock a little on heavy acceleration. It was enough to make me decide to stick with the 87 octane the manufacturer reccommends.
LSC
I used to fill 92 octane in my 98 concorde lxi.
Once i just decided to try 87 octane and found that the car drove better. Have been using 87 octance since.
Moreover .. I have noticed that Amoco works better for me than any other brand. I just get the feeling that the engine is a bit smoother.
LSC
Thank you,
James
Now I use only 93 or 92 octane for my brand new Civic - engine runs quieter (19,000 miles)than of those of my friends.
Sign me up for that eXXon clean stuff.
Andrey2
Your Civic requires '87, right? Try a tank of '87. You probably won't notice any difference in power or smoothness. That should tell you that '87 is fine to use, and there is no benefit of higher octane. (I've owned an Integra and an Acura CL, which has an Accord engine.) When your Civic has 80k+ miles, it may start pinging, and necessitate the high octane.
To reduce carbon buildup throughout the life of the engine, try to do extended highway drives of 30+ miles on a weekly basis. That darn stop-and-go does the most long term dirtying of the cylinders.
Maxim, see if you can get an explanation of this. I've never heard it, nor read it in Acura materials. Also, try asking another dealer about this.
guitarzan
Community Leader/Vans Conference
If you own a euro car, chances are the compression ratio is higher than 8.5 and will require something a little higher. Volvos for instance require premium due to the 9.5 compression ratio. Although if you live in a cold climate, the carbon build-up within the engine will be less and one could use a lower octane for a while.
The HONDA line should only require regular gasoline but you may want to put a bottle of Chevron Techron about every oil change interval, say 3000 to 5000 miles. This should keep the Honda running very nice. Your engine will thank you.
Also using 93 octane is waste of money because your car's computer is not adjusted to differentiate or see the difference between 87 octane and 93 octane. even though you use 93, your car thinks that you are using 87. Plus higher octane will cause carbon built up in combustion chamber in long run.
Octane creep-up is common in old cars, gitarzan is correct. A booster additive like Techron will often help. Beware, some aftermarket additives are crap...just mineral spirits with a bit of old-technology cleaners maybe.
"EPA minimum" gasoline only has enough additive to keep injectors clean...you can get combustion chamber buildups with these Polybuteneamine based products added to the gas. Major oil co's. (Chevron, Texaco, Shell, Amoco are some) likely use Polybuteneamine chemisty additives that do not permit carbon build-up/octane creep. Engine sensitivity to carbon build-up is also big factor...insensitive engines might be fine with cheap gas. Even some "big" gas brands at retail do not use good detergents in my opinion. Price is a good clue, not marketing.
I'd almost bet a day's pay the Caravan discussed above used cheap gas a lot...
Octane/supreme fuel use is commonly misunderstood.
Life has no free lunch...cheap gas
can have problems.
Disclaimer: I have a Chemical Engineering background & work for major oil co. The informed opinions above is my own and is correct. Be careful in Edmund's Townhalls, these are *great* & fun forums, but some opinions are not at all informed but are offered authoritatively anyway. Caveat emptor.
"... At least 89 AKI or 95 RON. Because these engines are equipped with predetonation detectors (knock sensors) they automatically adapt for operation with fuels of various specifications etc.... The higher-octane fuels will provide increased performance and fuel economy, while the use of gasoline with a lower octane rating will have an inverse effect".
So, they're saying it's up to you, you don't have to buy premium, but if you want 100% output from your car - you better use premium.
Any ideas on that. Maybe it's true for any car.
but have second thoughts when it comes to
gasoline.
Does anyone have any facts supporting brand name
fuels, such as Chevron, being better than generic
brand fuel? I live in Northern California where
gas
prices are unreasonably high, $1.60 for brand name
87 octane.
I've heard ethanol and some other "fillers" can
leave valve deposits. Is this true? I've also
heard
MTBE (added to Ca. gas) has harmful effects. Any
thoughts?
Can this be so?
Thanks
ps: I have been using 91 oct and getting 25mpg (40mile commute 50/50 city/Hwy).