EricW Posted April 6, 2005 Share Posted April 6, 2005 Since my washing machine got fixed courtesy of the forum, it's time for the car-care portion... Here in Taliban-occupied territory, it has been decreed that we must run oxygenated-fuels during the winter months. Is the correct procedure to compensate for alcohol-laced gas to richen the mixture? I have a Chevy 454 with what appears to be throttle-body injection. (I could be wrong, but I don't see provisions for a float mechanism of any type and there are two nozzles above the butterfly valve that appear to spray gasoline.) Anybody have a clue if I can adjust the mixture on that manually or do I need to do it via computer? We just switched back to regular gas and my mileage leaped upwards, but I'd like to be ready for next year. (P.S. Oxygenated fuel is the stupidest thing in the universe.) Link to comment Share on other sites More sharing options...
outerlimits Posted April 6, 2005 Share Posted April 6, 2005 Since my washing machine got fixed courtesy of the forum, it's time for the car-care portion...Here in Taliban-occupied territory, it has been decreed that we must run oxygenated-fuels during the winter months. Is the correct procedure to compensate for alcohol-laced gas to richen the mixture? I have a Chevy 454 with what appears to be throttle-body injection. (I could be wrong, but I don't see provisions for a float mechanism of any type and there are two nozzles above the butterfly valve that appear to spray gasoline.) Anybody have a clue if I can adjust the mixture on that manually or do I need to do it via computer? We just switched back to regular gas and my mileage leaped upwards, but I'd like to be ready for next year. (P.S. Oxygenated fuel is the stupidest thing in the universe.) <{POST_SNAPBACK}> here in the people's republic of kalifornia, we just add a tablespoon or two of WW 452AA to each tankfull. Link to comment Share on other sites More sharing options...
calhunter Posted April 7, 2005 Share Posted April 7, 2005 If it's injected the oxygen sensors will automatically compensate for it there are no adjustments. as long as you don't have a Check Engine or Service engine soon light you are good to go. Oxygenated fuels are usually supplied during cold weather. We have been stuck with them for several years in So Cal. You could lose a little mileage but there is not much that you can do about it. Its just one of the joys of living in enviromentalist land. The 2 nozzles that you mentioned are the fuel injectors. They should spray a cone shaped spray downward towards the butterflys. There should not be any fuel anywhere else. Depending on the year there are aftermarket chips that will (Maybe) give it petter performance although seldom help the fuel economy. You should spray clean the throttle body with Carb Cleaner the same way that you would a carb. The only other thing that I would recommend is that you run a bottle of Techron from Chevron about every 6 mo. It's about the only after market fuel additive that works. You usually have to get it from a Chevron Station or distributor. My truck doesn't get a lot of use right now Gas is $2.52.9 a Gal at the cheapest places. Steve ASE Certified Master Tech Link to comment Share on other sites More sharing options...
Kory Posted April 7, 2005 Share Posted April 7, 2005 The O2 sensor will notice the change, and the CPU will do all the adjusting you really need. Link to comment Share on other sites More sharing options...
EricW Posted April 7, 2005 Author Share Posted April 7, 2005 Thanks guys. I didn't know if the O2 sensor was that sensitive or not. I've got to invest in code scanner I guess. My mileage seems to have taken a huge jump here with the advent of real gas again. I wonder if my O2 sensor is getting a little long in the tooth. Link to comment Share on other sites More sharing options...
Kory Posted April 7, 2005 Share Posted April 7, 2005 The stoichiometry of gas compared to alcohol is a huge difference. Alcohol runs nearly twice as rich a mixture. Gas blended with ethanol will require a richer A/F ratio, so milage will decrease with that gas. Your vehicle's CPU will make the adjustement and dump more fuel, and you'll notice it. If it has over 80K miles, the O2 sensor may be worth replacing. What is it a 454SS chevy pickup? Link to comment Share on other sites More sharing options...
kimel Posted April 7, 2005 Share Posted April 7, 2005 Techron injector cleaner is usually available at Costco. Six bottles to a case for around $10 (if memory serves). Both my rigs get a bottle every 2000 miles whether they need it or not. Link to comment Share on other sites More sharing options...
calhunter Posted April 7, 2005 Share Posted April 7, 2005 The Techron I'm refering to usually comes in a large black bottle and will work in both Gas and Diesel. The one Kimel mentioned will work and is good stuff, but if it is the Blue bottle it is probably not the same formula I use to buy it from a distributor for about $65 for a case of 12. The tip off is the use in gas or diesel. On the injectors, if you have a timing light you can hook it up the usual way but shine the light on the injector spray. the flashing strobe will allow you to see the spray pattern. It should be a fine mist in a cone shape. A code scanner won't tell you anything about the fuel system other than a hard code that would turn on the check engine light. you can do the same thing by shorting together the a and b terminals on the diagnostic plug which is under the dash on the drivers side (Usually). If the truck's oxygen sensors have over 60000 miles on them they're probably ready to be replaced. It's cheaper for you to replace it or them than to buy a tester. they screw in and look kind of like a spark plug. and are located on the exhaust manifold or the upper part of the exhaust pipe. Most good scan tools that are capleable of reading the sensor cost $1-3K. To read an O2 sensor you need a digital oscilloscope (Spelling) the sensor normally operates between .2 & .9 volt which would not be hard to read except it constantly switches between these two extreems. The trick to telling if they're good is they have to be able to switch in about 80 thousandths of a second If your truck has a single wire the sensors should cost about $30 at a NAPA or other parts store. Try to use Bosch sensors or GM (Which are probably Bosch They invented them) they're pretty reliable. If they have 3 or 4 wires (those are heated O2 Sensors) they will be $60-$80. Link to comment Share on other sites More sharing options...
EricW Posted April 7, 2005 Author Share Posted April 7, 2005 Thanks guys. This place is so cool. It's like having a personal oracle. Link to comment Share on other sites More sharing options...
standles Posted April 7, 2005 Share Posted April 7, 2005 You can also keep your gas mileage up in the winter by purchasing a 250 gallon farm tank and getting it filled with regular unleaded just before the mandated switch to O2 fuels. Link to comment Share on other sites More sharing options...
geezer-lock Posted April 7, 2005 Share Posted April 7, 2005 You can also keep your gas mileage up in the winter by purchasing a 250 gallon farm tank and getting it filled with regular unleaded just before the mandated switch to O2 fuels. <{POST_SNAPBACK}> I'm thinking that 454 will require a MUCH bigger tank to get through the winter. geezer Link to comment Share on other sites More sharing options...
bountyhunter Posted April 7, 2005 Share Posted April 7, 2005 No worries. If it's a 454 you will either be selling it or parking it real soon. Basic unleaded topped $3 up here today. Link to comment Share on other sites More sharing options...
EricW Posted April 7, 2005 Author Share Posted April 7, 2005 Gas prices are bothersome but not too much of a worry. I buy older cars and pay cash, so a few extra dollars a month is a little painful, but doesn't bother me too much. I'll let y'all do the new car financing routine. Besides, what always happens is that greed kicks in. There is no way the players aren't going to tap into this profit bonanza. The flat price of gas we enjoyed during the late 80's through pre-9/11 were a direct by product of the 70's "shortage". Anyone in the oil industry will tell that there is no oil "shortage". There is a shortage of pumping and refining capacity. OPEC isn't stupid. They know that if the status quo continues, everyone will buy an econobox and they won't be pumping squat in 5 years. /end free market rant ============================================= Back to the topic.... So, if I'm understanding this correctly, there is no computer diagnostic code to check for the O2 sensor aside from clipping up the ol' o-scope. (Which I want to buy anyway, now that I won't have ones off the U to slum off on.) Are there any other fuel system components that I should be checking/replacing? I plan to keep this rig for 5 years or so. Is there any merit in buying some spares at the junkyard, like a spare computer, spare ABS unit, etc? I'm going to buy some Techron on the way home. Link to comment Share on other sites More sharing options...
calhunter Posted April 9, 2005 Share Posted April 9, 2005 I'm guessing your truck is a early to mid 90's. The light will come on if the sensor stops switching (dies). The Manufacture recommends replacing them every 60000 but most people don't. A code reader will only give you the code and possibly a description. you can do the same thing by shorting the a & b terminals together with the engine off and the key on. and counting the blinks of the check engine light. 2 blinks a short pause and then 5 blinks would be code 25. If there are multiple codes there will be a slightly longer pause between sets. A regular scan tool will read the data stream from the computer which, depending on the year and system, will give you sensor voltage, crossovers which is the number of times it switches and system status, open or closed loop, which means whether or not the computer is in control of the system. It will also give you Block Learn and Intergrator these tell you if the system is compensating for a overall rich or lean condition, a reading of 128 is normal. If it varies from that a considerable amount the computer is either adding or subtracting fuel to compensate for a problem such as a vacuum leak injector problem etc. The range is 0 - 255. A scan tool gives you a lot of info, trying to understand it might make you crazy To top it off anything older that about 1997 (Pre OBDII) GM, Ford & Chrysler all have different data and acronyms for they're systems. Link to comment Share on other sites More sharing options...
EricW Posted April 9, 2005 Author Share Posted April 9, 2005 callhunter, Thanks! It's a 94 with very low miles. A new sensor was only $25, so I just traded it out. The huge jump in gas mileage with the change in gas formulations seems like a pretty good diagnostic that the O2 sensor is not doing it's job. Finding the silly thing was an adventure! Holy cow! I practically had to go spelunking.... All is good now. The truck seems to be idling better too. Link to comment Share on other sites More sharing options...
calhunter Posted April 9, 2005 Share Posted April 9, 2005 callhunter,Thanks! It's a 94 with very low miles. A new sensor was only $25, so I just traded it out. The huge jump in gas mileage with the change in gas formulations seems like a pretty good diagnostic that the O2 sensor is not doing it's job. Finding the silly thing was an adventure! Holy cow! I practically had to go spelunking.... All is good now. The truck seems to be idling better too. <{POST_SNAPBACK}> Anytime, I've been at this for 38 years. Keep that 94, some of the new ones have as many as six of those sensors @ $80 - $100 each!. At least I can explain this stuff better than I did that Gas Price Poll, boy did I screw that up. Link to comment Share on other sites More sharing options...
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