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89 Brougham, 98 Deville, 04 DTS, 05 Deville
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Discussion Starter #1
alright I searched the forum but didn't find a definite answer for this so I apologize if this has already been answered
I always fill up with mid grade because it knocks when I turn the car off if regular is used. But the question is, should I fill up with straight gas if it is available? Where I live and usually fill up at contains 10% ethanol, because the county's pollution requires it. But I live a little less than 10 minutes from the county line and the next county doesn't require the 10% ethanol, so there its straight gas. Should I get the gas that doesn't contain ethanol?
 

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1989 Brougham d'Elegance, 1985 Fleetwood Brougham *Coupe*
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The ethanol content is marginally decreasing your mileage, but the 307 was designed to run on E10, so using it is not damaging anything.

The 307 was also designed for low octane, so the dieseling is a mechanical issue and not because of your fuel choice. Check you vacuum routing and replace any old lines:



If the routing and the vacuum lines are fine, try a fuel system cleaner like Sea Foam or Gumout with Regane, to clean the carbon deposits off the pistons. If that doesn't solve your problem replace the knock sensor, check and adjust the timing, check and adjust the cruise control linkage, and verify that the problem isn't cause by overheating.

My car was dieseling really bad last year. Took it to Cadillac and paid them $200 to tell me the knock solenoid wasn't working (they bi-passed it by hooking the ILC to TOP SOL one [see diagram]). That made the engine idle smooth as glass; until I turned on the defroster, then the car turned into an ass-massager. A few weeks ago I got around to replacing the Knock solenoid. I went to re-rout the lines correctly, and found that I had installed the VDR backwards, last summer, which was causing the problem to begin with. Moral of the story: make sure everything is routed exactly the way it is supposed to be.
 

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89 Brougham, 98 Deville, 04 DTS, 05 Deville
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Discussion Starter #4
alright Thanks again sven, my knock solenoid probably is the cause then, I mean if yours needed replacing mine probably does too. I'll check all the vacuum lines tomorrow. But is this the cruise control linkage? it was loose so I moved the pin one hole tighter.

 

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1989 Brougham d'Elegance, 1985 Fleetwood Brougham *Coupe*
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^That's the linkage.

Mine is a little loose too. By moving it one hole tighter, what way do you go?

Moving one hole up toward the servo will increase your problem, because it is going to be forcing the throttle slightly open.
 

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89 Brougham, 98 Deville, 04 DTS, 05 Deville
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Discussion Starter #6
^That's the linkage.

Mine is a little loose too. By moving it one hole tighter, what way do you go?

Moving one hole up toward the servo will increase your problem, because it is going to be forcing the throttle slightly open.
It was really loose before and now its only a little loose, when I took the pin out I pulled on the rod a little bit to feel at what tension the throttle opens cuz I figured that it would hold the throttle open if I made it too tight, but I'm certain that the throttle isn't being held open cuz there's still no tension on it. to feel tension I have to pull it a little bit
 

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94 Fleetwood Brougham
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The sick (really sick) part of that is when I had my 85 Cutlass 307, and I put in the 350, later sold it, a year or so after that it got sold again and the guy put in new head gaskets and couldn't figure it out because they didn't mark anything.

I was able to put it all back together correctly. I remembered that all...... I need to get out the FSM for reading material and get my head out from under the hood now and then.....

If the vacuum mess is dead on, then you will need to pull the carb off, and run a drill bit down of the EGR Jet extensions. They are directly under the carb. GM does NOT recommend removing them. I have (probably have mine laying around). But they cake up with carbon at the bottom, and restricts the EGR flow, causing knock issues. My 307 had to have 93 octane to not ping. I cleared those and I was back on 87 AND had better hp and torque. It made a WORLD of difference on the 307. The 350 was another story....

That diagram is so money.

Oh, if you can get gas without ethanol, get it.
You said it! I found a consistent drop of around 0.15 mpg with 10% ethanol fuel. That was on a LT1 with 10:1 compression, expect a lower compression engine to be a bit worse. Note the CAR companies never intended ethanol in, the politicians did. What is up with that crap? Somehow politicians are emissions and fuel experts? Right.....
 

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89 Brougham, 98 Deville, 04 DTS, 05 Deville
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Discussion Starter #9
N0DIH, I dont understand what you mean by "run a drill bit down of the EGR Jet extensions" please explain. and yes the 307 vacuum lines are a mess even when set-up correctly. So i'm confused is the 307 Brougham made to run on regular unleaded E10 or not? I filled up yesterday afternoon at my usual station w/ mid grade E10 before I posted this thread. I'll check the vacuum lines later today but if they're all good I'll have to wait till my take gets pretty low to put some regular unleaded to see it knocks [only had one tank of regular unleaded in more than 4 years, that was more than 2 years ago and it knocked when I would turn the car off], so if it knocks with the regular unleaded I guess I should replace the knock solenoid. where can I get one and how much?
 

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No, GM did not DESIGN it to run properly on 10% Ethanol fuel, will it run? Yes, GM DID design in the parts that would withstand the 10% alky in the fuel by the mid 80's or earlier. The A/F is calibrated for living @ 14.67 AFR, but 10% ethanol fuel is around 14.1 AFR. So it will adjust to the right fuel mix and run @ 14.1, but the calibrations are hard coded and assume pure gas. So everything in reality (like cold start, WOT, etc) run leaner than stock is intended to. So EGR flow being restricted becomes more problematic, as it is leaner and has added timing during the time EGR is turned on. Knock is going to happen.

As for the EGR Jet Extensions, shut the engine off (cool is best), take off air cleaner, climb up and look directly down the 2BBL side, move throttle to WOT. Look UNDER the bottom butterflies, you will see dead center on them, 2 tubes sticking up. These are the culprits. They get clogged up with carbon (heat, raw fuel, lots of time) and cause reduction in EGR flow.

What happens on the later 307's, they did add knock sensors, but that is a crutch or bandaid to cover up the problem, the real problem is the KS sees the knock and pulls out timing. And you lose power and economy to get less audible knock, and now the car doesn't go back to the dealership for warranty work. Is it good? Sure, helps save the life of the engine where the knock isn't beating on things, but the problem is almost always EGR flow. About every 3-4 years pull the carb and clean the tubes.



N0DIH, I dont understand what you mean by "run a drill bit down of the EGR Jet extensions" please explain. and yes the 307 vacuum lines are a mess even when set-up correctly. So i'm confused is the 307 Brougham made to run on regular unleaded E10 or not? I filled up yesterday afternoon at my usual station w/ mid grade E10 before I posted this thread. I'll check the vacuum lines later today but if they're all good I'll have to wait till my take gets pretty low to put some regular unleaded to see it knocks [only had one tank of regular unleaded in more than 4 years, that was more than 2 years ago and it knocked when I would turn the car off], so if it knocks with the regular unleaded I guess I should replace the knock solenoid. where can I get one and how much?
 

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Discussion Starter #11
alright I understand, thanks for explaining further!:cool2:
 

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1990 Cadillac Brougham; 1989 Cadillac Fleetwood
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The ethanol content is marginally decreasing your mileage, but the 307 was designed to run on E10, so using it is not damaging anything.

The 307 was also designed for low octane, so the dieseling is a mechanical issue and not because of your fuel choice. Check you vacuum routing and replace any old lines:



If the routing and the vacuum lines are fine, try a fuel system cleaner like Sea Foam or Gumout with Regane, to clean the carbon deposits off the pistons. If that doesn't solve your problem replace the knock sensor, check and adjust the timing, check and adjust the cruise control linkage, and verify that the problem isn't cause by overheating.

My car was dieseling really bad last year. Took it to Cadillac and paid them $200 to tell me the knock solenoid wasn't working (they bi-passed it by hooking the ILC to TOP SOL one [see diagram]). That made the engine idle smooth as glass; until I turned on the defroster, then the car turned into an ass-massager. A few weeks ago I got around to replacing the Knock solenoid. I went to re-rout the lines correctly, and found that I had installed the VDR backwards, last summer, which was causing the problem to begin with. Moral of the story: make sure everything is routed exactly the way it is supposed to be.
Thank you man! I am SURE my car isn't hooked up correctly. The thing won't idle. We have replaced the fuel pump and brake booster, which was bleeding air internally, but the problem is still there. I suspect a gasket problem on the carb, because if you spray carb cleaner around the bottom of the carb the engine will surge. I will have to spend some time this weekend and verify that all the lines are there and functioning properly.
 

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You said it! I found a consistent drop of around 0.15 mpg with 10% ethanol fuel. That was on a LT1 with 10:1 compression, expect a lower compression engine to be a bit worse. Note the CAR companies never intended ethanol in, the politicians did. What is up with that crap? Somehow politicians are emissions and fuel experts? Right.....[/quote]




Some environmentally involved college students and their professor evoked this fuel additive hypothesis on to Congress. Chemistry projects in a lab may show enhanced properties to one property or another to the burning of fuel. Your Congressional leaders don't neccessarily understand all the technical data thrown at their feet, it just looks good on paper. They don't do any tests on the fuel or it's resulting impact on how effective an engine will run on the new fuel, i.e. loss of mileage, therefore more consumption. Additional wear on engine parts is another area not covered by these laboratory studies. In general, the majority of car owners turn over their cars within a 3-5 year time frame and, of course, Washington would rather have everyone buy a new car every 2 years.
Cost of fuel manufacture also is effected by this chemical change. Fuels have to change with the seasons as the climatic temperature changes effect the way these fuels react while stored or combusted in colder/hotter weather. Ethanol will break out of the chemical chain and evaporate.
 

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I am NOT a fan of E10 (or Minnesota going to E20 in a couple years), but E85 I am a fan of.

BUT not in a flex fuel car. Those are a comprimise to run 87 octane or E85. They aren't the same.

I want to see dedicated E85 cars, 13:1 compression, direct injection, cams that optimize the burn rate of E85. Then kill off lots of timing to make it run on 87 or 93 octane.

But a pure E85 engine would be a dream. It would be nearly as efficient as gas engines if done properly. But it takes effort.

I am toying with doing my LT1 like that....
 

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I want to see dedicated E85 cars, 13:1 compression, direct injection, cams that optimize the burn rate of E85. Then kill off lots of timing to make it run on 87 or 93 octane.

But a pure E85 engine would be a dream. It would be nearly as efficient as gas engines if done properly. But it takes effort.

I am toying with doing my LT1 like that....[/quote]



I'm not sure I understand the concept. A pure E85 engine? Wouldn't that be the same as running pure alcohol? Drag Racers have been working with this fuel for years. Experimenting on different delivery systems and even carbureted. Biggest drawback is engine fires. You can't see the flames.
 

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1989 Brougham d'Elegance, 1985 Fleetwood Brougham *Coupe*
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^Drag racers and other professional performance engines use Methanol (Methyl Alcohol), which is distilled from wood. Methyl Alcohol is highly toxic and fatal if ingested. It is used because it is easier to put out with water than gasoline. Methanol burns with a hard to see, white flame.

Passenger cars use Ethanol (Ethyl Alcohol), which is distilled from corn and sugar cane. Ethyl Alcohol is commonly ingested is the primary ingredient in every alcoholic beverage. Ethanol burns with a blue flame.

E85 is a 85% ethanol/ 15% gasoline mixture. The gasoline is used as a deterrent against pump drunks, and to improve cold weather starting. Today's E85 engines are "Flex Fuel," which means they can run on either E85 or E10. The ECM calculates the ethanol content of the gasoline based on how rich or lean the O2 sensor are reading. If the O2s are reading rich, then the computer adjust the fuel trim, injector pulse, and ignition timing to run on E10. If the 02s are reading lean, then the computer will adjust appropriately. The downside to this method is, if you have a quarter tank of E10, and fill up with E85, then the the O2 sensors will read lean, but he fuel coming into the engine would be an E45 mix. Needless to say, the engine wouldn't run right.

A dedicated E85 engine wouldn't have the capability of being run on regular gasoline. If you take out the necessity for the ECM to adjust the fuel trims depending on the fuel in the tank, you can more accurately tune the engine to run on a specific fuel. A dedicated E85 engine would be more efficient and powerful than a flex engine.
 

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Discussion Starter #17
alright well now i've about 4 gallons of mid grade and the other 21 of regular in the tank. gas going up and u guys say regular should run fine i decided to give it a shot, well idk if it was by chance but I'm leaning to the direction of somethings wrong, here's what happened. drove home from gas station turn car off no knock, drove to friends house [1 mile+ away] turned off no knock.
6 hours later on the way home the car randomly dies:banghead: So i stopped started back up then she died, sat for a minute thinking WTF started up and drove home fine. She hasn't done this to me EVER in the 4 years we've been driving together so I can only think that its related to the regular gas? what you guys think
 

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There are four things an engine needs to run; spark, air, compression, and fuel. When your engine stalled, it was not getting one of those four things. Being that you have had problems with dieseling, I think you still have a vacuum leak. Vacuum leaks drive the air/fuel ratio too lean, which causes the engine to stall. You might also have a problem with the carburettor being out of adjustment, and drowning the engine in fuel; especially if it happened while you were driving.

Low octane will not cause the engine to stall. High octane fuels will cause stalling, because they are designed to resist ignition.
 

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Discussion Starter #19
thanks sven, drove today fine and didnt knock or diesel. i think I should just go ahead and replace all the vacuum lines. so if it does start to diesel when i turn the car off where can I get the anti-diesel solenoid and how much?
 

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You can get one from any place that sells AC DELCO electronics (Advance Auto for one).
 
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