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YOUR RESEARCHOctane booster recommendation
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Adjust she is
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After the knock sensors adjusted she is running like a top again.
Leading evidence: 'Adjust she is' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is '87 octane and i think it is a mistake' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Adjust lower octane' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Is it possible the retailer had just had the tank re-filled - sometimes that stirs up "junk" in the tank.
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I was daily driving a Boxster with some crazy mods and I ran 87 in it...
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After Katrina our area ran low on fuel and no one had premium....
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You will have to dump in gallons of octane booster to raise 87 to 90 (the minimum octane I think Porsche recommends be used).
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Suggestion
Based on the fact 90 is the lowest octane grade Porsche says is ok to use I suspect the DME is unable to adjust the timing enough to accomodate 87 octane.
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Suggestion
Jamming a smaller hose or other crap into the valve may damage the expensive, delicate mechanism, making it impossible to fill the tank at a gas station.
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87 octane and i think it is a mistake
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Suspected cause
I think the way the engine was running was due to the 87 octane and I think it is a mistake -- to put mildly -- to assume the OP can just drive the gasoline out.
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Based on the fact 90 is the lowest octane grade Porsche says is ok to use I suspect the DME is unable to adjust the timing enough to accomodate 87 octane.
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Outcome without a verified action link
I let it sit there and idle for a little bit after add in the bottle and still having problems and then it settled down and ran fine.
Just put a full tank of 87 in my car and she is pissed. Luckily I was less than a mile from my office and am borrowing a car to go pick up some octane booster. Any recommendations?
You're gonna need a lot of torco to get six full R+M/2 points.
Just drive the car easy until you can fill up, or find someone who sells Sunoco GT100 and mix.
No, wasn't paying attention to what vehicle I was in. One bottle of octane booster didn't make a difference. Will try a second.
Won't even make it a mile down the road, even after 1 bottle of booster.
That makes no sense. The car should run fine at part throttle on 87. And the standard bottles of octane booster at the auto parts store don't do anything (i.e. from 87 to 87.2)
The royal Purple (listed above) claims to boost it 30 points so theoretically it would have brought it up to 90. I normally run 91 without issue. The car kept dying even though I was trying to baby it and didn't want to restart. I let it sit there and idle for a little bit after add in the bottle and still having problems and then it settled down and ran fine. So I figure m it really worked as advertised or the ECU adjusted to the bad gas coincidentally at about the same time.
FYI, it was explained to me is that if you have a tune, an episode like this can really screw some stuff up since it doesn't allow the ECU to adjust.
This. The car will be perfectly fine, no need to borrow another car. As long as you don't mash down on the throttle, push it on a hot day or take on any uphill mountain passes, the engine will be happy.
Ha, that's the exact same thing my car said! The royal purple raises it 30 points so that puts it at 90 and she seems pretty happy. Keeping it under 4k rpm just to be safe.
You have some learning and reading to do. Have the stuff you are claiming doesn't happens for the reasons you say they do. The ECU uses the knock sensor to pull timing if detonation is detected. Low octane fuel can pre ignite (resonate) in a high compression or an advanced ignition timing engine. The ECU can pull a lot of timing to fix this problem but it will cost horsepower. However there is a limit where the ECU can not compensate anymore. As others said, staying out if WOT should make the engine run fine until the tank is empty. The octane boosters more gimmick than anything else. Even if the royal purple claim 30 point rise, I would be very careful. Also, 87 octane is not "bad gas", on the contrary, it has more power than higher octane blends because but because ignites earlier than for example 94, it is less controllable in high compression engines.
Are you daft man? The car went from running like a top to dyeing on me 5 times in little over of a miles stretch. This had nothing to do with WOT, this had to do with it not being able to make it to 2500 RPMs. Not only was it dyeing but then I had to crank the hell out of it to get it to restart. This started as I was pulling out of the gas station. That's when I realized the mistake I had made. The problem went away about 3 minutes of run time after I added the octane booster.
Those are all just facts. Feel free to properly interrupt this information for me. I'm always looking to learn something.
Bad gas could cause results like you experienced but 87 octane wouldn't cause those results - must me something else. Was your tank almost empty when you filled? Is it possible the retailer had just had the tank re-filled - sometimes that stirs up "junk" in the tank. Maybe something wrong with your DME that it couldn't adjust for the lower octane. Seems like there is more to your problem than just an octane difference. Good luck tracking it down.
Nearly empty tank and it was at a Conoco that I've never had issues with. No need to track it down, seems pretty simple and don't plan on testing it again to prove one way or the other.
I would be curious to know if anyone else with a '99 (5.2 DME) has ever put a tank of 87 in and not had any issues.
According to the API the only time to use a fuel, or oil additive... Is NEVER.
Pull the fuel line, bypass the fuel pump relY and pump that junk gas out of the system... Then replace with the proper premium fuel.
Your knock sensors, pistons, and rod bearings will thank you.
Ok, on it. Thanks for chiming in.
No, I remember 87 and black handle. It's what goes in my Expedition. My wife drives a '12 dodge 2500 mega can diesel. So I'm always double extra careful when there is a green handle or a green gas cap.
Slakker, what you are describing does not happen due to pumping 87 into 17 year old 911. You probably ran it low on gas, you sucked some gunk from the bottom of the tank, that caused the misfire. Your N/A car will run just fine on the 87 if it needs to, just don't push it.
For Gosh sakes Man....Pay Attention!!!
FWIW...I have twice driven off from a gas pump with the hose still attached to my car (not the Porsche). That's what you can do if you REALLY want to feel like a dumbass...
You will have to dump in gallons of octane booster to raise 87 to 90 (the minimum octane I think Porsche recommends be used).
God only knows what that amount of octane booster will do to the fuel system and so on.
My recommendation is to have the car flat bedded to a shop and have the 87 octane fuel removed and then refill the tank with the proper grade of premium fuel.
And in the future pay close attention to when filling the gas tank.
Why let them have all the fun? Tried to do it last night but the only hose I had was 5/16 ID and I'm guessing it needs something closer to a 1/4 as it almost sealed but not quite. Will get the hose today and get it drained. It will make great lawn mower gas.
Fair enough. Third time we've made a mistake between the two of us. I put gas in the dually once but realized it and ran off the other tank until I could siphon it out. Wife put diesel in the F150 and it stalled before she got out of the gas station. Both of those were 18+ years ago so we've been on a pretty good run. I've had 4 MB, 2 bimmer and another pcar and never had an issue.
Slakker, the reason you are unable to siphon gas from the tank, (like grandpa used to do from his beloved old Grand Torino) is all modern cars have a ball-check or shutter valve at the top of the tank. This is to prevent gas from spilling out in a roll over or other crash that damages the filler cap area. Jamming a smaller hose or other crap into the valve may damage the expensive, delicate mechanism, making it impossible to fill the tank at a gas station.
Gasoline in a complex compounding of 500 straight chain and branched chain hydrocarbons. Regular and premium grades are 99% alike, premium only differing in the blending of slightly more small branched hydrocarbons and/or additives that only exert themselves under the extreme conditions that cause �engine knock�.
No petroleum engineer or engine designer would account your experience of poor idling, stalling, hard starting to the gasoline octane number.
The online owner�s manual for 1999, like the manual for more modern P cars, does state the requirement of higher octane gasoline, but recognize a situation when only lower octane gas may be available. It says to go ahead and temporarily use it as the engine�s knock sensor system will prevent any harm.
Urban myth! It was pre fueling anyway. :P
Not arguing that the octane was or wasn't the cause. It seems like it was but who knows. I'm not going to test the theory again but I encourage someone else with a DME 5.2 to see if they get the same result.
I'll drain it simply because it's easy, it's something else I can learn how to do, and I can reuse the gas. Plus Jake recommended it and being that this engine is going to visit him in 6 months it wouldn't make sense not to follow his advice.
Pretty easy process and pumping much quicker than I had imagined. 1/4 ID fuel line from lowe's was the ticket. Made a small set of jumper cables so it would be easier to tape and protect at the battery terminals.
Didn't time it but seemed around 15 min for about 14 gallons. You've told me about the Durametric before but I had forgotten. The relay jumper was easy enough to use that I will probably just use it again next time. I put some solder on each end of a piece of #10 then pounded it flat and trimmed in about half.
Maybe you can sell your story to Royal Purple...that sounds like one hell of a testimonial. I can see you and your Pcar in the next RP commercial. HAHA
Ha! I had no idea I was walking face first into a full blown controversy. The whole thing seemed like a simple story. Lol. I am going to see if anyone around here will test gasoline samples. Maybe it will shed some light on the situation.
The difference between regular and premium is more than just a dash of additives.
IIRC Porsche states the lowest octane that should be used 90. The OP put in 87.
These engines have a very high compressoin ratio and 87 octane is not up to it.
Based on the fact 90 is the lowest octane grade Porsche says is ok to use I suspect the DME is unable to adjust the timing enough to accomodate 87 octane.
Or possibly in attempting to adjust the timing the timing is delayed so long the engine simply won't run right? Also, by delaying timing this raises the exhaust gas temperature and thus exhaust valves, O2 sensors, converters are at risk of damage from this elevated exhaust gas temperature.
I think the way the engine was running was due to the 87 octane and I think it is a mistake -- to put mildly -- to assume the OP can just drive the gasoline out.
Maybe he can, but if he can't there's a lot at risk.
I prefer to sacrifice the least costly item in this situation and that's the 87 octane gasoline in the tank. Hence my recommendation to drain the tank.
If the gasoline can be saved to be used in another compatible vehicle, that's fine, if one is comfortable with that much gasoline around hopefully in appropriate containers.
Like I said, pop off the fuel line and place an extension hose into a container that's safe to store fuel in... and bypass the fuel pump relay... The tank will be emptied in about 5 minutes, as well as the fuel system.
Refill with the proper fuel, and give the DME some miles to adapt. You'll be good.
We drain the fuel this way in ever6y car that we see for an engine reconstruction. I don't trust the fuel that was in the tank, under any circumstance.A new engine has zero tolerance for that.
I should probably put my Flame Suit on before writing this, but on my Fuel cap it says MINIMUM RON 91
This is what I got from Petro Canada website :
A vehicle that calls for "91 RON" should use 87 octane gasoline
Now, go ahead, flame away
Macster, if you peruse the American Petroleum Institute�s web site you will find, after distilling down all the technical explanations, that the only difference between regular and premium grades of gasoline is the antiknock capabilities. Hence the reason several people commented that the difference in octane rating would not cause the hard starting etc symptoms, and would not be fixed by the addition of some rather useless booster additive.
Humans are funny, they like to jump to conclusions. On the other hand, we are led to understand that cars only obey the laws of logit. However, what would you think, if your somewhat aging car started acting up. You being a big strong hothead man�s-man cursed and said �you ungrateful SOB, if you don�t stop this right away, I�m getting the 20# sledge hammer from the other side of the garage and beat the hell out of you�. Now if at that exact moment the car started running perfectly what would you conclude? Your big manliness scared the car, or your actions had nothing to do with it and the hiccup corrected on its own. The OP�s lack of attention to detail caused him to put the wrong fuel in the car, so it gives pause to wonder about his powers of observation (just joking).
By the way, this simple DME has no idea what grade of fuel is being used. It can only react to engine knock. If I�m find myself in some scary Hill Billy town late at night and only the regular gas pump outside the sketchy bar is working. I�m going to pump enough of that stuff to get to civilization. Crossing the great flat high planes of the U S, even a high performance Porsche engine will never know if I slip it some low octane gas. The caveat is that I must keep the engine in a happy RPM range and use a super light throttle. Of course nobody wants to live like that and the danger of engine detonation (knock, ping) is not worth the risk on a regular basis.
So are you volunteering to drain yours almost empty and then try 10 gallons of 87 to see if your experience is different? It would be great to get some additional data one way or another.
Based on your request of examples and no responses (limited sample, I understand) makes me conclude:
No one has used 87 before or if so, either experienced no issues or not willing to report.
My unscientific conclusion about your issue is that you got to the bottom of the tank of a 15 year old car and your fill-up stirred up whatever was lurking at the bottom of the tank and made its way into the fuel system. You mentioned that you were low on fuel before filling, was your low fuel light on?
Sounds like you're on your way to a fix - congrats and also we'll all be waiting for a report next year on the 3.8 conversion.
It was just in the range of the low fuel light. Just below 50 "miles until empty" which is where I usually fill up at. Like most disagreements on Rennlist, this debate has been fascinatingly enlightening.
Well Slakker and Jhbrennan, you don�t need amateur antidotal observations per se, as there is 100 plus years of scientific research on every facet of this matter. Just as a side thought, have you ever driven the 30 mile Mt Evens Scenic Byway? The 14,000 foot altitude will mean that a Porsche will run as best it can (at that altitude) without a hint of engine knock on #87 octane. The thin air means that notwithstanding the high compression ratio the Mean Effective Pressure in the cylinder will never reach a level that will promote pinging, knocking.
Jhbrennan, one thing I often hear people say is not to run the fuel level extremely low in the tank. They explain as you did that the engine will now pick up the gunk from the bottom of the tank with deleterious results. I�ve never been able to get my head around this. I assume the fuel pick up is always at the bottom of the tank and every bump, corner and movement of the car should be constantly mixing the gas, so what difference does it make if you run the tank only half empty or almost all empty before refueling?
Slakker was this gas 10% ethanol? If so as there is a greater chance of getting phase separated or water contaminated fuel.
I would guess it was not the octane per se but your Conoco 87 maybe E85 or close to it. It could have given your system a shock cleaning
Lucky for us that so many things in OK sucks, it keeps TX from sliding into the Gulf.
I'm away from Rennlist for a few days and this is what I come back to? And why am I not surprised it involves my buddy Slakker? Ha! Has KK chimed in on a simple DIY for how to completely remove and clean the fuel system with parts acquired from Dollar General?
Slakker, let me break it to you gently.. Your car is having fuel related problems because it's the 1999 dual row bearing IMS. The regular IMS P cars don't have problems with bad gas! Ha! Budda Bing!!!
Actually this was all just ploy. I made the whole thing up to see if I could convince people the 91 was better than 87. Oh well, it was worth a try.
Seriously though we had some subject matter expert sideliners chime in that I hadn't seen before so that was cool. I've since gone back to the same station, verified with the clerk that they hadn't refilled the tanks, and got a 1 gallon container of the same gas from the same pump. I also cleaned out one of the 5 gallons gas cans really well before I drained the tank into it. So if I can find a lab to test both samples (untreated and treated) without driving to Cushing, OK then I will post the results.
But first, I've arranged an entire business trip around the fact that Motorsports Ranch, which is four hours away, has a 3 session track night tomorrow. When you got the bug, you gotta go. Even if it is in my DD with stock alignment, suspension, and street tires. So some non-antidotal data will have to wait until next week.
Welcome back!
My absent mindedness seems to run in pairs. 1000 miles in two days and I frickin do it again 60 miles from home.
No cheesy additives this time. When she started coughing and didn't want to restart I shut her down and called AAA. This will be the last time this happens I guarantee it. She deserves better. But the least I can do is a proper ride home and another full draining of the tank.
Now who was it that said 87 wouldn't make these run bad?
You can get away with it more in cooler weather... In winter if the engine can be driven lightly long enough to adapt, it can work ok... After Katrina our area ran low on fuel and no one had premium.... I was daily driving a Boxster with some crazy mods and I ran 87 in it... Had to... I could not run it in my AirCooled cars at all, and I didn't care if I blew the Boxster up... Ran it that way for a month and after a week it had adapted.. Had crappy power and the knock sensors were working over time...
I have learned that every time someone has my engine and has any sort of drivability issue that we have them pull a fuel sample... I have had a lot of people do the same thing unknowingly... Especially wives...
One of my higher CR engines really hates 87 octane..
Ya, I'm going to have to implement a procure to ensure it doesn't happen again. Even if it's just touching the 93 and touching my gas cap every time. There's a reason I have 5 things to do to get ready every morning and I actually count out loud to ensure I don't forget any.
Ha, my 13 year old son made the same recommendation when I finally got home last night. But I'm thinking it needs to be something more dramatic, like a picture of Forest Gump or something.
Good idea. Finally got back from vacation tonight and finished draining the bad juice and getting in the good stuff. After the knock sensors adjusted she is running like a top again. Tried using the Durametric to activate the fuel pump but it wouldn't stay activated. Went back to jumpering the relay and it worked like a champ.
How about circling the sticker that says minimim 93 octane with a red sharpie? That would seem more effective than just a piece of red tape which doesn't really indicate anything.
It doesn't have to, just needs to be a visual cue to stop and think about what I am doing. The gas cap on our diesel is green which works as a great cue for it since most diesel handles are green. The locations that have 93 or even 100 around here will typically use a red handle so the color has significance, even if you are just selecting 91 on a black handled pump.
Admit it - you did this a second time on purpose just to prove some here wrong...
I'd bet this(the poor performance with regular fuel) has to do with the fact that your car has a tune which doesn't allow the DME to retard the timing enough to compensate for the 87 Oct. fuel. I can't believe a stock 996 would perform this poorly with 87...although I can't say for sure because surprisingly in 10+ years of 996 ownership I have never mistakenly used 87 Oct., at least that I am aware of anyway.
I'm up to 40 gallons. One more time and I'll have your drum. Of course $.05 of red electrical tape has permanently solved the problem so there is no chance of a threepeat. None.
Red tape or not, I can see the OCTANE MINIMUM 93 warning from here.
Found this thread late because I'm researching additives for my Boxster S with that same warning sticker. It just bogs down in the middle RPMs sometimes with the California 91 gas. Thanks for sacrificing yourself on the altar of knowledge.
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