My 2005 XF is detonating!

I don't drive it much, and it did fine on the tank of gas from/during the winter. But then I filled it with the local Premium gas (only 91 octane here) a couple of weeks ago, and soon got detonation.

I've been reading the related threads here, and elsewhere. Sounds like at least two things: 1) warmer/less dense air, and 2) low octane.

Adding a jar of lower-cost octane booster only slightly reduced the problem.

After reading a thread here, I'll now add a bottle of gas-dry and check the error codes (no warning light showing now).

Could have been bad gas from the BP station. Insert BP jokes here ...

Other ideas?

 

I would guess a bad tank of gas, unless it continues after you fill up again. Octane boosters barely raise the octane rating of any gas. While it may help a little, be sure to add some gas treatment. I wouldn't go back to that station. Might want to report them to the Department of Agriculture too. The number is on the pump. They are the ones that regulate the weights and measures of gas pumps in the US. Who knows, maybe you'll get reimbursed for your bad tank and any damage it might or may have caused. They could/should get shut down, or at least fined.

EDIT: Little tip. BP uses the lowest quality and lowest amount of detergents that is legally allowable in their gas. Look up on toptiergas.com and see if there is any of those stations around you. They use detergents that are above government mandated standards, that way they help prevent carbon build-up in your fuel system (injectors, etc.) better than stations like BP and Citgo.

 

Thanks. I had a thought -- E85 is sold at a station here. My tank is almost full, so I was thinking of getting a gallon or two of E85 in a can to add to the XF -- a lot more alcohol and cheaper than the little bottles of "gas-line antifreeze" sold. Know what the max ethanol percentage the XF can handle safely?

BTW -- the local WM did not have any of the little bottles in stock; wrong season.

 

E85 won't work in these cars. Ethanol needs a specially designed engine, like those in flex fuel vehicles, to run properly. While all gas can contain up to 10% of it, it's limited to that because most petrol engines can't burn more than a 10% concentration of ethanol properly. Also, as you can see just by the numbering system, E85 has a lower octane rating than what is allowed by manufacturer's specs. That will cause pre-detonation. Putting a higher amount of ethanol in a petrol engine most likely will cause catastrophic failure or at least gunk up your fuel system/engine pretty bad. I don't specifics right now though.

There's a good amount of gas treatments available at stores like Autozone, etc. If they don't have any, or even if a gas station didn't carry any inside, I would be really surprised. If you want to fill the empty space in your tank, get a hold of some gas treatment if you can, then go to another station and fill up. Make sure to check on the pump and see when was the last time they were certified by the DoA. They have to be certified once a year for the same month, so don't be alarmed if it says "Oct 2009". It's certified until Oct this year when they'll retest it.

EDIT: Here's an example of what to look for when looking for gas treatment- http://shop.advanceautoparts.com/web...ci_sku=7080522

I would expect Walmart to have that. Every Walmart I've been to did. Just remember to follow the instructions on the back of the bottle.

 

Thanks, but actually E85 means 85% ethanol, 15% gasoline (but more gas than that in winter to help with cold-starting). Ethanol has a higher octane rating than gasoline, something like 105 if I'm remembering correctly. But a lower heating value, so lower mileage.

Those expensive little bottles of gas-line antifreeze are mostly, if not only, ethanol. So E85 is a much cheaper source.

I'm not looking to run straight E85, just to add some to raise the octane. What's the highest percent ethanol that the XFs can handle?

 

Hi,
As far as I know, 10% is the limit. Even my old 1986 2.2 Omni had a computerized knock sensor to retard timing and avoid engine damage due to low octane. The Crossfire shouldn't be knocking, even with a lower than premium fuel rating.

 

Yah,
I think it could be Bad Gas NOT low octane.
I am assuming you have a n/a not a SRT, you should be able to run lower than 91 no problem in it.
Save your $$ and forget the octane boost, if you could rid your tank of what you have in it and refill with 91 add a can of fuel additive for ridding any H2O you can get rid of and if it were to persist "you got me?" but that should do it.
If you live in an appartment or haven't anyplace to really drain the tank just add H2O displacement additive and it also should help, only take longer.
Good luck,
Montana

 

Oh, I know. There's no production car out there that runs straight ethanol. Maybe some experimental ones, but nothing you can buy from Ford or the like. Either way, E85 would be sure to ruin your engine. I don't think the Germans have even considered ethanol as a fuel source.

Like someone else said, I doubt it's a low octane that you bought. Almost any new car with computer-controlled timing can retard the engine to allow for the use of lower octane gas. You won't get as good of mileage and it might hurt the engine, or at least put some stress on it, but it won't knock. Not for long at least.

The bad gas was most likely high in water content. Again, gas treatment may help with the problem. Most of those little bottles like octane boosters and fuel system cleaners are made of petroleum distillates, something of which your engine has no problem lighting on fire. So they might be better than gas-line antifreeze. They usually include some other chemicals for their purposes that your engine can burn.

Either way, the answer is still 10%. I can guarantee using anymore than that will damage your engine.