# 04 power loss



## wareaglebaby (Jul 8, 2012)

im new to this whole forum thing so bare with me. i have an almost stock 04 a4 that i let my sister drive for about 2 months and i found out she used 87 octane the whole time. when i got it back there was a huge power loss. ive went through about 3 tanks of 93 octane and its still weak. i recently tried resetting pcm by unhooking the battery and it ran great for about an hour and after that it started running badly again. my question is did running the cheap stuff that long damage something any advise is greatly appreciated. only mods are trick flow cai,resonator delete,spintech mufflers dumped in front of rear end,x pipe.:confused


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## Papa Rad (Apr 30, 2012)

you probably have some damage. running on the improper fuel will set off your knock sensors right away. running on it that long, theres going to need to be some repairs.


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## silversport (Mar 23, 2007)

I don't see how running 87 octane would cause you these issues...the computer should dial back the timing so that she would have had less power during the time it ran 87...the car should be able to read the better octane you are putting in it and advance the timing and run correctly...

Bill


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## HP11 (Apr 11, 2009)

I don't know. I could see that possibly causing damage. The owners manual states:


> Use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use middle grade or regular unleaded gasoline rated at 87 octane or higher, but your vehicle's acceleration may be slightly reduced. If the octane is less than 87, you may get a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 or higher as soon as possible. Otherwise you might damage your engine.


I realize that this insinuates that 87 is "okay" but you are talking about the *prolonged use* of fuel that is 4 octane points below the recommendation as opposed to once or twice.


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## jpalamar (Jul 22, 2008)

Are you throwing any codes?


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## wareaglebaby (Jul 8, 2012)

not throwing any codes no cel on at all, i thought maybe i have bad knock sensors but wouldnt that throw a code?


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## svede1212 (Nov 1, 2005)

Ya the only way the computer knows to drop to the lower octane table is from a whole bunch of knock. Outside of that it has no idea what's in the tank. That said the only way I'd bare is maybe with the sister . It may be a good idea to get to a knowledgeable tuner. It could be your MAF is off that much possibly from the CAI (I've heard of course of Trick Flow but I've never seen that CAI).


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## wareaglebaby (Jul 8, 2012)

i planned on getting a tune one day anyway but i didnt think it was a good idea with it running like this but ill look into it theres an ls shop in marrietta ga, as for the cai the car was doing this before the install and it was sold by trick flow in a trick flow box with trick flow stickers but it has a k and n filter and has k and n on the elbow


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## HP11 (Apr 11, 2009)

I know that this is an old thread but I saw this earlier this morning. For those that don't think running too low an octane can potentially cause problems:
TBSSOWNERS.com Forums - The #1 TrailblazerSS Dedicated Owners Forum - View Single Post - Tune Time CTS-V


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## Papa Rad (Apr 30, 2012)

HP11 said:


> I know that this is an old thread but I saw this earlier this morning. For those that don't think running too low an octane can potentially cause problems:
> TBSSOWNERS.com Forums - The #1 TrailblazerSS Dedicated Owners Forum - View Single Post - Tune Time CTS-V


I had to go in and ask if the premium was working at my gas station the other day. guy was just like "you really needs that, everyone just thinks they do your waisting you money" I didnt bother with the conversation, I just said "with my car, I feel comfortable paying the extra 45 cents a gallon"


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## silversport (Mar 23, 2007)

wow....45 more a gallon for Premium???...look around unless you have to have Premium from a certain retailer...should be about .20 more...at least in ChicagoLand...

Bill


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## jpalamar (Jul 22, 2008)

silversport said:


> wow....45 more a gallon for Premium???...look around unless you have to have Premium from a certain retailer...should be about .20 more...at least in ChicagoLand...
> 
> Bill


Prem used to be 20 cents more... now its consistantly at the 30-35 cent plus range here.


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## Papa Rad (Apr 30, 2012)

silversport said:


> wow....45 more a gallon for Premium???...look around unless you have to have Premium from a certain retailer...should be about .20 more...at least in ChicagoLand...
> 
> Bill


im in down south hick vill nowhere IL, the only thing around here is corn fields. there are 3 local gas stations, only one has premium. it averages 35-45 more a gal


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## svede1212 (Nov 1, 2005)

Only 20-25 cents more here in Michigan where gas isn't inexpensive


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## silversport (Mar 23, 2007)

ouch...

Bill


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## HP11 (Apr 11, 2009)

silversport said:


> ouch...
> 
> Bill


Is that in response to the gas prices or the damage to that Caddy's motor back in post #9?


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## Rukee (Feb 8, 2007)

HP11 said:


> I know that this is an old thread but I saw this earlier this morning. For those that don't think running too low an octane can potentially cause problems:
> TBSSOWNERS.com Forums - The #1 TrailblazerSS Dedicated Owners Forum - View Single Post - Tune Time CTS-V


I'm pretty sure that's what my truck motor looks like now. I got gas at a station I normally don't and pulling the boat to the lake. About 6 miles into the trip the motor started pinging soooo bad I didn't think I was going to make it there!! Temp went through the roof, oil pressure dropped to almost zero, power dropped dramatically. Left the boat at the lake lot and even coming home with an empty trailer it still pinged like hell. Changed the oil, drained the gas, changed the thermostat and plugs and retarded the timing about 10*. Runs with a rough idle and drives okay with noload, but hook up a trailer and it falls on it's face. Being it has 246,000+ miles and it's only a 2wd I'm not going to pull it apart. I know if I pull the motor out and rebuild it that the tranny will take a crap. Plus there is a couple boat landing where I really need a 4wd to get the boat out as it fairly large. So now I'm looking for a newer truck, thanks MOTO!!


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## silversport (Mar 23, 2007)

HP11 said:


> Is that in response to the gas prices or the damage to that Caddy's motor back in post #9?


da boat of 'em...

Bill


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