Very low mpg, help plz

[911monty]

Damn I'm such a newbie lol. I've driven a manual car before but it wasn't a sports car and this my first car with manual. So I've been lugging my engine for like 3 weeks I hope I didn't screw things up too bad.[/QUOTE]

Mike; I went and looked at your original posts and hopefully without starting a war I noticed you are aware of the IMS. There is lots of informative reading on this subject in here when you have time and popcorn. Jake Raby is a very knowledgeable resource. I hope he doesn't mind my referencing him but he has stated that the IMS has the most loading at low RPM. IMHO This is why there is a theory that engines that have been driven hard have less IMS failure than a garage queen, Lugged around engine. Hence the statement Drive it like you stole it! These cars love to rev! Their pedigree is racing. Get out and enjoy the way it was meant to be driven!

[Mike689]

I guess I'll use some injector cleaner, fill up the tank with chevron a couple of times, and replace the spark plugs. I hope this takes care of it.

[Fintro11]

how is your air filter / tire pressure?

[epapp]

It couldn't hurt to disconnect the battery, turn the key in the ignition to drain all power, and then reconnect the battery to reset the car's learned driving/throttle values. That, combined with your new gas type, injector cleaner, trying a different gear on the freeway etc will rule out all of the easy things.

[JayG]

Interesting comments about shift points

If I am doing just regular cruising, I shift right around 3k. For performance, I'm looking around 5.5-6.5k shifts. On the track, I may hit the rev limiter every now and then. On the freeway in 6th, 3k =~78 displayed, 75 actual mph, right at the bottom of the power curve.

[Mike689]

Originally Posted by JayG

Interesting comments about shift points

If I am doing just regular cruising, I shift right around 3k. For performance, I'm looking around 5.5-6.5k shifts. On the track, I may hit the rev limiter every now and then. On the freeway in 6th, 3k =~78 displayed, 75 actual mph, right at the bottom of the power curve.

That's how I've been driving, I'm a little confused. Do you have the base model or an S? Wouldn't the rpm and shifting change?

[JayG]

Originally Posted by Mike689

That's how I've been driving, I'm a little confused. Do you have the base model or an S? Wouldn't the rpm and shifting change?

I have a S with a 6 speed, so yes, the shift points could be a little different as to speed. In any case I don't see why you need to rev high for just cruising other that the wonderful sound at higher rpm. Certainly don't want to lug the engine either.

IIRC many that track the 986 prefer the 5 speed because of the gear ratios

[911monty]

Hey JayG; Good to have an instructor chime in! I hope I'm not giving bad info. Some of my style may be due to my driving a 2.5 so keeping it in the power band (3.2k+) is a job. When on the freeway I typically don't use 5th until above 75 indicated where I can keep in the aforementioned power band. That said in response to the OPs question regarding poor fuel mileage my thought is he is shifting just as he is entering the power band but more importantly may be spending too much time below the power band and in the lugging range of the engine with the knock sensor picking up the gears/chains lashing, then retarding ignition timing causing the poor fuel economy? If he is shifting 3.2 k then he is 2.2k after shift. OP lives in Monterey so as I'm sure you know it is not all sea level driving there. Viva Laguna Seca!:dance:

[JayG]

Originally Posted by 911monty

Hey JayG; Good to have an instructor chime in! I hope I'm not giving bad info. Some of my style may be due to my driving a 2.5 so keeping it in the power band (3.2k+) is a job. When on the freeway I typically don't use 5th until above 75 indicated where I can keep in the aforementioned power band. That said in response to the OPs question regarding poor fuel mileage my thought is he is shifting just as he is entering the power band but more importantly may be spending too much time below the power band and in the lugging range of the engine with the knock sensor picking up the gears/chains lashing, then retarding ignition timing causing the poor fuel economy? If he is shifting 3.2 k then he is 2.2k after shift. OP lives in Monterey so as I'm sure you know it is not all sea level driving there. Viva Laguna Seca!:dance:

Not an instructor (yet, maybe one day) but an enthusiast.

I don't see how shifting below 3.5 will reduce MPG. If anything running at higher RPM will decrease MPG. My 996 has a tip ( same tranny as 986 tip) and unless I am putting my foot into it, will shift right around 3k My guess is the tip in a Boxster will shift pretty much the same.

I would think that higher RPM = lower MPG n matter what gear or tranny you are using

[Giller]

I think OP should check his math. Based on what he has said, no leaks, no odours - it might just be bad math? 16 mpg is quite low. He hasn't answered Monty's question about total miles driven per/trip. If it's start, short drive then stop, that will impact economy more than anything really.

[NewArt]

My 01 S is a tip. I get around 24-25 on the highway but generally around 12 around town (Montreal, stop and go, like any big city). Does anybody with a 3.2 tip get those 20 mpg figures with inner city driving? I don't think so.

[Mike689]

Originally Posted by Giller

I think OP should check his math. Based on what he has said, no leaks, no odours - it might just be bad math? 16 mpg is quite low. He hasn't answered Monty's question about total miles driven per/trip. If it's start, short drive then stop, that will impact economy more than anything really.

I got 16 for sure. I'll be refueling and calculating again in a couple days.

Originally Posted by NewArt

My 01 S is a tip. I get around 24-25 on the highway but generally around 12 around town (Montreal, stop and go, like any big city). Does anybody with a 3.2 tip get those 20 mpg figures with inner city driving? I don't think so.

I drive mostly on the freeway though. I should at least get 20 mpg.

[herve_g]

Originally Posted by NewArt

My 01 S is a tip. I get around 24-25 on the highway but generally around 12 around town (Montreal, stop and go, like any big city). Does anybody with a 3.2 tip get those 20 mpg figures with inner city driving? I don't think so.

I get about 16 mpg in Montreal, 26 to 28 mpg outside the city though, in a 3.2

[jdlmodelt]

Originally Posted by Mike689

Hello I just bought a 01' Boxster S about 2 weeks ago. I changed the oil a few days later and I drive at around 3k rpm. I'm still only getting about 16 mpg and I drive mostly on the freeway. Am I doing something wrong or is it the car? and how do I fix it? thanks!

I live in Colorado, 6200+ft elevation, I can typically only get 91 with ethanol. A station nearby recently started offering 91 without ethanol! Yay!. I get about 28.5 hiway with 91 ethanol and 30.5 with 91 non ethanol. I'd make sure your MAF sensor is clean. Of course fresh spark plugs don't hurt if its been a long time.

[fatmike]

Welcome to Porsche ownership.

Get yourself a custom license plate:


LOL16MPG


/

[Mike689]

Originally Posted by jdlmodelt

I live in Colorado, 6200+ft elevation, I can typically only get 91 with ethanol. A station nearby recently started offering 91 without ethanol! Yay!. I get about 28.5 hiway with 91 ethanol and 30.5 with 91 non ethanol. I'd make sure your MAF sensor is clean. Of course fresh spark plugs don't hurt if its been a long time.

I'll look into the MAF sensor. I think my spark plugs should be ok, I just bought my car a few weeks ago with 78k miles. It passed the SMOG a couple months ago so it could be fine. I'll probably replace them next oil change.

[Mike689]

I refueled today around 3/4 tank. I had 61.0 miles on 4.142 gal which is a whopping 14.7 mpg. I had the tank filled with arco 91 and I used chevron today. I figure I'd make the change to chevron slowly. I also added injector cleaner yesterday so its only been a day with it.

I'm replacing the air and pollen filter on Friday, I'm hoping this helps. I'm also getting new rear tires tomorrow. Other than spark plugs and maf what else should I look in to?

[Gilles]

Arco…?

[BIGJake111]

I drive an S and get about 60 miles for each quarter of a tank myself. I usually fill up around 230 or so as this is usually near where the light comes on. The more highway driving I do the more these numbers creep up, the difference from city to highway seems massive on these cars, I'd say that your numbers are not that far off unless you are doing 50 mile round trips on the highway and getting these numbers.

[BH2000S]

Thanks for starting this thread. I'm also a Boxster S newby and have put about 1000 miles on my 2000 that has 54k on the ODO and 25k on the crate engine Porsche put in it. My computer was telling me over 21 MPG but that seemed high. I checked on the last tank and it was below 16 MPG (I also figured out how to reset the MPG on the computer and it is now reading about 15.8 MPG). Everything checks out, fresh oil change, correct tire pressure, clean K&N air filter. I do mostly city driving using crap Los Angeles 91 octane gas, mostly Shell. I did run a bottle of Techroline through the tank recently. I try to shift at higher RPM's but that usually puts me way over the speed limit and on the brakes so that I don't rear end someone. Going to keep watching MPG closely, maybe fresh plugs too. Car seems to run great.