Jump to content
LegacyGT.com

What's your gas mileage?


Recommended Posts

  • Replies 53
  • Created
  • Last Reply

O2s typically last about 60k miles. Maybe if you were pouring raw fuel and burning it in the exhaust you could maybe overheat them enough to hurt them but I doubt it as there would have to be air in there as well to support combustion. If you coat the tip in antiseize I'm pretty sure you can hurt them. If you don't mount them in the factory location, but instead move them about 5 times closer to the head you can overheat them to failure.

 

If you have 1 month old O2s that you got from a legit supplier *not ebay* and you didn't do something outrageous to them, then either they are fine, or you are the most unlucky person in the US who got bad ones from the factory.

 

Can you get access to an OBD tool that will show live data? That would really help here. You've replaced lots of parts and it still is running bad. That typically means the replaced parts are fine and something else is confusing the computer leading to the problem.

Link to comment
Share on other sites

It was a legitimate maf cleaner.

 

The intake is factory, I had to replace the cold air intake with the factory box setup with the little bowl thingy in the fender when I first got the car

 

went from CAI to factory and cleaned the MAF? id look up the specs and test that bad boy. on one of my outbacks i had similar issues, it would run great then sputter out and die. went through all the same shit, first thing i did was clean the MAF. i even went so far as to go section by section in the fuel system, and blow air back to the gas tank to verify i wasnt getting chunks, and there were no clogs. full intake dismantle and cleaning, FI cleaning and tests, new coil/plugs/wires, new O2 sensors and everything. the one thing i never changed (because it was clean) was the MAF. a friend that owns a shop was borrowing the car and driving it daily, so he was the one that ended up buying me a MAF to test with and it cleared up completely, regardless of mine seeming to be clean and good. its a costly gamble, but it paid off on mine.

Link to comment
Share on other sites

I do have a little Bluetooth OBD scanner and that reads me simple data like what hp im running at what rpms and my idle, vacuum pressure, fuel pressure. I have no check engine lights and the O2 sensor actually got moved farther back in the exhaust away from the head with the new headers. And the O2 were denso

 

I'm thinking it twisty has the right idea because I've done the same, done all I can think of except the fuel pump and actually replace the MAF. The fuel pressure runs in the high 14 psi which according to my book is good so that just leaves that junk yard MAF to give me issues. My brother drove the car and he said the same thing happened with his BMW E30 and it felt all lurchy and low on power just like mine until he just sucked it up and bought a new MAF

Link to comment
Share on other sites

Also the OBD tool that I have doesn't pick up info about my O2 sensors or my catalyst which I have no idea why, it just says not complete on the process check. Most people I've asked just say it's because the car is old so it doesn't "talk" to the Bluetooth adapter so to speak
Link to comment
Share on other sites

Did you mean 41 psi on the fuel pressure? 14 is definitely way too low for idle pressure. The 2.5 has a different spec than my 2.2, but mine is 30 idle up to 39 WOT. The looking I did seems to say 40 to 50 psi for a 2.5.

 

You have new Denso O2s (both by the price), and a junkyard MAF? I know where I'd put the blame. I get it, as the OE is pricey. I worked hard to find a MAF for testing when that was my choice.

 

Does your OBD tool show you MAF g/s? Mine does. We could come up with some expected numbers based on what you're doing and see if they make any sense.

 

If your fuel pressure regulator fails internally it is possible for it to send the excess fuel through the vacuum sense line instead of back to the tank. That might give you severe lean at WOT and severe rich at idle and cruise. If it isn't leaking in this way, but is only giving you half pressure you would be lean all the time. Bear in mind that the lean and rich conditions could be within the ability of the ECU to try to correct. That would leave you with corrupted LTFT tables and it would run crappy becuase you would always find yourself in one of the corrupted cells in the table.

Link to comment
Share on other sites

It may have been 41 lol it's been awhile since I've checked. But yes that is 2 new O2 but junkyard MAF lol it's just like 300 for a new MAF it's crazy.

 

My obd doesn't even tell me that actually, might be the cheap ass connector I have. I haven't been able to keep and eye on my fuel to air ratio while I'm driving but with the smell and extreme excess of soot in the tail pipe I want to say that it's just rich but haven't been able to confirm it.

 

When i drive the car really hard it kinda smells a little funny but just kind of like and old engine working hard. When I shift too it spurs out a bit of smoke but it's not blue smoke like I would see in the case of piston ring, been told by elders it's most likely excess fuel, and this is only when in really driving the thing hard

Link to comment
Share on other sites

That MAF price is crazy. I couldn't believe it when I was searching. I tried for a couple months to find someone I could meet up with who would let me swap MAFs for a few hours of testing. Not many people willing to let you drive off with a few hundred dollars of their stuff in your car.

 

I wish we had more ECU sensor data to go on, but that isn't a sure fix even with it. I didn't figure mine out until I connected an oscilloscope to look at the injector impulses and spark events and such.

Link to comment
Share on other sites

I'm kind of at the point to just dump some money into the MAF sensor to make sure it goes good and if that doesn't work try the msd coil pack which I'm doing either way and if that doesn't work then I would have no idea
Link to comment
Share on other sites

The car was purchased in Oregon and it wasn't passing emissions placed their so I do have a receipt for tuning to get the car passing emissions for 700 $ but this was by the previous owner. It started failing again which is why he sold it to me so cheap, and I don't have any emissions here in Washington so maybe there was like a tune done to it?
Link to comment
Share on other sites

I would find it hard for some to "tune" the car through software changes. These ECU's cannot be written to so the mechanic who "tuned" it sold them some snake oil fix and a less than legit method of getting it pass emissions. I used to see that in NY State, shady inspection station people plug in another car to the OBD machine that will pass emissions inspection, slap on the inspection sticker, and they charge the customer a hush fee in exchange to have your car legal for another 2 years. A lot of shops got busted for it.
Link to comment
Share on other sites

+1 to the not as fun ECU in our cars. :( Unless the 'tune' was to fix some failing part, I'd have serious doubts. I bet there is some kind of thing like put a quart of acetone into 3 gallons of gas and do the emissions test on that. Or some other chemical silliness to get a very short term change.

 

I didn't have bad luck with this:

https://www.amazon.com/gp/product/B0091J4QTW/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

 

I switched back to my OE MAF once this one didn't help. Also, as much as I could tell from the very basic data logging our ECU allows, this one gave numbers for airflow that matched the OE. So I can't speak to it's long term performance, but this unit did not explode my engine or let my dog run off leash.

 

Ugh, NM. I forgot you have the 2.5. Maybe that link will help you find a 2.5 part from the same place that isn't as outrageous on price.

Link to comment
Share on other sites

I was getting 200 miles a tank and just changed my knock sensor and cleaned my iacv and whilst doing that found a injector oring intermittently leaking only at idle. Replaced all of that and now I just got 295 on a tank. Witch I can only seem to fit 11 gallons in so my fuel economy Is pretty good I'd say.
Link to comment
Share on other sites

Witch I can only seem to fit 11 gallons in so my fuel economy Is pretty good I'd say.

 

Sounds like my car. I fill up when the needle is touching E now because I have verified my fuel level sending unit is reporting incorrectly. Our cars have a 15.9 gallon fuel tank and I can only get 12 gallons in when it is on E. I'm averaging about 23-25 mpg but I don't exact drive like a decent human either. I guess that's what happens when you have a modified exhaust.

Link to comment
Share on other sites

I guess i averaged about 26 mpg last time and that was alot of highway I'm almost done my next tank and it doesn't look as good haha. I'm glad to see I'm in check with everyone else's fuel economy now tho. That knock sensor really hurt it.
Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.




×
×
  • Create New...

Important Information

Terms of Use