PonchoCatalina Posted February 15, 2008 Share Posted February 15, 2008 I know this has been covered many times, and I have read just about all the posts I can find related to EA82 SPFI fuel mileage, but I'm just not having any luck boosting the fuel efficiency of my 91 Loyale. Maybe someone can point out whatever it is I'm missing? Currently I'm getting about 20.5 mpg. The best I've seen is about 21.7, the worst about 19.8. This is all city driving. I don't expect much, but 24-25 in town would be great at this point. As it is, my 86 diesel Suburban gets about the same MPG as my Loyale. This is what I have done so far to try to improve things: 1. New O2 sensor 2. New NGK plugs 3. New air filter 4. Changed oil from 20w50 to 10w30 5. Made sure 36 psi in all four tires 6. Cleaned MAF with CRC MAF cleaner 7. Verified timing at 20 degrees BTDC After making these changes, I haven't seen any appreciable change in MPG. I believe my coolant temperature sensor is working correctly, as the car starts at a higher cold idle (about 1200-1500 rpm), then falls back to a steady 700 rpm, as it should. I have no check engine light on. The only other things that might be significant are an occasional hesitation at part thottle when the engine has not warmed up, and there is a sort of rich smell to the exhaust when I'm standing still (at a light, for example). I figured the new O2 sensor would have fixed a rich-running condition. Perhaps I need to wait a while for the computer to adjust to the new sensor? I welcome any ideas. Thanks! Quote Link to comment Share on other sites More sharing options...
dhise Posted February 15, 2008 Share Posted February 15, 2008 I am getting around 30mpg, 50/50 freeway/city driving. You probably could use the rest of the tune-up items ie, cap, rotor, plug wires, pcv valve. Check the vacuum hoses, and check the brakes to make sure a caliper isn't dragging. Quote Link to comment Share on other sites More sharing options...
ScottG Posted February 15, 2008 Share Posted February 15, 2008 dhise has already hit almost all the points I was going to make. Just one more thing i can think of: proper adjustment of the TPS. Refer to your Haynes or Chilton's for the proper procedure. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted February 16, 2008 Share Posted February 16, 2008 Your injector may be leaking, or the fuel pressure regulator may be allowing more than 21 psi through the system. Higher pressure, or a leaking injector will show as high fuel consumption. Cars should seriously come stock with A/F ratio meters for problems like this. And fraknly, for what you are losing in gas mileage, you could probably easily pay back the investment in one. You might also want to check the valve timing. Even a single tooth off can run *almost* correctly, but the mileage will be horrible. My co-worker just found his timing off a tooth after owning his car for a YEAR. Needless to say he's seeing the whole vehicle in a different light now. GD Quote Link to comment Share on other sites More sharing options...
heartless Posted February 16, 2008 Share Posted February 16, 2008 didnt see any mention of which tranny you have - manual or auto??? manuals tend to get better mileage than the auto will... would also check into doing the things suggested by GD Quote Link to comment Share on other sites More sharing options...
PonchoCatalina Posted February 16, 2008 Author Share Posted February 16, 2008 didnt see any mention of which tranny you have - manual or auto??? manuals tend to get better mileage than the auto will... would also check into doing the things suggested by GD It's a five-speed manual, so I'm good there. I appreciate everyones' ideas, and as soon as it stops raining, I'll look into the suggested items. I'll start by checking out the PCV valve and verifying my valve timing is correct, then go from there. If I achieve success, I'll post the outcome. Thanks! PS to GD - Maybe I should just build one of these to monitor my A/F mixture: http://www.scirocco.org/tech/misc/afgauge/af.html Quote Link to comment Share on other sites More sharing options...
NewDriverOlderRide Posted February 16, 2008 Share Posted February 16, 2008 fuel filter also Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted February 16, 2008 Share Posted February 16, 2008 PS to GD - Maybe I should just build one of these to monitor my A/F mixture: http://www.scirocco.org/tech/misc/afgauge/af.html Sure - that will definately give you a good start. Personally, I'm going with a wideband unit that is a bit more accurate. But for your purposes, just a regular narrow band such as that is more useful than nothing at all. Narrow band (almost all vehicles) is a 0 to 1 volt signal O2 sensor. Wideband (very few vehicles, around $250+) is a 0 to 5 volt O2 sensor with much more complex "controller". GD Quote Link to comment Share on other sites More sharing options...
ScottG Posted February 16, 2008 Share Posted February 16, 2008 I thought of one more thing that I don't think has been addressed - the thermostat. How's your heater working? If it's not nice & toasty, you may need a new thermostat because the old one may be partially stuck in the open position. This will keep the fuel enrichening circuit open, dumping lots of gas into the injector Get a new 180 or 195 degree thermostat from the dealer & see if that helps. If cash is short, use some cardboard to partially block the radiator (this is just to test - don't let this last for more than a test drive), to see if you get rid of that 'rich exhaust smell' you mentioned. It may also get rid of that 'dead spot' in the accelerator, as well as greatly improve MPG. I just thought of something else - your catalytic converter. Check your exhaust for free flow. Hope all the advice you've been getting has helped. ScottG Quote Link to comment Share on other sites More sharing options...
idosubaru Posted February 18, 2008 Share Posted February 18, 2008 city driving does not make for good gas mileage. the closer you get to 0 mpg (sitting there idling) the less noticeable difference you'll see between any vehicle. i'd complete the tune up - i always do plugs, wires, cap, and rotor at the same time to keep things simple. except that i exclusively use Magnecor wires which never need replaced so after the first time it's plug, cap, and rotor only. GD brings up a good point - i've sent away a few sets of fuel injectors to companies that flow test them before and after cleaning/repairing. subaru injectors seem robust but they typically have some dripping/bleeding, whatever they call it at higher mileage/age. 'im not familiar with SPFI as mine have all been MPFI units, but given that GD already mentioned it, it could be worth checking into. RC Engineering and other companies will test them before and after cleaning/rebuilding. RC is rather expensive...but it doesn't really cost that much anyway. There are much cheaper companies out there. Quote Link to comment Share on other sites More sharing options...
The Dude Abides Posted July 2, 2008 Share Posted July 2, 2008 ill rehash an old thread. i just cheked my mileage and im getting about 20 mixed city and highway. Now im no baby to this thing i romp on it pretty good sometimes but should i be getting better. New plugs, wires, and fuel filter but since i seafoamed the gastank i might need the filter again. Cleaned the maf. Where else should i go. Ben p.s. 5 sp Quote Link to comment Share on other sites More sharing options...
hooziewhatsit Posted July 2, 2008 Share Posted July 2, 2008 I only get about 22ish with city/highway in my 91 loyale. Strictly highway is 34ish. So a bit of city driving really kills the mileage. Quote Link to comment Share on other sites More sharing options...
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