Lost my gas mileage after timing belt, coil and tire replacement

Didn't check the PCV yesterday, went bird hunting instead. It is taking more time to start now and still not check engine light. I will try to check the PCV in the morning.

It has a new starter, new fuel filter and fuel pump.

I would choose hunting over wrenching most days as well.

Amen, it's getting close to my time of the year where I take two days off a week! Bird hunting and got a big elk hunt planned if the fires stay in check.

Roof racks definitely make a difference.

Would you have any insight on positioning/placement of crossmembers that might allow for less MPG loss. I thought about experimenting some to see if they have less drag further back.

Aero is dependent on speed, so front to rear might work fine at one speed and be a big loss at another speed. Also, to get anything realistic you would have to check various amounts of cross wind.

Before computers airplane guys used to tape hundreds of 3 inch bits of yarn all over and then observe which way they pointed in use, or if they didn't point, but whipped around instead. But that mostly only works for surface flow.

A smoke wand could do it, but I don't know how you would do that while driving, and I doubt you can put it in a wind tunnel.

Maybe if you could come up with a very thin standoff like an antenna and a much longer bit of yarn you could move it around to see where the yarn flies.

Me, I would take off the cross bars and only put them on when I needed to strap something to them.

doublechaz, back when I first got this car I had the cruise control issue we addressed here. Before I did find the vacuum leak that was the problem, I monkied with the throttle cable and matched it more to my 97 legacy. I'm thinking that might be the reason it now tends to stall if I drive and stop and it then almost stalls when I take off from that idle stop and it does it more obvious when it is 100 degrees outside like it happens to be now.

Any suggestions on how I might set it back to factory default settings?

On mechanical throttles like cars our age you should be fine if the cable lets all the way off and it does not idle fast, and also if it opens all the way when you floor it. All that cable is doing is moving the butterfly valve to allow or block air. The air for idle goes through a different way. For these I have always adjusted it sloppy loose, and then tighten it until it starts to idle faster and then back off until a little looser than when it is back to normal. Then I shut down and visually verify that it opens all the way for floored.

There is a throttle position sensor to tell the computer what is going on. I don't think you could mess it up while working on the cable, but I'm not completely sure.

Nearly dying when you pull away sounds more like another vacuum leak. I don't remember how much of the vacuum lines you replaced, but originals are likely problematic at this age. A few years ago I really tore mine apart for a 250,000 mile refresh. That included replacing every single vacuum line. That is kinda a big job on our cars because some of them go under the intake, but I would definitely consider replacing all that you can, if you didn't already.

I have done damn near everything you can think of trying to improve my gas mileage. Pcv, air filter, fuel filter, checked for carbon build-up, tire pressure, removing junk, etc.

The only two things I’ve been able to see a difference in mpg with have been changing my spark plugs and having the roof rack off. I’m going to get a new front O2 sensor soon and see if that helps as well. Do the spark plugs if it’s been a couple years. I got 4 oem’s and didn’t spend more than $15.

On mechanical throttles like cars our age you should be fine if the cable lets all the way off and it does not idle fast, and also if it opens all the way when you floor it. All that cable is doing is moving the butterfly valve to allow or block air. The air for idle goes through a different way. For these I have always adjusted it sloppy loose, and then tighten it until it starts to idle faster and then back off until a little looser than when it is back to normal. Then I shut down and visually verify that it opens all the way for floored.

 

There is a throttle position sensor to tell the computer what is going on. I don't think you could mess it up while working on the cable, but I'm not completely sure.

 

Nearly dying when you pull away sounds more like another vacuum leak. I don't remember how much of the vacuum lines you replaced, but originals are likely problematic at this age. A few years ago I really tore mine apart for a 250,000 mile refresh. That included replacing every single vacuum line. That is kinda a big job on our cars because some of them go under the intake, but I would definitely consider replacing all that you can, if you didn't already.

That sounds like a very good idea changing all the vacuum lines I can. I've already replaced most of the components that would otherwise affect the hesitation with no satisfaction.

I have done damn near everything you can think of trying to improve my gas mileage. Pcv, air filter, fuel filter, checked for carbon build-up, tire pressure, removing junk, etc.

 

The only two things I’ve been able to see a difference in mpg with have been changing my spark plugs and having the roof rack off. I’m going to get a new front O2 sensor soon and see if that helps as well. Do the spark plugs if it’s been a couple years. I got 4 oem’s and didn’t spend more than $15.

I'm pleased to say that I am back to getting 24 to 24.5 miles to the gallon after removing the roof rack cross members. It clearly makes a 2mpg difference easy.

That is a lot of difference, but there is a lot of turbulence up there with the cross bars on.

I don't do that well around town, but that is because I installed the binary gas pedal mod. Highway only I can get up around 29.

That is a lot of difference, but there is a lot of turbulence up there with the cross bars on.

 

I don't do that well around town, but that is because I installed the binary gas pedal mod. Highway only I can get up around 29.

I've been taking it salmon fishing for the past 4 weekends which is a 220 mile round trip and then driving it around town till I'm down to 1/4 tank and fill up for the next trip. The trip takes me through the mountains and some very windy roads. When I had the crossmembers on, I couldn't get better than 22 on pretty much the same travel.

Doublechaz, I went ahead and replaced my Mass Airflow Sensor for $40 from Parts Geek hoping it would solve the slight hesitation I experience. I was pretty optimistic for several days but now we are hitting record highs in temperatures and I am still having some issues but have it narrowed down a bit. I feel like there is some improvement. Here is what I have left going on. When I am driving around during the heat of the day running errands, it only seems to hesitate right after starting it up and going in reverse so mostly when I am in a parking space leaving a store. It doesn't seem to hesitate at stop signs and lights from an idle. I haven't parked in a way I could take off forward instead of reverse but could set that up to test that.

I know my battery is a little weak and I am noticing it seems to take a little more effort to start that I feel it should. It always starts, it just seems to take a few more turns before she goes.

No check engine lights ever. I haven't replaced anymore vacuum lines because I haven't found any that even looked rough much less lose. I know there are dozens of possibilities but just seeing if you or anyone can use the info to maybe narrow it down to only a dozen possibilities. I've had weak batteries on Subaru's before that caused some very strange issues so I will never rule them out after a car being down for over half a year just because the battery was too weak to make everything perform as designed.

Too HOT to FISH.

I just drove 4000 miles and it wiped my memory so forgive me if I'm repeating myself.

When you first get in turn the key to run, but give it a three count before you try to start it. If it starts better that way it is a little slow to build fuel pressure. If it was 1997 it would hold the pressure for days so starts would be smooth. If the check valve in the pump, or the pressure regulator weep a little, or an injector or its seals leak a tiny bit, then the pressure bleeds down to zero when parked and it takes the pump a bit to catch up. If it is really noticeable dig in to it, otherwise just let it have that slight pause in key use at startup.

I forget if you have measured fuel pressure during driving. If it is a little low all the time, perhaps it is correcting for that with fuel trims except during tip-in.

I just drove 4000 miles and it wiped my memory so forgive me if I'm repeating myself.

 

When you first get in turn the key to run, but give it a three count before you try to start it. If it starts better that way it is a little slow to build fuel pressure. If it was 1997 it would hold the pressure for days so starts would be smooth. If the check valve in the pump, or the pressure regulator weep a little, or an injector or its seals leak a tiny bit, then the pressure bleeds down to zero when parked and it takes the pump a bit to catch up. If it is really noticeable dig in to it, otherwise just let it have that slight pause in key use at startup.

 

I forget if you have measured fuel pressure during driving. If it is a little low all the time, perhaps it is correcting for that with fuel trims except during tip-in.

I've been concerned about the fuel trim all along. I did just put a brand new battery in it, the top of the line and my old battery though only 4 years old tested pretty poorly. I notice some difference.

I haven't tested the fuel pressure while driving. I did replace the fuel pump when I first noticed the problem. I will give it to the count of three.

The hesitation only happens when very hot outside and it has been running for a while. I'm thinking it is also more extreme when the AC is running when I start the car and pull out of parking spot.

I also screwed up adding refrigerant to my A/C and overcharged it so now I am gradually lowering it because when it is 105 outside the AC starts cutting in and out and it makes the engine jerk and junk. It seems like the directions on the refrigerant can are too complicated for me. It was blowing cold, I just thought it should be blowing colder and screwed it up at a very bad time to screw it up. Hopefully after work I can drive it home with the AC running.

I'm going to look into the fuel trim more, it was suggested by someone here when I replaced the timing belt.