In reference to "shitty gas mileage, what the frack do I do?" Being it might not be related, I thought it best to start a new thread.
We might be in the same, expensive to run, boat. Our '95 3.5L has 120K on it, and for the last 5K miles, or so, MPG has gone from mid-20's to upper-teens. Driving habits didn't change, I've gotten gas at a half-dozen different stations, even pulled the timing belt cover to make sure the timing was still good. All was well, though I moved a cam from right on the timing mark to just barely between the two. After that much work, I was gonna do *something*. Plus, I thought it might be related to not being able to pass emissions, but just barely not being able to pass.
I put in new O2 sensors when I couldn't pass the OR emissions test. No change. New NGK plugs, replacing the Boschs the Trep never did like. Nothing. New wires...ooooh, a *tiny* improvement, like 1 MPG, up to 19 MPG on a 300 mile trek around the DFW area to use a tank of old fuel. Was still 80F, so A/C was on most of the time. Turns out, the A/C was on when the test was being performed. Ah, HA!
It turns out this low MPG happens only with the A/C on. I disconnected the electrical connector for the compressor, to take that drag out of the loop, and tried a tank with the A/C on, but not really 'on'. Bingo, shitty mileage. A/C off, all is well. Also, while the A/C is 'on', I get the occasional code 51, which I recall as running lean.
More stuff, one bank, I don't remember which side now, runs leaner than the other with the A/C on, verified by looking at the plugs. I mean *china* white lean. Tried a new engine computer...nada. Replaced the PCV valve...I think that's what it is, the little black part which screws into the driver's side of the side of the intake manifold. Still nothing. This is the part which causes ultra-rough running when it sticks. Thought about replacing the EGR valve, but that thing is a total ***** to get to, and it didn't seem to be causing any problems.
I've thought about an intake leak, but vacuum is perfect, and it wouldn't change with A/C-being-on electronics working their magic. Wait, I never checked vacuum with the A/C on vs. being off. Hmmmm. I can't imagine anything changes...though I know GM's used to use vacuum for the ventilation duct doors.
I'm almost certain there are a few others here with a similar problem, anyone have a clue? The car is in storage for a while, so while I can't check anything for a while, the car is a long-term keeper, so I'll eventually get to try things.
What really sucks is, over the past year, while not being so much as started, it managed to lose about 1.5 gallons of coolant...no drips, no leaks while running before or after I parked it, nothing. I added only water, as I overheated a few miles from the storage place...mom's house...and I forgot to add coolant back to it...duh. Damn, I feel like a complete idiot now, 'cause of course it was gonna be winter, but was warm at the time. I'm not sure where the coolant is going, but it isn't leaking out of the reservoir, so with any luck, there's an air pocket in the block somewhere. It's done this for years, now. It used to be a drip from the water pump, but that was fixed a good while ago, and the behavior never changed. It's time-related, not engine runtime related, which is even stranger, at least to me.
On the cold front, the car is in Dallas, TX, but they just got into the teens, tempwise. I think, because I had 60% antifreeze before adding a gallon plus of regular ol' H2O, I'm good to around 5F, but does anyone know how much the whole system holds? If so, I can do a couple of calculations to get a feel for how low it's safe to, and if need be, I'll beg my bro-in-law to go over, drain some water, put in straight antifreeze, fire it up, let it circulate for several minutes, then shut it back down. Ack, the thought of a cracked block is downright painful.
Sorry for the rambling, multiple topic post, but I don't know how long I have my current connection.
We might be in the same, expensive to run, boat. Our '95 3.5L has 120K on it, and for the last 5K miles, or so, MPG has gone from mid-20's to upper-teens. Driving habits didn't change, I've gotten gas at a half-dozen different stations, even pulled the timing belt cover to make sure the timing was still good. All was well, though I moved a cam from right on the timing mark to just barely between the two. After that much work, I was gonna do *something*. Plus, I thought it might be related to not being able to pass emissions, but just barely not being able to pass.
I put in new O2 sensors when I couldn't pass the OR emissions test. No change. New NGK plugs, replacing the Boschs the Trep never did like. Nothing. New wires...ooooh, a *tiny* improvement, like 1 MPG, up to 19 MPG on a 300 mile trek around the DFW area to use a tank of old fuel. Was still 80F, so A/C was on most of the time. Turns out, the A/C was on when the test was being performed. Ah, HA!
It turns out this low MPG happens only with the A/C on. I disconnected the electrical connector for the compressor, to take that drag out of the loop, and tried a tank with the A/C on, but not really 'on'. Bingo, shitty mileage. A/C off, all is well. Also, while the A/C is 'on', I get the occasional code 51, which I recall as running lean.
More stuff, one bank, I don't remember which side now, runs leaner than the other with the A/C on, verified by looking at the plugs. I mean *china* white lean. Tried a new engine computer...nada. Replaced the PCV valve...I think that's what it is, the little black part which screws into the driver's side of the side of the intake manifold. Still nothing. This is the part which causes ultra-rough running when it sticks. Thought about replacing the EGR valve, but that thing is a total ***** to get to, and it didn't seem to be causing any problems.
I've thought about an intake leak, but vacuum is perfect, and it wouldn't change with A/C-being-on electronics working their magic. Wait, I never checked vacuum with the A/C on vs. being off. Hmmmm. I can't imagine anything changes...though I know GM's used to use vacuum for the ventilation duct doors.
I'm almost certain there are a few others here with a similar problem, anyone have a clue? The car is in storage for a while, so while I can't check anything for a while, the car is a long-term keeper, so I'll eventually get to try things.
What really sucks is, over the past year, while not being so much as started, it managed to lose about 1.5 gallons of coolant...no drips, no leaks while running before or after I parked it, nothing. I added only water, as I overheated a few miles from the storage place...mom's house...and I forgot to add coolant back to it...duh. Damn, I feel like a complete idiot now, 'cause of course it was gonna be winter, but was warm at the time. I'm not sure where the coolant is going, but it isn't leaking out of the reservoir, so with any luck, there's an air pocket in the block somewhere. It's done this for years, now. It used to be a drip from the water pump, but that was fixed a good while ago, and the behavior never changed. It's time-related, not engine runtime related, which is even stranger, at least to me.
On the cold front, the car is in Dallas, TX, but they just got into the teens, tempwise. I think, because I had 60% antifreeze before adding a gallon plus of regular ol' H2O, I'm good to around 5F, but does anyone know how much the whole system holds? If so, I can do a couple of calculations to get a feel for how low it's safe to, and if need be, I'll beg my bro-in-law to go over, drain some water, put in straight antifreeze, fire it up, let it circulate for several minutes, then shut it back down. Ack, the thought of a cracked block is downright painful.
Sorry for the rambling, multiple topic post, but I don't know how long I have my current connection.