Can a bad VSS cause poor mileage ?

[Cd]

1993 Civic DX Auto(tragic) close to 150,000 miles.

My mileage is horrible lately , but what puzzles me is that the car fires up with great gusto. Turn the key and it seems to explode to life. Not even a single rev of the starter is heard. Every time.
Despite this, the car has always had super weak yellow spark. I changed out the distributor and have new wires and plugs. The car is grounded well.
I don't get it.
For the longest time I had an issue with the car not starting when it was humid outside. It was extremely predictable that the next day that the car failed to start, it would be raining.
I changed out the main computer box - the ECU- and that fixed the problem.
I guess that having the windows cracked was letting in just enough rain to trickle down into the ECU. ( which is located in the passenger side footwell )

As I posted in a separate thread, I sometimes smell a gas odor in the cabin after a fill up ( No it's not coming from me ) I changed out the fuel pump when i had the ECU problem, and the seals around the access panel are in good shape. I'll update you guys next time I fill up, since i will check the seal then.

Now, onto the VSS problem . For the last few months, I have been driving around with a funtional speedometer, but a non functioning odometer and trip meter.
Fairly recently, the speedo has stopped working as well. Sometimes it does, sometimes it doesn't.
I notice one of the things that makes it act strange is to go over railroad tracks.
When i do that, the speedo goes nuts and bounces all around. What could that be a sign of ? ( this is an automatic )

Today I replaced the VSS ( Vehicle Speed Sensor ) three times, and each one failed on me.

So to ask my original question, could an otherwise reliable car ( cranks right up every time ) be affected by a bad VSS to the point of losing 15 mpg ?
The transmission shifts at all the correct points and makes no funny noises at all.

I think i have a combination of things bringing my mileage down, but it just puzzles me that the engine fires right up and the transmission shifts fine as well.

Thanks guys. You are appreciated.

[Cd]

I just thought of something obvious : Perhaps the car is just running too rich a fuel mixture ? What are the symptoms of that ?
The exhaust smells normal, and there is no fuel vapor left at the tailpipe.

I worked with a guy that had a hatch just like mine. He ran the car rich, and I remember the fuel stain behind the car. ( The ground was literally wet under his tailpipe from spent fuel )

[P-hack]

I didn't see any mention of the ignition coil/ignitor.

[Cd]

That's a new part as well. I bought and installed a new distributor, which has all new parts.

[California98Civic]

What about break drag? How about a compression test? Is it bruning oil? The rail road thing suggests an open in a wire somewhere to the speedo or VSS, but I can't imagine any of it is related to your FE drop.

[user removed]

If the speedo was working when the odo was not, it has to be in the speedo head.

Speedo reads current speed (frequency of vss signal)
odo reads distance travelled (total number of vss signals)

BOTH require a functional vss (its a revolution counter), so if one is not working while the other is then the vss is not the issue.

If you are recording mileage based on the odo then there is your problem.

replace the speedo head.

regards
mech

[user removed]

A tired O2 sensor can cause a 25% loss in mileage without any cel.

Bad fuel pressure regulator, check pressure, or pull vacuum supply lime and check for fuel leaking into the line.

What do the plugs look like?

regards
mech

[Cd]

Thanks Mech. The plugs are fine. A bit of oil blowback on the threads from not sealing all the way, but otherwise fine.
When I got the car, I replaced the O2 sensor, eventhough nothing was wrong with the old one because I was looking for ways to decrease the emissions over stock. It's a Bosch brand, and has been on the car for maybe 5,000 miles.

Hey - here should be a big clue for you guys too : When i plug in my SuperMID and drive the car, the data changes constantly with a functional VSS.
However, now all i get is the timer function. If the speedo cluster is bad, this wouldn't have a thing to do with the SuperMID function, correct ?

I'd like to change out the gauge cluster anyway, because it doesn't have the tach. ( which is admittedly useless on an auto. )

[Cd]

Originally Posted by California98Civic

What about break drag? How about a compression test? Is it bruning oil? The rail road thing suggests an open in a wire somewhere to the speedo or VSS, but I can't imagine any of it is related to your FE drop.

Brake drag is not an issue, because I can put the car in neutral and coast with no issue. I suspected my brakes were dragging because i have to give the car gas to get DOWN a hill while in Drive.

But then i found out that is just a wonderfully delightful design flaw with a dreaded autotragic

Burning oil - not anymore than normal for a car with this many miles. The oil smells like it should. It's a dark honey color, since the car is due for a change.
Something I'd like to ask about is if it is normal to have your exhaust smell like oil after a change. Open a bottle of oil and take a whiff and that's what I smell some of in my exhaust. That tells me it's burning oil, yes, the oil is the correct color, the car does not smoke, there is no drop in the level of the oil, and a big clue for me is that when I get my emissions test, the car does fine.

As far as the open wire, you have a good point. I'll have to tighten those wires better .

[Cd]

I filled my car two days ago. This time, I stopped before the 'click' of the gas pump.
When i got back in the car, I didn't smell a strong gasoline odor, like i sometimes do after a fill.
This led me to start thinking I was just smelling the results of overfilling the tank.

However, today on the drive home, I smelt the gasoline smell again. ( 35 minute drive, five or six stop lights, idle of maybe three to four minutes tops. Temp today was 70 degrees. Car was at normal temp and running perfect. )
I noticed the gas smell when i had my window rolled down, but when rolled up, no apparent smell.
When I got home, I opened the hood and sniffed all around the engine, the fuel pump and the lines.
No smell and no leak at all.
I then lifted my back seat and smelled there where the fuel pump is .
No gas smell.
Puzzled, I crawled under the car.
No leaks on the tank or lines going to it. A very slight gas smell there, but most likely normal. It smelled like when you have a gas can that is plugged up with a rag. It's vague.

Now here is something that caught my attention : I heard a hissing coming from the gas tank . I will upload a video tomorrow of it so you can hear it. ( cell phone and laptop not communicating at this time. )
The tank was very cool to the touch - not even warm in the slightest.
Is this normal ? It sounded like a steeping tea pot.

What would cause this, and where in the heck is the gas smell coming from if its not under the hood, not in my cabin, etc.

Is there a crack in the gas tank as you guys suggested ? I guess it would have to be at the top, eh ? If it was on the sides or the bottom, i would see leaking fuel - which i do not.

Regarding the VSS problem, I took off the VSS entirely and drove around the parking lot. The car acts the same as when i have it hooked up and the VSS acts up. The needle flatlines, but the car drives fine otherwise. No symptoms.

I reattached it and the speedo worked fine for most of my trip, getting a "nervous" bounce towards the end of the trip. The odo kicked in for a few miles as well, but then failed again.

When this problem first started years ago, my speedo would get the nervous bounce always around 10-12 minutes into a trip. Just as the car began to fully warm up. I thought it might be a transmission issue.
Curiously, my odo and trip meter never failed though.

Thanks for the patience guys !


So why not just take the car into a shop ??
Well ...I'm cheap.
I'm cheap, and i also live paycheck to paycheck. My rent is always going up but my rate of pay stays the same.
Also, the car is worth around $ 500 if i sold it. That is what finding one of these issues would probably cost me.