The VX

[krousdb]

Picked up the 1992 Civic Hatchback VX over the weekend. The car needed more work than what the ebay ad said. Not surprising I guess.

So I'm on I-90 in Indiana, and I start hearing a bump, bump, bump sound over the Thunk, thunk, thunk sound caused by the the rear tire with the bulge in it. The bumping soon turned into clunking then clattering so got off the toll road and limped to the nearest town which was Grainger IN. Remember now, it was the 4th of July.

I found a Advance Auto parts store that was actually open. I asked if they could fix my car. They said nope, but we have the axles. They gave me directions to a number of repair shops but all were closed on holiday. I went back and asked if I could change the axles in the parking lot. The manager says OK and lets me borrow tools. So I get out my Haynes manual and start following directions. I get to the part where you remove the axle nut. Holy hell! Those things aren't coming off. I also noticed that my warped rotors are dangerously thin and pieces of the brake material are missing.

So I go back in the store about to ask where I could find a motel. An older guy was getting parts for a repair and he asks if he can help. I said that he certainly could if he can help me install the axles. No problem he says but I only take cash. I had cash so no prob. Then I say, do you do brakes? He says no problem. Then I ask the clerk if he has rotors and brakes, he says no prob. So I buy the axles ($60 each) the rotors ($18 each) and the Pads ($22 each). Total was $190 minus the core.

So this guy Fred is a retired state corrections dept guy drives my car while I follow him in his van. 6 miles later we are at his house over the state line in MI. Over the next 3 hours I learn how to replace axles and install new rotors and pads. The worst part was removing the axle nuts. He had to get out the "Fire" wrench. He charged me $125 for his time and by noon I was back on the road again.

Spent so far:
$1800 for car
$110 for plane ticket
$325 for O2 sensor
$215 for muffler
$315 for axles and brakes

Total $2765. $1735 left over to spend on the body and paint. Hopefully the sale of the VX rims will pay for a cat if I need one.

[diamondlarry]

What kind of mileage are you getting?

[philmcneal]

awesome, working with mechanics while he teaches how to work on your own car, i wish i had someone like that.

sounds like the VX is almost ready for its prime...

Well hopefully the engine won't be as beat as the rest of the car. That would suck if it's got engine problems too and you could only get 35-40mpg or so. Good luck with it, 15 year old cars can be an adventure. I should know; I had a 1988 Civic in 2003.

[krousdb]

I had a look at the plugs and they are all colored very nicely. That leads me to believe that there are no compression or ring problems. I'm thinking that the bad O2 sensor killed the cat. I have a used one being sent to me for only the cost of shipping. The problem I have now is the main fuel relay which doesn't like to activate the fuel pump after every FAS. So I am avioding FAS until I get that fixed. I have adjusted my route for more highway to take advantage of the lean burn since I cant FAS. My FE has been in the low 60's as a result.

[Chuck]

I hope your new car ultimately runs well in it's old age.

I keep thinking about what that 1988 CRX HF would be like if I'd treated it kindly (probably 350,000 miles in it's 18th year).

If it turns out to be bad, it has to be better than this VX

Low 60's is still excellent! Glad to hear it sounds like the engine is healthy even after all these years. So how many miles are on it anyway?

[krousdb]

Originally Posted by AZBrandon

Low 60's is still excellent! Glad to hear it sounds like the engine is healthy even after all these years. So how many miles are on it anyway?

Only 132k. Interior is very good condition. A few rust areas outside where you normally see them. I can fix those no problem. First I have to get the cat installed and get it inspected. Then the underbelly and Mobil 1 in the engine and transmisssion. Then it is time for bodywork.

Today I decided to drive completely without FAS. That included stop lights (Wayne is cringing now). The trip to work (not much traffic and short periods of idling) yielded 62.27 MPG. The drive home (more traffic and longer periods oof idling) was 56.62 MPG. The RT ave was 59.27.

[krousdb]

I'm starting to get the hang of the lean burn on the VX. It feels strikingly familiar to the Insight lean burn. First, some info from the OBDI training manual.



The LAF (Lean air fuel) sensor can be used to detect AF ratios in a range from approx 12:1 to 22:1. These were used on the 92-95 VX and 96-98 HX. If an AF ratio richer than 12:1 is required, the ECU will go into open loop.



A good way to monitor AFR is to attach the positive lead of a DMM to the Pump Cell Control O2 lead and the negative DMM lead to the O2 reference voltage lead. This shifts the O2 output such that 0V is stoich, a negative reading is rich and a positive reading is lean. To test the LAF, when introducing propane to the intake would create a rich condition resulting in a reading of -1.3. To create a lean condition, you could disconnect one of the fuel injectors which would result in a 0.4V reading.



In practice, I have found that lean burn does indeed result on a reading of 0.4 to 0.5. That is similar to the reading that you woulld expect when you have one injector disconnected. I could then logically conclude that lean burn could reduce fuel consumption by as much as 25%.



Of course it takes time for the cat to warm up enough to enable lean burn mode. When starting cold, you will notice a reading of -0.77V. This is also what you would read if the LAF was disconnected, and similarly, you get the same reading when the LAF is dead. After a few minutes, the reading will oscillate between -2.0V to 0V. After another minute or so you will notice the reading stabilize around 0V and then climb to 0.40 to 0.45V during a lean burn cruise. During idle, the reading is cut in half to about 0.22V.



Lean burn on the VX has more range than on the Insight. I can climb even the steepest hill on my commute in 2nd gear and maintain lean burn mode. Moderate hills can be climbed in 3rd and more gradual hills in 4th. On the highway, lean burn mode can be held at speeds up to 65-70 MPH, much higher than the Insight. Once your vacuum drops below a certain point, it seems like VTEC kicks in and your instantaneous FE drops immediately by 1/3. For example, While climbing slight grade in 5th at 55MPH, I can hold 45MPG indefinately. When encountering a steep grade, you would open the throttle to hold your speed. As the injector pulse width reaches about 6.3ms before dropping out of lean burn. The instantaneous FE drops immediately to 30 MPG. This is very similar to what you would feel during a NOx purge in the Insight.



There is a downside to lean burn in that when you don't have it, the FE is worse than what i got with the Del Sol. And after a long engine off coast, the LAF has to warm up all over again. This means that I need to rethink my route to take advantage of lean burn. I am still learning the tricks and techniques and Im not doing to bad considering the fact that I have a bad fuel relay and I have stoppedengine off coasting. As soon as my relay arrives, I will try to push the VX to the limit. Until then, I will use the time to learn how to hypermile all over again.

[hobbit]

That's an awesome discussion. But does the pulsewidth go to
6.3 ms while still *in* lean burn, or is that the not-lean-burn
width? That's almost exactly the injector time the Prius exhibits
when in highway cruise, with very little variation. And that
in theory isn't lean-burn but *should* at least be a high torque
scenario.
.
I've spent most of the day upended under the dash of the Prius,
doing another round of mods pre-Hybridfest. I'm thinking of
throwing together a stupid-simple integrator for the injector pulse
which I've already got into my panel, and get some ballpark idea
of percent-duty in realtime while driving. Might be instructive
to have it for an 1100 mile drive...
.
_H*