Vx bad 02 sensor diagnosis

[GasSavers_ElCheapo]

Hey guys,

Question for you regarding how to diagnose a bad 02 sensor on my 93 vx. A few background bits.

I bought the car about 2 years ago with 135k on it, now 155k. Totally stock, down to the 13 inch rims. Whilst not bought from the original owner, it was bought from their car wash guy who bought it for his nephew who didn't want it. As such their was no additional mileage put on it after the original owners, so the car was in very good shape. Lucky me. Sweet rust free ride for $2200 cash.

The problem: my car has never gotten that good of gas mileage (by vx standards anyway). The lifetime average (that I have had it) is 38.97 mpg (80% city/20% highway, 60-65mph) with only 13 tanks being > 40 mpg. Of those 13, 1/2 of the high mpg tanks were followed by lower than average tanks. I drive pretty darn docile, with most of my shifts being about 1600-1800 rpms, and lots of coasting to stop lights to maximize coast and not come to a stop.

I have researched quite a bit on here but don't see any easy way as to conclusively diagnose a bad o2 sensor. This thread http://www.gassavers.org/showthread.php?t=2427 shows a way but that gets a bit complicated. I will take that routes if necessary, but rather avoid it.

When I bought the car the sensor wires looked pretty darn clean so I wondered if it had been replaced already. What it is stamped on the outside of the sensor: c6 (I think) OOo L1h1 Japan.

Additional to the bad mpg sometimes my sil works, sometimes it doesn't.

What I have done regarding the o2 sensor:
1) Unplugged it. Cel is on, car runs much smoother, no lean burn stumble. Just did a run around the block so no mpg results.

2) Paper clipped the jump socket on the passenger kick panel. I got NO flashes at all, just a solid light.

What I have done to the car:
Dunlop A60(?) tires, inflated to 37psi (5 above limit)
New Bosch plug wires shortly after purchase. Just replaced these yesterday as they were arcing already.
Honda fuel filter
Sears die hard battery
Every 12k miles:
Splitfire platinum plugs
Honda air filter
Honda cap
Honda rotor


On a side note, my car beeps six times on start up. I don't recall it doing that before but it's quite possible it did. Seems like a lotta beeps though.

Thanks VERY much for any help you can give.
ElCheapo

[GasSavers_ElCheapo]

This seems pretty simple. You can just use a standard digital volt meter instead of the gauge correct?

http://www.youtube.com/watch?v=1mb4V...eature=related

[GasSavers_TomO]

First off, get rid of the Splitfire plugs and get the Stock NGK Vpower ZRF4-11 that should be in there. A set of NGK cables (or NGK Power Cables if you can afford them) or the OEM plug wires from Honda are best. Platinum plugs are not effective in the D15Z1.

You can just hook up a Digital multimeter to observe the O2 sensor. This will give you an idea of it's response time and if it's getting lazy or out of range. The O2 should be quick to react and be consistently changing values even when holding the gas pedal steady there will be some slight fluctuations in the readings. But change those plugs first, that will help immensely.

A solid CEL when jumping the service connector can sometimes be an indication of a faulty ECU. Maybe see if you can pick up another P07 ECU for cheap and try it out for a few tanks.

Driving around city isn't the VX's forte, but can be made to get anywhere from 40-45mpg for city driving.

The beeping 6 times when starting is just the seatbelt reminder.
Try this:
Sit in your car, buckle up, then insert the key and turn it to the run position...the lights should illuminate on the dash (oil, battery, SRS, CEL, and upshift light) and there should be no beeping.

Do it all again but don't buckle up this time, it should beep 6 times.

[GasSavers_ElCheapo]

O so knowledgeable TomO.

Thanks for your reply. A few more questions please. In your experience with the ZFR4F-11 are there local auto parts stores that stock these? Big nationals (AutoZone, Advance) don't list them o/l, but PepBoys does. Nearest one of those is 20+ miles away. Or if only o/l how would you recommend to buy from?

I've done a little more research on testing the o2 sensor (it was about 2 am when I posted originally lol) and that seems pretty straight forward.

As far as the ecu is concerned, what's a good price? $50 plus shipping seems to be the norm on one of the civic forums on another site. Is it true that a "L" near the end of the ecu number designates it as a California ecu?

Thanks for all your help and clarification on the seat belt reminder. lol.

[GasSavers_TomO]

All the locals (NAPA, O'Reily's) carry them near me in MN. You can order from both of those stores online: Oreily's and NAPA

To me (and me being a cheap tightwad) $50 plus shipping a a tad much, but I usually score VX parts for free since ll the racers/ricers get rid of all there VX/CX stuff for free. But if $50 plus shipping is a good price to you then go for it.

The 49 states version of the PO7 ECU ends in "A01" or "A00" (there was a 92-93 "A00" version and a 94-95 version"A01)
The california version ends in "L00" or "L01"

So the ECU number would read: 37820-P07-XXX Where"XXX" would be the A01, A00, or L01