New 1993 Civic VX owner - O2 question

[B16DelSolVX]

FYI, i signed up for ecomodder because of this thread. i am a auto tech by trade, and a life long honda enthusiast, and am going to get to the bottom of our problem. I am having the exact same symptoms in my del sol vx. i thoroughly checked all the wiring, checked o2 readings and resistance, which are all good. it goes into lean burn and goes WAY too lean, which causes the car to buck and hesitate. i ordered a replacement ecu, which should be here tomorrow. i'll let you know if i have any success.

[93civicvx]

I received my 2nd NEW O2 sensor last week...

The 1st was the Walker brand, which behaved no differently than the malfunctioning O2 that was in the car when I got it.
This 2nd one is a Denso and it APPEARS to be working properly !! Instead of the distinct - ruff running, bucking, sputtering and basic crappy performance at ANY speed in ANY gear, the car runs "smooth" albeit the feeling of mushiness when trying to ecomod it ( mushiness is the best term I can use to describe how it runs, I assume, in Lean burn mode ). When getting on it from a stand still ( pedal to the floor ! ) it took off and pulled strong throughout the gears ( no mushiness ) - despite my cringing at the amount of fuel I was wasting ! LOL This was the method I used to determine between 8v vs 16 valve performance...

I received my MPGuino back from repairs about a week before the 2nd O2 install. Out of the box, the MPGuino was within 1 MPH in accuracy as referenced to my cars speedo speed wise at any speed and also within about 1 mile as referenced to my odometer distance wise. The MPG was high and so made 2 adjustments to narrow it in... It isn't dialed in perfect yet, but irregardless, it is ready to evaluate the 2nd O2...

During the week on my normal commute to work, I collected MPG data numerous times on the same stretch of road at given speeds ( 45, 50, 55 & 60 ) in 5th gear so as to have a reference point when trying out the newest O2. At these speeds I was careful to make sure the speed was very stable for a bit and that the MPG was locked on - not increasing or decreasing...

My observed PRELIMINARY gain ranged from about 10 - 18 MPG !!!!
Now, as excited as I am about this, I will await the raw numbers when I fill up at my next tank ( keeping in mind that the newest O2 was installed with about 140 miles on the clock, as well as run at least 1 or 2 more tanks thru it ). Look at my garage to see how my gas mileage has been for my 14 previous tanks... I believe I have a good reference base to measure against.

I will keep everyone posted as well as let you know the part # and place of purchase and who to talk to once I confirm satisfactory results...

[B16DelSolVX]

Thats very interesting that the manufacturer of the O2 makes that big of a difference. I received my new ECU just to find it was a CALI unit falsely/accidentally posted as a FED unit. Now, im curious to discover if the O2 is actually my problem. With my current ECU, which is a P07-A, there is no Check Engine light, but when it goes into lean burn, it goes way lean according to the sensor, 1.3 volts. Does anyone have any info on what the cheaper sensors read when having problems with them, or does this sound like an ECU issue?

[93civicvx]

Filled up today, with much anticipation...
50.8 mpg for this tank !!
Keep in mind, that the first 140 miles or so was WITHOUT an O2 connected !!
So, this next tank will provide the real mpg. Than of course, as repeated over many more tanks, yield the realistic consistent MPG AVG...
Turns out, that the 2 tweaks I did to the MPGuino regarding gas consumption, were nearly dead on. The MPGuino "TANK MPG" was 51.0 and my trip meter/gals fuel consumed, was 50.8 - I can live with that.

More to follow...

[93civicvx]

The DENSO 234-5052 O2 solved my failed '93 O2 issue. I tried the Walker version specified for the car but it behaved the same as the existing failed O2...
The DENSO was the second choice of the 4 I had to choose from, yet it was only the 2nd most expensive - $200, hence it being my 2nd choice.
You can find it for about $180 on the net + S/H...
Hope this is of some value to someone banging their head due to the finickiness of the VX's O2.
I am now in the 50's mpg wise ( if you look @ my garage, PLEASE read the details of my gas logs, as it is more accurate than what the bar graph indicates.
Douglas

[B16DelSolVX]

I bought the NTG 5-wire sensor from Summit Racing, which they had in stock and price-matched for me. The best MPG I got before, was 47. I installed the new sensor at 130 miles on this tank, and I could tell very quickly that it fixed my problem. I will post the results from this tank and the next very soon