Adding an O2 sensor?

really? can you post a pic? it's hard to imagine the point of running fuel injection absent the sensor because without it, the ecu doesn't know for sure how much gas to inject.

presumably.

presumably, but you may need to do extensive wiring mods. it could save you significantly in gas.

double check on this "common knowledge" thing - i've never seen any electronic fuel injection system that doesn't have a sensor - without it, the ecu is "blind". check both sides of the cat as well as in the manifold. it would be amazing if one wasn't there somewhere.

Interesting. Early fuel injection systems sold in the US were indeed open loop designs, such as the Bosch D-Jetronic which was installed on many late 1960s and early 1970s era Volkswagens and Volvos. Closed loop came into general use about the same time as three way catalytic converters did. Late 1970s and onward.

I suppose that it is possible that car makers built open loop versions for countries without emissions regulations much later than the 1980s, but I have no idea how it was done or if it is possible to easily convert such systems to closed loop operations.

John

Hello again and thanks for the replies. I've posted photos at this link, if you're interested:

I think this version (ESi, Philippines) is a "stripped-down" version, if you will, of the EG 4-door coupe (92-95) with a D16Z6 engine, minus the VTEC. I've been using the service manual for some time now, and all other parts match. The manual doesn't say anything about other O2 sensors though.

This may have been done to make it more affordable, even though at the time this was the top-of-the-line model here. Also, the emission laws here aren't as strict as in the U.S., and back in the early '90's they were even less so.

Am I missing something here?? Are our civics "crippled"?

John Horner wrote:

it certainly looks that way! john raises the good point about pre-catalyst injection systems not having sensors [i'd forgotten that - it's /so/ long since i've seen one!] and you've posted the pics. but it still amazes me. the cost of a sensor, in bulk, to a manufacturer has got to be less than $50. it's astonishing that honda would elect not to use one - maybe there was a legal reason.

getting back to your original question, you can almost certainly retrofit, but there will obviously be wiring involved and it would probably require acquisition of a new ecu. interesting project though! and you may as well go for the vtec while you're at it!

you're absolutely right.

John Horner wrote in news:49MMg.2566$xC3.1076@trnddc06:

Corvettes used to have a MECHANICAL fuel injection option(totally open- loop),long before EFI came to be.

"Jim Yanik" wrote

Anyone remember the Lucas mechanical FI system? Wonderful when it worked properly, a pig when it didn't, which was most of the time, being made by Lucas ...

And some Peugeot 404's had a mechanical FI system too.

sd

Does it have a converter?

Al

Look at any old diesel engine, particularly those on tractors and heavy equipment... mechanical FI there as well.

Now that you mentioned it, it's also "common knowledge" here that this ESi doesn't have a catalytic converter! I'll have to go check.. where might it be located?

it's a huge bump in the exhaust, round about where the passenger seat is. but if you don't have an oxygen sensor, you won't have a cat.

regarding retrofit, it's not essential to have the cat. - the important bit is the sensor.

Fuel could also be an issue. In places where tetra ethyl lead continued to be used as an additive there would be an O2 sensor contamination issue. TEL was outlawed in the US many years ago, but much of the rest of the world continued to use it as an octane improver.

That would explain the lack of O2 sensors in countries where the use of TEL continued.

John

That could be it! Unleaded fuel was introduced here in 1994, while the EG line was from 1992-95. Is it true that leaded fuel could damage the O2 sensor?

If this is the reason, and not cost-cutting, then could I simply, as jim says, "retrofit" a sensor? (Taking care to use only unleaded fuel, of course).

The ECU is a P27 (OBD-1 EG JDM Civic 1600 sohc VTEC) which I think is the same as the one used in the EX US version. However this model has no VTEC, and no O2 sensor. Could they have left the ECU "as is"? Wouldn't Honda have used a different ECU code if it's not the same one? I'm just hoping that it is, since it means I could just plug a new sensor in.

I'm not after the VTEC, just want to save on gas.

Absolutely. Leaded fuels also deteriorate spark plugs, but they are readily changed. In the days when leaded fuel was the norm in the US, typical spark plug change intervals were 12-15k miles. Now with unleaded fuel and slightly better spark plugs the norm is 100k miles.

TEL leaves nasty deposits when it burns. These rapidly build up on oxygen sensors and ruin it. They also build up in exhaust systems and on exhaust valves. Oddly enough, the build-up on exhaust valves acts as a sort of solid lubricant. When the conversion to unleaded happened in the US, some older cars had very rapid exhaust valve seat wear due to the lack of TEL's valve lubricating side effect. Other than for exhaust valves, everything else about TEL fuel is a downside for the motor!

You would need someone who really knows the Honda fuel injection system in detail to answer that. Perhaps you can get your hands on a parts manual for your version and the US version and try to compare what is different from one to the other. Maybe it is as simple as connecting an O2 sensor, maybe not. The US version is certainly capable of running open loop in the case of a failed O2 sensor.

Do you have any friends in Honda's engineering department :) ??????

John

John Horner wrote in news:alpNg.1569$FS.37@trnddc04:

I believe the ECU would be a different model than a US OBD-I ECU,as a US ECU will set a code and light the check engine light if the O2 sensor fails. "not present" counts as "failed".(open) The Euro ECU's program would have to know to ignore the missing sensor,thus a different ECU. ECU programming is fixed in PROM,thus a different PROM,and a different ECU p/n.

Tell that to my '87 Accords, all of which have had cats and no O2 sensors.

Or my old '80 Mazda GLC, for that matter.

The cat IS essential if your local emissions laws require it!

ok.

indeed, but this is apparently not the case for the o.p.

...or my '82 & 83 Civics.

'82 is exempt and '83 soon will be!

JT

these are using ECUs programmed for mileage. Stock ECUs are programmed for emissions. . . . You should count yourself lucky to live in a jurisdiction with more reasonable emissions laws and thus a simpler vehicle. Honda OEM oxygen sensors and cats are priced in the hundreds of dollars."

I respect TeGGer's responses, but do you guys think he's right on this one? What if our cars here in the Philippines are programmed for mileage, instead of emissions as TeGGer says?