Question about O2 Sensor

[EburgE]

Just about to start the Zetec for the first time in my Caterham. Unfortunately, I missing the O2 sensor for the enhaust.

 

Engine building says I don't need one.

 

Dealer says to get one from Ford dealership, but the Focus connector (round weatherpack) does not match the Caterham wiring harness (square).

 

Any advice? Would it hurt the engine to not have the sensor in place?

[slngsht]

not in the short term for driving around, but you shouldn't drive long distances without it. You do need something to plug the hole before you drive. I *believe* some spark plugs have the same thread... If you are totally dying to drive it in the rain tonight :lol:

 

Anyhow, it wont hurt your engine, but if the base calibration is too rich, it can hurt your cat.

 

what does the Caterham use for the O2 sensor? I imagine it would just be another ford part number.

[EburgE]

I have bung plugs, so that's not so much the issue. (Think it is M18X1.5, and yes I hear the spark plug trick works too.)

 

Just wondering whether I need it in there to start the car, and in the long term. Sounds like not necessary to start the car.

 

In the long term I will either

1) order the sensor from Caterham with the proper connector or

2) use the Ford dealer's sensor and replace the Ford connector with the style that Caterham has on the harness.

 

 

[Boxologist]

hal,

were u using the Ford ECU or going to a standalone unit? when the ECU was ripped out in NC last summer my car died on the spot, but i feel that it may be due to the ciruit being ripped instead of seeing a failing O2 sensor.

 

it won't harm teh engine in either regard. I expect that with teh Ford ECU u will be in either limp mode or the engine just won't power teh ignition.

[BobDrye]

Just about to start the Zetec for the first time in my Caterham. Unfortunately, I missing the O2 sensor for the enhaust.

 

Engine building says I don't need one.

 

Dealer says to get one from Ford dealership, but the Focus connector (round weatherpack) does not match the Caterham wiring harness (square).

 

Any advice? Would it hurt the engine to not have the sensor in place?

 

 

 

A modern engine computer uses many sensors to determine the injector pulse width. The O2 sensor is just 1 of many. The primary pulse width is determined by either map or air mass sensor, and then by engine speed. Other sensors such as TPS, CTS, IA, Throttle position, O2, are used to further fine tune your injector pulse width. This is used to run at an air fuel ratio that is best for emissions, not power. When all of the sensors are operating and the engine is warm enough, it will go into a finer state of tune called "closed loop". Without an O2 your engine will never go into closed loop. Modern emission engines default into a catalyst protection mode, which means that it will run leaner than normal. It should run well in a seven, even in open loop.

 

 

[JohnK]

Bung for O2 sensor is 18mm - 1.5mm pitch thread, some US cars use that size spark plug.

 

All of the systems I've worked with only listen to the signal from the O2 sensor when doing moderate driving - it doesn't enter into the running of the calibration during aggressive driving.

 

The sensor sends a small voltage to the ECU when there is little oxygen in the exhaust stream (i.e. running rich), so without the signal from the sensor, the ECU will think the engine's running lean. Since the range that the O2 sensor is listened to by the ECU is limited to modest driving, the safest thing to do is drive real fast ;-). Depending on your ECU, there may or may not be an issue; question is, is the ECU smart enough to know that the sensor is not working and ignore it in its calculating. I would expect that a standard FORD MAF controlled ECU is that smart. I've never heard of anyone frying an engine by running without this sensor, but if the engine is high output (runs closer to the edge), I'd be a bit concerned, particularly during light throttle steady cruise.

Cheers,

[EburgE]

Once again, thanks for the answers. I don't know where I'd be without you guys.

 

My current strategy is to adapt the O2 sensor from Ford to match the Caterham harness, but not worry about it for starting the engine.

 

I will put a bung plug in the rear hole. (Did I just say that?):ack:

 

The cooling system has been filled. Tomorrow the battery will start to charge. The engine should come to life this weekend.:7frog:

[EburgE]

Thanks again, everyone for all the help. O2 sensor is not required for this ECU program.

 

Not to hijack my own thread, but from my blog www.hals7.com...

 

After almost four months of building, tonight the engine started. Words cannot express my sense of relief. The day began with a trip to Quicksilver RacEngines in Frederick, Maryland to pick up the ECU, with a stop on the way back for battery acid. Needless to say, the fun was just beginning.

 

The Startup Procedure was the most useful section of the Assembly Guide so far. After a number of cursory checks, the procedure calls for disconnecting the inertia switch and then cranking the engine to build up oil pressure. That part worked. Unfortunately, oil was seen gushing from around the filter. After a quick trip to Walmart for a filter wrench, the filter still suffered from major leakage. There was nothing left to do but drain all the oil from the engine and inspect the filter. As soon as the filter was removed, the problem was obvious: the old filter gasket had not been removed when the new filter was installed. Two gaskets is not twice as good.

 

The next step called for connecting the switch and turing on the ignition to listen for the fuel pump. The fuel pump was very easy to hear in this case because fuel was gushing from the upper fitting. They guys at the factory must have pounded a few at lunch that day. No problem, I should have checked their work.

 

Next, while refitting the oil filter all hell broke loose and sparks were a flying. My bad: I managed to dislocate the power line from the battery at the alternator resulting is a major short circuit on the chassis. That took only an hour or so to fix. To my surprise, the rest of the car's wiring was okay, the battery was okay, and not one fuse was blown.

 

Finally, around ten o'clock, the engine cranked right up. Good oil pressure, fine smoke from the new header pipes, and no obvious water leaks. The engine ran for only about 5-10 minutes, just long enough to register some temperature on the gauge. After it was shut off, the clamp on the bleed nipple at the top of the radiator was opened and only water, no air, was found. That may be a good sign. (Later I will post about the procedure for filling the cooling system after confirming that there are, in fact, no air pockets.)

 

Tomorrow is another day. The goal for this week is to get insurance in preparation for a blat!

[slngsht]

congrats on the major milestone.

 

as soon as i read oil leak at filter, I knew there'd be double O rings, or in your case, gaskets. you should never have to use a wrench to tighten an oil filter.

 

well, you'll have your car on the road way before me.

[EburgE]

congrats on the major milestone.

 

as soon as i read oil leak at filter, I knew there'd be double O rings, or in your case, gaskets. you should never have to use a wrench to tighten an oil filter.

 

well, you'll have your car on the road way before me.

 

Thanks, Mazda. In the past I have never used a filter wrench either. I just assumed this engine was different.

 

Oh yeah, and that "fine smoke from the new header pipes" was not the headers. It was the unused O2 sensor connector that I forgot to tie up melting on the exhaust! Doh!!! :banghead: