Time for o2 sensor to reach 600 degrees?

[TX82FIAT]

Folks, How long does it take a cold Spider after start up sitting idle to get up to the required 600 degrees or so for the o2 sensor to close the loop and start feeding readings to the ECU? 2 minutes, 5 minutes?

I have a megasquirt system that is running well with the exception of cold start up. On cold start it runs a little rich and that is not an issue as long as I get it on the road and warm. The laptop has not been connecting lately so I added the blue tooth connection and an application on the android phone. All readings are displayed on the phone fine with the exception of air fuel ratio. Currently the car is on jack stands until later this weekend so I can only start it and run it at idle for now. However, i was thinking the manifold should still reach 600 degrees within five minutes or so at idle. Ran it last night in the garage for about 4 minutes and the air fuel ratio read the minimum reading of 9:1 with no fluctution at all. It take a good 10-15 minutes for the coolant to get to operation temp at idle? I'll find out more when i get it on the road this weekend. Just hoping i don't need a new O2 sensor.

Thoughts on warm up period at idle to close loop and get io2 sensor up to 600 degrees?

[So Cal Mark]

you'll likely never reach that temp with the engine idling. Consider a heated O2 sensor instead

[TX82FIAT]

I was thinking that would be the response. So, In order to work on the car when running and not on the road it makes sense to have a heated sensor in order to avoid a prolonged potential running rich situation. It would also be beneficial in the event you stick your foot in the gas prior to full warm up...always a bad idea to push a car before warm up.

[majicwrench]

Are you sure the 9;1 was wrong?? Perhaps the O2 sensor was operating, and the engine is just running that rich. Too rich == cool combustion too.
They make fairly inexpensive non-contact thermo guns now days if you wish to verify the temp.
As far as coolant, did you drill a hole in your thermostat?? That will keep it cool longer than it should.
Keith

[TX82FIAT]

I have the hand held temp gun and it was within a couple degrees of the gauge on my phone reading from the ECU. I am almost sure the 9:1 was wrong based on a couple things. 1. the reading did not change as you changed the RPM's. 2. The exhaust smell in a the garage did not seem that strong and I have to think that visually the smoke out of the tail pipe would have been very dark pushing to black if i was running that rich. 3. The tables for the program at no point go that high. Even the limp home mode does not go that high while the min reading of the system is 9:1. 5. I looked at the plugs a couple months ago and they were not black dry fluffy colored, they were in great shape.

Maybe I'll cut out from work early today and see if i can get the car back on the road Saturday. I'm going to check the plugs again and change the oil to be safe since it is almost that time anyway. Hopefully, when i get her on the road and to heat the air/fuel will look reasonable at idle and across the RPM range. If that is the case I'll avoid excessive cold start idling unitl I install a heated 02 sensor. I'll let you know how i make out.

[majicwrench]

Well, it should work fine without a heated O2, you should not have to avoid cold start idling. And why wouldn't you want it to idle?? Did I miss something? (lkely)

[TX82FIAT]

I hear Ya! I'm have probably not been clear on some of my assumptions. I think it is running a little rich at start up but certainly not 9:1. If it is not getting on the road as i work on it then it is not getting up to 600 degrees for the loop to close and the programming to kick in. Therefore, my "assumption" and it could be wrong, is that the car will continue to run a little rich without me being able to tell how rich when at idle. The car can Idle all day once it is warm since the loop would be closed from prior high temp at the manifold. Once the manifiold is up to heat from running I don't think it would open the loop back up because it easily cooled below the 600 degrees again shutting down the o2 sensor that is a viotal part in controlling fuel mapping.

As Mark said, "you'll likely never reach that temp with the engine idling. Consider a heated O2 sensor instead".

In any event, I'll know a lot more when i get her back on the road tomorrow. I certainly appreciate the insight of this forum. Thanks, Ray

[majicwrench]

I'm gonna speak from my early years of O2 sensors that weren't heated, back in the late 70's and early 80's.
If they fast idled properly, yes, they could get sensor up to temp to start closed loop operation.
It was possible for them to cool enough at extended idle to go back to open loop.
Open loop should not be way too rich. Just not feedback controlled. In other words, computer will run mixture at whatever pre-set value is programmed into it.
What makes you assume it is running too rich at idle or start up??
Keith

[TX82FIAT]

Keith, I think you are on point. Plugs are fine, a hint of gas smell in the oil. I changed the oil and unhooked the O2 sensor taking it for a spin this morning. Same reading as yesterday with it plugged in. The computer has been running on the presets and not off the o2 feedback. Looks like I need a new O2 sensor. who knows how long it has been runing this way. Now I'll have to verify the programming that was done needs the O2 sensor to adjust on the fly or is it fixed based on the initial set up. It may may have been fixed all along.

[majicwrench]

Well not sure why you think the 02 sensor it bad. They are a fairly sturdy part. Can you read O2 voltage on you phone??
Keith

[TimpanogosSlim]

Well not sure why you think the 02 sensor it bad. They are a fairly sturdy part. Can you read O2 voltage on you phone??
Keith

"fairly sturdy"? Most modern cars give heated o2 sensors a projected lifespan of 60-80k miles.

[majicwrench]

"Most modern cars... 60-80k miles" You're gonna have to show me that. I do this for a living. O2 sensors last a loooong time. In theory they should last forever. Older cars had mileage recommendations for O2 sensor change, but that went away a long time ago. How many miles do you think he has on his Spider's O2 sensor??
Keith

[timinator]

Thoughts on warm up period at idle to close loop and get io2 sensor up to 600 degrees?

Base sensor operating temp is 250 F.

Thoughts on warm up period at idle to close loop

If you want the engine at operating temp quickly, put a piece of card board up against the front of the radiator and hold 1500 rpm.

On cold start it runs a little rich and that is not an issue as long as I get it on the road and warm.

What does your sensor read when, on the road and warm, it is "not an issue". Have you removed the sensor and tested it for ambient reading. Also not clear is what type of sensor it is. Single wire, 4 wire, or wide band will all fluctuate unless the A/F is beyond their range.

I do not have any experience with Megasquirt, but I assume there is a cold enrichment function that needs to be programmed. Just a wild guess would be that the units preference for A/F is set to methanol instead of gasoline which would be 9:1 A/F on cold start before you went to closed loop mapping.