Tuning FI for altitude with Wideband O2

[Clem Z.]

Re: Tuning FI for altitude with Wideband O2

jerry buy a portable EGT exhaust gas temp unit and all you need is a 3/16" hole in one header pipe 1-1/2" from the the head. the one i have holds the highest reading so you can check after making a run. the model i have is a "computech" model 4005

mine is something like this. i velcro the unit inside the race car. http://www.jegs.com/i/Computech-Syst...oductId=752362

[Jerry G.]

Re: Tuning FI for altitude with Wideband O2

I think that may be the practical solution here. How long does the O2 sensor live in leaded race fuel?

[Jerry G.]

Re: Tuning FI for altitude with Wideband O2

I've got another problem. i head for Portland on Tuesday to head for the race and no UPS deliveries on monday. Anybody live in portland with a portable O2 sensor? Also clem i just looked and don't see a model 4005 unit . I wonder if it's discontinued.?

[Clem Z.]

Re: Tuning FI for altitude with Wideband O2

I've got another problem. i head for Portland on Tuesday to head for the race and no UPS deliveries on monday. Anybody live in portland with a portable O2 sensor? Also clem i just looked and don't see a model 4005 unit . I wonder if it's discontinued.?

the one i posted the 4105 is the one they now list which i assume is a updated version of the 4005 as mine is 10 years oid. the thermocouple is not effected by leaded fuel . mine was in the car during a wreck and the force threw the 9 volt battery and the battery cover out of the car but the velcro held the unit in place.

[Jerry G.]

Re: Tuning FI for altitude with Wideband O2

jerry buy a portable EGT exhaust gas temp unit and all you need is a 3/16" hole in one header pipe 1-1/2" from the the head. the one i have holds the highest reading so you can check after making a run. the model i have is a "computech" model 4005

I need an O2 sensor for A/F ratio not an exhaust temperature sensor don't i? The widband O2 sensor get affected by lead I thought.

[Paul Y.]

Re: Tuning FI for altitude with Wideband O2

If the vacuum drops at high altitude it is not noticeable on my F.I. I can stop on Independance Pass and shut it off and start it up and it idles fine. I do notice a bit of power loss but it does not run noticeably richer that it affects the idle and starting ability. The above pass is 12093 feet and I go over it multible times in the summer when it is open. I have just set my injector up with the manometer but when it was checked for emissions it ran very close to highest and best efficiency. Maybe I'm just lucky. I have an appointment next week to set a 61 unit up and calibrate it so I can report any findings back as long as they drive the car in the high country. Many people I know don't take them out of Denver which is 5280 feet.

[Jerry G.]

Re: Tuning FI for altitude with Wideband O2

If the vacuum drops at high altitude it is not noticeable on my F.I. I can stop on Independance Pass and shut it off and start it up and it idles fine. I do notice a bit of power loss but it does not run noticeably richer that it affects the idle and starting ability. The above pass is 12093 feet and I go over it multible times in the summer when it is open. I have just set my injector up with the manometer but when it was checked for emissions it ran very close to highest and best efficiency. Maybe I'm just lucky. I have an appointment next week to set a 61 unit up and calibrate it so I can report any findings back as long as they drive the car in the high country. Many people I know don't take them out of Denver which is 5280 feet.

EXACTLY Paul. You get a reduction in power but not a signifcant richening of mixture.thats been my expirience also. Jerry In Boulder colorado

[Clem Z.]

Re: Tuning FI for altitude with Wideband O2

I need an O2 sensor for A/F ratio not an exhaust temperature sensor don't i? The widband O2 sensor get affected by lead I thought.

you use the EGT gauge to make sure you don't go over 1350 degrees. you want to stay between 1250-1350 degrees for safety and max power

[Jerry G.]

Re: Tuning FI for altitude with Wideband O2

So you don't need to worry about A/F the temperature tells you the same thing?

[Clem Z.]

Re: Tuning FI for altitude with Wideband O2

So you don't need to worry about A/F the temperature tells you the same thing?

yep if you watch dyno tests they have TC in the headers. if you get above 1350 you are too lean.

[Clem Z.]

Re: Tuning FI for altitude with Wideband O2

also if you do have 14:1 CR i would watch the water temp because if it starts heating up even with the correct mixture you can go into detonation.

[Mike R.]

Re: Tuning FI for altitude with Wideband O2

Gentlemen...in addition to the vette I have a Ford GT and have been convinced by someone that it would be useful to have a datalogging wideband O2 monitor to aid in tuning that car. I bought a new-in-the-box Innovate LM2 with dual O2 channels from a guy on the Corvette Forum. It should be here the end of the week. I will weld some bungs into my OEM (but not original) side exhaust and we will see! I also bought a MAP sensor so we will have O2, RPM and MAP (Vacuum). The lowest elevation around here is 2100' and the highest nearby paved road is 4200' so those will be the test points. Stay tuned.

Mike



quote=Duke Williams (22045);496347]Velocity through the venturi is not effected by air density. The air meter vacuum signal is based on volume flow, so, yes you will be lean at sea level.

You may need to go back to the dyno and develop a sensitivity curve for the economy and power stop settings. For example, how much more percent fuel will the system add with each quarter turn of the adjusting screws. That would be a real useful piece of information for any FI owner, and I'm sure it's been done, and maybe one the the guys here who has a lot of hands on FI tuning experience has an idea. I'd also suggest you contact Jerry Bramlett with the situation. and I'm sure he'll be able to give you some decent guidance.

Then figure how much denser the air will be at Portland and make the suitable adjustments. The good news is that once you have the sensitivity profile for the power and economy stop settings, you should be able to adjust the system for any air density conditions you meet.

You want the power stop A/F to be in the range of 13.5-12.5:1

Even better would be a wide band O2 or CO sensor in the exhaust. There is a near linear correlation between CO and A/F, with 6 percent CO associated with 12.5:1 and near zero equal to stoichiometric.

If you had a carburetor, you'd have the same issues - set it up at 6000 feet and you will be lean at sea level. At least with the FI system the adjustment is simple - no disassembling the carb to change jets - just the turn of a screw.

Duke[/quote]

[Mike R.]

Re: Tuning FI for altitude with Wideband O2

I think EGT varies with altitude even at the same mixture.

yep if you watch dyno tests they have TC in the headers. if you get above 1350 you are too lean.

[Clem Z.]

Re: Tuning FI for altitude with Wideband O2

I think EGT varies with altitude even at the same mixture.

all the data i have seen there was no correction for altitude

[Clem Z.]

Re: Tuning FI for altitude with Wideband O2

there is no substitute for a plug read but the EGT gauge will warn you of trouble.