[Ruslow]

Need to know whether I play with the MAF transfer to get the Af at what I want, or do i use the commanded O/L AFR to tune to then change it to the AFR the I wish to have?thanks Stan

[decipha]

the fuel table is the commanded afr known as the LAMBSE

set the fuel table to your desired fuel at your desired load
for example on most tunes everything 60 load and below can be 14.64 and everything above that can be 12.5 for a n/a car

now log your wideband and compare your afr to your lambse

lambse is the afr the ecu is demanding
afr is the actual afr at the wideband

once those two match your golden

[Ruslow]

Thats what I figured someone would say.lambse is commanding 12.47 and I have the actual af is at 12.7.So I guess when I get back will reset to the commanded 12.47 and then command the 12.7 is that correct?STan

[87coupe50]

no... if you want to achieve what you are commanding (12.4) then you would need to adjust the MAF transfer (in that voltage or Flow area) a little higher to run a little richer, get that WB reading of 12.7 down to 12.4

[Ruslow]

Sorry but what I am wanting is the 12.7 but the commanded in the program is 12.47.So i need to change my maf to 12.47 then I can command the 12.7.Rite now the af is at 12.7 ,with it[eec] commanding the 12.47Hope this is making sence.STan

[87coupe50]

I am assuming you have some sort of tuning device to read/change the tune.

ok, seems that you are wanting 12.7 but the tune is commanding 12.4. You will need to change the tune to command 12.7. Then, most likely, your WB will be reading even leaner (than 12.7); so, you will need to adjust your MAF transfer (in that voltage or Flow area) a little higher to run a little richer to get that WB reading down to 12.7

[decipha]

why would you want to go from 12.5 to 12.7

i seriously doubt you would notice any difference in power and your just taking away from safety

the correct way would be to adjust the base o/l and stabilized o/l tables, find everything 12.5 and change it to 12.7

[Ruslow]

Big reason is fuel mileage. as well as i am running at 5000 feet.When you have a limited amount of fuel [22 gal] and have to run for 90 miles at speeds over 150 that extra .2 is worth almost .6 mpg more.I have run in this event and when I finished I filled back up and the cell took 21 gallons.At 5000 feet I still have a big safety margin.When I get back for the event i will redo the transfer to reflect the eec setting.So that I can command the fuel in the table instead of redoing the transfer.Stan

PS I am tuning it at 1000 feet

[avbronco]

Are you talking full throttle or cruse, 12.47 is kinda rich for cruse. 90 miles at over 150mph?

[Ruslow]

Well it will not be WOT for the full length but it will be over 150 for the full distance,probably closer to 160 with a short run to 180.I reset to command O/L at 115mph instead of the 128mph.So that IF I do slow down for a few turns it does not try to go C/L.I plan on running the car faster and hope to get to 200 or over.Already did one run at 140mph average for 100 miles and that was the break in for the motor.This will be holding the RPM at 4800 and above,throttle will be atleast 3/4 down.Stan

[cgrey8]

What EEC are you using? You don't have a signature that lists your EEC, the engine you are tuning, or any other significant details for us to better advise you.

ASSUMING you are using an 89-93 Mustang (GUFx) EEC, forcing OL is no problem. That's easily done. And if you patch the tune to include FN1360, then you can control AFR, not only by ECT and Load, but instead by RPM/Load. This will allow you to create a fuel map that will run you leaner in the lower RPMs where you can afford a leaner mix, but quickly richen it up as the RPM/Loads get higher.

As for the endurance application you are tuning for, it's very different than the avarage person here. I openly admit I know nothing about how engines behave when they are sustained at the RPM/Loads and long periods of time you are referring to. So enlighten me as to what the other challenges/limitations are. For example, why must the engine run 12.7? What would be the harm in running it in the low 13s? Does it just run the engine too hot? Or does it kill performance? I'm just thinking if fuel economy is an issue, why wouldn't you attempt leaner-than-WOT AFRs over those long distances? And if the engine is capable of running you upwards of 200MPH at WOT, but you sustain 140+, then for your application, you are not at true WOT conditions all the time. What would be the disadvantage to running an EGR system to keep EGTs lower allowing you to run a leaner mix? Just added weight?

[Ruslow]

sorry for no sig.i will correct that but if you are wondering what I am doing you can read the thread I started, viewtopic.php?f=2&t=16966

IF I thought I could run the 13 a/f I would but am somewhat of a fraidy cat to.I have to start at one end and FINISH at the other with no fuel stops no nothing and be on time [average speed] IF I get the aero package rite NO I will not be WOT at 200 cruising.Just wot to get there.i ran a 99 lightning for years and over time IF I cruised at 130 my boost was just at 3 lbs.It is more in the aero work, to be able to cruise part throttle.HP takes fuel why not free up some hp by slicking the vehicle up.Less fuel less hp needed = less strain on the driveline=more reliablity.


thanks Stan

[cgrey8]

It sounds like you could put an EGT in along with your WB and monitor whether the exhaust is getting too hot. EGTs aren't that expensive and are used quite extensively on Diesels. I've heard it said that the EGT sensor is as important to diesel tuning as a WB is for conventional tuning. So while you are testing out the tune, you could load up a few different tunes, each that results in different AFRs at your typical cruising RPM/Loads. Then take it out and flip between the different tunes to see which results in acceptable EGTs. You may find you can safely cruise the thing in the low 13s. Of course, you would want all the tunes setup to deliver the same AFRs at WOT. If installing an EGR was easy enough, you could also see just how effective the EGR was at keeping your EGTs lower. Although if you are able to make the trek in 21 gallons and you can hold 22 with your current setup, there's no real value in saving too much fuel is there? Saving fuel just means you haul more weight for longer. But I kind of suspect that at those speeds, that the drag of an extra 10lbs of fuel is dwarfed by the wind drag.

[Ruslow]

The problem with running egr is at those speeds vac is not that good and also egr may help with richening the a/f up a bit but the heat that it would put into the intake system would offset the gain I feel.As for still having fuel yes I did but as I move up in speed that fuel will become more important.Example at an average speed of 130 running on 5 cyl's the last 10 miles I used 15 gallonsThe last event I did at an average speed of 140 for over 100 miles, I averaged 5.26. Now if I run the 150 averrage i will use 17.1 gallons.BUT that is if all stayed the same.We all know that as you go faster resistance [both in drivetrain loss and aero will double]plus add in the wind.This is why I am trying to get some fuel mileage,and still have a responsive vehicle that has safe a/f.Stan

[cgrey8]

If you run excessive EGR, then yes you can actually burn more fuel. Since all the research about EGR is as it relates to burning at stoic, I have no clue if running EGR at rich AFRs would even have any kind of positive benefit. It'd be one of those things you'd have to actually test to know. But at those speeds, your air intake is at least 5x what it would be in a normal 45-70MPH cruise. You could probably run the EGR wide-open and not get the percentage of EGR gas in your intake that the stock tune mixes. So unless you are just experimental, then I guess EGR is out.

But what are your thoughts about EGT (Exhaust Gas Temp) sensor? Knowing what your EGTs are might give you an idea of whether running a leaner mix will be safe or not. I believe stock NA engines run somewhere around 900°F at WOT. Heavily modified NA engines get into the 1100s. Boosted engines get well into the 1300-1600s which is why heavily boosted engines have to be enriched to the 11:1 or lower range just to keep the EGTs manageable and not melt piston tops. Now each of these are typical WOT conditions that don't last more than 15 seconds sustained. You are talking about running high, but not WOT loads for long periods of time and I don't know what the technical engine challenges are there. I can see how running near stoic could be devastating to the pistons and exhaust valves. But I also don't know if running 12s is any better on the engine. I guess after 40 minutes of hard running, it needs an oil change due to carbon soot in the blow-by.

[Ruslow]

Already have the EGT it is on #8 cyl about 1 inch out past the exhaust port.Only problem with it is IF it spikes it is to late.I plan on running a Wide band during the run and monitor the a/f as best as poss.but it will only be monitoring 1 bank.EGT is on driver side and wb is on pass.biggest problem with doing these is there is no testing before the event you go out cold to the course.And since I know of NO place to run at a steady speed of 150-160 in the US this is a one shot deal.Thanks Stan

[cgrey8]

A dyno could emulate the loads you would see at 140-160...for how long the dyno can sustain resisting an engine putting out that kind of HP, I have no clue. I don't know if what they use to "fight" the engine is a brake, electric motor, or some kind of hydraulic resistor/motor.

So with your EGT, what kind of values are you seeing for what you can test for?

[Ruslow]

I have access to a dyno with a load cell.The problem therre is cooling.You can not get enough air flow to the motor to run any time.ISince I do run those speeds I can get away with a much smaller opening for cooling.I do drive the car [as bobcat will atest to] but I drive like an old man on the street since I have NOTHING to prove and pretty much know what any car that pulls along side me can do.I ahve a few days before I need to leave and if I can mount the lap top so it will pass tech I will data log the run and post it but it will be about 40 minutes long.That way everyone can see what I am talking about.Stan

[cgrey8]

Will the EGT and WB get logged as well?