Bought my FC pre-modified from Japan, has a T04E on a tubular manifold, etc etc etc, and I just hooked up (a brand new) Innovative LM2 wide band, calibrated it (so showing about 20:1 with the engine off), and went for a drive...

AFRs were in the 9s at idle, and considering the way even standing behind the car for 2sec makes your eyes sting like hell, I wasnt surprised.

Flat out on boost though, tried at 0.85 and 1.1 bar, the AFRs were averaging 8.6:1 with no water, and 8.3:1 with the pre-comp WI on Stays fairly stable right through to 8k at this ridiculously rich level...

I get the very occasional light missfire even with the HKS twinpower fitted and modified/uprated coil setup, and I guess this is a rich missfire if the AFRs are correct.

I accidently ran it once at 1.6 bar and it didnt go pop, and with these AFRs, I guess I know why now.
You can see overfuelling smoke in the rear view mirror when beasting it, not tuned diesel style, but noticable.

Surely it wasnt mapped like this in Japan, so what you reckon is up? I wanted the car safe as it gets used hard, but this must be hugely losing power at this stupid level of rich.

 

You are going to need to get it retuned. The elevation from where it was tuned in Japan to where you live could be different so that is probably the variable that has changed.

 

I would try to calibrate it again (has to be in free air not installed on car).

Where did you mount it?

If you're running 8.3:1 with AI I want to know your ignition setup LOL

 

i believe usually below 10 AFR will cause black smoke, but if it is below 9's you should feel stumbling. sounds like cal is off

 

yeah it should read 14.7 with the car off

 

lol or NOT 14.7 is stoich for gas!!! or at least shouldnt as i have the xd-16 guage on mine FREE AIR or over 8hrs engine off is 20.9 to verify atmospheric oxygen calibration. BUT if engine off after running it will display last AF as the exhaust gas mixture is still in the pipe. THAT is why the lc-1 says recal in free air or ONLY after the engine has been off over 8hrs so that atmosphe disipates the exhaust gasses. im assuming on a stock gauge it will read MAX AF so what standard cal is 22.39 at 5v

z

 

It cannot be stressed enough that a free-air calibration can only be performed in free-air. The air in an exhaust pipe can remain very different to free-air for hours or even days. Always remove the sensor from an exhaust pipe, or for an exhaust sniffer-pipe, make sure you flow fresh air through the pipe before calibration. Your breath can have an 0xygen content of 15% rather than around 21% for free air, so don't blow on the sensor during calibration.

 

Let the car sit for a bit and perform a free air calibration. You don't have to remove the sensor if the engine hasn't run for a day.

You can also perform a calibration if you are coasting down a hill (throttle fully closed) for a little while. the pumping action of the engine will clear out the exhaust. I have done both of those methods successfully. You are reading the AFR right off the LM2 display?

There is no way you are that rich at idle. No way.

 

Your wideband is definitely the problem. Elevation makes NO difference on a MAP based cars tune.

thewird

 

Great stuff, this is what I hoped to be the case! This is why I love this forum, people actually do stuff, im used to useless replies of "take it to your tuner"...

I did the calibration engine off but sensor in the downpipe still, engine was only off for maybe 10min, so thats no good.

Ill go and do the calibration in free air then. Does it need to be calibrated every time, or just first time and it remembers it from then on?

 

Actually on "map Based" tune elevation does make a difference it needs to be baro corrected also otherwise at high elevation the tune actually runs leaner
It has to do with pressure on the exhaust (overall pressure ratio across engine) which is lower causing a lower load calculation on the base fuel table. For more information go to www.efi101.com and look at altitude correction where ben strader explains how the ecu calculates it.
BUT i dont think this is a problem for the guys car which is the question in hand.
Free air calibration for lc1/lm1/lm2 should read 20.9 AFR as stated above.
What size injectors are you running and do you have a datalog for us to have a look at?

 

hey stav, you only have to do this once and it should be fine.

rememeber though the more you calibrate it, the closer to being accurate it will be.

for me if it was a daily driver id calibrate it every 3 months as id like to know my numbers, that might be over the top, im not sure, but id rather do it alot than not enough.


I get the impression yours is just a fun car so doesnt get used everyday so id probably do it every 6months.

there are people on here who will know more than me but try that.

any pics of your gauge setup, im looking around now at innovative ones now and still deciding which one to go for.

from a group test of 7 setups, innovative comes out best though

 

Your tune will not change depending on altitude, it will not leaner. A map sensor doesn't care where it is as its already calibrated to sea level. For an ECU that relies strictly on a MAP sensor, you tune will not change. What can change is because your turbo has to work harder in higher altitude, is your boost may drop (with single setting boost controllers). And the opposite is true if you bring a high altitude car to sea level, boost may go up and require lowering the boost controller. You may notice it run leaner but that is because you are running less boost so the computer adjusts for that. I have been in the mountains, I have been at the beach, I never touch my tune and it pulls the same AFR's every time at the same boost level. You may notice a change in idle but that is because the engine is pulling a different vacuum and if your map is tuned correctly, it should still idle fine (this is where the ISC comes in handy since it will keep your idle always at the same RPM).

thewird

 

GREAT NEWS Thanks to your info i learnt I was just being a retard and doing it wrong, lol.
The instructions dont specify the sensor needs to be out of the exhaust, or at least the engine off for quite a while, so it didnt occur to me.
Bloody important though, I mean thats a LOT out!

I re-calibrated it with it out the downpipe and all is fine now.

Just tried it then, and was seeing high 11s on a dead cold start, getting to mid-high 12s as the engine warmed up.

Cant tell you what im getting on the move yet as its raining, and wet road and semi-slicks while pushing the car hard dont really mix.

Soon as it dries out a bit, hopefully later, ill know for sure.

Thanks again

Toaster- Its the usual Innovate LM2 setup with the hand held unit, seems pretty good to me. Had a friend in passenger seat keeping an eye on things while I drove. Can datalog too, but I needed to be sure it wasnt doing anything dangerous as we was doing it.
Once its all sorted ill remove it; I dont plan to run it as a permanent fixture; though for Brunters its probably a good plan to put it somewhere in the line of sight so you can take a look when going for 200+ lol.

 

There is baro correction for MAP sensors.

Fluctuations in barometric pressure vary the density of the intake air of the engine. At lower
barometric pressure, the engine cannot breathe in as much air, and therefore the amount of
fuel delivered to the engine must be reduced. This is necessary when a large change in altitude
is expected during a driving period (a Hill Climb event such as Pikes Peak in the USA is a
good example).

For instance the haltech has two methods for MAP (one for Throttle).

It can do an automatic reading before start up. You can also reset it but is only done for large elevation changes.

9.5.2 Barometric Correction - Method 2
This method uses a barometric pressure reading taken prior to cranking the engine. This
method is restricted to applications that use MAP sensors for load sensing.


The other is a use the internal sensor with an external 1 map sensor.

These are read together to provide constant feed back.

9.5.3 Barometric Correction - Method 3
This method of barometric compensation allows the ECU to continuously measure barometric
pressure and adjust the fuelling throughout the period of operation.

When the ECU is configured to measure load by MAP sensor the external MAP
sensor is connected to the Spare A/D input.

You can correct for it but most people running MAP do not.

 

The factory FD computer has an on-board barometric pressure sensor for altitude compensations. So do Hondas from that era, which are all speed density.

Now if you have a decent tune on a system that does not use barometric correction (Power FC) you probably won't notice a big difference as altitude changes, except for the aforementioned boost control issue. But that doesn't mean MAP-based systems don't normally have barometric pressure sensors. I wish the PFC did. It's pretty lame that it doesn't.

 

Heres some reading for you

Posted: Thu Nov 12, 2009 9:53 pm Post subject:

--------------------------------------------------------------------------------

RootesRacer wrote:
BARO should not be needed for any density related compensation on speed density setups.

On a true (pure MAP sensor) speed density, the motor really doesnt know the difference between being at 8500 ft with wide open throttle at 70Kpa, vs being at sea level at 1/4 throttle at the same manifold pressure.

The same fuel should be calculated, as well as the ignition timing for each case.
.


Not to sound like a jerk, but that statement isn't true at all. At sea level the only way to get a lower Kpa in the manifold is to close the throttle which will limit the VE.

The main difference is the total pressure ratio across the engine.

Assume a sea level BARO pressure of 100 Kpa, then

70 Kpa of MAP would be 70/100 = 70% LOAD

at altitude where the BARO is 70 Kpa then, 70/70 = 100% LOAD

The VE at sea level WOT is the same as the VE at any altitude WOT, but the DENSITY of the air changes directly proportional to Barometric pressure, and indirectly proportional to temperature.

Because when you tune the engine at sea level you must limit VE (by closing the throttle) in order to achieve (for example) 70 Kpa, then a "MAP Only" speed density system will cause the engine to run lean at altitude.

This is because while we are doing a correct "density" calculation at the higher altitude, the Volumetric Efficiency reported will be lower because the number in the base fuel table at 70 Kpa is smaller than the one at 100 Kpa. When we tuned our engine at sea level, the only way we could get less manifold pressure was to reduce the amount of incoming air by closing the throttle. At higher altitudes with full throttle the situation is not the same.

Remember that MASS = Volume x Density, and so the correct density calculations must be made based on pressure and temperature, but the Volume must also be reported correctly.

In order for a speed density system to work properly at various altitudes, the "load" must be calculated with a MAP and a BARO sensor as:

(MAP/Baro)*100 = % Load

This is a subject I have been lecturing about for years, and have on many occasions driven people from where I live to an elevation of over 6000 feet a short distance away, and so I speak not only from theory, but from actual tests and observations.

Sorry to seem like I'm "calling you out", I don't mean to, but this topic sort of a pet peeve for me!
_________________
Setting the Standard


This was stated by Ben Strader the founder of EFI University.

 

I can only assume this must be some old style of thinking or tuning MAP based cars. When I tune a car, I don't use partial throttle to tune different boost levels. I adjust the boost controller to run WOT pulls at different boost levels and tune boost levels completely separate. As far as I know so do most tuners on this forum. You can then extrapolate quite accurately the boost levels below your wastegate spring and above your target boost level as its usually very linear. So the above post is assuming you tuned your fuel map wrong to begin with and is not proof of anything.

And after writing this, I still don't believe it has any merit even if that is how the car was tuned. A MAP based engine works in an isolated environment referenced to the MAP sensor which is calibrated to sea level already. The map sensor does not care at what altitude its located. 10 PSi of air at sea level read by the map sensor in a closed system contains the same amount of air as 10 PSi of air at 10,000 feet using the same system. That is because the map sensor references everything to 101.3 kpa (1 atmosphere) regardless of where it is.

This Ben fella keeps talking about VE tables and engine load so maybe he's referencing a different method for ecu's to calculate fuel delivery. ECU's that we use in our cars (PowerFC, Haltech, Microtech etc.), you enter the exact duty cycle you want at X boost & Y RPM.

I know for example on the stock RX-8 computer you tell it your injector sizes and it calculates a load value for you based on your MAF and TPS calibrations and then you have a fuel table where you tell it exactly what AFR you want. You then have VE table which you can correct a percentage at given load vs RPM if the computer isn't calculating it accurately. That's the only way any of that makes sense. But still does not apply to how most of us tune our cars.

thewird

 

[QUOTE=StavFC;9983114

Toaster- Its the usual Innovate LM2 setup with the hand held unit, seems pretty good to me. Had a friend in passenger seat keeping an eye on things while I drove. Can datalog too, but I needed to be sure it wasnt doing anything dangerous as we was doing it.
Once its all sorted ill remove it; I dont plan to run it as a permanent fixture; though for Brunters its probably a good plan to put it somewhere in the line of sight so you can take a look when going for 200+ lol.[/QUOTE]

i was thinking of getting the DB kit as its only £170 new for everything and its permanently installed, wanted to get a steering column mount so its always in my view so i can map it on pump fuel myself, leave the race gas map for ross.

oh yeh, the china gt45 turbos are £299 in the uk if you finally decide to go a bit mental.

buy a £100 tubi manifold and you could destroy everything you could possibly come across.

when you take it for a boost tomorow if its not raining, if it goes above 11.8afr with the w/i on then your into the danger area, since your running a decent amount of water id probably turn your boost up until you reach around 11.5afr, hopefully that will be a nice chunk of boost and with it come what we all love from a turbod engine......torque!


going off what your bad calibrated numbers compared to your calibrated numbers ill take a guess and say on 1.1bar your about 10.9/11.1afr with w/i on, let us know what you come out with

 

Alot of ecus use VE tables ie haltech platnum , motec m*** , link g4/vipec just to name a few , ive tuned some of these ecus as well as microtech etc and have found VE (volumetric efficiency) table tuning very simple and easy to use.
I dont think you have read it properly or understand it . At first i didnt understand it.
So you dont steady state tune? You only do WOT Tuning?
I didnt want to start a argument nor a debate on this subject but just remember this guy TEACHES some of the best tuners in the world.
Please read it again and have an open mind.

 

VE tables are used in GM-based speed density systems, especially the late 80s V8 engines. Megasquirt, UTEC, FAST XFI, and a number of other engine management systems use volumetric efficiency tables. The old GMC Syclone and Typhoon are the main turbo application for this, and these are 4.3L single turbo V6 engines. But the Syclone does not have a barometric pressure sensor. So you can definitely get away with not having one. The early 90s Hondas do have baro sensors (none of which are turbo), and they are speed density as well.

If you are interested in the architecture of a VE table based speed density system, see this technical documentation on the '88-'93 GM turbo speed density ECUs: https://docs.google.com/fileview?id=...NjA4NDIz&hl=en That is the "grandaddy" of all these Haltech etc systems using VE tables. It's not like these aftermarket companies made this stuff up. The first speed density system was the Bosch D Jetronic in the 1970 Porsche 914... and the first airflow meter based system was the Bosch L Jetronic in the Porsche 924. The technology was licensed to Denso in the 70s (and later I assume GM) and then refined from there. The aftermarket is always playing catch up.

FYI The Rx-8 has a hotwire MAF but also uses a barometric pressure sensor:

 

WOT pulls is the easy part of tuning since it takes no time or effort or any real thinking for that matter imo. Say I'm tuning a stock twin turbo FD, after doing all the vacuum tuning, tps adjustments etc, and overall streetability, I just do some partial throttle boosts to see if the current fuel map is "ready to boost" (safe). Then turn off the boost controller and do one pull which is at about 6-8 psi assuming there is no boost creep, make adjustments do pulls, raise boost, rinse and repeat etc until whatever amount of boost the owner wants say 10-14 psi. I then have rows that I know are perfect between 6-14 PSi and can then very accurate guess the other rows. I then make changes without even needing to be in the car, load up the map and verify putting the car under different loads and RPM's and at some point later the car is eventually tuned. Here is an example fuel map to show how its linear once completed..



I always have an open mind. However, if you think about it it doesn't make sense. Let's say you have a 1 liter solid jar with a MAP sensor hooked up to it pumped up to 10 PSi read by the map sensor so it contains X amount of oxygen. You then take this jar to 10,000 feet and read the map sensor again, it will still read 10 PSi and contain the same amount of air. That is exactly whats happening after the throttle body on a MAP sensor based car. If its reading 10 PSi at sea level and 10 PSi at 10,000 feet, its still flowing the same amount of air.

I knew the RX-8 had a barometric sensor and any MAF based system would make sense to have one. That is why I mentioned the RX-8 computer since I have worked with it before.

thewird

 

After reading your posts i think you are caught up in the BOOST part of the map which is only half the map in my books, what about vaccum which is the part of the map which needs baro correction because of the PR across the engine.
Which is way on most decent ecus they use MGP rather than MAP on base fuel tables.

 

I was trying to point out that the turbo GM speed density systems did not have a baro sensor back in the 80s. So clearly there is truth to this line of thinking. That being said, you may want to change the target AFR (or idle control, boost control, whatever) at higher altitudes for improved driveability, emissions, or safety.

 

Vacuum is a reference to a pressure differential. 0 PSi read by the map sensor is 14.7 PSi absolute pressure (1 atmosphere). When you see -400 mmHg (15.7 inHg) on the PowerFC commander, its actually 7.73 PSi absolute. This value will always contain the same amount of oxygen and require the same amount of fuel because the map sensor is referencing everything to 14.7 PSi absolute so it doesn't care weather its in outer space or at sea level, it will still read the same. Your mechanical boost gauge may read different, but that is because its relying on external pressure for its reading and not using absolute pressure. The computer displays positive pressure and vacuum so its easier for us to read since we talk in vacuum and boost but you can always convert it to absolute pressure so in reality we are always technically under boost . Hope that makes more sense.

Changing target AFR's may be the advantage to having a baro sensor and I never thought about that before but haydenw was suggesting your AFR's change. Your AFR's will not change if your map is tuned correctly due to change in altitude on a MAP sensor based car.

thewird