fast efi xfi stick shift car help sugestions or ideas greatly apreciated

[racefast]

the load points occupy the same cells while in differnt gears so in one gear a value of 69 would be good but in another gear it needs more or less fuel depending on the load. i have gotten small consensus from other tuners that this is true. This is also the reason why the learning feature does not work with a stick shift. From my understanding learning will set the fuel when you are cruising in fourth gear so when you shift to first its too lean and then will tune to 1'st gear which will make the other gears rich.

[racefast]

Yes I have been reading this and the first thing i would check is to make sure that the fuel pressure is steady then make sure the injectors are clean and not leaking fuel in to the motor. I don't have any of the problems with the tune changing in different gears it stays close to where I have the O2 table set, but I dont have the turbo. I cant see that being a problem. Where is your O2 sensor located?

Unfortunately i wired my fuel pressure to the fast dash data logger but it quit so i haven't been able to log fuel pressure. i am working on getting it wired to the xfi so i can log it.

originally where the car was tuned at it was in the driver side collector at 22 o clock. My tuner sugested i move it to the down pipe so i did its now 3 inches from the turbo 12 O clock.

the injectors are clean the were new when installed ( i did not have them flowed) and have been inspected the car only has 700 miles on it since the injectors were new

i was told that the bosh o2 isn't reliable and i need an ntk do you have a preference.

does your green football occupy the same cells while in different gears?

[racefast]

it crossed my mind but efi is the wave of the future

[TheSilverBuick]

If the engine pulls any kind of vacuum then it will not occupy the same cell in two different gears with more load in one of the gears. More load means less vacuum. I've been running a 5-speed and EFI since 2009 and tuning it myself (not a pro by any means, but the car runs well).

[JeffMcKC]

Almost forgot, usually the first thing I ditch on a XFI 2.0 "default tune" is the MAP-based enrichment. I bet this is what causes your problem. There's a table for MAP-v-AE that I set to all zeros. By default the XFI comes with BOTH MAP-based enrichment, and TPS-based enrichment. You will only want TPS on the stick+turbo option.

First check that you have both enabled. If you did, when you zero it out the car will need retuned.

I think he addressed it already in your other thread

[alain]

With a street driven turbo car, you need to have the fuel table set up to MAP and RPM. TPS will not cut it, because you can have the same TP% at the same RPM, in a different gear and have a completely different load (which translates to fuel requirement). Load is reflected best in your MAP pressure. The beauty of EFI is that you can have the AFR spot on at any load and any RPM.

A TPS tune really only works well in all out drag cars with loose converters that run almost the same rpm all the way down the track. I'm not familiar with FAST, as I run ViPEC and also have experience with Autronic, but I assume FAST also has an auto tune function that you can run off the datalog. I do this with the ViPEC unit in my twin turbo Dart. Works like a charm.

As for a wideband, I once bought an Innovate LM-2, but it has given more headaches than anything else. I have an NGK AFX mounted permanently in my Dart with the output connected to the ViPEC and it works flawlessly. They say NTK sensors have a quicker response than Bosch sensors do.

[dieselgeek]

both are being used which one do you suggest. do you know what a good base line starting point would be

You want to use only TPS AE enrichment. Not MAP-AE. Zero out the MAP AE table, and consider finding a tuner who knows what they're doing! MAp AE *definitely* does not work with turbo engines, the problem is that your fuel table is always being augmented by MAP changes. I am sure that in your datalogs when you notice different AFRs in different gears you would also notice a *different pulsewidth* on the injector, this is how you or your tuner would pick up on the fact that you get different fuel quantities at the same load cell on your fuel table.

I hate to rant but, there are just too many "tuners" out there, or guys who "got one running once" who shouldn't be charging people money for tuning yet.

If you want, email me your .gct file (tune) at [email protected] and I'll be glad to help you get it set up right, remotely.

-Scott

[alain]

I can't agree with you Scott. My advice isn't based on "got one running once". It's based on the general physics of an Otto cycle internal combustion engine.

Your fuel table doesn't change unless you put in a change. The injected amount of fuel is what is changed by the reading of the MAP sensor plotted against an rpm. The higher the load, the more fuel an engine needs. The higher the rpm, the more fuel an engine needs. These two factors are plotted in a table on an X and Y axis and the motor management reads the corresponding value in the cell.

Air has a density of 1.2041 kg/m3 at 20 degrees Celsius. To completely burn 1 kg of gas, you need 14.7 kg of air. That's a fact. In an internal combustion engine, you don't, however, have atmospheric pressure and don't have 20 degrees Celsius. During cruising you won't have a complete fill with air because of parasitic losses and if you're running boost, you will have more air than the volume of the cylinder. That's where the Gas Law comes into play. The Gas Law states that density is the ratio of Absolute Pressure divided by the product of the Gas Constant and the Absolute Temperature, or, Density = P/(R*T).

Stoichiometric combustion doesn't state that you need 14.7 m3 of air to burn 1 kg of fuel. You can't mix and match. This means that if you have a decrease in temperature, the density will rise. That's why at night, in cool air, you will need more fuel to the engine because basically, you are getting more air (and thus oxygen) in the motor due to the higher density (more kg per m3). The other factor, pressure, means that if you increase pressure, you are getting a higher density, so also more air (thus oxygen) into the motor and will need a corresponding increase in fuel to not go lean.

In an ideal situation, you will have a motor management system capable of factoring in these variable parameters. You will in fact need a 3D table which will not only determine required fuel by pressure and rpm, but also temperature. Purely basing fueling on the position of a gas pedal will NOT cut it. You can hold the gas pedal at 40% (TPS reading) right from driving off from a standstill till however fast she'll go in the highest gear (with an automatic). Tell me if you honestly believe that the engine requirements are the same from start to finish.

Diesels are a different story. Diesels control power and rpm by the amount of fuel injected and will work with TPS based tuning.

[TheSilverBuick]

I can't agree with you Scott. My advice isn't based on "got one running once". It's based on the general physics of an Otto cycle internal combustion engine.

Your fuel table doesn't change unless you put in a change. The injected amount of fuel is what is changed by the reading of the MAP sensor plotted against an rpm. The higher the load, the more fuel an engine needs. The higher the rpm, the more fuel an engine needs. These two factors are plotted in a table on an X and Y axis and the motor management reads the corresponding value in the cell.

Air has a density of 1.2041 kg/m3 at 20 degrees Celsius. To completely burn 1 kg of gas, you need 14.7 kg of air. That's a fact. In an internal combustion engine, you don't, however, have atmospheric pressure and don't have 20 degrees Celsius. During cruising you won't have a complete fill with air because of parasitic losses and if you're running boost, you will have more air than the volume of the cylinder. That's where the Gas Law comes into play. The Gas Law states that density is the ratio of Absolute Pressure divided by the product of the Gas Constant and the Absolute Temperature, or, Density = P/(R*T).

Stoichiometric combustion doesn't state that you need 14.7 m3 of air to burn 1 kg of fuel. You can't mix and match. This means that if you have a decrease in temperature, the density will rise. That's why at night, in cool air, you will need more fuel to the engine because basically, you are getting more air (and thus oxygen) in the motor due to the higher density (more kg per m3). The other factor, pressure, means that if you increase pressure, you are getting a higher density, so also more air (thus oxygen) into the motor and will need a corresponding increase in fuel to not go lean.

In an ideal situation, you will have a motor management system capable of factoring in these variable parameters. You will in fact need a 3D table which will not only determine required fuel by pressure and rpm, but also temperature. Purely basing fueling on the position of a gas pedal will NOT cut it. You can hold the gas pedal at 40% (TPS reading) right from driving off from a standstill till however fast she'll go in the highest gear (with an automatic). Tell me if you honestly believe that the engine requirements are the same from start to finish.

Diesels are a different story. Diesels control power and rpm by the amount of fuel injected and will work with TPS based tuning.

Scott isn't proposing running an Alpha-N setup based on throttle position, just the "Accel-Enrichment (AE)" aka, accel pump shot tied to the throttle position. If he has the MAP tied to the accel enrichment then as the manifold pressure changes with boost and vacuum it's manipulating the fueling in the engine in addition to the VE fuel table that is based on engine load (vacuum/boost) and rpm. Sometimes in unpredictable ways, especially if you are feathering the throttle for traction or such.

[alain]

Ahhh....mis-communication on my part then. My apologies. I thought he was suggesting to run Alpha-N, but yes, I agree, acceleration enrichment is best tied to throttle position. That's the way I would (and do) do it too. We're on the same page again.

[LAGNAF]

You have to watch the wording of those guys across the pond.... A kilo over there, aint a "kilo" over here!!!!!

[alain]

Hahaha Dan!