Timing problems with 750s

[amaank]

Hi,

We recently installed FIC 750cc injectors on our 92 tsi awd and have a few questions. Before the install i searched the forum and plugged values in on a dsm tuning sheet confirming that i needed to set my safc at about -30 to -40.

After they were installed we turned the car on and it idled horribly with the afc set to -32 on the lo throttle. It sounded like a go-cart engine and seemed to idle at about 500-700rpms, so basically it was hardly even running. All cylinders had spark, fuel and good compression.

The timing however was strangely high... 14-20 degrees, something like that. I turned the fuel upto 0 and the timing dropped to 8-11 degrees. We adjusted the biss screw to get the idle upto 800rpms. The car seemed to be idling a lot better.

I was informed that i needed some better tuning device and that when i turned the safc down to lean it out it pushes the timing up and leaves the ecu completely confused. The fuel gauge located on the return line shows 50psi of fuel pressure while the car is idling... i know the 1gs are supposed to be at 37psi. The car is equipped with a b&m fpr.

So here's my dilemma, i need to lean it out but also need the timing to stay put. Timing at idle is 8 degrees. When i lean it out with the afc the timing goes up and the car goes into 2-cylinder mode. I also know that the b&m fpr won't let me decrease the fuel pressure below... well 50psi, which is what the guage shows at idle. Is there a solution to my problem without having to purchase a costly afpr? perhaps messing with cas?

I did not build this car and the parts used are the choice of the previous owner. It is equipped with a walbro 255 pump. I have only installed the 750cc injectors. I am definetly new to dsms. I can post a log of it idling if it gives you guys a better idea... after the install all my fuel trims are stuck at 100% and the o2 sensor is giving no feedback at idle.


Thanks in advance.

 

[amaank]

guys who are running 650s 750s on an afc, how are you doing it?

 

[pooya]

Those injectors are way too high for a AFC. 550 is the biggest I would go with.

Your gonna get advanced timing...unless you get a better way to tune.

 

[amaank]

Those injectors are way too high for a AFC. 550 is the biggest I would go with.

Your gonna get advanced timing...unless you get a better way to tune.

is there another way i can tune where i can lean the car out and leave timing dead set at 8 degrees?

dsmlink perhaps?

 

[dedlewamp]

guys who are running 650s 750s on an afc, how are you doing it?

With a EPROM ECU and a chip to compensate for the bigger injectors.

 

[amaank]

With a EPROM ECU and a chip to compensate for the bigger injectors.

So if i get a chip with 750cc injector compensation i can lean the afc out as much as i want without pushing the timing up?

 

[pooya]

is there another way i can tune where i can lean the car out and leave timing dead set at 8 degrees?

dsmlink perhaps?

DSM link is your best bet.

Of course there are other tools like: AEM EMS, Greddy E-Manage, and Wideband. That's not all, but those are the most popular.

 

[amaank]

Well if i can get some good compensation going with a chip then i'd rather go with that.

I really don't have the money to buy dsmlink.

What is a Eprom ecu? is it just a socketed ecu?

 

[dedlewamp]

So if i get a chip with 750cc injector compensation i can lean the afc out as much as i want without pushing the timing up?

No, you can't lean it out as much as you want without affecting the timing. But, you won't have to lean it out as much, as the chip is already compensating for the larger injectors. A EPROM ECU is simply a ECU that has the EPROM chip in it. You will need to get it socketed, in order to accept the burnt chips from the vendor of your choice.

 

[amaank]

Ahh ok, thanks for the help so far.

But i'm really really confused... with the chip with 750cc inj compensation i can set the safc to 0 for stock settings?

so you cannot socket a normal ecu but instead only an eprom ecu?

 

[Dragon TalonTsi]

The SAFC can only go past a certain percentage increase from the stock setup. Its largest capacity it can hold is 680 CC's, so let's see, 450's are stock, and 680's, that's 230 CC's that it has to advance or adjust to. That is only what the SAFC can fully tune by itself. That is it, but look it all up at www.apexi.com , they should have all of the print outs and tech support on that....

 

[amaank]

The SAFC can only go past a certain percentage increase from the stock setup. Its largest capacity it can hold is 680 CC's, so let's see, 450's are stock, and 680's, that's 230 CC's that it has to advance or adjust to. That is only what the SAFC can fully tune by itself. That is it, but look it all up at www.apexi.com , they should have all of the print outs and tech support on that....

So if i could somehow decrease my fuel pressure enough to get the 750s to act like 680s my safc would be useful.

does the stock fpr have a 1:1 increase in fuel pressure from boost reference? Because my fuel pressure is 13 psi over what its supposed be at with the B&M thing.

 

[amaank]

Just checked i do have an eprom ecu. so one last time... how does injector compensation work? after reading the little expanation on dsmchips i don't think i understand where i would put my afc settings with a chip or how it would help my timing problem.

 

[dedlewamp]

Just checked i do have an eprom ecu. so one last time... how does injector compensation work? after reading the little expanation on dsmchips i don't think i understand where i would put my afc settings with a chip or how it would help my timing problem.

Q: Do I need an AFC or a piggy back system when I have installed the upgraded chip?

A: Generally, yes. Although the changes I make to the Global Fuel and MAS Compensation are very close to the stock and that makes it easier to tune. It is still recommended that you have some tune-ability, such as an Air Fuel Computer or a GOOD adjustable Fuel Pressure Regulator, so you may require more or less fuel depending on your car setup.

The injector compensation just makes it so you don't have to be pulling crazy amounts of airflow out, just to get your car to run. The chip compensates for this for you, so you still have room to work with on the AFC. With less aggressive settings on the AFC, your timing maps will remain closer to stock.

 

[jepherz]

Don't think of a different eprom as "compensating" and it's easy to understand. Think of it as if Mitsu built the car with 750's. In a perfect world, the eprom reburned for 750s would be all you need. The safc will still be nice to make fine adjustments.

 

[andymoraitis]

Q: Do I need an AFC or a piggy back system when I have installed the upgraded chip?

A: Generally, yes. Although the changes I make to the Global Fuel and MAS Compensation are very close to the stock and that makes it easier to tune. It is still recommended that you have some tune-ability, such as an Air Fuel Computer or a GOOD adjustable Fuel Pressure Regulator, so you may require more or less fuel depending on your car setup.

The injector compensation just makes it so you don't have to be pulling crazy amounts of airflow out, just to get your car to run. The chip compensates for this for you, so you still have room to work with on the AFC. With less aggressive settings on the AFC, your timing maps will remain closer to stock.

Nicely said and absolutely correct!

Andy

 

[daren_p]

The safc is a piggy back system, it tricks the ecu. When you remove fuel via the safc it takes the MAF signal and reduces it, this does 2 things it reduces the amount of fuel that is injected but since its telling the ecu there is less airflow then what you are actually seeing it advances the timing (less load = more timing). Thats why they recommend up to 680 injectors with the safc, any larger then that and you have to take away so much fuel with the safc to get the correct air/fuel ratio that you get a crazy amount of timing makeing it extremely hard if not impossible to tune properly. Now if you get an eprom chip burnt it will compensate for those 750 injectors. So you get the chip & if you leave your safc a zero it will pretty much run like the factory 450's did as far as air/fuel ratio & timing. With the chip you still want to run the safc for fine tuning but since most of the compensation is done with the chip you won't get crazy timing advance.

As for your fuel pressure your just making things even worse. You can reduce your fuel pressure below the normal 43 psi that the injectors are rated at to reduce their flow but this isn't the best method. The b&m unit is useless with the 255 pump. The stock fpr return is too small for the 255 pump and the b&m does nothing but make the stock fpr adjustable. To run that pump properly you need a real adjustable fpr such as the aeromotive unit. Tuning will be a real pain until you get your fpr over run condition sorted out.

You said you had an eprom ecu so you just need to get the ecu socketed so you can easily swap chips whenever you want. Then just order up a chip with the specs you require.

 

[amaank]

wow thanks for all the help guys! really helps me out!

That last reply really cleared things up!

 

[gsxtacy]

If you must keep driving your car, you gonna need to go way leaner on the SAFC.

With FIC 650's in my car tuned with an SAFC, my settings ranged from -34 to -38 on 18 psi, and you have 750's.

Try this:

Hi: 75
Lo: 35

Hi:
1k 2k 3k 4k 5k 5.5K 6K 7K
-39 -39 -38 -40 -42 -44 -44 -44

Lo:

1k 2k 3k 4k 5k 5.5K 6k 7k

-41 all the way across
Might even go as far as -46 all the way across

But yeah get your ECU socketed, and get a chip for compensation, when you tell the ECU that -44 % less air is coming in, it puts you off in a different timing map that isn't aggressive, you'll get everything you ever need (accept the ability to make DSMlink like adjustments) in a tiny chip.

Good luck man.

 

[amaank]

Thanks gsxtacy!

Does your car have a chip?

my car wants to turn off at about -35ish. The timing goes crazy at that point.

 

[gsxtacy]

Yes, I now have a chip from Jeff O. at Dsmchips.com
works great too.