Complex tuning question

[Jorgen]

Hey everyone, my 1g dsm has an oldschool tuning setup (technomotive stage III chip), and I have an apex-i afc for fuel control. Right now I have an fp3575 with all supporting mods (tre trans, built motor, cams, etc). Fuel system is a rewired in tank walbro, and 780cc injectors. With no timing control, am I better off staying with the smaller injectors? I want to aim for 550whp on pump and meth, but I'm concerned that I may not have quite enough injector. With my old mkiii supra and a map-ecu, I know that the map-ecu simply fooled the stock computer, and modified the injector signal. So, for instance, I ran 750cc injectors on my supra, and the stockers were 440cc. When I would go wot, what used to be 80% injector duty cycle was now 50%, because the injectors weren't opening as much, the ecu accessed a more aggressive timing curve because it thought it wasn't under as heavy of a load. I don't think I'll have this problem with a dsm because as I understand it, the timing curve is based on tps, not injector duty cycle. Am I correct?

So, I guess the real question is, can I run larger injectors without fear of running too aggressive timing tables when I only have fuel control?

I eventually plan on going to an evo8 or dsmlink v3 eventually, but this is what I have for now.

fyi: I'm sure most of you have never heard of the technomotive stage iii eprom mods, so here's a link.

EPROM Modifications

It essentially adds nlts, 2 step launch control, and a higher rev-limiter.

 

[Bling_23]

Basically if you "trick" the ecu's airflow reading when running larger injectors the timing will still be aggressive at wot. It will still run a stock timing map and think its running factory injectors and airflow. You will have neither, so with that said you will eventually hit knock at some psi. Most likely not the psi your happy with power wise. Dsmlink is magical when it comes to getting the most out of your setup.

 

[Arthris]

If your car is already chipped you could get a ostrich and either tune the stock E931 bin or you could go SD with jackal. If you go with the ostrich you will have complete control of timing and airflow. So you can get your car running correctly

 

[knochgoon24]

Timing on DSMs is based on engine load. And the load is based on the MAF Hz reading (Karmen type air flow meter). So what most piggyback tuning systems do, like the AFC, is trick the ECU by taking an input frequency from the MAF, applying a user defined percent correction, then output the new frequency to the ECU. The ECU sees a lower airflow, and therefore injects less fuel, but also adds more timing.

Usually, 680cc is the acceptable limit for injectors. At that point, you're applying a correction that really affects the timing.


Best bet: save up for a more up to date tuning system.

 

[bryanwheat]

I recommend having a custom chip burned for the injectors and then fine tuning with the safc. You can do chips up to 1,000 cc injectors, maf compensation, rev limit, timing and fuel tables, and idle speed.

 

[tkelly27]

Ostrich is a good idea if you already have a chip. You can run tunerpro or DSMap or any number of things with it and they are $190. You can also buy a USB eprom programmer for $40 on ebay. Digikey will give you sample 27c256 chips sometimes. Otherwise they are ~$2 each. A UV eraser is $20 or so too.

Until you can afford that, you can control the timing with the cam angle sensor. You can advance or retard the base timing. It will run poorly at part throttle, but at WOT it will be safer. Very much not ideal, it's like changing your fuel pressure to tune AFR. Look into the items in the first paragraph, I think you'll be surprised at how much tuning you can do for your dollar.

 

[bryanwheat]

The 27sf512 is by far a better chip, you can do dual maps if you'd like, and they are actually re flashable. I use the moates burn1 chip burner, for burning chips it is real nice. Their flash and burn software is real easy to use also.

 

[tkelly27]

You're right! I use a 27sf512 as a flip chip in my van : D I like the A&B tuning. I put a new tune on it in the morning and try it out during the day to see if I like it. You can get 27c's for dirt cheap though. I got a stack at the local electronics surplus place for less than the cost of one 27sf. It's also nice to burn cheap chips when you've never done it before. It's also nice to have the 27c when you get a good tune in your friend's car and you want to get your Ostrich back. Fun fun.