20G on DSMLINK Best options for me.

[DSM_ThuNDeR]

Hello Guys, I wanted to know what would be the best option for me since, I HAD the afc but did not really know how to work with it, and plus the last owner of my dsm took the engine to the grave melting every single piston, so I'm a little afraid of it. Here is a list of what I have done so far to my engine as far as mods:

Balance Shafts removed
ARP Head Studs
Front Mount Intercooler
2.5 Piping
tdo5 20G
walbro 255
3" catback
95 Eprom ECU
boost/af ratio gauges


I'm not really a newbee when it comes to working on these cars(engine wise) but I think tuning might be a little different for me since I've never actually done anything like play around with the AFC. Back when I had it, I switched over to back to 450cc's (previous owner had 650cc's with a 16G) and set the levels to 0. The reason why I'm posting up this post is because I want to know WHAT SIZE injectors should I use with my 20G and my basically stock(internally) engine. And also HOW will I be able to use it (I'm am so sorry for being such a newbee to engine management).

Here are the things/mods I plan on getting before the purchase of DSMLINK:
3" downpipe
Injectors
EGT Gauge

thanks guys.
Tony

 

[JusMX141]

Tuning is a completely different ballgame from wrenching. I know guys who make poor mechanics that are great tuners, and vice versa.

If you were using the AFC, I'd recommend 650's as the injectors of choice for the 20G because you're right at the tuning limit of the AFC....anything bigger and you may need compensation beyond -50%, and the AFC is out of range.

If you're seriously considering DSMLink, go ahead and buy whatever injectors you find a deal on that are 650cc or larger. Many guys will buy 1000's because you can set the global compensation and deadtime to spec with DSMLink, making 1000's tune as easily as 550's. With 1000's, you'll basically never need to upgrade injectors again.

You already have the EPROM ECU, and you can probably get $150ish out of your AFC, perhaps another $50 out of your stock 450's....a nice income tax return and DSMLink and your injectors of choice are within your reach!


I'm not familiar with ECMLink yet, but in my opinion DSMLink V2 was easier to use than an AFC because it took the guesswork out of your global tune. With the AFC, you're compensating for added fuel through reduction of airflow....you'd have to select all of your throttle points and adjust those to your global compensation, then drive the car and figure out where you need to add or remove air to make it run perfect. For example, airflow drops significantly when you're off boost, so from your AFC's global compensation you'd have to have to take away fuel to get the car to idle stoich and add fuel on boost. With DSMLink, you simply move the global slider to your desired compensation, and all you did was modify the stock fuel map to your injector size without screwing with airflow.

For your gauge wishlist, I'd pass on the EGT gauge in exchange for a wideband o2 setup. Using a wideband is like cheating...you can set up DSMLink to log your exact air/fuel ratio so you can see how it directly responds to fuel corrections. EGT's are fine, but they're rather expensive and slow to respond. Often by the time you figure out that you're too lean with an EGT, you've already damaged something.

 

[toofast82]

Yeah id skip the egt and go for the wideband! If youre going to use dsmlink i would just get 1000cc probably which will allow some room to grow or run e85 if you decide that route

 

[DSM_ThuNDeR]

Sorry guys, but I don't know what a wideband 02 is. (LAUGH ALL YOU WANT!).. Where do I set it up to? I have a apexi turbo timer that displays various numbers from an 02 oxigen signal, is that it? I'm so confused when it comes down to these tuning bits.

Also does dsmLink give me the option of choosing the proper injectors or do I have to set the correction levels as well as an afc?

Thanks again. Any advice is always helpful.

 

[JusMX141]

Wideband o2's are a seperate o2 sensor that reads out the exact air / fuel ratio of your exhaust. This makes tuning nearly hassle-free because you can tell EXACTLY what your tune is like at all RPM points....so if you're tuning and all of a sudden your A/F ratio dips down around 10.0 at 5k RPM's under load, you know you're too rich at 5k. Lean it out a couple points, and try again. Honestly, it's like doing your math homework by reading the answers in the back of the book.

Many guys install widebands in their downstream o2 sensor bung if they're not running a cat, but being that you're from CA you'll probably need that for inspection. You'll simply need a hole drilled and bung welded somewhere in your downpipe, pre-cat.



On DSMLink, you calculate how much global correction is needed for your injectors size, adjust that on the global scale, then begin your tune from there. Say you're running 650's....the following equation will help you determine your global correction:

(450 / 650) - 1 = Global

So 450 / 650 = 0.69230769, -1 = -0.3076923. You'd need approximately -30% global correction to run 650's. The 650's will flow roughly 30% more fuel at the same duty cycle than the stock 450's would.

DSMLink applies the global injector size correction to the fuel map, so it's more accurate than the correction done by an AFC. An AFC calculates fuel correction through airflow, so you'll still need approximately the same correction although it will be based on a curve.....you'll need less fuel at idle, and more fuel at wide-open throttle based on airflow.