I have a stock D16y7 that I have been getting ready to turbo. I installed my rebuilt 450cc blue top dsm injectors today(I also wired in the required resistors) and adjusted my fuel maps with the fuel multiplier in Crome. I don't have my wideband setup yet, but using the stock narrowband sensor with datalogging shows that it's running way lean. If I tell Crome that I'm using 350cc injectors it runs much better and my a/f ratios look about right. I'm not sure what is going on here, as it was running fine with a stock map and stock injectors before I put in the dsm's. Any ideas why they would be underfueling?

 

http://www.xenocron.com/install/CromeGuide.htm

Check out the section on adding fuel tools.

 

I already have fuel tools installed.

 

Have you adjusted the injector offset, or any of the individual fuel trim characteristics? There are also the advanced tables for injector battery offset, there is a setting for using DSM 450cc injectors. It shows it all in that tutorial if you haven't already done any of this stuff.

 

Tuning on a narrowband is pointless. Get a wideband before you start trying to mess around...

 

Nope. I took the stock basemap and adjusted the fuel map with the fuel multiplier tool according to the size of my new injectors. I don't fully understand what the injector offset does, but I guess I can play around with it a little.

edit: I know it can't be tuned on a narrowband, I was just using it to make sure I wasn't pegging it on the rich or lean side all the time.

 

I kind of figured that you were unaware of what those features were for. That is why I posted that link. If you read it, it explains them a little bit. Biggest thing is he mentions that it all requires tuning....ie wideband O2 sensor, datalogging etc..etc...

 

Thank you for your help, I guess I will have to learn more about the offset.

 

At least select the offset for the dsm injectors that will get you close. This will help http://forum.pgmfi.org/viewtopic.php...njector+offset

 

I tried using the DSM 450 offset today, still running waay lean throughout the whole range. Also, whenever I add fuel tools (plugins>fuel tools) it wreaks havoc on my tune. I can grab my working tune from the chip, add fuel tools, and burn it back to the chip and the car will stop running with no other changes. For some reason, when I add fuel tools it instantly fouls the plugs with too much gas. Doesn't matter what tune I'm using, it does it with all of them. Any ideas?

 

What is your final multiplier? it's located down at the bottom of the Crome screen.

Now that you have the DSM battery offset in there have you tried adjusting the injector offset? That is really the key one to focus on when trying to get your injectors set up. Again a narrow band sensor will not help you with getting the correct offset number. I usually start with an injector offset around 30-40. Run it and adjust the AFR's accordingly.

 

When I have it set up for 440cc injectors the final multiplier is .54. That setup hardly runs the car though, I've been using a .71 final multiplier instead so I can drive my car to work. When you say injector offset do you mean the setting under the advanced tab on the multiplier calculator? I tried several different values from 0.00-1.50 and none of them helped, the car is still so lean it barely runs. My wideband should be in the mail right now, so hopefully I can see exactly what it's doing soon. You have no idea how much I appreciate your help with this.

 

set the injector size to 450 and dont touch the final multiplier, then add 50 to offset and see how that runs

 

again you really need a wideband before you try tuning anything.

 

I've done that, still way too lean.

 

If your using 450cc DSM's your final multiplier should be in the .5* range. You should try a value of 30-40 in the injector offset under the advanced tab to start. .00 & 1.5 is a wee bit low. 50 might be a bit high (lean) try 30. Honestly though you are jsut shooting in the dark until you get a wideband. I figured I would say it again becuase you haven't heard that enough already.

We just ran a B16 with 550cc with a FM of .436 and an inj offset of 33. Runs a bit rich (13.7 afr) but that's where we wanted it. it's not a street car so fuel efficiency is not an issue. I had it @ 14.5 and the offset was in the 40's.

 

Ohhh, I was thinking that 45 was really .45, I guess I misunderstood something in the guide. I will try that out and let you know how it goes.

 

I changed the injector offset to 45 and it's MUCH better. It's on the rich side, but I don't think it's bad enough to wash out the rings so I'm going to leave it as-is until I get my wideband and new head gasket in the mail. What exactly does the offset do? From my understanding it is added to the battery offset to come up with a final number(the xenocron guide uses .92 as an example), but what does this number mean? If it alters the pulse width why doesn't that show up in the fuel maps? Sorry for all the questions, I'm just trying to understand what is going on when I change it.

 

This is better than me trying to explain it in my own words.

http://support.moates.net/2010/02/10...njector-model/

 

I read over that a couple times and I think I understand the latency issue with different injectors, but I still don't get the additional offset under the multiplier calculator. I guess it would help if I understood what the numbers mean. When I put 45 in the offset does that add an another .45ms to the injector pulse? And wouldn't that be a drop in the bucket compared to the overall pulse when it's under heavy load? I'm just trying to understand how it can effect anything other than idle.

 

Additional offset is this...

Each point in the Battery Table has that offset value added to it. So if your value at the 14 volt point in that table is .90 and you are using an offset of 45, you put a decimal point in from of the offset value, and add it to the value in your battery table.

In this example, .90 + .45 would come up with a final offset of 1.35 ms

The Offset value in Crome is a GLOBAL offset adder...

 

That's what I was thinking. So the effects of the offset will be most noticeable at idle and gradually decrease as the injector pulse lengthens under load?

 

Typically yes...latency is most noticeable in the low pulsewidth areas.

 

 

Thanks guys. I've got my wideband now so I'll mess around with that and see what I can do. I really appreciate all of your help with everything.