I installed 650cc injectors and changed the injector constant to 0.15432 because I had 310cc with 0.32359 so 0.32359*(310/650) = 0.15432

The car idle is very lean 18+:1 and would stall in Open Loop but when I step on it it seems very rich.

It seems to be a little better in closed loop but theres something wrong.

So for now I've put a higher injector constant so I can idle and not stall at every light.

Anybody had this problem? Thanks!

Yeah, the injector constant is more than just a number relating to the injectors...

What you need to do is to get it to idle right, then adjust the VE tables to get it to where you want it. You can't just change the injector constant and leave the VE table alone and expect larger injectors to work right.





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Thanks for the reply!

I now have set a higher Injector constant so I don't stall at all red light and it's still too lean.

So I just increase the injector constant more so I can have a perfect 14.7:1 AFR in open loop? Is that right?

Thanks again!

No...

You change the injector constant so you have a good solid idle (which isn't necessarily 14.7:1). After you get the idle right, you LEAVE the constant where it is, closed loop should be fine. To tune open loop, you have to set your target AF in the PE parameters (in open loop, aka acceleration enrich, 14.7:1 will probably end you up with a damaged motor). On an NA engine you will probably want to aim for about 12.5-13:1. You set the target AF in the PE parameters then do the VE tuning (works best with a wideband), to dial the VE tables so that they hit your target AF.





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Something else that might be causing your problem is that when figuring the injector constant using that equation, that's assuming each set of injectors were at the same fuel pressure. However, one may have been rated at a different pressure. Another thing which I believe could be a problem is that you may have had some of these problems before (with the VE tables)...just to a lesser degree. What I mean is you more than doubled your injector size which cut your constant down to less than half of what it was before. That in turn could double any errors you had before, so an afr that seemed reasonable before may be way off now. To verify this you would want to compare AFR commanded and the actual AFR with each set of injectors (or the AFR error). The reason you can get a bigger error, especially when you start making your constant that low, is that even a small difference off can be a fairly substantial % difference off. Which brings me to another potential problem. If the injector constant (not just the VE) was off before, it will be off now, too.

So, hypothetically, if you already had your injector constant and the VE tables right, and you took into account fuel pressure...I believe it would be as easy as just doing the basic equation to go to a new size of injector. However, usually some tweaks are involved.

If you start throwing other mods in there, especially if its at the same time as the injectors then the calculations can really get messy. Which, honestly in that case, sometimes it can be better to start with a calculation and then make educated guesses on what to change it to next until you get to a reasonable idle afr.

I should mension this before. 2001 2.4L Turbo 60 trim .60/.63 with no major engine mods.

I found that I can idle with the injector constant at 0.18238 but it's running very lean around 18:1 AFR. When I touch the gas pedal and the engine goes to 2000 RPM it is very rich(between 10-11:1 AFR) and it don't recover idle well, he want to stall(lean).

Now I tried adding 2 and more everywhere the Idle VE table and it do the same thing.

Should I try a bigger injector constant so I can idle a little richer and drop the idle VE table so I won't flood the engine like it do now??

I will do complete VE tuning with AEM WB but I just can't figure out how to have a good idle and when pushing the TPS to 1-2% it don't go to 10:1 AFR.

Thanks you guys!

Yeah, raising the injector constant is something you might try...also though, i could be wrong on this...but it seems to me like at lower rpms, the ecu may use more than one table for ve...like say idle and low rpm, so you might try making the values the same or similar for cells that overlap (ie. you could be in either table at the same time). I realize one is based off of vac and rpm and the other tps and rpm but you can still probably find some sort of correlation.

It also might be that your injector constant if even too high if you're going straight to rich...then you'd just want to add a little to the idle ve. This may be what you need to do since you mentioned more than once about it getting very rich when you step on it. Either way, you probably will want to try the cell "matching" i described earlier. If you have any more questions/problems feel free to ask.

my injector constant is .15 for 750cc injectors. idles stoichly.


-Trailblazer SS - not so custom 6.0L - custom intake - custom tune
- (1) 2.4L on an engine stand (1) blown trans (2) good quad trans (1) eco trans = party

My constant is .18500 for 750cc injectors with 43 P.S.I. fuel pressure. A/F in open loop at idle is 14.9-15.3,

lean.... GM wants Quad-4 cars at 14.6. for best burn. dont know why, but thats what the tec manual\ traning vid's all say. (LD9\LD2\LG0)

Chris


'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08

SpyhunteR wrote:my injector constant is .15 for 750cc injectors. idles stoichly.

J S wrote:My constant is .18500 for 750cc injectors with 43 P.S.I. fuel pressure. A/F in open loop at idle is 14.9-15.3,

My I/C for my 750's is 0.13375.... idles at 14.4-15.0 for the most part. It does stall out at times though and HUNTS for idle when stopped. Also running about 43psi @ Idle.










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SpeedRacerZ wrote:

SpyhunteR wrote:my injector constant is .15 for 750cc injectors. idles stoichly.

J S wrote:My constant is .18500 for 750cc injectors with 43 P.S.I. fuel pressure. A/F in open loop at idle is 14.9-15.3,

My I/C for my 750's is 0.13375.... idles at 14.4-15.0 for the most part. It does stall out at times though and HUNTS for idle when stopped. Also running about 43psi @ Idle.

KEEP IN MIND elevation plays a huge part


THERE CAN BE ONLY ONE, i have already died once and im still here so lets just leave it on the track