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How can I be lean in both banks?

R

RAD Merc SVT

CEG'er
Joined
Aug 2, 2010
Messages
489
Location
Phoenix, Arizona
I have a 3L port match with Big-Bore LIM, Acid ported UIM, minor head work, and headers. I was running lean on the 19# injectors I had so I decided to put in some 24# because I would rather be rich than lean. I am in Colorado altitude and the car is untuned and I just threw a 171 and 174 lean in both banks how can 24# injectors be lean? I feel like something is wrong. Any ideas?
 
Your PCM is probably trying adjust for the significant amount of fuel going in, thus throwing the code.

You. Need. A. Tune.
 
I would say you need a tune. I had Joey tune my car with the 3L UIM and TB, but when I put on the ST220 UIM and 65mm TB I was running pretty lean, like 13.9. So all that extra air and different injectors have no idea what they are doing together. Thats my guess, presuming you don't have a vacuum leak anywhere.
 
You cant put bigger injectors in without a tune and expect it to run good. The PCM thinks they are 19s... you need a tune for the 24s for it to run right.
 
If you are getting ANY codes then it obviously doesnt run perfect. it may feel fine, but something is obviously wrong, at least according to the PCM.
 
I think the work you did getting more air flowing has maxed out the 19lb injectors. Like said you can't just put in a bigger injector and expect more fuel, so you need a tune which we all know is pretty pricey. Obviously you need an Xcal, and you can either get a mail order tune from NPG that will work just fine and will require you to do datalogging, but isn't going to be as good as a dyno tune which will run about $300 more. PM me if you need to find a shop in the Denver area that will dyno tune it as I know of a few.
 
I actually talked to a shop in Denver that is expensive $800-$1200 for the whole deal Xcal, dyno and A/F gauge included but it sounds like they know what they are doing. I went down there and they explained everything to me and I would definitely trust them. I don't have that money I am saving up to go to school.

So I understand I need a tune and I really want to but then I won't make it to school. but let me get this straight. I add a lot more air with only 19# injectors and my O2 sensors realize the mixture is lean so the computer holds the injectors open for as long as possible (within its limits) and when that doesn't work it throws codes. I replace the 19#s with 24#s and my O2 sensors "should" be reading rich so the computer holds the injectors open for as little time within its limits. And if it starts to read lean than it should be able to hold them open a little longer. There is no way I'm flowing enough air to max those out. so why isn't my computer holding them open longer?
 
Theres an xcal for sale right now in the classifieds for $225, plus $200 for a tune from NPG and your good to go. If that one is snatched up try ebay and other forums just make sure it is unlocked. I even have an X2 that might be able to be sent into SCT and be repaired. Otherwise a new Xcal 3 from NPG and the tune would be $500 total, thats not too bad. Theres no need for a wideband unless you want to get your air/fuel exact, which Joey at NPG will pretty much get it exact without one.

Make sure its not something silly like leaking gaskets or some kind of leak first. And I would get those 24lb injectors out of there asap, your computer has nooo clue those are in there and has no idea what to do with them. I dont know specific details about injectors and how they work with the computer but if the computer is tuned for 19lbs then thats what you should have in there. You could always get a stock non svt intake manifold and TB and see what happens with that on there.
 
no, the 19# injectors are maxed closer to 225WHP.


dont forget guys, he is at over 5000ft elevation as well, which will change how the car runs.
 
it also depends on what fuel pressure you are running and the engines actual BSFC. you can make 19# injectors flow 21#s with ~55PSI. You could get 250BHP (not WHP) out of 19lb injectors (at 43.5PSI rail pressure) if you have a .45BSFC (which is kind of on the low end for an NA engine) with 100% duty cycle. using .5 BSFC (probably a little more accurate) you would need 21# injectors to get the same 250BHP (or run 55PSI rail pressure on 19# injectors). as you can see, there is a lot of variability (and a lot of tune-ability if you have an AFPR).
 
SJon85 said:
Make sure its not something silly like leaking gaskets or some kind of leak first. And I would get those 24lb injectors out of there asap, your computer has nooo clue those are in there and has no idea what to do with them. I dont know specific details about injectors and how they work with the computer but if the computer is tuned for 19lbs then thats what you should have in there.
Click to expand...

Yes, this is what you should start with. The stock tune in your car sounds like it is for 19# injectors so the 24# injectors will be dumping too much fuel into the mixture, so I would stick with the 19#. Plus you should stick with the injector style that is meant for the LIM. The vac leak sounds like it could be your issue, and this is free to diagnose so that's where to start. Check all the vac lines and the EGR system for leaks.

This is just my guess/opinion, but I am not positive the lack of a tune would cause the issue, plus if it's not the issue you can't really tune until the other issues if any are fixed. The elevation thing is a factor but honestly I don't know if that would throw things off enough to cause a lean code, especially if you aren't running the car wide open. If it's throwing the codes during normal driving then it seems like there is air getting in somewhere it shouldn't be
 
I will check everything but again I know you guys are all saying something is wrong and it is impossible to run 24# injectors on a stock tune but it runs great. I have had no issues it runs just like it did before the engine swap (but without the rod knock) I guess I'll just keep driving it like this and stay out of WOT and get a tune from Joey. My worries are that Joey hasn't tuned for altitude often, or 24# injectors or the more air I'm flowing. I'm not trying to say he doesn't know what he is doing but I feel like he will be taking an educated guess. Plus I won't have a wideband to help him datalog it
 
he tunes for 24# injectors all the time. honestly though, I would get a wideband for the tuning because you are at altitude. it will help him know just how the engine is running so he can make the proper adjustments.
 
I had joey tune my oval port 3L at that elevation and it ran fine, no problems. Then when I got a wideband the air fuel was just fine as well. He definitely knows what he's doing as far as tuning goes on our platforms, but if I could go back I would have got a dyno tune instead.
 
I guess my best option is pay Joey the $500 and get it so it runs safely. Then if I want the power I can re-tune it on the dyno and not having to buy the Xcal will cut my dyno costs in half. Also, does Joey tune the MAF so it runs like stock? for example if I get it tuned up here and move down to Arizona like I am in a month will the MAF adjust for the lower altitude or if humidity is 10% one day and 80% the next everything will run the same right? because the MAF is adjusting for it
 
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