I have a severe rich problem. I just swapped out the spark plugs after they fouled out. I checked my BLM's and they were locked at 108 at idle and low load. I have 42# injectors and had the injector constant at 42.5. I raised this 45# but the BLM's still pegged low at idle. I didn't drive it around so i couldn't tell you the other rpm's. Do i need to start changing the MAF tables at this point? BTW i have a custom cam and ported heads too in case your wondering. I just need to subtract some from the gps number telling the PCM its getting less air, therefore it will get less fuel right? Am i shooting for 128 BLM's at idle as well as across the board? I know the bounce around alot when looking at the logged files. Or should i just try and keep them close.

Bill

 

Are these SVO's? In any case, you should be able to bring the blm's in line by raising the injector constant. If you raise the constant but do not reset the PCM by removing power it will take quite a while to learn them higher.

 

No these are Delphi 42#ers

Well i figured it out, I first changed the injector constant back to 42.5 like i had it before. Then i took the first two MAF tables and reduced all the values by 10%. That got them a little leaner, but in the areas between 20-45gps it was still really fat, so i leaned these areas out another 5% and then smoothed the transitions between all the areas i changed. Worked like a charm and BLM's are very close to 128 with the exception of at idle where they are a little fat yet. I tried leaning the area where it idles, but I then got a huge split with the right side going to 108 and the left around 120, so i just put it back where i had it. At least when i'm cruising around it isn't so fricken rich anymore and it should help cure my fouling plugs. I hit the Dyno on thursday for my own WOT tuning. I'll post how it goes.

Bill

 

If you want to try it, keep changing the maf tables at idle to get the blm where you want it, and then when it starts to split you can start screwing with the closed tps spark advance and the IAC counts.
I was just doing this an hour ago on a hotcam car and it worked great. Eventually got the blms to 129L and 126R....good enough for me.

 

I have played with my Closed throttle spark advance and have it at 34 deg's around idle. I have gotten my idle MAP to around 39. What are you doing with the IAC counts and how. All i see to modify with the IAC is target rpm in drive and park/neutral. Are you playing with the rpm's?

Bill

 

There is also something called injector offset. It has a direct effect on how the computer percieves the injector. I'm very sure your 42# delphi injectors have a much different offset table than did the original 24# injectors.

I would suggest going back to where you got them and try and get this information.

I also sent you an e-mail with some offset tables in it, but not for delphi injectors ... GL

I just stumbled upon a bit of information, that Delphi injectors are actually Lucas injectors, so the table I sent you may be valid ... GL

Hope this helps

LWM

 

By screwing with the minimum air gap/throttle stop screw you can change how much air is going through the IAC valve as opposed to going right through the throttle blades into the intake.
Sometimes you can get the idle blm to change a little by closing off or opening the throttle blades.
34 degrees closed TPS spark advance sounds high, but the 39 map is good.

With the twin turbo setup, where is the maf sensor located?

 

LWM,

I got your email, are these injector offsets the offset vs voltage?
I will check on them and update them. The Injectors are from Racetronix.

Dan,

Twin intercoolers, single turbo. Its ATI's kit and it has been modified to be used with the turbo. The MAF is right before the throttle body elbow, just as it is stock.

Thanks for the pointers guys. I just developed another exhaust leak, this time at the pass side header gasket, so it looks like i'll be replacing that one again. My tuning will have to wait till that is fixed.

Bill

 

LWM,

The offsets for the MULTEC 24 GM injectors look alot different than whats listed in my program for stock injectors. It also looks like my tunercat lists the injector offset in usec. (micro sec's) It appears that the table you sent was in millisec's. Just wasn't sure what units your table was in, nothing was listed. Thanks

 

In those tables, which are looking like they are a cut and paste type of deal from the LT-1 editor, the top row is volts and the bottom row is milliseconds.

The difference between micro and milli ... would be a factor of 1000??

You may be able to use the bottom table, it might give you a direction to get headed in at any rate.

I'm in the process of trying to decide which injectors to use and am still groping in the dark about this that and the other.

Let me know how the injectors work.

LWM

 

Yep that is exactly what i did. I am starting to tear into the exhaust on tuesday. The leak is so bad, it sounds horrible. I'll post when i get it fixed to let ya know how the offsets work out

Bill