355sbcTPI

Hi everybody, I have a quick question about modifying the "Injector PW vs. Battery voltage". I am running $6E mask using Tunerpro and my idle is very rich. I'm sure it's because of my larger injectors as well as the cam that I have. As of right now, I just started this rebuilt motor so I'm trying to tune my idle before I start doing road tests. I've changed my injector constants to match the flow of my injectors. I'm using APYP bin for my 1988 355ci Tuned Port with Vortec heads. I'm getting code 44 which is lean but trust me it is idling very rich. My cam is an Extreme Energy Comp Cam with .503 intake and .510 exhaust. Not sure what the duration is because I misplaced the card that came with the cam at the moment. I guess what I need to know is if I add time to the PW vs. Battery table does it hold the injectors open or closed longer? I'm not sure, I've been reading a lot lately about it...now I'm getting information overload! Anyway, Thanks for the help.

RBob

iTrader: (1)

Increasing the values in that table will increase the injector PW. The table values are added to the PW prior to the ECM hardware being programmed.

Note that it is best to get the correct values for this table and fill it in.

RBob.

84Elky

It appears you have the CompCam XR276HR as that is the only non-marine v8 cam listed with .503/.510 lifts. LSA is 112*. With advertised I=276/E=281 degree durations, your overlap is 54.5*. I'm running a similar Howards cam with 54* OL with a 110* LSA with no idle problems whatsoever. And the 110* LSA should be more problematic at idle than 112*. Don't think the battery tables are causing your issue unless the values are way larger than they should be for your injectors.
It could be your VE values at idle (say from 400-1000 RPM) are too high. Try bringing them all down in stages and log. Don't worry for now about only changing the values in the idle kPa range. Also, if you haven't done so, might consider setting your Spark tables from 400-1000 RPM to all the same value for all kPa values (with Vortecs, something in the 21-22 degree range should work). This will provide your true INTs and BLMs at idle: https://www.thirdgen.org/forums/diy-...-log-file.html. Might also search for "big cam" and you'll see many posts related to the issue your having.

Dominic Sorresso

Agree w RBob. Plug in the correct values for the injectors ur using. Then tune from there. It makes getting to the right tune much easier.

355sbcTPI

Thanks for a quick reply guys. RBob...I was hoping that you would chime in I fully understand injector pulse width now.
84Elky...You just assisted me with a lot of help as far as using the tables for idle rpm. I'm using a MAF system so I think SD systems use VE tables. The XR276HR cam is the one I have. My thinking was I wanted a .500 lift cam and SummitRacing had that at the time. I'm totally going to use your suggestions with the spark tables.
I have to apologize for not initially telling you guys what my injectors are (be easy on me!)
I have 42.5lb Lucas injectors. I bought them long ago along with two T3/T4 hybrid Garret turbo's. My plan was to make a 383 twin turbo sbc. Well...that's a long term project. I also have a TPIS mono blade throttle body as well.
I think I'm going to have a hard time tuning idle with those big injectors!
This is what I have going...
1988 TPI 350 bored .030 over
balanced
decked
ARP rod bolts
10/10 crank
hypereutectic flat top pistons
Vortec heads with 2.02/1.60 valves
LT1 springs...I think
The cam listed in the previous post
TPIS Monoblade throttle body
adjustable fuel pressure regulator
42.5lb Lucas injectors
SLP intake runners
SDPC intake manifold for Vortec heads
March underdrive pulley set
Scorpion aluminum 1.5 roller rockers
Double roller timing chain
I wanted to tune the injectors but I think it will be too much work. Now I am ready to buy the right injectors. I'm thinking 30lb or 32lb injectors. If anyone could recommend a set of injectors?..I would appreciate it. I'm hoping for 400hp at the wheels or maybe that's a dream? Anyway, thanks again!

Mark_ZZ3

I'm tuning a modified 305 with 350 injectors at the moment. The only way I could get it to idle well (so I could start tuning) was to both adjust the BLM and INT limits to be way higher/lower. The computer was trying to lean out the engine but would hit the BLM low mark.

I tried adjust thing INJ constant ... not much luck for me.

Adjusting the MAF tables is where the big difference was made. I modified the first three tables and kept the "graph" looking smooth and connected from one table to the next.

I was able to get the engine to idle and the BLM to start moving up.

Now I can at least work on the tune vs. keeping it running.

Hope this is useful. I can't claim to be an expert ... only what worked for my setup.

Cheers!
Mark.

Keoman

iTrader: (3)

In the same boat as you are more of less. Cam with lots of overlap.
Seems that this tricks the O2 because of all the fresh air getting into the exhaust and causes the rich condition.

this helped me alot

https://www.thirdgen.org/forums/diy-...ome-those.html

84Elky

I'm wondering if it's injectors > 22#/hr that are causing some of the large cam idle problems. I'm running $8d with a 54* overlap cam on 110* LSA with no idle problems whatsoever, but using 22# injectors. BPW at idle is 2.1-2.3ms. Can larger injectors be a/the contributor to the idle issue?