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i was running my 383 engine build with a 7730ecm and $8D on a chassis Dyno today. I got everything to tune nicely except when doing a pull from 2000 rpm to 5500 rpm at wide open throttle the AFR leaned out to around 18:1 at 3000 rpm and richened back up to 14:1 around 4500 rpm. It is a nice gradual arc that looks like it’s programmed to do. My fuel pressure remained constant. The lean curve was very consistent and it never changed shape while adjusting PE tables. Nothing seemed to change significantly. Has anyone else ever come across this anomaly? Engine has a FIRST Fuel injection intake manifold, 36 lb injectors, AFR 195 heads.
Any tunerpro data to go with this? Maybe post your bin...
You're probably reaching peak VE at 3500 rpm and the tune is not delivering enough fuel to it. 383 with long runner manifold is going to have a serious torque/VE peak at that rpm.
Do you have a datalog from the dyno pull or some WOT log from the street, please share? Check the injector pulse width behaviour during WOT. It sounds like you are experiencing a $8D injector pw limit issue. You need to tweak your bin code:
Im running a comp cams xtreme energy 288 Hydraulic roller cam.
I can can post the bin files and some data logs ASAP. The tech at the dyno shop was a nice guy that didn’t really know how the system works I think. For instance, the VE tables are maxed out in some areas, which seems unlikely or undesirable. I had been road tuning for closed loop operation for some time. But I brought it to the dyno shop to get the timing tuned and the PE mode tuned.
Any tunerpro data to go with this? Maybe post your bin...
You're probably reaching peak VE at 3500 rpm and the tune is not delivering enough fuel to it. 383 with long runner manifold is going to have a serious torque/VE peak at that rpm.
Here's what I found.... (see if you can post the raw .xdl log files as well...)
1.) your displacement constant is a little off at 771 cc/cyl. 383 in^3 = 6276 cc. 6276 / 8 = 785 cc/cyl
2.) Is this how your VE map looks when you open it as well (picture 1 below)? If so, it needs a lot of work. If you are able to run TunerproRT, I've attached an adx file that has a BLM histogram capability. That combined with my EZ VE tool should get your VE tables in line pretty quickly. PM me an I can work with you on how to use it. You'll have to change the adx file extension from zip to adx (this is the only way I'm able to post the adx file here).
3.) This area of your VE table is most likely your culprit (picture 2 below) at WOT. My guess is your MAP sensor may not be hitting exactly 100kPa exclusively due to the leaning and richening.... which means you may be bouncing around between the 90kPa column and the 100 kPa column. Those two columns have too many abrupt changes in VE.
4.) Can't really judge your PE tables without a WB O2 report. But once you get the VE table ironed out, you can start playing with the fueling via the PE vs RPM table.
1. My engine is actually a 377 stroker as I’ve used a brand new block that wasn’t bored .030 over. I forget to mention that.
I will try and post raw datalogs but the website wouldn’t let me attach those kinds of files.
I noticed the area of VE that you are referring to and I agree that is a huge swing. Also, did you notice that several of the VE blocks are maxed out? That shouldn’t be, right? I can’t believe that 36lb injectors can’t keep up. My fuel pressure remains constant and I have a 255 lph fuel pump.
Thank you very much for replying and helping. I will try to get you more info ASAP
I don't think you're running out of injector per se. you just to scale entire VE table down so you have some more head room to work with in the individual cells that need it.
what you can do is set the injector constant to say, 34 lb. that'll force you to scale down the entire VE table by essentially a factor of 34/36 =.94. at which point you can go back in and raise certain areas as needed.
dont feel that the injector constant MUST match the advertised flow rate or else.
that's definitely not the case.
btw, what injectors are you running? Bosch III style? and if so, do you have the correct voltage offsets?
Do you have a datalog from the dyno pull or some WOT log from the street, please share? Check the injector pulse width behaviour during WOT. It sounds like you are experiencing a $8D injector pw limit issue. You need to tweak your bin code:
I think you are on to my problem here. While my Bin files do need tuning work for sure. However, on the dyno yesterday we even tried a bin file from a stock 350 TPI (we modified the scalars to reflect the displacement and injector size.) and it produced a very similar lean condition in the same areas. Tweaking my Bin code is quite foreign to me thus far though. I have no idea what i'm doing at all in that regard.
I don't think you're running out of injector per se. you just to scale entire VE table down so you have some more head room to work with in the individual cells that need it.
what you can do is set the injector constant to say, 34 lb. that'll force you to scale down the entire VE table by essentially a factor of 34/36 =.94. at which point you can go back in and raise certain areas as needed.
dont feel that the injector constant MUST match the advertised flow rate or else. that's definitely not the case.
btw, what injectors are you running? Bosch III style? and if so, do you have the correct voltage offsets?
Yes, Bosch III style and I'm pretty sure I got the Voltage offsets from you. They calmed down my VE tuning considerably a month or two ago. I hadn't thought of scaling down the injector size and that's a brilliant idea. I will say that one of the things I tried on the dyno yesterday was to increase the displacement by 20% and while it still produced the same lean condition but lower on the AFR scale as you'd expect.
10-12-2018, 08:12 PM
