Read this in a post. Traxion told someone to do this with their hotcam car. Just curious. Mine is waaay rich at idle.

 

Show me the post. If anything he may have stated that it was possible to do. You must force a lean condition unless you edit source code. How do you know yours is rich? Smell? Do you have a cat?

 

Hey I know a girl from Jackson MO...how 'bout that.

Anyway...just reduce the values in the idle area of the VE table. I like to use an open loop idle.

 

How do use an open loop idle? And if you do not use an open loop idle changing the VE tables wont effect anything if the blms are in reason.

 

The post is further down this page entitled "Need LT4 hotcam bins" or something like that. As for knowing my car is rich... hmmm BLMs bottoming out, smells rich as hell, you can see it in the exhaust sometimes, and I'm still running a 19# inj const when I really need a 24# constant, but when we changed it... the car ran like total crap. I have NO cats at all, LT headers, with a custom y-pipe and 3" dumps.


*What should I do then?? I just don't understand why the car won't respond well to the inj constant change. Aynone?? THANKS!!

 

What were the blms when you changed the inj constant?

 

The main problem is that you'll have a couple minutes when you first start the car BEFORE the ECM enters closed loop during which time the cylinder bores are being washed with raw gas and the exhaust is blowing fumes out the back that make your eyes water. During this time the ECM is going off the VE table (along with some other adjustments). Reducing the VE in the idle region will reduce fuel during open loop. Also, if the camshaft produces a very very low volumetric efficiency then chances are that even when the ECM does go closed loop that both the BLM and INT will bottom out and the no more adjusting can be done. Thus, pulling fuel via the VE table will have an affect in this situation too.

Tim

 

My BLMs were still way too low. And it started bucking and stumbling and running poorly by just changing the inj cons. We were stumped and didn't understand it.


*Traxion... so I guess I need to play with fuel in the VE tables at idle and mess with the inj constant more or what? I just want to get started on tuning this thing the proper way. THANK YOU!!!!

 

The injector constant change changes the fuel across the *Entire Range* You changed the injector constant numerically higher resulting in a leaning across all rpm ranges and Kpa values. Since you needed less fuel at idle, this would help the idle. But since you probably need more fuel off idle this would cause the off idle BLMs to be on the lean side and possibly beyond 160. Just be careful you dont go in to PE with everything lean. So, you need to pinpoint the places where you need fuel or not, like traxion said.

I would set my injector constant and not touch it. Pick a number and stay there!

 

You have a scan tool. With SD it is very easy to get reasonably close.
Whats your MAP and RPM and BLM reading at idle?
go to those cells and cells close by and start lowering them.

I told champo some stuff you needed to do in some e-mails. Did he ever tell you?

 

Take the time and read the sticky near the top of this board on part throttle fuel tuning for speed density engines. There's really no point in me repeating everything that I said in that post.

Tim

 

"How to "take fuel out at idle??""
was the orginal title of this post. Why are you talking about part throttle? I am talking about idle

 

I know the inj constant changes it across the total spectrum, but I can't even get it to 24 like it needs to be. WTF? I have 24's and I'm running a 19# constant. I need to get that straight b4 I tune the rest of it. Right?


Aaron, I'll have to check my MAP/BLM's at idle again. Champo never really told me much about what u told him. I gotta get a burner soon and start getting somewhere on this thing.


Traxion-Yeah I've seen that post, but thats not what I'm talking about.... yet!


Thanks to everyone!

 

Who cares. It's all MAP vs. RPM. It's all done the same. If you read the post I mentioned then you would see that I specifically talk about idle richness when running bigger cams and that adjusting this situation is the same as adjusting part throttle.

Tim

 

Tim, right? Wheeeeeeeew! Just got done reading that entire post. THANK YOU!! That actually all made sense to me. I understand what I need to do with my lower VE table to lean it out some at idle and then work on the upper VE too. As for my inj constant though... should I set it at 24 or so first, even if it kinda runs like crap, and then work on my VE tables. Thats what I'm getting from the posts I'm reading:
1) set injector constant
2) then work on VE tables

*Is this what you recommend?? I just still don't understand why it runs so poorly on a 350 chip (22# or 24# constant)??? Thanks again for the help!

 

If it were me I would set the injector constant to 24lb, set the fuel pressure to 45psi, and then work on the VE tables to bring the BLMs to around 128. The car is still gonna run like chit on a stock 350 chip because the VE tables (i.e. the fueling) isn't correct for a 218/228 cam.

Tim

 

Thanks Tim. Thats what I'm thinking, but I don't have an AFPR anymore, the diaphram broke and I figured I didn't really need it. Can't I tune more thru the computer? Well, guess its back to trying to tune again. Thanks again!!