MAP swings at high rpm, what can i do.

[whittlebeast]

There are all sorts of things we can do if it really presents a problem. Making big decisions that complicate the the tuning process is not wise when based on looking a one pull worth of data.

[martin2day]

Andy,

data is no problem.
This is my last run. https://www.dropbox.com/s/jsm7bi02k5yf2 ... 9.zip?dl=0

Martin

[martin2day]

Hello,

Andy, thank you very much for the good video about ITB.
I think if i use ITB i have got the same problem i have with SD.

Looking at histogram i think i can use only SD for my cobra.

MAP.png (484.24 KiB) Viewed 366 times

I think the MAP Signial is very smooth over the TPS Range.

But: With my setup up to 48%TPS the rear too throttle blades are full closed.
At 49%TPS the begin to open. At 100% front and rear are full open.
So i think i have to use staged injection table as a function of TPS.

At SD it is a function of MAP... this doesn't work.
I can only tell at xx%TPS staged is full in... but i don't think this is good.
I think it is posible, that the rear cylinder can get to much or to less fuel...

What is the staged Table in ITB mode use? I think it is also load... ITB load.
What do you think?
Do i over thinking this?

I think if the front blades are open 60% and the rear blades are open only 10%... than i must adjust the amount of fuel at the same rate... 6:1.

Thank you so much for helping me.
Martin

[whittlebeast]

You are over thinking this.

Where are your injectors located? Up near the throttles or down near the intake valves?

You were not pushing the throttle down far enough at low RPM in that screen shot to ever get to 90 KPA.

Andy

[martin2day]

Andy,

the injectors are over the throttle blades.


Okay you tend to use ITB?

Martin

[whittlebeast]

Your setup will need to run Staged injection based on TPS. It may never jun correct as you may end up with fuel distribution issues. Injectors at the valves may be your only good option. The throttle body will be fine.

Yes I do run true ITBs

Andy

[martin2day]

Andy,

thank you very much.
You are right... my TBI is not the best setup... but i don't have to pay for this components.
So today i don't want to buy new stuff.

Did you or the others have a look at my long LOG in the post.
I think the TBI with the EAE activated and the change i have make are not so bad.
Some parts are not optimale... but it looks good.

By the way: Is there a change to get or to buy a cheap ITB for my SBC Gen1.

Martin

[spitnl]

Why did you change the setup from all the throttles opening together to staged?

You could drill the intake and epoxy 8 injector bungs in.
Not sure how durable that would be though....

Cheapest chevy ITB is probably this one:
https://www.ebay.com/itm/Maximizer-ITB- ... 1865073916
No experience with it so can't comment on the quality.

Fred

[martin2day]

Hello,

the light car and the pig power of the engine was hard to drive.
Off idle was also harder to tune.
Setup the idle was also hard. To set the front and rear the same amount...
With this change it is much easier to drive the car. And the throttle response is much better.

I copy this from the carbureter with second vacuum blade...
Edit: And so i can run 4 squirts per cycle... because i have only 2 inj. at idle (with 4 it is not possible)

Martin

[martin2day]

Hello,

today i drive a little trip. It is very cold in germany. (8°C)
I change the EAE to react slowly. I also change the IGN Load to Alpha-N.

The problem is gone. The PW looks much better and the car sound better.
And the AFR at accelerating is also better.

I am very happy. The cobra drive very nice.

Thank u for helping.
Martin