Friends,
Recently I am working in the installation of a TBI package with ECM 747, modified ANLW.
Here in Brazil we have two types of fuel, E25 and E100.
I opted to use E25 that is the closest of the fuel found in the USA, with 75% of pure gasoline and 25% of etanol, with 95 octane and AFR = 13.0
I adjusted VE and SA tables according with the fuel. BLM is in 128.
In the general, everything is working well, less the idle.
Programmed for 600 rpm, ECM insists on 1000.
With the hot engine, at startup, before CL, idle is close to 600, then it is going growing up to the 1000. I am using a heated O2 sensor, so I have C/L very soon.
If I disconnect IAC, it is easy to get 600 stable, with 5% of TPS. Seemingly there are not vaccum leaks. I made the experience of introducing a vaccum leak in TBI and the IAC count falls...
My bet is that I have a rich mixture and that ECM compensates opening more IAC (near 100)
I tried to adjust VE table without result. Only BLM is going out of the 128.
Can anybody give me a light?

p.s. Excuse me for my English, but it is not my default language ... and and I will probably be long to give feedback (needs translation).

 

The idle control on the '747 is a little lacking. In park/neutral there isn't a set idle speed, just lower and upper limits. The engine coolant temperature also plays a role in idle speed control.

In this thread is an article about the '747 IAC control. The last post of that thread adds/changes some of the information in the article. It may be the most important part.

https://www.thirdgen.org/forums/diy-...-follower.html

RBob.

 

Hi RBOB.

I already knew this article on IAC...
I didn't alter the 'kick down steps' and nor the table 'IAC position vs. coolant'. In this bin, the kick down steps is with 25 and IAC position vs. coolant exactly with the numbers of the article, ie 24 in the temperatures above 56c.
I never distrusted the temperature sensor, because I follow with WinALDL and the normal temperature of this engine is about the 80c. I am using two fans, the first at 80c and the other at 95.
On this weekend I tested with another ECM, the 8063 + AKRL and the behavior was same, but with a normal IAC count (~30)... The problem is that I don't have a IAT sensor and I don't know how inhibit it in the bin. In fact I don't get a ecu or xdf with enough information for the 8063.
I suppose that the things would be simpler with EBL...The problem is that this is a little expensive for me due to customs... but I will still have one!

Thank you,
Marcus

 

For running E25, you need to set the Stoichiometric value at LD2AA for 13.3 then scale the VE tables accordingly. This will set the closed loop fueling to properly calculate injector pulsewidth. HTH

 

I did it already...