Injected BBC Idle Quality

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EFIBBC

Guest
Hello,
First time here but am very impressed with your site. I have a Merlin 540 C.I. Big Block Chevy with a BDS 8-71 Blower and a Enderle Injector Hat converted to Electronic Injection (16 Injectors) with a Speed Pro ECU. It is a limited use street car that is fast but has below average idle characteristics. Would the optional IAC (Remote Version) help much or be a waste of money. Any other tips on taming this motor's bad idle and low end response would be appreciated....thanks!
 
I do not have DFI, but I have some info you can think about. I am ASSuming that you have no IAC at all. When my IAC (stock Buick Turbo) went bad, I was trying to cure the bad idle (did not know IAM was bad) and stall problem by changing the throttle position. It did not work for crud since things are always changing. So with that, I think that the IAC would help idle characteristics due to having better control of letting in the air for idle.

If this does not help maybe someone else can tell me that I am way off and give you a better idea.

What does that beast run anyways? ERIC. :D
 
I am fairly new to this system so take this for what it is worth.


Do you have the wb O2 sensor with your system? If so, what is the sensor telling you your A/F ratio is at idle? Have you tried setting your system to idle in closed loop?

Without the IAC controlling the amount of air at idle, I would think the VE settings would have to be lean to make it idle. Or like the old mechanical systems, it would be extremely rich at idle just to compensate for the stumble. This the case, your enrichment settings and VE table would have to be just right, to make it not stumble or dog off idle.
I would think the IAC would be a sound investment.
 
re:

Does it have that "cyclic" up/down idle that alot of roots blower cars seem to have?

TurboTR
 
Hello and thanks for all of the responses. It does have the WB O2 Sensor and it does tend to surge (like some carb blown motors)even with the A/F ratio around 13 to 1. My hope was that injection would lower the idle and help response but I think the cam is just too big for the street and making the engine lazy at lower RPM's.....
 
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