The car is a 1992 Firebird convertible with a 700R4 transmission
Engine is a 383 - I'm using a "First Fuel Injection" TPI system - Comp 280XFI cam - Brodix IK200 heads - Hooker 2460 headers
Let me say now - that this is a "cruiser" and will probably never see a drag strip.
I'm using Rbob's EBLp4 and Tuner Pro for engine management - I like the system!
I have a few of issues and I hate to bother Rbob - I know he is busy.
For the spark table I'm using the 3005 stock TPI profile.
As a secondary table I blended a 3000 MPFI table with the 3005 TPI table. Disabled the knock sensor as the after market valve train gave too many false knocks - run 93 octane and the plugs show no sign of detonation.
I know that everyone jealously guards their spark advance tables but a little helpful information would be appreciated.

The two main issues I have are:
At idle when I "blip" the throttle it take 20-30 seconds for the engine to return to my commanded idle of 875rpm. This seems excessive
The "cruise control effect" - while driving at slow speed (under 25mph) I do not have to touch the throttle and at lower speeds (between 5 - 20 mph) rpms tend to "creep up" requiring me to continually brake.
If I slip the transmission into neutral while moving the rpms go to roughly 1800rpm and "hang" there - do this to any other auto transmission and the engine would "idle down" to normal (some would wonder why I would do this but I get tired of "riding the brakes and it's really useful on icy roads to control skids - just like pushing in on the clutch).
I'm guessing the VSS signal comes into play with the IAC -looked at Tuner Pro parameters but I must be missing something.

I'm still teaching myself tuning so I appreciate any help!

 

I've had this issue before.. A few questions:
1) Do you have EGR? Smog pump? 9th Injector?
2) What mask do you have? Is it 6E? (does the EBL use the same masks as TunerPro?)
3) What temp. do you run at?
4) Do you have a heated O2 sensor? (usually headers need this in order to go into closed loop)
5) How old is your IAC valve?
6) What is your TPS set at? Should be 0.54v.. What are the volts at when in drive and it's at the commanded 875rpm, and what is the voltage when you blip the throttle and you are having the cruise control effect? Perhaps the throttle blades are stuck open and is what is causing this?
7) There are ways in TunerPro to get the idle down but it appears you are having this problem in drive.. What are your BLM's at during this period of "cruise control effect"?

That's all I can think of at the moment!

 

Sounds like an IAC issue or the IAC tables need to be changed. need to datalog the event and see what the ECU is commanding the IAC to do. In log you will see commands not the actual position of IAC. But it is most likey the same. I believe there are decay filters for IAC.

since you swapped intakes a vac leak has to be ruled out.

 

Thanks - gives me more to think about!

 

No vacuum leaks and I do need to review the data logs concerning the IAC.
I'm using an Chevy S-10 torque converter (old trick) which may not have enough stall for the cam. My engine combination has tons of torque.
Hey - Thanks for the reply!

 

In the Scalars of the BIN I'm using in Tuner Pro I changed the setting of: Idle-MPH Threshold to 30 mph (stock is 4 mph) and it really made a difference.
No longer have to "ride" the brakes at slow speed.
Not much information out there about this setting but I thought I would try it as nothing else seemed to help.
Anyone have a similar experience?

 

Check what the spark advance is doing. It may be too high in the areas where the engine just keeps going. By changing the MPH for idle higher the ECM will switch to the set idle SA value at a higher speed.

The set idle SA is likely lower then the areas that would normally be used.

RBob.

 

I will do that - and thanks for the info!