540's on the stock ECU + piggybacks

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ChrisD

New member
Has anyone done this? I'm interested in finding out the idle adjustments that you have made to base fuel pressure, and the piggyback settings (if any). How is the quality of idle?

Any info is much appreciated. I've just got mine installed, trying to get it to idle nicely for me.

:)

Chris
 
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ChrisD

New member
I am interested in *ANY* info that anyone has on this, no matter what kind of piggyback they use.

However, I have:

Perfect Power SMT6. Allows fuel/ignition tuning. Fuel is altered through manipulation of the AFM voltage. 128 site maps.

I also have an Aeromotive adjustable FPR.

:)
 
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OlyST185

Active member
firstly you should know that the OEM 2nd gen fuel isnt enough to support 540cc.. tests has prooven 10% fuel pressure drop at the 4th injector
 
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ChrisD

New member
OlyST185":p9r414yg said:
firstly you should know that the OEM 2nd gen fuel isnt enough to support 540cc.. tests has prooven 10% fuel pressure drop at the 4th injector
Click to expand...

Well, I don't fully agree with those findings, but none the less I am well aware of the study by wolfkatz. I do in fact have the stock 2nd gen fuel rail, and am using a 255lph fuel pump. Regardless, I'll be tuning rich enough that this wouldn't be a problem.

enzytebob: thank you for the link. :) I actually made a few posts in that thread. Only Jekylandhyde seems to have posted any specifics of his actual set up.

Anyways, I'm still interested in hearing what anyone has to say on this topic! :)

Chris
 
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935motorsports

New member
I used RC 550s on my ST165, stock everything, no piggies.

The car HAD a FCON w/ GCC when it was running properly. I got it without any electronics, so I had to play with the AFM.

The idle was always solid and started great every time. It was really rich under boost and with the VTA bov at the time made for some huge fireballs.

I have no clue about the A/F at the time though. I was running 18 psi. Now that I think back on the setup, I realize that the AFM was most likely tightened. I recall that the top had been opened and re-sealed.

I didn't know anything then :)
 
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AWDios

New member
Chris you know my story.

At first with the 185 ECU I was running around 6:1 at some RPM's Then we used the S-AFC2 to tune to about 11 on the dyno. Spun a rod bearing on the dyno.

Now I have the SAFC out and the 185 injectors in until I get all the stuff I need.
 
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ChrisD

New member
Thanks for the info Rob. :)

Roger, I know you had the stock FPR on the 540's with the 185 ECU, so fuel pressure was stock, but did you make any SAFC adjustments at idle? How did it idle when you didn't make any adjustments?

I'm thinking more and more my dumb-ass didn't plug something in properly. I haven't found a single person who said it wouldn't run. Maybe the ISC, or the TPS... I don't think there's anything else that is important in the throttle body area that I might have forgot?
 
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AWDios

New member
I should have a 205 FPR (don't know if it's different) but 185 fuel pump.

At idle, when it was cold, I'd have to run it pretty rich, (assuming this is due to the lack of a cold start injector) and then after it warmed up, I'd almost lean it out to the max the AFC would allow, otherwise it ran pretty crappy.
 
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ChrisD

New member
Fark I'm pulling an AFM code, all connections check out. Hopefully I didn't fry the ECU... :(

Anyone know what happens if you send too much voltage to the AFM signal ?? Lets say 10V... :(
 
___Scott___

___Scott___

Active member
It's tough to say without the electrical schematics for the inside of the ECU, or without probing around in there for an afternoon. If the input has over-voltage protection (or at least current limiting), then you should be OK. If not, it has probably fried one of the A/D input pins on the microcontroller.

If anyone has schematics on the inside of an ST165 ECU, I would love to see them.... GARY...??? (who seems to have pick of everything) :D
 
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ChrisD

New member
Thanks Scott, good to know. My ECU is an ST185 model too. I will have a spare ECU to test out for this weekend, from a '93 Alltrac, so I'll give that a go and see what happens. :)
 
___Scott___

___Scott___

Active member
As a safety net, you might consider using the same zener diode that people use for their DIY FCD and applying it to the AFM signal input. It will protect the input by limiting it to 4.7V
 
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ChrisD

New member
Never thought of that. I'm sure I've got a spare sitting around somewhere. Thats what I'm using as an FCD as it so happens. Or I could just not be a dumbass and have the global settings adjusted properly.
 
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