More newbe questions

[Subfixer]

I just replaced the original injectors with FIC's from Jerry's. Replaced the coils also.
The observations below were happening before and after the work above.


1. When I take my foot off the accelerator, there is a slight surge before the car actually stats decelerating.


2. Also, when coasting down a long hill with my foot off the gas, there are slight surges about every 3 seconds.
Thought is was the compressor cycling, but A/C is off.


3. When the engine goes from the primaries to secondaries, there is a very noticeable "kick". Not a smooth transition.


So, are these normal functions?
Thanks.

[garyhugo]

Can't answer 1 or 2 but 3 is a definite yes. When the secondaries come on there is a real kick and it's not smooth.

[32valvesftw]

For item 1 , maybe check your fuel pressure
2 happens to me but I think it is the result if my chip, but could be some small exhaust leaks were causing issues that the computer was trying to adjust for, when i sorted the leaks that got better
3 is normal for mine

[Paul Workman]

What year is the Z?

I keep my scanner in my glove compartment. My point is, I can run a diagnostic check - some 41 dynamic checks in all, AND read any/all codes. BEST DAMN TOOL I every bought for my Z!

That said, fuel pressure is not directly monitored - only indirect (O2) and block learn measurements to indicate possible fuel delivery issue among others. For direct reading you need a fuel pressure gauge taped to the windshield so you can watch it at normal and WOT.

Are you running with a custom chip, and if so, who's? Did you do anything to the exhaust system, e.g., add headers, etc., WITHOUT re-addressing the chip calibration?

I feel like a sucha dinosaur - relegated to only an AutoXray scanner. But, Dominic (for one) can coach you far as equipment, software and a notebook (computer) to do data logging to end ALL the guesswork when it comes to troubleshooting!

And, (belated) welcome to the BROTHERHOOD OF THE BEAST!

Paul.

PS: Ah, your #3. I don't remember feeling the secondaries coming on. I'm not saying there was no surge...but I've been running since about (?) '09 w/o the dang things in there and I can't remember the surge if there ever (probably) was one.

Note: I would never reinstall the SPTs either. I love the instant throttle response, the clean intake valves, NO maintenance, etc. (can't actually - due now to my 37.5mm porting).

[Subfixer]

Car is bone stock. No mods. I'll check the fuel pressure next.
Anyone have a fuel pressure guage recommendation?

[Ccmano]

What is the IAC count at idle and did you verify the throttle position sensor at .54 volts at rest? For IAC count you’ll need a Tech1(A) or equivalent. It tells you what the idle air control valve is doing. Could be the source of your hunting on deceleration. May need reset after you have everything apart. Same for the throttle position sensor. That voltage can be tested with simple volt meter.
H

[Mystic ZR-1]

Originally Posted by Subfixer

Car is bone stock. No mods. I'll check the fuel pressure next.
Anyone have a fuel pressure guage recommendation?

I’ve got a gauge you can use.
Call me or wait till Saturday b-fast?

[XfireZ51]

The oscillating idle when freewheeling is typical of the LT5. It can be mitigated w some tuning. Depends on how “wild” the seesawing is. Its a bigger issue w mods like cams.
As for the “kick” when getting into the secondaries, there is a delay built into the tune for “turn on” of secondary injectors. My suspicion is its there to give the throttle plates a chance to open before the injectors start spraying. Eliminating the Port Throttles operation allows u to zero out that delay.
Finally, the FIC injectors have a different Injector Bias than the stock Bosch units. This affects particularly small Pulse Width fueling like idle, trailing throttle, decel, and closed throttle. The IB, because it is a constant, constitutes a significant part of the PW whenever the PW is small. As the overall PW is calculated to be larger and larger(as in WOT), the IB becomes a smaller percentage of the overall PW and so affects the tune less. That part of the calibration should be changed so the ECM is utilizing the correct constants as part of its calculation of the required PW.

[Top Toy]

Suggest you pull your chip out to confirm it's still the original. And even if it is, it may not be the latest revision from GM. The problems you're experiencing could also be attributable to a less than ideal tune.

Sent from my HTC U11 using ZR-1 Net Registry mobile app

[Subfixer]

Since I don't have a Tech-1, will this work?

1320 Electronics OBD1 Bluetooth scanner.
http://www.1320electronics.com/products.html

Has anyone used this?

Thanks, Paul