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Discussion Starter · #1 ·
Jeez Louis... I *cannot* get it to quit doing this.

at very low throttle downhills, the A:F oscillates between 12 and 18 and the car surges over a 2 second or so frequency.

I have heard of others having this issue, but I've never heard what tuners do about it.

I have:
Perrin Mod'd STI injectors (soon to be swapped with my 720 JECS)
Blow-through MAF (I dont think has much to do with it)

Any helpful hints?

Thanks,
Chris
 

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RainMaker said:
Jeez Louis... I *cannot* get it to quit doing this.

at very low throttle downhills, the A:F oscillates between 12 and 18 and the car surges over a 2 second or so frequency.

I have heard of others having this issue, but I've never heard what tuners do about it.

I have:
Perrin Mod'd STI injectors (soon to be swapped with my 720 JECS)
Blow-through MAF (I dont think has much to do with it)

Any helpful hints?

Thanks,
Chris
yes. I get this too. It did it while stock just not as noticable. It's going from injectors completely off to barely on. I just choose a different gear to keep the car on one side or the other.
 

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Discussion Starter · #4 ·
well, the IDCs oscillate down to 3.X. They idle at 1.15 or so... so Im suspicious of the idea that they turn "off" at 3.something.

Help?
 

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Discussion Starter · #5 ·
Well, either way. it appears that switching form the Perrin Mod'd stock injectors to the JECS/Nismo 720cc fixed (for now) the issue totally.

-chris
 

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Bump...

My car is doing this too... pretty badly after installing larger injectors. Idle, part throttle, and full thottle are fine, but decelerating in gear surges badly. I am aware of unfavorable issues with the Helix injectors, but is this really just the type of injector? What else could it be? Bad injector o-ring allowing fuel to be sucked in during the high manifold vacuum of decelleration maybe? Weird vacuum leak?

Thanks...

Matt
 

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Been searching for answers or fixes on this too, I experience it mostly from crusing on the freeway. With the foot pressure on the gas pedal held constant, the throttle would surge and recede, like someone is modulating the gas pedal ever so slightly. I have Deatschwerks 740cc injectors.
 

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that's why we don't have hills in IL. ;)

fwiw- i was experiencing this while turning tightly... i never thought of it is an engine related event, more so something caused by a diff. i think i'll do some logging now.
 
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