Low RPM + High boost = Bent rods?

General Tuning Questions And Discussions
'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

85 to 90% duty cycle would be as high as you'd want to go. I think you are too lean @ 12.4.
12.0 is more desirable. You could be even richer than that. You don't have any headroom in your injector.
Did you look into what happened to the other one.
It's tempting to add more timing if you're seeing good gains with it, but I would add in 0.5 degrees at a time, keep an ear out for knock through your set-up (pre-amp) and read what the plugs are doing.
You're running Double fire now I see. How would you go running the bigger injector (if you could get another one), up to, say 2.0 ms Minimum BPW sync Double fire upper value, and 1.5 ms Minimum BPW sync Double fire min value.
BennVenn
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Re: Low RPM + High boost = Bent rods?

Post by BennVenn »

I agree with the headroom on the injector. I'll fit the new one again and have another crack at tuning. I think it might have been the lower o-ring that blew out given how much fuel was rushing out of the throttlebody. When i removed the injector it looked to be in position...

Looking at the log when it failed, it hit 155kpa and then afr went <10 and it stalled so it makes sense the o-ring was the cause of it. The injector is identical to within about 0.25mm, maybe that's enough for the oring to slide off. Will report back tomorrow on that.

Are there any other tables I should be looking at when trying to lean out the idle on this oversized injector?

I'll set the target AFR to 12.0 across the board and go from there. I'll probably wait for the cold air intake bits before messing too much with the timing. I'd feel better with ambient IAT's
'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

Set these scalars (image)
Upper Value to 2ms.
Min Value to 1.5ms.
You could set your AE vs RPM table even lower ie 0.30 @ 800 and ramp up towards your 0.90 figure @ 2400.
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delcowizzid
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Re: Low RPM + High boost = Bent rods?

Post by delcowizzid »

You won't want to use the low pulse width mode with tbi it has to fire every pulse to keep the manifold full of fuel and all the cylinders at the same fuel ratio
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

Even with an overly large injector and at very low pulse-widths?
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Re: Low RPM + High boost = Bent rods?

Post by antus »

charlescrowns good working TBI Turbo bin is here if you want to compare for notes viewtopic.php?f=26&t=6786&p=100922
Have you read the FAQ? For lots of information and links to significant threads see here: http://pcmhacking.net/forums/viewtopic.php?f=7&t=1396
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Re: Low RPM + High boost = Bent rods?

Post by BennVenn »

Idle Afr's remain the same on the stock injector in both modes. I think there is little enough airflow to get away with it. Off idle you can hear the difference.

I'm going round two with the larger injector now. I think it was just a leaky oring messing with my idle AFR.
'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

The knockout round! :thumbup:
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Re: Low RPM + High boost = Bent rods?

Post by BennVenn »

old_highpressure_5.xdl
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Pulsar_18apr21_stockInjWoundUp.bin
(32 KiB) Downloaded 106 times
Large injector blew out the o-ring again, twice. Unless i modify the throttle body to add a retainer this injector is not an option. Fueling at idle was still too rich even with single/double mode though it did help get it up to 11:1.

Increasing the regulator pre-load boosted fuel pressure and lowered afr's 1 point. We're now at 5000rpm, 8.25psi, 11.5 ARF right before it hit fuel cut. Looking at the size of the regulator spring/diaphram/control plate I don't think this reg will track boost linearly. I should pop a gauge on there to confirm but it'll be easier to just use an external reg. With a little more fuel pressure or a rising rate reg this injector should be OK.

I wanted to limit this motor to 6psi. Might be time to look at a bigger turbo.
'quipt4it
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Re: Low RPM + High boost = Bent rods?

Post by 'quipt4it »

I thought that o-ring security issue might be a reoccurring one.
+1 on the external regulator.
Is that a larger VNT turbo?
Do you think the motor won't handle more psi? 6lb is barely breathing on it!
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