Evo 8 580CC injectors lean out in boost. - Miata Turbo Forum - Boost cars, acquire cats.

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Old 08-18-2017, 02:34 AM   #1  
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Default Evo 8 580CC injectors lean out in boost.

So I was running RX-8 yellow injectors, ran great hit boost great and it never leaned out. Now my friend sold me his 580 CC evo 8 injectors, we redid the connections and everything with no resistors or anything. Just the day before he was running them perfectly on his e85 miata 1.8 without any issues nor resistors. Now in my car they idle and drive great. But as soon as I start getting into higher boost they lean out. Any ideas what could possibly cause this? No matter how much fuel we add in the VE table they will not stay at the correct afrs. Could I be overloading the stock FPR? I have a 320lph fuel pump, the exact same one he is running. Worst comes to worst I go back to rx8 yellows. Any help is greatly appreciated. Here is a datalog of this event. As you can see once I get into boost at hit 6 psi it leans out all the way. https://drive.google.com/file/d/0B6M...w?usp=drivesdk

Edit: after some reading from my understanding my DIYPNP can not give these injectors enough power to run these injectors correctly which is what is causing it to lean out under high load? Correct me if I am wrong thanks.

Last edited by polarity8181; 08-18-2017 at 03:32 AM.
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Old 08-18-2017, 02:45 AM   #2  
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Here you can see where it occurs and what is going on. We are both stumped on what this could be. It honestly idles great and drives fine. Once it hits boost though that's where it leans out even though the duty cycle is only 60 ish percent.
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Old 08-18-2017, 01:57 PM   #3  
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There is a negligible difference between 550cc rx8 and 580cc. Not worth doing. If the 580cc are low impedance it would explain the problems.
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Old 08-18-2017, 02:35 PM   #4  
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There is a negligible difference between 550cc rx8 and 580cc. Not worth doing. If the 580cc are low impedance it would explain the problems.
I have 420 CC rx8 injectors so this is a decent upgrade. They are low impedance. I'm pretty sure at 2-3 ohms. Would I need a 10 ohm resistor for these per injector?
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Old 08-18-2017, 02:37 PM   #5  
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I hope you got them for $3.50 because they're junk.
But yeah you'll need to wire in resistors to run these. Which ecu was your friend using them with?
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Old 08-18-2017, 03:13 PM   #6  
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I hope you got them for $3.50 because they're junk.
But yeah you'll need to wire in resistors to run these. Which ecu was your friend using them with?
I got them for 50$ with the harnesses attached already. He was using a megasquirt as well. They ran perfect on his car without resistors however he has a 1.8 and I have a 1.6. Mine Is a diypnp I think his might just be a mspnp. So does a 10 ohm 10 watt resistor wired right into the 12v work right before each injector. Such as this one. http://www.frys.com/product/472305?s...H:MAIN_RSLT_PG
The evo 8 injectors are 3 ohms.
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Old 08-18-2017, 03:22 PM   #7  
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buy some real injectors and stop janking around.
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Old 08-18-2017, 03:25 PM   #8  
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buy some real injectors and stop janking around.
​​​​​​:( they are real injectors
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Old 08-18-2017, 04:11 PM   #9  
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No, no they are not. Thats why they require all sorts of f-ing around. FlowForce and prosper. its 350 bucks to start winning at turbolife.
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Old 08-18-2017, 04:25 PM   #10  
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No, no they are not. Thats why they require all sorts of f-ing around. FlowForce and prosper. its 350 bucks to start winning at turbolife.
Well I may just put the rx8 ones back in, I just wanted some more head room on my duty cycles. If these resistors don't fix the issue I'll just put those back in and go back to boosting perfectly.
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Old 08-18-2017, 05:55 PM   #11  
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Peak and hold versus saturated
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Old 08-18-2017, 08:12 PM   #12  
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Peak and hold versus saturated
Yeah I know these are two types of injectors and these are peak and hold, they ran perfect on my friends 1.8 boosted miata though.
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Old 08-18-2017, 09:10 PM   #13  
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Double post.

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Old 08-18-2017, 09:18 PM   #14  
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Yeah I know these are two types of injectors and these are peak and hold, they ran perfect on my friends 1.8 boosted miata though.
Well, you can adjust your megasquirt to run peak and hold injectors.


No one ever does for the following reasons:

1. There is no advantage.

2. We mostly run saturated injectors.

3. It is a huge pain in the *** for no advatage.

4. No one wants an additional tuning parameters for no advantage.

5. No one want to wire in a resistor box. (Ive done it, this sucks) for no advantage.

By all means, if you think this makes you a super cool pioneer, do it. I ran low z injectors like 7 years ago. I am not a pioneer. Ask your best friend how he did it. You need to change some settings, which at this point i have forgotten. You have to dick with the pwm settings on the megasquirt or something. I am sure if you search you will find it.

20 years ago, peak and hold injectors may have provided slightly better control over garden hose injectors on a small turbo engine. Today we have excellent things such as sequential injection and ev14s.
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Old 08-18-2017, 09:44 PM   #15  
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Originally Posted by chicksdigmiatas View Post
Well, you can adjust your megasquirt to run peak and hold injectors.


No one ever does for the following reasons:

1. There is no advantage.

2. We mostly run saturated injectors.

3. It is a huge pain in the *** for no advatage.

4. No one wants an additional tuning parameters for no advantage.

5. No one want to wire in a resistor box. (Ive done it, this sucks) for no advantage.

By all means, if you think this makes you a super cool pioneer, do it. I ran low z injectors like 7 years ago. I am not a pioneer. Ask your best friend how he did it. You need to change some settings, which at this point i have forgotten. You have to dick with the pwm settings on the megasquirt or something. I am sure if you search you will find it.

20 years ago, peak and hold injectors may have provided slightly better control over garden hose injectors on a small turbo engine. Today we have excellent things such as sequential injection and ev14s.
im not trying to be a pioneer but I'm just trying to make these work. He didn't change many settings other then adjusting his dead time and correction and ran them fine. I will however be going back to my RX-8 injectors for the time being to avoid the hassle.
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