Begi Turbo Kit Running Lean
I recently picked up a 96 miata with a begi system IV turbo kit with #1 intercooler running 5 psi. The previous owner installed this kit in 2002 and daily drove it up until last year.
I hooked up a wb02 to it yesterday to check the AFRs and it was running very lean, 15:1. So I checked the fuel pressure gauge and it was running 120+ psi under boost! The onset was set to 70 psi, so I reset that back to 50 psi. The max fuel pressure was still hitting close to 100, but still ran lean. What could be causing the car to run lean? I checked the timing and it is set to 8. Recently changed the fuel filter and fuel lines. Could there be a problem with the injectors? |
it was running 15:1 IN BOOST?
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stock injectors running 120psi should have more than enough pressure behind them to support 5psi. I've run 12psi (200rwhp) with 305cc injectors with just around 90psi of fuel. are you sure your wbo2 is calibrated corrected, that engine wouldn't last long with AFRs like that in boost.
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Originally Posted by 18psi
(Post 584504)
it was running 15:1 IN BOOST?
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Originally Posted by Braineack
(Post 584505)
stock injectors running 120psi should have more than enough pressure behind them to support 5psi. I've run 12psi (200rwhp) with 305cc injectors with just around 90psi of fuel. are you sure your wbo2 is calibrated corrected, that engine wouldn't last long with AFRs like that in boost.
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as brain said, either your wb02 is off or you'd have blown up
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Bad o2 for the loss. Actually, what are your AFR's not in boost, and where did you position your wideband sensor?
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Originally Posted by dustinb
(Post 584544)
Bad o2 for the loss. Actually, what are your AFR's not in boost, and where did you position your wideband sensor?
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It could be it's too close to the turbo and isn't reading properly / damaged. The wideband should be quite a ways downstream.
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DEFINITELY sounds like a faulty wb
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The position of the sensor is not for readings, but too much heat.
if it's idling at 14.7:1 chances are it's outputting correctly, just doesn't sound right as 265cc injectors with 120psi of fuel behind them should be plenty for 220rwhp. |
Megasquirt.
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My guess is that the WB02 is fine at idle when your EGTs are probably sitting around 250 F post turbo. When you floor it and they start cranking along at 1200 F plus at that spot, the sensor has problems. My bet is that it starts getting wonky under any conditions within a month or two.
Having said that, you could actually be running that lean. Dont boost it untill you figure this out. Its pretty amazing how long an engine will run with detonation sometimes. Other times it will just fly apart pretty quickly. Long story short, dont assume your WB02 is off, even if it almost certanly is. |
I killed my WB02 on my rotary in a month.
Move it like 5 feet down stream. Get a new bung welded in. Make a copper heatsink as well. Is it and LC1? |
It was an innovative LM-2. It was temporarily screwed into the dp and was also placed at the end of the exhuast. When it was post cat, it was running slightly richer, but still showing lean.
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Is it possible that you are locking up the injectors (100% duty cycle)?
I had something similar just a few weeks ago with a non-intercooled shanghai. After the stock injectors were replaced with tan tops, the AF improved drastically. I am now running 11.xx under boost versus 12.xx that would occasionally dip to 13.xx. If I increase the pressure on the AFPR, it can get the AF to 10.xx under boost (I had this for a few days when we were in the 90's here and I thought I heard some pinging under WOT). |
I'm leaning towards the injectors. I will probably pull them and have them cleaned and tested. I've been reading a lot about megasquirt, so I may go that route.
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Originally Posted by bobbybouchet
(Post 584957)
It was an innovative LM-2. It was temporarily screwed into the dp and was also placed at the end of the exhuast. When it was post cat, it was running slightly richer, but still showing lean.
Stephanie |
I read thru half the thread and got bored. Ifi repeat I'm sorry. Exhaust leaks can give a false lean reading I battled this. I also batlled my begi being stubborn. Then I bit the bullet and got megasquirt. I hotly recckmend it takes away your head ache
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Also only running 5 psi I would get somw 1.8 injectors and thow them they go right in, inspect the orings for cracks or you'll have a leak....
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