2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Runs Bad Over 4k

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Old May 1, 2004 | 12:40 AM
  #1  
gergrx7's Avatar
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From: Gainesville, FL
Runs Bad Over 4k

hey guys i finally got my car back together with a nice newly ported wastegate to about 25mm, which will hold about 8psi. but i can barley get my car over 4k. a friend of mine told me that i could be running to rich. i have messed a little with my safc2 but i dont want to lean my car out to much becuase im scared of blowing this motor up. i have greddy 720cc secondaries and a Walbro fuel pump. rest of mods in sig. my safc settings are likt -8% at 1k-3.5k and -20% from 4k-8k. should i set the secondaries injectors down more so the car stops like cutting out. it sounds like its breaking up above 4k. how far should i set it down. i dont need it to be set for exact tuning but jsut for it to run right untill i get a chance to get it tuned.

please help.
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Old May 1, 2004 | 03:39 AM
  #2  
BOOSTED Vert
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From: Miami
If its shaking alot then its a blown seal. if not check the spark plugs and the wires...
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Old May 1, 2004 | 09:11 AM
  #3  
Roy James's Avatar
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From: Augusta, GA
Run an ignition scope on it, see how she's doing up there. When you rev it up at Idle how does it do? If it breaks up the same then do the test at idle, if not you have to put it under a load to get the proper test. Not saying its your ignition, but it could pinpoint to which rotor it is. Im not sure how a power balence test is done on an Rx7, but that would help some too. Run a compression test while you're at it (cant ever hurt on these POS motors)

On a more realistic note, those are some pretty big injectors you've got running up there. Are you still on the stock turbo? It looks like it, in which case id *think* those would be a bit much, not saying you cant use them. In all honestly, its going to take a sniffer and ignition scope to tell you exactly whats going on. Did you clean the injectors before you installed them (always good on any new part).

Sorry this post is so drawn out. Hope this helps you out soon. You would blindly lean it out some more, but damn I wouldn't.
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Old May 1, 2004 | 01:25 PM
  #4  
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mmmtrbo.
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why did you lean out your primaries? I would leave the primaries at 0, (so no tuning from 1k-3k) and actually richen them 2-3% at 3.5k then after 3500, lean them to what you are at. You could do 22% lean on the secondaries, and still be above stock. I am having a similar problem right now, but when i hit 3800 (thats where yours is, not 4k) i have nothing, just complete bog. I see that your car is an 87, you may have the resistor pack for your injectors if your car was made before 87.5. Look at my thread and test your resistor pack. Also, your wastgate might not be enough, and you could be boost creeping past 8.6. What you could be feeling is fuel cut.

link to my thread

Ben
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Old May 1, 2004 | 01:27 PM
  #5  
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mmmtrbo.
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ps. if you really want to be safe and get the most power, go to a dyno and get it done.
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Old May 1, 2004 | 04:26 PM
  #6  
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From: Gainesville, FL
yea im gonna go to a dyno but i need to get it running right first. my car is 10/86 so i konw that it has low imdepence injectors so i ordered the greddy 720cc's. but how do i test my resistor? the link didnt work. My wastegate is ported huge. the max you couls go. i ported it to about 25mm with a 27mm flapper.

i put a spark tester on the car today and spark was cutting out over 4k. i tried changing coils and wires but didnt help. the only thing that i could think it could be is a burnt resistor on the computer, becuase i had to buy a new ecu becuase i fried mine. and the new one i got had a slightly burnt resistor. so im getting that fixed today.

i dont think that im hitting fuel cut becuase i have a FCD, and i dont think that its bad because before the wastegate was ported i hit 14psi.

thanks for the tip about the primary injectors, i though i should dial them down a bit becuase of a bigger fuel pump, but i guess not.

thanks for the help
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Old May 1, 2004 | 04:54 PM
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Try putting your settings back to zero and see if it will run then, you might be running lean. Pull your sparkplugs and see what color they are if they are white then you running to lean and if they are darkish brown to black then you are running stoich to rich thats the color you want. Check your grounds to, when I went FMIC I didn't tighten my coil down all the way and it did the same thing at higher rpm's.
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Old May 1, 2004 | 06:36 PM
  #8  
gergrx7's Avatar
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Boosting Again
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From: Gainesville, FL
no the spark plugs were black around -15% but now at around -20% they are more brownish.

does anyone have a thread on what needs to be grounded?
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