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  1. #1

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    AFR at idle with the Riva ECU?

    What AFR # are you seeing with your Riva ECU at idle?

    On the stock ECU with Rotax 42# injectors and a RRFPR set to base 60, I was a bit too rich at idle (12.0), but I had to be rich down low to try and have enough fuel at WOT and 12# of boost.

    So, I figured that if I use the Riva ECU and Bosch 48s... since the Riva ECU is mapped for the larger injectors, that I'd be somewhere in the 13s at idle, BUT instead, now I'm seeing 11.5 at idle. It's almost like I just threw in the 48s with the stock ECU?!?

    Mid-range looks good at about 13.0. With it so rich at idle, I figured at least I'll have enough fuel for WOT... wrong again, at about 8250rpms, the LC-1 is showing about 14.0! I haven't repitched the prop to get the higher RPMs yet, but I know the AFR will just get worse. Next thing I'll do is work with the RRFPR to make sure it's working at boost, but right now, I'm just concerned with this idle number. I can lower the RRFPR base to correct idle, but then I'm really screwed WOT.

    Just seems like the ECU isn't mapped for larger injectors. BTW, I'll have to send my Riva ECU back, because when activating, they didn't marry it to my display correctly... my instruments freak out and just blink on and off; could that be the problem?


  2. #2
    shrabber's Avatar
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    Well my stock ecu with cp pistons new motor etc with 48lb injectors 12 lb boost its idle's at 12.5 mid 13.5 wot 11.9-120 in my opinion with 48's 60 base is way to much.

  3. #3

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    Quote Originally Posted by shrabber View Post
    Well my stock ecu with cp pistons new motor etc with 48lb injectors 12 lb boost its idle's at 12.5 mid 13.5 wot 11.9-120 in my opinion with 48's 60 base is way to much.
    Yeah, I'm almost hoping I find the RRFPR isn't working, and I can get it fixed or get a new one, lower the base pressure and I should be good across the board. But, let's think about this... if these injectors are about equivalent to when Riva recommends for the ECU, and if I just had the stock regulator, which is locked-in at 58, I'd expect the idle ARF to be higher. I doubt I'll be in the 13s by just lowering to 58 from 60. Just seems something's not right. If anything, seems the RRFPR should sense of vacuum at idle and possibly lower the fuel pressure?

  4. #4
    Mod less, ride more! troyheb's Avatar
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    With 48's and a Riva ecu I am running about 42 psi base. Wot afr's are 12.0
    Are you running the reference line attatched?

  5. #5
    mac_man_luke's Avatar
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    Remember the Riva ECU is setup for there #50 injectors which behave differently to bosch

    But i think quite a few people are running bosch #48s with no issues

  6. #6
    Gomer Pyle starter99's Avatar
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    am running bosch 48# and had to set base at 66 psi to get afr right

  7. #7
    Mod less, ride more! troyheb's Avatar
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    Quote Originally Posted by mac_man_luke View Post
    Remember the Riva ECU is setup for there #50 injectors which behave differently to bosch

    But i think quite a few people are running bosch #48s with no issues
    +1

  8. #8
    West Texas RXP skoepp's Avatar
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    I'm running Bosch 50s with riva on 2 rude.
    A bit rich at idle to be good up top.
    Bosch seem to run a bit richer at idle with riva then riva injectors.
    But work better at wot no mater what reg is at.

    As rpm and boost go up above your 8200 rpm the RRFPR should increase fuel pressure if working correctly and get richer.
    Something does seem a bit off to be at 14 at 8200 rpm and your pressure setting tho.
    Maybe not rising at correct rate.

    I would get your rpm up to 8500 and then adjust to good wot afr and see what happens.

  9. #9
    formerly Gold06RXP Turbo Nick's Avatar
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    Riva ECU is very rich at idle. Need a Rude controller to clean it up or just deal with it

  10. #10

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    Vx1, can you monitor fuel pressure gauge? When I went through the exact same symptoms, it was the either the fuel pump or fuel filter since I replaced them both at the same time. This was on a ski with a riva ecu and Bosch 48.

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