Thread: RPM's MISSING?
05-19-2010, 07:11 AM #1
Wanted to see if anyone else would shed some light. I purchased a used Riva ECU and 50 lbs. injectors from WFO. the other mods that I have are as follows: Les Cooke retainers, X-charger, X-S intercooler with bleed mod,15-20 4blade solas, grocco strainer, free flow exhaust. My question is that I took it to the dealer and had the buds connected and reset the throttle to zero and also programmed the practice key as well. took it out this past weekend and all it did was 74.4 @8100 rpm's...... I have the blow off valve blocked off and can't seem to find a boost leak as I rechecked everything and it is all sealed up good. for some reason I'm not seeing 8400 rpm's + or even 8500........ Water4fire has a similar set-up and is doing 83+ in the same condition with the exception of a ride plate and open loop cooling. this is sort of frustrating because i have followed instructions to the "T" ....I'm now wondering if the knock sensor update has anything to do with it as this is a 2004. Funny thing though because before I did these mods I was still hitting 8100 RPM'S with a stock boat and prop, so I'm thinking it doesn't have to do with this sensor update?
I'm not certain , however if some one is familiar with this set-up please let me know as this is baffling.
05-19-2010, 08:41 AM #2
does the ECU have a riva sticker on it?
what boost are you seeing?
have you checked SC slip?
definitely check for the knock sensor update in the wiring harness
05-19-2010, 08:51 AM #3
[QUOTE=dhoad;1432155]does the ECU have a riva sticker on it?yes
what boost are you seeing? I don't have a boost guage on it yet
have you checked SC slip? No it only has 5 hrs. on it I Bought it new.
definitely check for the knock sensor update in the wiring harness Will do
05-19-2010, 09:12 AM #4
Re: RPM's MISSING?
Normally you have to have your prop tweaked after an aftermarket ecu change bro. its probably that simple.
05-19-2010, 09:49 AM #5
05-19-2010, 10:34 AM #6
i disagree, the only difference between a stage 3 kit without ecu and with ecu is the injectors. s3 with stock ecu and #42 = 75mph, s3 with riva ecu and #50 = 80+.
the ecu makes a huge difference and the prop stays the same.
i just added rr ecu and the rpm came up 400rpm. no tweaking of the prop necessary. i believe the stock ecu has way less aggressive timing curve and really cuts out around the stock rev limit
05-19-2010, 11:22 AM #7
05-19-2010, 03:41 PM #8
- Join Date
- May 2007
check the fuel pressure when ski running. must 4 bar.
05-19-2010, 09:10 PM #9
05-19-2010, 09:21 PM #10
You have to remember there is speed in the hull too.
You have gone quite up on the impeller(prop) too.
The thing, or trick is the pump nozzle pressure is where it all comes from as far as the ski being pushed along the water.
Maybe the orig numbers were in the 65-67 mark, and you have gained 8-ish MPH, which is respectable.
Sounds like the pump is loaded up to hold it down to 8100 though. Can you put a 14/19 in there to see if the RPM rises at all?
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