Upgraded 496, Fuel Pressure and AFR
10-12-2011, 09:30 AM
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Upgraded 496, Fuel Pressure and AFR
We had the boat out four times now and I am starting to figure things out a little bit.
I had an O2 bung welded on a tail and was able to get some O2 reading with fuel pressure.
I put a fuel pressure gage and O2 gage on it and it confirms it is rich at idle. I made some adjustments to get the idle O2 reading to 13.5 and I could hear a distinctly better idle but I could not leave it there, because once it had a load it quickly became too lean giving me an O2 reading of 14.7-15.5. I readjusted the fuel pressure to give me an O2 reading with a load 12.5-12.9. But the fuel pressure now is VERY high. 58-62psi. But this now gives me an idle O2 of 11.8-12.0. Also, there seems to be a lean spot at the 4500RPM point, it gives me 13.1-13.2 while operating at that RPM.
(The fuel pressure gauge is not calibrated but brand new)
The temp for the day I took these readings was in the mid 70s at 800' MSL.
Here are some other RPMs and readings....
Idle (700RPM) 11.8-12.0 w/ 58-62psi
1500RPM 10.8-11.0 w/ 56-60psi
4500RPM 13.1-13.2 w/ 58psi
WOT 5400RPM 12.6-12.9 w/58psi
Thank you VERY much for reading and any assistance.
I had an O2 bung welded on a tail and was able to get some O2 reading with fuel pressure.
I put a fuel pressure gage and O2 gage on it and it confirms it is rich at idle. I made some adjustments to get the idle O2 reading to 13.5 and I could hear a distinctly better idle but I could not leave it there, because once it had a load it quickly became too lean giving me an O2 reading of 14.7-15.5. I readjusted the fuel pressure to give me an O2 reading with a load 12.5-12.9. But the fuel pressure now is VERY high. 58-62psi. But this now gives me an idle O2 of 11.8-12.0. Also, there seems to be a lean spot at the 4500RPM point, it gives me 13.1-13.2 while operating at that RPM.
(The fuel pressure gauge is not calibrated but brand new)
The temp for the day I took these readings was in the mid 70s at 800' MSL.
Here are some other RPMs and readings....
Idle (700RPM) 11.8-12.0 w/ 58-62psi
1500RPM 10.8-11.0 w/ 56-60psi
4500RPM 13.1-13.2 w/ 58psi
WOT 5400RPM 12.6-12.9 w/58psi
Thank you VERY much for reading and any assistance.
10-12-2011, 09:31 AM
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From another thread...
sounds like there is no way around it, you need to have your ecu specifically tuned for your set-up. I never did hear-do you have the merc 555 or was it converted to the mefi 4a/b. I hear not many places can tune a 555, a few yearsago I remember hearing that Crockett was converting these to mefi4's, that is a step backwards as far as things go but at least anyone could climb in your boat and tune it properly. With accurate afr readings though you might be able to send your ecu to Whipple or Raylar or maybe even Crockett has a 555 program these days, I haven't talked to him in a long time, Smitty
10-12-2011, 09:32 AM
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Smitty, so my findings and numbers are not good for prime performance? And could be the reason for some of the problems?
It has already been specifically tuned and it is the ECM that I believe it can only be tuned by three people. What I am worried about is not having it on the engine when it was/is re-flashed, having to send it out without knowing what was done or changed and knowing it fixed the problem.
Thank you for the reply!
It has already been specifically tuned and it is the ECM that I believe it can only be tuned by three people. What I am worried about is not having it on the engine when it was/is re-flashed, having to send it out without knowing what was done or changed and knowing it fixed the problem.
Thank you for the reply!
10-12-2011, 09:35 AM
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From another thread...
Your ecu may have been specifically tuned for your combination but looking at your numbers it could really be straightened out from some on the water tuning. If thats not possible you could make a real detailed chart of where your afr's are all the way up and down the rpm band at different loads. You then send your ecu back to your tuner to make some adjustments and test againuntil you are pretty close. Back in the 90's this was the normal routine for tuning the mefi 1-3 equipped boats, I think AZSM was the only one who could do it at first, then a few guys were doing it (Crockett/Whipple) and now every shop has a tuning program. Unfortunately with your "555" you are going to work with the few who has it, call them and make detailed afr notes, it can be done mail order, it just takes time and patience, Smitty
10-12-2011, 09:35 AM
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Thank you again for the help.
I can make a detailed chart of the afr's. Question, what increments would be best? Also when you say "different loads" are you talking about different trim positions?
I have the Innovate LM-2 "Basic Kit" because I did not think there was a way to record RPMs with our engine like you could with the OBD-II. Is there a way I can get the RPM info on the Innovate LM-2?
I am going to repost our discussion, there are probably some not reading because they may think it is a ***** fest.
I can make a detailed chart of the afr's. Question, what increments would be best? Also when you say "different loads" are you talking about different trim positions?
I have the Innovate LM-2 "Basic Kit" because I did not think there was a way to record RPMs with our engine like you could with the OBD-II. Is there a way I can get the RPM info on the Innovate LM-2?
I am going to repost our discussion, there are probably some not reading because they may think it is a ***** fest.
10-12-2011, 10:14 AM
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It was already reprogrammed with the build and it wasn't done by either of the two listed above. And it is my understanding that there are only three people in our country that can work on this ECM.
I also need to know what data they need to make re-flash it properly.
I also need to know what data they need to make re-flash it properly.
10-12-2011, 10:30 AM
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If you have an AFR tester on a laptop run the boat hard, record the data and fuel pressure and send them the file. They will do the rest.
10-12-2011, 04:54 PM
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When I tuned my Normally aspirated setup ecu on the water, I ran boat at all rpm settings from idle to rev limiter, part throttle, wide open throttle, I ran with a short prop, I ran with a tall prop, I ran dragging the tabs hard, etc, etc. By doing this I was able to vary the load and the "map" setting motor was at at different rpm's-example at 4000 rpm's with 24 pitch, it might be at 70 map (light load) and 14.5-1 afr, at 4000 rpm's with tabs dragging and a 28 pitch (heavy load), it might be at 95 map and 13.5-1 afr so when I go into my fuel tables I would increase my injector time at 4000 rpm's and 70 map by 10% to try to achieve 13-1 afr and I might change my mili seconds/injector time at 100 map by 5% to achieve 12.80 afr and my 90 map ms by 7% to get something in between, that is why (as you probably already know) that you can't just turn fuel press up or down. If you had a O2 sensor and a engine scanner that would show you what map your at your reprogrammer could do a lot to straighten out your fuel curve. Something else to remember though, I think you mentioned earlier about still changing your intake to something better, MAKE ALL YOUR COMPONENT CHANGES BEFORE TUNING IT, other wise your really wasting your time as things change. I tried to get my boat to run in as many map settings as possible when I tuned it on the water, by doing this my fuel curve/afr's matched the load and rpm's pretty good without just making it pig rich acrossed the board and if I am running light or loaded down hard it won't melt down either, Smitty
10-12-2011, 06:37 PM
#10
We had the boat out four times now and I am starting to figure things out a little bit.
I had an O2 bung welded on a tail and was able to get some O2 reading with fuel pressure.
I put a fuel pressure gage and O2 gage on it and it confirms it is rich at idle. I made some adjustments to get the idle O2 reading to 13.5 and I could hear a distinctly better idle but I could not leave it there, because once it had a load it quickly became too lean giving me an O2 reading of 14.7-15.5. I readjusted the fuel pressure to give me an O2 reading with a load 12.5-12.9. But the fuel pressure now is VERY high. 58-62psi. But this now gives me an idle O2 of 11.8-12.0. Also, there seems to be a lean spot at the 4500RPM point, it gives me 13.1-13.2 while operating at that RPM.
(The fuel pressure gauge is not calibrated but brand new)
The temp for the day I took these readings was in the mid 70s at 800' MSL.
Here are some other RPMs and readings....
Idle (700RPM) 11.8-12.0 w/ 58-62psi
1500RPM 10.8-11.0 w/ 56-60psi
4500RPM 13.1-13.2 w/ 58psi
WOT 5400RPM 12.6-12.9 w/58psi
Thank you VERY much for reading and any assistance.
I had an O2 bung welded on a tail and was able to get some O2 reading with fuel pressure.
I put a fuel pressure gage and O2 gage on it and it confirms it is rich at idle. I made some adjustments to get the idle O2 reading to 13.5 and I could hear a distinctly better idle but I could not leave it there, because once it had a load it quickly became too lean giving me an O2 reading of 14.7-15.5. I readjusted the fuel pressure to give me an O2 reading with a load 12.5-12.9. But the fuel pressure now is VERY high. 58-62psi. But this now gives me an idle O2 of 11.8-12.0. Also, there seems to be a lean spot at the 4500RPM point, it gives me 13.1-13.2 while operating at that RPM.
(The fuel pressure gauge is not calibrated but brand new)
The temp for the day I took these readings was in the mid 70s at 800' MSL.
Here are some other RPMs and readings....
Idle (700RPM) 11.8-12.0 w/ 58-62psi
1500RPM 10.8-11.0 w/ 56-60psi
4500RPM 13.1-13.2 w/ 58psi
WOT 5400RPM 12.6-12.9 w/58psi
Thank you VERY much for reading and any assistance.
