Dyno Numbers on my SE30

#21

If I remember correctly, the ECU sets F/A on the O2 sensor at part throttle, and full throttle up to a certain RPM…I do not remember what. However, at that point, the engine tuning goes to the map in the ECU. That is why several ECUs should be taken to any dyno session. Also, if the TPS does not function tell the ECU that the throttle is wide open, the ECU will continue to run on the O2 sensor. You have to check every link in the chain. Chuck

#22

My understanding is that when the WOT switch is open the O2 sensor data is used to adjust fuel trim, but with the WOT switch closed the DME ignores the O2 sensor but does apply learned fuel trim to the map data.

When at WOT the DME uses only inputs from the IAT, ECT, AFM, CPS up to the point that the AFM maxes out (~4500rpm). Above that point the DME doesn’t use AFM data.

#23

As for the dyno sheet - unfortunately the rain we got that weekend ruined the print out and the ink ran and they didn’t keep an electronic file in memory. He did point out to me that the HP and TQ curves were very squiggly and he figured it was something electronic so I am figuring the TPS wasn’t working right and the DME was getting signals from the O2 sensor and not running on the WOT maps.

I did manage to put in some 110 octane race fuel (expensive) to richen the mix but i want to nail down the problem.

Any hints on removing the TPS? I tried to pull one from a junkyard car and it seemed to be threadlocked in and i just tore up the philips head screw. I figure i can put some heat to it or worst case drill it out from the top and reinstall with a long bolt with a nut on top.

#24

If the threads are seized to the point that the screw head strips out, grid off the heads and use vice grips, PBlaster, and heat to get the screw body out.

#25

Just use the whole throttle body. CB

#26

Adding race fuel will not affect your air/fuel ratio. However, it will raise the point at which detonation occurs, which allows you to run more ignition timing advance.

Also, the use of leaded gasoline (as many race fuels are, although yours may or may not have been) will eventually contaminate your O2 sensors. For best results, make sure that your gasoline is unleaded.

Mark

#27

I got the report back from RC Engineering on my fuel injectors. See what you think, and whether this would cause the power to be low:

  1. 132 cc/min good flow pattern
  2. 127 cc/min good flow pattern
  3. 135 cc/min good flow pattern
  4. 128 cc/min good flow pattern
  5. 131 cc/min good flow pattern
  6. 122 cc/min dripping
    Thats 129.2 average cc/min.

When they came back they were all between 139 and 141 with “excellent” pattern, with an average of 140 cc/min.

What are the odds that the injectors were so clogged they were killing the air fuel ratio?

-Scott

#28

I did some simple math. Don’t know what your original “lean” A/F ratio was, but assume it was 15. A/F = 15/1. Use 130cc for fuel (F). Then A/130 = 15 and A = 1,950. Now assume A stays constant at 1,950 and F = 140. Solve for the A/F ratio and you get 13.9. If you plug in your actual A/F ratio instead of 15 you should get similar results. If my simple equation models reality, then you dropped your A/F ratio to a decent range.

#29

Looking at your dyno files and comparing them to mine, I am not sure it is a fuel injectors problem. We are pretty much the same until the upper RPM range. I’m definitely adding sending mine off to RC engineering to the list of future projects.