ever seen a spike/dip in a fuel map like this? the AFRs are very smooth in the low 11s, and this is just "what the engine wants," as they say: (done with steady-state tuning and hitting each cell individually, and shooting through the transition and back, primary-hold mode)





the car runs very nicely and consistently, but i'm confused as to what could cause this need for so much more fuel at 4000rpms... something in my turbo setup?

i am running a BW EFR8374 (internal wastegate), turblown shorty T4 manifold, 3" exhaust, 4x id2000 injectors, CJ rails/lines, aeromotive FPR, walbro 400 pump, haltech ps1000.

 

here's part of your map viewed from a spreadsheet line chart. it sure takes a dive at 2.2 then progresses upward albeit jumbled a bit.



this view might be of help.

howard

 

that looks horrible. the fuel map should be fairly linear in boost. maybe they were tuning around a fuel pressure problem?

 

howard, thanks for the graph. however, i was talking about the 4000rpm--6000rpm 8/10/11psi range that i marked with the blue lines, not the drop in MS when the secondaries come on. (running in primary-hold mode BTW)

and GXL90rx7, i tuned it. i am not logging fuel pressure, but the fueling is very consistent and the AFRs are quite smooth.

 

maybe it has something to do with thottle postion when you were tuning certain cells.. when you tune cell by cell, you have have to go part-throttle to stay in the cell, which changes airflow at a given boost pressure. since the ecu is map-only, it doesnt account for restriction caused by part-throttle, unless it has a tps correction capability?

 

Whats your injection timing look like in those cells?

 

the injection time is shown in each cell.

maybe you're talking about injection angle?

 

Speedjunkies and I cars both have humps with flat AFR's. I am not sure why, but we have them.


I attached a chart of my injector Ms on-time vrs. AFR chart.

you can see a hump in my Ms on-time, its like that on my car and others. I think it depends on certain items in the intake tract and porting of the motor that makes this unique to every car. I know my car likes to boost like mad and hits a spot in the map or for the engine and slows down, and then ramps from there.

My new map, my cruise cells are 15's AFR in very low vacuum. I ramp the cells to lower afr's as I approach boost in vacuum. This helps with spool of the turbo, I also run richer afr's on the far left cells of lower rpms at higher loads to help spool the turbo for ramping up (full throttle) acceleration, the higher rpms I don't do this because the engine is already pumping more exhaust. so I can cruise on the highway and get 22MPG, and still be able to spool the turbo like a mad man. I also run high 13's AFR at higher rpms in vacuum since I don't live up there much in terms of cruising and figured better performance and power.

 

Mine does it between 4800 rpms and 5200 rpms with blue printed stock ports with a short manifold GT35R. Happens at higher rpms with lower boost then goes towards lower rpms with higher boost.

My upper intake manifold has the secondary butterfly assembly removed with the center post also removed. This may or may not cause the affect which I believe is caused by some harmonic in the intake or exhaust.

The same engine did not do it when running the twins in non-seq mode.

 

Do you switch on any sort of AI at that point?