Originally Posted by
svony
Okay fellas... back to the programme!
I started doing some logs yesterday and began making some minor changes to the fueling, but only to the off boost, lower scale of the map. The car idles much better but hunts with anything below 13.5 AFR. Under boost the AFR is as rich as 10.1 but I'll leave that part of the map for the rollers or when I have someone that can drive while I make small incremental changes. Now the one problem I seem to be having is, the car goes totally lean (22 or higher AFR) as it transitions from vacuum to boost, it seems to happen right at the zero mark on the factory gauge. The car begins to sputter and bog down, if I let off the throttle a bit and then get back on it everything is fine... this doesn't happen all the time and I can seem to pickup the fault form the log. Is it possible I have a bad TPS or MAP sensor?
Hi.
Your TPS is only there for transient adjustments. So when you move your throttle, the TPS tells the ECU to dump an additional X amount of fuel for X amount of time. If you accelerate from idle and hold your throttle steady and then it hits the lean point whilst you're throttle angle isn't changing then your transients are not the issue.
Is you fuel map even? No sudden dips along the atmospheric line? Try interpolating the lines across atmospheric so it makes a smooth transition from negative to positive pressure visually on the load sites.
The other thing to do is try turning off your decel fuel shut off by setting the RPM switch off point as high as possible. If this makes no difference, set it back to how it was.
Also check your ignition table is quite flat. If you've got sudden dips in it, that can cause the fuel to burn incorrectly very suddenly and give odd AFR readings.
I would look at replacing your MAP sensor too. Unless you can see the trace cell working correctly every time you rev the engine and it hesitates.
With the idle, try adding/subtracting ignition advance in 5 degree increments to see if it'll lean out any further. The other thing to consider there is cam timing affecting the way the car runs by being a few degrees out on 1 cam or both. I'm assuming it's on verniers?