I installed my LT8 in my friends car(WOW! that was easy) until my motor is finished. On the Manual it says that street ported rotaries should be tuned through the TPS, but when I switch it from (Map sensor) to (TPS) the car turns off. And If I try to turn it on TPS mode it wont start.

What am I doing wrong?


PS: yes I did calibrate the tps!!


Now keep in mind I'm new to this stuff so please no bashing

Thanks you

Luis

 

I didn't even know the Manual made reference to street porting. I better look Into that lol.

 

I doubt the ports are big enough to warrant you needing to take a load reading from TPS rather than vacuum, how much vacuum is the motor pulling?

Daniel

 

run it in MAP mode, only switch it to TPS only if you have a very irregular vacuum

 

This is what our first and only drive looked like.

RPM Max 5320 Min 1380 Avg 3511
LOAD Max 09 Min -25 Avg -09
TPS Max 99% Min 00% Avg 61%
IGN Max 30° Min 00° Avg 19°
INJmS Max 8.48mS Min 1.86mS Avg 4.52mS
Wat Max 94°c Min 88°c Avg 90°c
Air Max 92°c Min 72°c Avg 81°c
Batt Max 13.25v Min 12.75v Avg 13.05v
AFR Max 19.0a/f Min 12.4a/f Avg 14.7a/f

 

http://www.imagestation.com/picture/...9/fb1164ce.jpg

 

Hahahaha that's killer!

The reason it won't start is because when you switch from MAP to TPS mode, it keeps the same fuel curve! That means if you were idling at (say) 15", which is the 4th load point from the far left, now you idle at 0%, which is the leftmost load point. It basically means that you've got to completely redo your low-load fuel curve. An easy way is to watch the car idle in MAP mode, and note the injector ms values that it uses, and flatline your idle fuel curve at that value. Be sure to also turn on your decel fuel cut-off - 25" is a good value. Otherwise, you'll be dumping fuel everytime you get off the throttle and the car will buck really nasty-like.

With all that said, I'll concur with Daniel and say that you probably don't need to use TPS mode. We only use it on huge-port engines where the vacuum reading is erratic and on certain low-vacuum N/A cars.

Brandon
BR7 Racing