INDY27

After taking off my throttle linkage and adjusting the throttle stop, linkage, tps sensor and throttle lever rest and wide open set screws my tps reads in the .52 range closed and the throttle is showing 100% at wot. I will run it tomorrow and see how it starts and idles.

JIMG

I've seen them hard to start when cold on that setup. I think it is because the fuel in the intake evaporates. the injectors are before the whipple and too far away to give it a crisp start when having sat for a week or two.

INDY27

Where did Merc put the injectors on the 600sci and up?

Whipple Charged

WOT tps has no bearing on running, you just need to check linkage mechanically, does it go WOT? If it does, leave it, will not effect anything. If it doesn't you have to readjust linkage so you can get WOT. Verify that blades are close to centerline when open WOT, verify linkage hits stop at WOT.

Dustin

Whipple Charged

Merc has them in the port. This raises the SC a good 3-4".

Whipple Charged

Always cycle key 3-4 times before starting. Always try starting with throttle in closed position. The fuel does evaporate after a few days, therefore the manifold, valves, etc. are all dry. It takes a bit to get the motor filled with fuel, and this is different amount when it starts later in the day. Therefore its touchy in the calibration. Make it perfect at cold start, its rich as all hell when you later startup. Because the motors always run cold, cold start and later start are very close in temp. We aim for the middle of the road for both.

One thing to note is that starting on a launch ramp is much harder than starting on a regular, flat ground. Because the vacuum is very little during cranking, going uphill makes it that much harder.

No matter what though, for your application, we can custom configure it to make it better via the computer. Every engine is different, as is the application, therefore we sometimes have to fine tune this.

INDY27

Dustin,
Thanks for all the tips! I have everything perfect on one motor and a few more adjustments should get the other one straight. What effect does the tps sensor have on throttle operation and performance? BTW, I did cycle the key a few times and the motors started a lot sooner.

Lee

pocketchange22

I have a '95 Formula sr1 502 mpi. Starts fine, can't get the idle to come lower than 1250 rpm; surges about 200rpm. Hit the throttle it will rev, then drop to 900for 2/3 seconds then go to 1250 again. Even after reaches operating temp.

This is the older style (mounts off the side of motor) My tps sensor usually mounted on the bottom of the secondary, was unpluged, and pluged into an auxilary fuel pump. (supply fuel to injectors on blower) What exactly does the TPS do?? Especially if it is unpluged. Am I missing a TEE to connect the TPS and the fuel pump. Any help would be great.
Thanks for reading

Hydrolift

The Throttle Position Sensor tells the ECU the position of the butterfly, in other words, how much throttle you are giving. The sensor is acutaly a variabel resistor, when the throttle is closed the value will be around 0V and around 5V at WOT. Together with RPM the ECU will then determine how much fuel is needed based on the fuel inj. map.

BTW
I would look at the IAC (Idle Air Control) first, if the idle is rough or RPM cycles up and down.

tcuda499

whipple charged,
How does being on an uphill ramp affect vacuum?