Butterfly has migrated.

[Zephy]

So, my 1994 sc2 is a factory stock oval track racecar, and although I'm extremely fast, I'm desperate to make the car faster. I removed my butterfly in my throttle body to allow for better air flow, and now the car acts like the maf sensor is bad. Do I just need to run the car until my electronics adjust or will the car have permanent problems as long as it is missing the butterfly? When I rev the engine the car definitely has a lot more power and torque, but when I let off it it slowly drops to 0 rpm.

[fdryer]

1-Describe "butterfly".

2-Your '94 doesn't have a mass air flow (MAF) sensor. Google images of maf sensors. What do you consider a maf sensor on your engine?

[Zephy]

Yes yes I know it doesn't, it acts like any car wit ha bad MAF would is what I mean. The butterfly is the round disc inside the throttle body that turns to open when you apply throttle and shuts off air flow to help keep the intake manifold cleaner and I assume improve gas mileage, as far as I know that's it's purpose. Intake manifold will be getting cleaned next week and monthly after that, along with my plugs, wires, air filter, oil, and oil filter.

[ssicarman]

You removed the entire throttle body plate/butterfly?????

The plate is what regulates the air flow into the engine from off idle to wide open throttle. The gas pedal moves the plate via the throttle cable. Without the plate you should be getting the equivalent of wide open throttle all of the time.

[fdryer]

Well, removing the throttle plate/butterfy valve doesn't work for several reasons. The map sensor detects incorrect manifold vacuum because none exists so the pcm can't determine correct fuel/air mixtures at low to mid rpm. My guess is at low to mid rpm the fuel mixtures are running very rich. at mid to high rpm the rich fuel mixtures lean out as more air flows thru the throttle body. Even if the throttle position sensor is working with the pedal moving, the pcm is still confused since the map sensor never detects vacuum at low to medium rpm. The map sensors main role to detect varying vacuum in the intake manifold, normally controlled by varying the throttle plate/butterfly valve. Throttle is never fully closed because its mechanically set partially open to prevent a complete engine shutdown if the throttle plate closed. The supplemental bypass port using the idle air control valve allows the pcm to adjust idle rpm at all times from subzero to desert temperatures, cold to warm engine.

If you wanted more air flow, trying a large bore throttle body and using an unrestricted exhaust will allow more breathing. It would be wiser to put the throttle plate back in place.

[colonelhogan44]

Put it back.

[fhritPT]

lol...too funny

[bumpdraft]

If you've ever seen 125cc 2-cycle motocrossers you'll notice they never let off the gas.

[Zephy]

Originally Posted by fdryer

Well, removing the throttle plate/butterfy valve doesn't work for several reasons. The map sensor detects incorrect manifold vacuum because none exists so the pcm can't determine correct fuel/air mixtures at low to mid rpm. My guess is at low to mid rpm the fuel mixtures are running very rich. at mid to high rpm the rich fuel mixtures lean out as more air flows thru the throttle body. Even if the throttle position sensor is working with the pedal moving, the pcm is still confused since the map sensor never detects vacuum at low to medium rpm. The map sensors main role to detect varying vacuum in the intake manifold, normally controlled by varying the throttle plate/butterfly valve. Throttle is never fully closed because its mechanically set partially open to prevent a complete engine shutdown if the throttle plate closed. The supplemental bypass port using the idle air control valve allows the pcm to adjust idle rpm at all times from subzero to desert temperatures, cold to warm engine.

If you wanted more air flow, trying a large bore throttle body and using an unrestricted exhaust will allow more breathing. It would be wiser to put the throttle plate back in place.

Gotcha. I'm full throttle 95% of the time. Just looking for any ways to be faster. I'm pretty close to the track record and won my last race by over two seconds, I just need a little more from my little factory stock engine. Can't go to a larger bore without risking being DQed if the tech guy catches on. Gonna clean my gas tank out and stop using a fuel filter, straight line, maybe that'll do it.

[Zephy]

Originally Posted by ssicarman

You removed the entire throttle body plate/butterfly?????

The plate is what regulates the air flow into the engine from off idle to wide open throttle. The gas pedal moves the plate via the throttle cable. Without the plate you should be getting the equivalent of wide open throttle all of the time.

I think you're thinking of carburated engines.

[ddeuces22]

cams....

[fetchitfido]

Originally Posted by ddeuces22

cams....

Oops, how'd that 2nd intake camshaft pop into the exhaust camshaft's place...(good time to find a early '93 head to take the flat face valves from for a slight bump in compression...) This moves the power band higher in the rev range.

Then add the '91-'92 header & downpipe if you haven't already.

All those are factory installed options for performance, though if it has to be factory to the year stock, it won't pass

[fdryer]

Originally Posted by Zephy

Gotcha. I'm full throttle 95% of the time. Just looking for any ways to be faster. I'm pretty close to the track record and won my last race by over two seconds, I just need a little more from my little factory stock engine. Can't go to a larger bore without risking being DQed if the tech guy catches on. Gonna clean my gas tank out and stop using a fuel filter, straight line, maybe that'll do it.

Throttle plates/butterfly valves were designed so we can drive as slowly as possible cruising the parking lot/blocking drivers on the road/finding a way out when lost, etc., to wide open throttle for stop light racing. If throttle plates didn't exist, there would be no way to control engine rpm. Removing the throttle plate simply removes engine control. Unless you have a specific way where you can start up, engage drive and allow the engine to rev up in wide open throttle 100% of the time, you're giving away throttle control. You've effectively left the engine at wide open throttle 100% of the time as soon as the engine can start up. Put the throttle plate back on and try other suggestions to raise power. If allowed, gutting the car to reduce weight creates a slightly higher horsepower to weight ratio.

Leaving out the fuel filter simply invites injector problems if a speck of dirt gets into the fuel lines. Leave it to protect injectors from damage. Fuel filters strangle fuel flow when ignored and never replaced at recommended mileage intervals. For racing, it may be just wise to replace it to ensure an old filter isn't partially clogged when a new filter ensures free flow. If you remove the fuel pump, you'll see the filter sock as the first barrier before raw fuel enters the pump. A fuel sock may show the extent of accumulated dirt and debris.

[ddeuces22]

Originally Posted by fetchitfido

Oops, how'd that 2nd intake camshaft pop into the exhaust camshaft's place...(good time to find a early '93 head to take the flat face valves from for a slight bump in compression...) This moves the power band higher in the rev range.

Then add the '91-'92 header & downpipe if you haven't already.

All those are factory installed options for performance, though if it has to be factory to the year stock, it won't pass

all good stuff here that would be very hard to detect for a non Saturn enthusiast

heres some more good stuff for you to look into

- deebs build
- 1st gen shaved pistons on 3rd gen rods
- Take a look at the difference trannies over the years. Some of the guys prefer a longer gear to prevent shifting

[ssicarman]

Originally Posted by Zephy

I think you're thinking of carburated engines.

Nope.

Fuel injected or carbureted they have throttle plates to control the air flow into the engine.

Side effect of no throttle plate is no vacuum in the engine. No vacuum will give the MAP issues.

[CZECHLAGER]

Hello, Yes a little confused. Removing the choke butter fly plate and shaft on the primary side of a four barrel carb did help back in the day. Rick

[Signmaster]

Actually some vehicles will run decent without a throttle body butterfly. It's all a matter of programming, and how much influence the MAP/MAF have in the equation.

It would most likely be possible to get any fuel injected car to do it, using a stand alone fuel and ignition control unit. It might still be very difficult to program in O2 sensor response, since the engine would still be pumping more air than normal when off the gas as well as on the gas.



In this particular case, much easier to hide a cam mod than a standalone controller.

[Zephy]

With the butterfly removed, the throttle is still smooth, I can hold it where I want it, and have the same control. The only problem is that the IAC is not working. The workaround to that is a longer throttle stop bolt to hold the throttle open a little bit. I am not under full throttle with it removed. I'm going to keep playing with it once I get a longer bolt, I had to throw everything back together for a race, but the throttle stop bolt wasn't long enough. By throttle stop bolt I mean the bolt that the hammer on your throttle body rests against. This is some redneck crap that you can't do to a street car but if it works it's worth the time and headache. I haven't done the dual intake cam mod or the 91 headers yet, but I will. Thanks for the advice and I'll keep you guys updated.

[Zephy]

Originally Posted by Signmaster

Actually some vehicles will run decent without a throttle body butterfly. It's all a matter of programming, and how much influence the MAP/MAF have in the equation.

It would most likely be possible to get any fuel injected car to do it, using a stand alone fuel and ignition control unit. It might still be very difficult to program in O2 sensor response, since the engine would still be pumping more air than normal when off the gas as well as on the gas.



In this particular case, much easier to hide a cam mod than a standalone controller.

Can't program but I can disconnect and hold the throttle open a little.

[Signmaster]

Originally Posted by Zephy

Can't program but I can disconnect and hold the throttle open a little.

Simple enough fix. I'm actually surprised that it works that easy on a car of that vintage. Fuel injection is more forgiving than most of us would think.


Even with large individual throttle bodies and butterflys for each cylinder, the V8 Formula 1 cars were running with wide open plates at just about anything other than idle. That way they could continue pumping more air over the diffuser and increase downforce. Made them sound really funky at times, but it worked.