Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[HiProfile]

got a TB from an old Explorer coming, I'll either hook it up to a cable or do some vacuum shit or something

Well that explains why the various youtube vids only show off-car tests, but never on-car shots. Nobody's DBW t-body ever holds up. Do you think it may have been from full 12v and not PWM?

I think I might convert mine to a IAB-style vac setup. It would use a small vac actuator run off a vac tank, activated by a solenoid. A simple honda purge solenoid would work, since that's what they use on the GSR's IAB vac tank. It's opening point could be set at any rpm, MAP pressure, or operated manually if wanted. The relay that works the solenoid would also drive an ECU input for 2nd maps. I'm also thinking about routing a 3" exhaust on my EG just like a crx does, then tee off with the stock muffler in the stock location.

BTW modular Ford 4.6L's all use about the same TB, but the newer models had the idle screw port sealed. Some also have a small hole in the throttle plate, but can be sealed with solder with some skill. They're 65mm, which is enough for a 3" DP if the cutout is placed at the car's rear.

[ratcityrex]

I would get a wastegate and use that for a dump. You can buy a China 60mm wastegate and use that and be way better off that taking a chance with another throttle body.

[HiProfile]

The wg would seal nice & wouldn't wear out, but I would just think it would be much more restrictive. You could have it open with vaccum in the same way as above, but you'd have to run a weak spring. If I didn't already own the ford TB's, I would give it a shot.

[SloS13]

I really can't say whether it's from the 12v or from non PWM.  Sometimes on the bench it would make a strugling noise at 12v, sometimes it wouldn't.  I never figured out how to hook up PWM to it.  I attempted some stuff with an arduino but was unsuccessful. I'll dissect it once I get it off the car to see if anything is obvious.

I might just go old school and use a choke cable.  I'd rather not run a vacuum line from the engine bay or go through the hassle of an external vac pump.  I had a choke cable/throttle body setup on my previous Miata and it worked great.

[PhilStubbs]

I guessing this is a non Honda since pwm control with an obd1 ecu is super easy.

[DSharp]

cheap or broken wastegate with a choke cable to actuate it.  find a weak spring somewhere and walla easy exhaust cutout.  I've taken the spring out of my wategate and it gravity keeps it closed untill I get on the throttle. 

[Cmak]

What on earth would possess you to take the spring out of your WG and run the car? Not bustin' balls, I'm just curious to what benefit or outcome you were looking for.

[jabberwock]

DDull = derp

[Random Hero]

I really can't say whether it's from the 12v or from non PWM.  Sometimes on the bench it would make a strugling noise at 12v, sometimes it wouldn't.

I tested this at work today. Hooked up strait 12v, about 15 mintues later the motor was hot and stock WOT. I put a coil resister inline and the second tb worked until i left at 3. so maybe throw a higher watt resister in line to cut out some amperage.

[DSharp]

What on earth would possess you to take the spring out of your WG and run the car? Not bustin' balls, I'm just curious to what benefit or outcome you were looking for.

I don't remember, there was probably something else broken. 

[HiProfile]

If anyone could come up with the frequency, I could make a rather cheap PWM dealio. It could be programmed to open (or close) with a grounded or +12vdc input, momentary or toggle/latched.


Edit: found some info that 1-3kHz is typical, but can range from 500Hz to 10kHz. SloS13, what if the TB actually was 0-5vdc and the 12vdc eventually killed it?

[SloS13]

Edit: found some info that 1-3kHz is typical, but can range from 500Hz to 10kHz. SloS13, what if the TB actually was 0-5vdc and the 12vdc eventually killed it?

That is possible.  It seemed as though it opened quick enough @ 5v but I cant say for sure

[HiProfile]

In that case it probably was 5v. I'd say if you tried again, use a 5v power source. AFAIK you could get a cheaper QR25 TB and swap motors. I know the TB's bolt pattern is different, but I bet the stepper motor assembly is identical.

[HiProfile]

Well I got 2 similar TB for ~$40 total, both are from a G6 3.6L/LY7. They look very similar to the Nissan, but they are machined weird (offset inlet/outlet) and use GM's molded rubber o-ring to seal. They have a 72mm opening, and are probably the same Hitachi internals. THe prob is there's no adjustment screw, but I can deal with it. It may even work out better if my microcontroller works, as it won't corrode shut. For wires I plan on just soldering to the tabs the putting silicone on them.


The way I think these TB's work is the eletrical equivalent to injector tip-in, or a carb's accelerator pump. They give it 100% PWM, then once it reaches a certain throttle angle, they taper off the PWM so it holds position. Imagine keeping a balloon in the air by tapping it's bottom ocationally. The spring wants to pull the TB blade shut between the PWM signals, and the motor moves it back during the energy pulse. Just like how PWM of an LED makes it apear to get dim.

I want to try testing a slew of PWM frequencies (automated via microcontroller), otherwise I'll try voltage. I think PWM will be easy, since the motor is directly connected to the outside terminals (no internal circuitry). I'm planning something similar to an P&H injector driver. I'll make a microcontroller zap it open for a second (either at 12v or full PWM duty cycle), then hold it open with the lowest voltage or duty cycle possible. I could even use it's internal TPS to provide feedback.


Otherwise I'll just hook it to a cable and a servo. It's still bigger than my Ford TB (72mm vs 65mm), nearly as compact, and easier to make work than the Ford TB.

[HiProfile]

Maybe I'm just talking to myself, but found this jem:

http://www.cvel.clemson.edu/auto/systems/throttle_control_demo.html

Shows how they've controlled a GM TB, exactly what I've got. This will be super easy. An 8m2 picaxe can provide a PWM output based on an input switch, and also control a relay that will tell the motor which way to go. That's needed since it's a 2-pole motor, not a stepper. It's rest position is also at 15% open, so you have to reverse the motor to close the blade to 0%. In case the link dies, it's 1kHz pwm at 12v & 1.6A.

Switch on, pwm to xx% duty cycle, relay on - throttle body open. Switch off, pwm to xx%, relay off - throttle body sealed. If I wanted to get crazy, I could also have it read the TPS and apply 100% duty when it's in the process of opening or closing.