Interesting Rev issue

Justin

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Mar 31, 2005
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I have a Q45 on a RonR short runner FFIM. When I hold the accelerator at about 1k the engine will pulsate from 1k to ~2.5K without even slightly moving my foot.

With the key in the Ign position the maft pro reads my TPS as from .35 to 4.~8.

Any suggestions?
 

Justin

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Mar 31, 2005
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I'll add, to bump the thread, that I have no codes. The car also runs and drives pretty darn well. It sounds like a subby though; my comparison, and another supra owners.
 

jetjock

creepy-ass cracka
Jul 11, 2005
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Stock TPS? If not what did you do about the idle contact? Does it do it with the pedal held to the floor?

Sounds like fuel cut caused by IDL remaining closed. Check to see if it's going to 5 volts when the throttle is cracked. A stuck IDL contact won't set a code and iirc is not monitored by the maftpro.
 

Justin

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Mar 31, 2005
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jetjock;980748 said:
Stock TPS? If not what did you do about the idle contact? Does it do it with the pedal held to the floor?

Sounds like fuel cut caused by IDL remaining closed. Check to see if it's going to 5 volts when the throttle is cracked. A stuck IDL contact won't set a code and iirc is not monitored by the maftpro.

Q45 TPS.

I'll go pull up the diagram I have of what I did, without it I will not have a clue how to answer your questions :)

What does it do with the pedal to the floor with the engine running? Begins to bring the revs up pretty damn fast :-D While the engine is running, and I'm just driving everything appears to operate correctly.
 

jetjock

creepy-ass cracka
Jul 11, 2005
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I'm not fam with that TPS but it must either have an idle contact or you rigged something else up. Anyway, it doesn't appear to be a case of grounded IDL because it'd do it anywhere off idle...even with the pedal floored.
 

adampecush

Regular Supramaniac
May 11, 2006
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did you calibrate the TPS when the engine was warm, or cold? Do you have the coolant lines hooked up to the TB? The reason I ask is that, when the throttle body is sitting at ambient conditions, a thermostat-like actuator keeps the throttle plate open a tad. When the engine warms up, the throttle plate closes. If you calibrated the TPS when the TB was cold, your IDL will remain closed when the throttle is opened slightly at operating temperature. Slightly opening the throttle plate at operating temperature (when the actuator allows for complete closing of the throttle plate) will essentially mimic full closure of the TB at ambient temperature. Hopefully that made sense.
 

Justin

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Mar 31, 2005
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My method of calibration was to adjust to a set voltage that has been used by many other Q45 users. I adjusted the TPS in the ''ign'' position, wth the engine off. I do not have any coolant lines running through the TB.

I wonder what the issue is :\
 

adampecush

Regular Supramaniac
May 11, 2006
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jetjock;984177 said:
I have no idea where you got that information but there there is no such thing.

that was an oversimplification. The thermostat/actuator (circled in the picture) pushes the throttle plate closed when operating temperature is reached (I assume...as it is connected to the coolant lines). If you have a q45 tb at hand, it is pretty obvious how it works.
p984482_1.jpg
 

p5150

ASE and FAA A&P Certified
Mar 31, 2005
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Central Idaho
adampecush;984482 said:
that was an oversimplification. The thermostat/actuator (circled in the picture) pushes the throttle plate closed when operating temperature is reached (I assume...as it is connected to the coolant lines). If you have a q45 tb at hand, it is pretty obvious how it works.
p984838_1.jpg

I second that. The Q45 TB has such a thing. Of course, that is assuming that you havent disabled it by pulling the arm that it actuates off of the TB.

I removed mine because I didnt plan on running the coolant through the throttle body, and I didnt want ambient temperatures and heat soak to change my idle characteristics.
 

adampecush

Regular Supramaniac
May 11, 2006
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Edmonton
That is the other way to go about things - I was contemplating doing this to avoid any potential interactions between the ISC circuit and the idle speed control on the throttle body.
 

p5150

ASE and FAA A&P Certified
Mar 31, 2005
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justin - how does the output of the q45 TPS compare with the stock specifications at different throttle inputs?
 

Orion ZyGarian

Jeff Lange wannabe
Apr 2, 2005
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www.suprastore.com
gofastgeorge;985049 said:
Best thing to do would be to mount the Supra TPS on the Q45 throttle....

I was considering this route if for nothing else than the fact that the TPS on our cars is adjustable unlike dumbass Nissan, who similarly, doesnt like to slot hoods to allow for adjustment either. Not to mention that you can keep the stock connector for the TPS. I'm going to have to look that up to see what people have done in that regard.

Well shit, since you can only search for terms that are 4 characters or more, "tps, q45," and "tb" wont show.