Hi All,

First I want to say that Im happy I found this site and Im looking forward to learning as much as possible. Ive search this topic but without any good results.

I have a 92 Q45 throttle body that is installed on my 91 Toyota Supra. When reading the Voltage with the throttle completely closed, Its sitting at .44v, Now when I start the car and rev the motor or hold the throttle at roughtly .60v - .70v (Which is where Im at when normal cruising mode) the voltage will suddenly drop to .15 then back up and then down again. Once this happens, my Wideband A/F meter goes crazy rich and the car stumbles or seems very slugglish.

I know its not a Infiniti but Its a Q45 Throttle body. Can anyone help me with this. Does it sound like I need another TPS and if so, where can I source one. Is there a Fix for this?

Thank you all

Robert

Welcome to NICO! I just pulled a throttle body off of a '91 Q to sell to one of you guys on eBay - seems to be one of the few valuable remaining parts off of the first generation Q.

Anyhow, it sounds like you have a bad TPS... it's a fairly rare failure, but it does happen. The best source for OEM new parts at a discount online is http://www.infinitipartsusa.com - or you could try for a used one again if you're not ready to shell out $200 and some change - it's not a super-common failure item. Of course if your luck is like mine, you might get another dud...

It also appears that AutoZone has a Duralast aftermarket one for about $60 but I have no idea if they're any good.

Heath
Modified by Q451990 at 1:25 AM 10/9/2009

Besure to monitor the input voltage to TPS to make sure it is not changing since TPS is nothing but a simple potentiometer.Designed to roughly reflect the throttle angle [amount of load].

Most ecu divide the TPS voltage into 10 load steps based on 0%, 10%, 20%, etc.................it all depends on how close to the edge on jumping over to the next step.

Why precision in setting idle voltage is so critical [+- 2.5% ] .....0.01 volt.......the ERROR MULTIPLIES