Idle problem sovled?

[PorterzSupra]

Okay I figured it out, my idle sensor seems to work fine when the engine is cold and then it wont idle when it warms up. I think I need a new one but couldent I just block off the coolant lines running to it for now to get it to idle? I think the coolant makes the switch idle down a little when it warms up and go higher if its cold right? My warm switch must be messed up. Can I block the coolant lines or connect them to each other and it will just idle higher all the time untill I get the part in?

 

[PorterzSupra]

Also, how does it make the car idle up exactly? How does it work? I know when its not working when you get off the gas the car dies, how does it prevent this? Does it have to do with mixture or?

 

[tonysupra]

I have no idea. But when i turn on the engine when its already warm, my idle goes up and down and up and down and the car shakes a little. It doesnt happen with a cold start tho. I mite be having the same problem.

Plus my car eats coolant like nothing. about an inch of coolant less than a day ago. does urs do that?

 

[jetjock]

What idle "sensor" is that? Are you making up parts now? .

I don't understand how you can be an active member of this forum and remain so uniformed about how things work. I'm not bashing you, I just don't follow how that's possible. Do you have TSRM? Do you want a simple or involved answer as to how the ISC system functions?

 

[PorterzSupra]

its the sensor beside the TPS with the hose the goes into the intake. I dont understand how it works, what makes the idle go up?

 

[PorterzSupra]

"Plus my car eats coolant like nothing. about an inch of coolant less than a day ago. does urs do that?"

Sounds like a BHG, when the car gets hot maybe its leaking causing the engine to load up with coolant and stumble at hot idle

 

[tonysupra]

"Plus my car eats coolant like nothing. about an inch of coolant less than a day ago. does urs do that?"

Sounds like a BHG, when the car gets hot maybe its leaking causing the engine to load up with coolant and stumble at hot idle

Can't be. A performance shop just replaced my head gasket with a hks mhg and arp studs last week. Nothing was wrong with the stock one, i just wanted a peace of mind.

 

[PorterzSupra]

then where would the coolant go? maybe they dident resurface the head and the head was warped?

 

[PorterzSupra]

jetjock.. can u explain how the idle works?

 

[jetjock]

That's not a sensor, it's the idle speed control valve. It's a stepper motor driven valve that opens and closes under ecu control to bypass air around the throttle plates. Disconnecting it's coolant lines won't do squat to solve your problem.

Short story: The ecu has different target idle speeds programmed into it. It looks at the rpm signal (NE) coming from the CPS and compares rpm to whatever target speed is needed at the time. If the error is greater than 20 the ecu tells the ISCV to open or close to bring the idle back to target. This action only can occur if the IDL contact in the TPS is closed (throttle closed) and the vehicle speed sensor in the combo meter shows the vehicle to be moving at less than 2 mph.

The target speeds vary based on coolant temp, oil pressure, headlight operation, electrical load, A/C operation, a bunch of things. How these target speed values correlate with the ISCV's position are always being learned, much the same way your fuel trim is learned. Pulling your EFI fuse also resets these values, same as it does with your fuel trim.

It's more complicated than that but that's the short story. What do you mean when you say it idles OK cold but not warm? I doubt your problem is connected to the ISC system but there are ways to check it. Again, do you have a manual?

 

[tonysupra]

then where would the coolant go? maybe they dident resurface the head and the head was warped?

Oh man maybe. They decked and cleaned the head. But thats all i know.:icon_conf

 

[PorterzSupra]

it idles cold but when the engine is warm and I rev it and let off it will die, thats why I think if I remove the coolant lines it will run cold and idle ok

 

[jetjock]

Come on Sport, you're not telling me much. This is a digital closed loop feedback system. You can't just say it "idles when cold". And forget the coolant lines, I already told you they aren't the problem.

How does it idle cold? When you first start it what is the rpm and outside temp? What is cold oil pressure? What is the idle when hot? If it idles when hot, does the idle change when you turn on the headlights, defogger, or A/C? If you have one is the manual idle screw in the TB fully closed? What does it idle at when T and E are jumpered? Do you hear the ISCV click just after you shut the engine down?

It dies? Could be the IDL contact in the TPS may not be closed so check that. And why do I get the feeling you don't have a manual? This'll be the last time I ask...

 

[jdub]

Come on Sport, you're not telling me much. This is a digital closed loop feedback system. You can't just say it "idles when cold". And forget the coolant lines, I already told you they aren't the problem.

How does it idle cold? When you first start it what is the rpm and outside temp? What is cold oil pressure? What is the idle when hot? If it idles when hot, does the idle change when you turn on the headlights, defogger, or A/C? If you have one is the manual idle screw in the TB fully closed? What does it idle at when T and E are jumpered? Do you hear the ISCV click just after you shut the engine down?

It dies? Could be the IDL contact in the TPS may not be closed so check that. And why do I get the feeling you don't have a manual? This'll be the last time I ask...

Awh JJ, you just like a challenge...LOL :biglaugh:

 

[jetjock]

Lol yeah, this kid is one alright but he still needs help and I'm trying the best I can. That said, unless he learns to help himself I'm gonna be forced to give up.

Nice avatar btw. It's cheating unless you own it though

 

[jdub]

Lol yeah, this kid is one alright but he still needs help and I'm trying the best I can. That said, unless he learns to help himself I'm gonna be forced to give up.

Nice avatar btw. It's cheating unless you own it though

Can't own one of those...got close to 2k flying one tho :naughty:

 

[jetjock]

Lol, no kiddin'. Good for you. Yeah, I know you can't own one. Mine is not all mine, two other guys involved. The thing would eat me alive if I owned it alone. Fun but no doubt gutless compared to the Viper/Falcon

 

[jdub]

Lol, no kiddin'. Good for you. Yeah, I know you can't own one. Mine is not all mine, two other guys involved. The thing would eat me alive if I owned it alone. Fun but no doubt gutless compared to the Viper/Falcon

Yeah...had to pay my dues in this first for about 4 years in Del Rio TX. Transitioned to the Viper...got time in the A Mod (Blk 10 & 15) and C Mod (Blk 25, 30 & 40). It was quite a machine, especially the Blk 30...best thrust to weight of all. :bigthumb:

Toys do get expensive don't they...LOL. Been kinda thinkin about doing that myself w/ some guys out here. Nice thing about PHX is it's almost always VFR!

 

[jetjock]

Lol, your breaking my heart. Why didn't you become a bus driver afterwards? Lots of guys I know came over from the military but we prefer transport types to fighter jocks. They're too hard to work with

The Talon is a thing of beauty alright. For it's age it's one of the best looking trainers out there. Used to be one in private hands but he lost it during a movie shoot afew years back. Ah well.

Jeez, tell me about the cost. I don't drive a 20 year old Supra because I'm crazy about it. The Albatros is in the restricted category but if I ever get out that way I'll bend the rules and we'll see if you still have what it takes

 

[JAB89]

it idles cold but when the engine is warm and I rev it and let off it will die, thats why I think if I remove the coolant lines it will run cold and idle ok

"I rev it and let off it will die" - check the dashpot.