High idle, please help before I push it off a cliff
05-27-12, 03:39 PM
#1
High idle, please help before I push it off a cliff
I'm having some trouble with the idle on my FD. First, some history.
I bought the car from a forum member, he didn't seem to know much about rotaries. He told me the engine had just been rebuilt by a mechanic local to him, and that it wouldn't take much to get it running right. When I got the car I found out it had bad coolant seals, so I took it to Fighters Garage in FL to swap the motor (I don't know if Fighters is still open, but if they are avoid them IMHO) and they tell me the car was an auto to manual swap. I was okay with that. What I didn't know was that the wiring harness and the ecu were retained from and JDM motor that was swapped in before I got the car, which they didnt tell me either.
So after fighters swapped the motor, the idle was never right. Sometimes it was okay, but other times it would hunt idle 900-1300. So I took it apart to redo the vacuum lines and test the solenoids, and there it sat for about 2 years. So about a month ago I decide to try and get it running. I get all the vacuum lines replaces with silicon, and test all the solenoids with a mity-vac. I found one bad solenoid. But it still didn't idle right, pretty much the same. After a compression test (which was nice and even on all rotors, 110psi front and back), I get into the wiring harness and find a nightmare of patched together wires, some not even crimped together. So I get the harness out, and find that the JDM harness isn't exactly the same as the US. The car doesn't have EGR or the AWS and 2 less ACV connectors.
After getting the harness somewhat figured out, I now have a smooth 1400-1500 idle and 20inHG vacuum. I know this is way too high. I've adjusted the tps, and every screw I can find that deals with idle to no avail. My throttle cable isn't sticking, I've left it unhooked and it still idles high.
My questions:
1. Did the JDM cars have an E/L unit? The pinout I have for a JDM ecu says that the pin for the E/L unit is a AC fan switch pin. And in place of EGR the pin is for the rear defrost. Both these go to the E/L unit in a US car. I've ran the E/L wire to the AC fan switch spot, and jumpered a wire from the rear defrost of the E/L to the rear defrost pin. If this is the wrong way, how should I wire it correctly?
2. Would thermowax cause a high idle?
3. Could a leaking/stuck injector cause it?
4. Port air conrol and secondary air switching, are these the same thing?
5. Will the fan control unit work if I wired it in even though it is a JDM harness & ecu?
I suspect I have a vacuum leak, but all the vacuum lines are new and I replaced the upper intake manifold gasket. I've tried spraying carb cleaner around, but the idle stays the same.
Any help would be appreciated.
Thanks,
Jeff
I bought the car from a forum member, he didn't seem to know much about rotaries. He told me the engine had just been rebuilt by a mechanic local to him, and that it wouldn't take much to get it running right. When I got the car I found out it had bad coolant seals, so I took it to Fighters Garage in FL to swap the motor (I don't know if Fighters is still open, but if they are avoid them IMHO) and they tell me the car was an auto to manual swap. I was okay with that. What I didn't know was that the wiring harness and the ecu were retained from and JDM motor that was swapped in before I got the car, which they didnt tell me either.
So after fighters swapped the motor, the idle was never right. Sometimes it was okay, but other times it would hunt idle 900-1300. So I took it apart to redo the vacuum lines and test the solenoids, and there it sat for about 2 years. So about a month ago I decide to try and get it running. I get all the vacuum lines replaces with silicon, and test all the solenoids with a mity-vac. I found one bad solenoid. But it still didn't idle right, pretty much the same. After a compression test (which was nice and even on all rotors, 110psi front and back), I get into the wiring harness and find a nightmare of patched together wires, some not even crimped together. So I get the harness out, and find that the JDM harness isn't exactly the same as the US. The car doesn't have EGR or the AWS and 2 less ACV connectors.
After getting the harness somewhat figured out, I now have a smooth 1400-1500 idle and 20inHG vacuum. I know this is way too high. I've adjusted the tps, and every screw I can find that deals with idle to no avail. My throttle cable isn't sticking, I've left it unhooked and it still idles high.
My questions:
1. Did the JDM cars have an E/L unit? The pinout I have for a JDM ecu says that the pin for the E/L unit is a AC fan switch pin. And in place of EGR the pin is for the rear defrost. Both these go to the E/L unit in a US car. I've ran the E/L wire to the AC fan switch spot, and jumpered a wire from the rear defrost of the E/L to the rear defrost pin. If this is the wrong way, how should I wire it correctly?
2. Would thermowax cause a high idle?
3. Could a leaking/stuck injector cause it?
4. Port air conrol and secondary air switching, are these the same thing?
5. Will the fan control unit work if I wired it in even though it is a JDM harness & ecu?
I suspect I have a vacuum leak, but all the vacuum lines are new and I replaced the upper intake manifold gasket. I've tried spraying carb cleaner around, but the idle stays the same.
Any help would be appreciated.
Thanks,
Jeff
05-27-12, 03:46 PM
#2
1. don't know, never dealt with a swap.
2. yes, if it is sticking slightly or someone messed with the initial setting
3. no
4. different but only relate to the smog pump and don't really affect the idle with the ACV and smog pump in place
5. don't know, but the fan wiring is all seperate from the ECU, the ECU just uses a reverse pull down signal to trip the fans on
6. disconnect the cruise control cable if it is still attached
7. under the throttle body elbow is a small hole with a flat head screw in that blind hole, turn it in 1 full turn at a time. if it screws all the way down until it seats and the idle is still high then you're idle set screw on the front of the throttle body is adjusted too far down, one of the idle solenoids under the UIM is stuck open, or you have more vacuum leaks after the throttle body that need to be repaired..
the idle generally hunts when the ECU cannot physically get the idle down to reach it's goal of 750 RPMs. in short this means a vacuum leak, too much air bypassing the throttle plates(air bleed screw under the throttle body elbow) or throttle cam hung open too far(idle adjust screw turned in too far or hung up on a cable binding). usually when replacing an engine the idle is set high for things to settle, rotaries need time to adjust to their new conditions.
2. yes, if it is sticking slightly or someone messed with the initial setting
3. no
4. different but only relate to the smog pump and don't really affect the idle with the ACV and smog pump in place
5. don't know, but the fan wiring is all seperate from the ECU, the ECU just uses a reverse pull down signal to trip the fans on
6. disconnect the cruise control cable if it is still attached
7. under the throttle body elbow is a small hole with a flat head screw in that blind hole, turn it in 1 full turn at a time. if it screws all the way down until it seats and the idle is still high then you're idle set screw on the front of the throttle body is adjusted too far down, one of the idle solenoids under the UIM is stuck open, or you have more vacuum leaks after the throttle body that need to be repaired..
the idle generally hunts when the ECU cannot physically get the idle down to reach it's goal of 750 RPMs. in short this means a vacuum leak, too much air bypassing the throttle plates(air bleed screw under the throttle body elbow) or throttle cam hung open too far(idle adjust screw turned in too far or hung up on a cable binding). usually when replacing an engine the idle is set high for things to settle, rotaries need time to adjust to their new conditions.
Last edited by RotaryEvolution; 05-27-12 at 03:51 PM.
05-27-12, 04:03 PM
#3
I dont have the cruise control installed.
I adjusted that screw, i read to screw it in all the way then turn it out 3/8 to 1/2 turn. It didnt affect anything. Ive backed out all the set screws to where they barley touch.
The idle doesnt hunt anymore, its steady at 1400ish. So i guess its a vacuum leak or a solenoid. Which solenoids deal with the idle?
I adjusted that screw, i read to screw it in all the way then turn it out 3/8 to 1/2 turn. It didnt affect anything. Ive backed out all the set screws to where they barley touch.
The idle doesnt hunt anymore, its steady at 1400ish. So i guess its a vacuum leak or a solenoid. Which solenoids deal with the idle?
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05-27-12, 05:03 PM
#8
means the fast idle system isn't working at all. should rev to about 2k and then drop down to idle.
anyways, i suspect the thermowax is sticking or there is more vacuum leaks that need to be found. would take a few for it to idle up that high.
last but not likely would be the TPS somehow is holding up the throttle cam or the throttle shaft itself in the throttle body is binding and not returning to rest fully. someone could have also messed with the secondary butterfly stop on top of the throttle body, some people mistake it for an idle set screw.
anyways, i suspect the thermowax is sticking or there is more vacuum leaks that need to be found. would take a few for it to idle up that high.
last but not likely would be the TPS somehow is holding up the throttle cam or the throttle shaft itself in the throttle body is binding and not returning to rest fully. someone could have also messed with the secondary butterfly stop on top of the throttle body, some people mistake it for an idle set screw.
Last edited by RotaryEvolution; 05-27-12 at 05:06 PM.
05-27-12, 05:26 PM
#9
I had the throttle body off and was looking at the plates, they seem to seal okay and dont stick open just from looking at them. Which screw is the butterfly stop? Is it one of the allen screw ones? I messed with every set screw I could find and set them to where they barely touched.
How do I check the thermowax?
I set the TPS with a volt meter, but it didnt do anything.
If its a vacuum leak then it has to be the LIM gasket, because that is the only place I cant reach with the carb cleaner spray. No matter where I spray it doesnt change anything.
By Fast Idle, do you mean the AWS? Because it doesn't have the AWS.
How do I check the thermowax?
I set the TPS with a volt meter, but it didnt do anything.
If its a vacuum leak then it has to be the LIM gasket, because that is the only place I cant reach with the carb cleaner spray. No matter where I spray it doesnt change anything.
By Fast Idle, do you mean the AWS? Because it doesn't have the AWS.
05-27-12, 06:07 PM
#10
one of the idle control solenoids opens up naturally(can't recall which of the 2), once the engine is running it settles down to idle, if it doesn't pop up in RPM when started at first then it isn't functioning as if stuck closed or blocked off.
i haven't messed with a thermowax on the FD yet so you would have to follow the procedures in the FSM for testing and adjusting it, i do know that the FC units are sticking left and right now due to age.
the secondary butterfly is adjusted with a small allen screw and 8mm nut, sits on top and in front of the throttle body.
is the LIM gasket metal? if not and it is original then it is quite likely, i have seen a number of original lower paper gakets blow out and cause vacuum leaks.
you could also try to physically turn the throttle cam reverse to see if that makes a difference at all.
i haven't messed with a thermowax on the FD yet so you would have to follow the procedures in the FSM for testing and adjusting it, i do know that the FC units are sticking left and right now due to age.
the secondary butterfly is adjusted with a small allen screw and 8mm nut, sits on top and in front of the throttle body.
is the LIM gasket metal? if not and it is original then it is quite likely, i have seen a number of original lower paper gakets blow out and cause vacuum leaks.
you could also try to physically turn the throttle cam reverse to see if that makes a difference at all.
05-27-12, 06:38 PM
#15
beyond that i'm about out of ideas. something is allowing air past the throttle body into the engine, ie a vacuum leak or some chucklehead drilled the air bleed holes in the plates larger for some unknown reason. try disconnecting the brake booster hose and cap off the port, could be a ripped diaphragm in the booster causing the havoc.
05-27-12, 07:05 PM
#16
Got the top off, everything looks hooked up properly. Tomorrow Ill take the solenoids out. The car is hot and im tired of burning myself.
The brake thing could be the issue. I pulled the ABS system so I could get the wiring harness out (I need to bleed the brakes anyway, new SS lines). If its not in the car could it cause this?
The brake thing could be the issue. I pulled the ABS system so I could get the wiring harness out (I need to bleed the brakes anyway, new SS lines). If its not in the car could it cause this?
05-27-12, 08:34 PM
#21
Saw this thread a little late so maybe you have tried this, but if you haven't then I'd try taking the elbow off and let it idle. Cover the secondary ports with a rag or your hand. If no change in idle then cover the primary ports.
This should tell you if it is a plate adjustment and/or the ISC. If the idle drops look for an incorrect adjustment. If it remains high look for a vacuum leak.
Let us know what you find.
This should tell you if it is a plate adjustment and/or the ISC. If the idle drops look for an incorrect adjustment. If it remains high look for a vacuum leak.
Let us know what you find.
05-28-12, 01:01 AM
#24
I'm a CF and poop smith
you can use some starter fluid to spray around all the joints which may be leaking and seeing if the idle changes when you do. Just have a fire extinguisher ready just incase you get a flash fire. you dont need to use a lot of fluid, just a small squirt should change the idle if there is a leaking gasket or hose.
check your ISC and wax rod, its in the downloadable fsm.
if you can find another FD near you, could might be able to just start swaping things over. either way, not sure why people love to keep the japanese ecu, seems like a headache to splice everything back together and it never seems right.
check your ISC and wax rod, its in the downloadable fsm.
if you can find another FD near you, could might be able to just start swaping things over. either way, not sure why people love to keep the japanese ecu, seems like a headache to splice everything back together and it never seems right.
05-28-12, 08:53 AM
#25
Gringo - The car doesnt have brakes so I cant travel. Im trying to get the motor sorted out before I do the brakes just in case I need to pull the harness out again. I pm'd him with a bunch of questions, but he couldnt really answer any of them. He just said if I have the JDM harness and ecu it should work. Then he said if I needed help he wasnt too far away, but I cant drive to him.
Skunks - I tried spraying carb cleaner everywhere, but it does nothing. I have a bunch of spare parts from the old engine when I had it swapped so I've been swapping things out with those parts. It wasnt my choice to keep the JDM ecu and harness, I didnt discover it until I pulled the harness to rewire it a few weeks ago.
Skunks - I tried spraying carb cleaner everywhere, but it does nothing. I have a bunch of spare parts from the old engine when I had it swapped so I've been swapping things out with those parts. It wasnt my choice to keep the JDM ecu and harness, I didnt discover it until I pulled the harness to rewire it a few weeks ago.