Random Idle Problems...
@DaleClark suggested I start a thread to see if the bigger brain trust here can help with a weird idle issue I started experiencing with my car a few weeks ago.
This is driving me nuts. Thankfully she didn’t stall during the Rotary Rally (had a blast!) a few weekends ago. Rotorsports Racing is about a 2 hour drive from me and they are pretty backed up with work. I also want to troubleshoot this myself so I can learn more about my car. Thanks in advance for the help. |
I had a similar issue, after the car was fully warmed up, I drove it and at random times, when coming to a stop light, I coast it in neutral and it would just stall on me. It turned out to be a faulty HKS Twin Power (brand new less than a year old) which basically craps out when the car is warm. Perhaps your ignition booster is the first place to start.
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Originally Posted by Billy7
(Post 12347188)
I had a similar issue, after the car was fully warmed up, I drove it and at random times, when coming to a stop light, I coast it in neutral and it would just stall on me. It turned out to be a faulty HKS Twin Power (brand new less than a year old) which basically craps out when the car is warm. Perhaps your ignition booster is the first place to start.
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Originally Posted by Djseto
(Post 12347191)
Hmm. How do you test it? I also have the HKS Twin Ignition Booster. It was on my car when I got it so I have no idea how old it is.
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The HKS twin power has a harness that just goes between the ignition coil harness and the front main harness. Takes like 2 minutes to unplug it and just plug it in like stock. May be worth doing for troubleshooting but I doubt that's it.
There's also a neutral switch on the transmission, it should show up in the sensor check screen on the commander. When you put it into gear the switch should disengage. Easy thing to check. Idle can be one of the toughest things to get right. There's a lot of factors that go into setting idle speed and things that can bog down the engine at idle that need to be compensated for. Also, the PFC is supposed to do an idle learn when you first install it, I'm wondering if it needs to be re-done since you now have working AC. I'm not sure of an easy way to re-start that process or if you need to per se, in my PFC FAQ you typically run the car with no electrical load/no AC for 10 minutes, then electrical load 10 minutes, AC 10 minutes, etc. At first the idle will surge but it will figure it out and smooth out the idle. The only way I've re-started this process is doing a reset on the PFC. But, if you do that you would lose the map and tuning done by Rotorsports. You would need a Datalogit to back up that map before resetting. Dale |
The neutral switch indicator doesn't work. I think it's because the previous owner wired the car to start without having to push the clutch in. I've thought about wiring it back. At the same time, it wasn't an issue before so I wonder why it would be a problem now? I'll try to put that stock ignition back. What risks do I run by using the stock? Will the car be harder to start if it does stall, etc.?
I've read about the PFC re-learn in my research and not being able to get my maps back is the one thing that's held me back. My wife asked me what I want for my birthday and I'm thinking a Datalogit might be it... |
There is 2 switches on the clutch pedal (for usdm). One is for the computer and the other is the starter interlock. I was having trouble with my car dying when coming to a stop and pressing the clutch pedal in. I removed the switch and found the spring very weak. I took one out of a writing pen and it has worked great since.
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Originally Posted by AE_Racer
(Post 12347218)
There is 2 switches on the clutch pedal (for usdm). One is for the computer and the other is the starter interlock. I was having trouble with my car dying when coming to a stop and pressing the clutch pedal in. I removed the switch and found the spring very weak. I took one out of a writing pen and it has worked great since.
So my issue happens regardless of whether the clutch is pushed in or not. If I'm coasting, I can drop her intro neutral and let off the clutch and she still stalls. I will check the spring though. |
I definitely would look at it. I believe the switch on the PFC is labeled as “CLT”. If its not lighting up, it may not be your whole problem but could help.
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Originally Posted by AE_Racer
(Post 12347220)
I definitely would look at it. I believe the switch on the PFC is labeled as “CLT”. If its not lighting up, it may not be your whole problem but could help.
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Originally Posted by Djseto
(Post 12347221)
The CLT light does light up when the clutch pedal is pushed. The Neutral indicator, as I mentioned above though, does not.
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Scroll to page 186 of this FSM and you can see the location of the neutral switch. Id just give it a look and make sure its plugged in and check the wiring. http://www.rotaryheads.com/PDF/3rd_g...ol_systems.pdf
i would imagine the switch is there for a reason, similar to how the clutch switch tells the ecu to catch the idle when you press it in. |
^Yep, check the neutral switch. If the previous owner tried to bypass the "push down the clutch to start the car" it would have been done at the clutch pedal.
If the car has/had a fancy car alarm with remote start sometimes they have to be wired into the neutral switch so it makes sure the car isn't in gear when it does a remote start. FYI those remote start systems are nothing but trouble, every car I've ever seen with those alarms had all sorts of weird electrical issues. Dale |
Ill check. The car doesn't have any aftermarket alarm. Stock one is still there (and works).
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Originally Posted by Djseto
(Post 12347166)
Also you may want to check your coils. I had an issue where my idle would bounce up and down but idle perfectly fine with A/C turned on. After looking for vacuum leaks repeatedly and adjusting my idle every which way 10 times I came across this thread where they had the same problem and ended up fixing the problem by replacing the coils. I replaced my coils with the SBG ignition system and it fixed my idle issues. |
So I think I got to the cause of my issue. When I checked the dashpot a few weeks back, I confirmed that when you press it, it pushes back. What I didn't do was confirm that when the throttle was closed that it was actually pushing on the pot a little. This is because at that time, I didn't know how the pot actually worked as part of the system. Was talking to Rotorsports Racing yesterday about some other things I had questions about and when I told him about that problem, he said to make sure the metal plate that pushed agains the pot is actually depressing it. He said the dashpot is essentially a dampener so when you come off the throttle, it allows the throttle plate to slowly close vs slam shut. Upon inspection, mine was touching the put, but not pushing against it. I loosened the nut, turned her a bit, and then went for a drive. During my 30 minute drive, the idles were smooth and she never once tried to drop into the low 600RPM when I put her in neutral. Will need to drive some more today, but so far, so good. Of course I just got my datalogit in the mail that I thought I'd need to troubleshoot...
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This thread is a great summary of all the troubleshooting steps for idle. I've been working out my idle issues and after reading this my dashpot and idle bleed screw were way out of adjustment. The plunger on my neutral switch is also broken, so the pedal was never engaging it. Still have some issues, but definitely seeing some improvements.
Stock ECU must have pretty robust idling logic that was compensating for all this stuff. |
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