Hunting Idle Tried everything searched everything still no fix!
11-09-06, 11:26 PM
#26
well I tried a known good working TPS tonight one from a car that didn't have that trouble. and yet still after setting it, it went into surging mode... cannot figure it out!!!!
I have tried everything I can think of there must be someone with some insight.
when I unplug the TPS while surging it goes down to 850 rpm and stays there but sounds like ****.... I cannot figure out why this is occuring!
Somebody Must have some insight.
I have tried everything I can think of there must be someone with some insight.
when I unplug the TPS while surging it goes down to 850 rpm and stays there but sounds like ****.... I cannot figure out why this is occuring!
Somebody Must have some insight.
11-09-06, 11:33 PM
#27
Originally Posted by ynkeetratr
I have the same issue, even with a rebuild.
My idle will sometimes fall to 850 RPM where I want it or fall to 1200 RPM, too high.
If I hold the brake and load the engine, it will go down to 800 RPM steady. It drives my crazy.
Checked
Throttle cable
Gas pedal
Cruise cable
TPS
BAC
you name it.
Iv'e noticed that if I apply the clutch above 2000rpm on decel it will fall to 850 but if I apply it lower than 2000 RPM, I get the high idle.
Any insight on this?
My idle will sometimes fall to 850 RPM where I want it or fall to 1200 RPM, too high.
If I hold the brake and load the engine, it will go down to 800 RPM steady. It drives my crazy.
Checked
Throttle cable
Gas pedal
Cruise cable
TPS
BAC
you name it.
Iv'e noticed that if I apply the clutch above 2000rpm on decel it will fall to 850 but if I apply it lower than 2000 RPM, I get the high idle.
Any insight on this?
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/how-do-i-disable-%2Asystem%2A-drops-idle-when-i-put-my-fc-into-gear-525044/
My problem is: After letting off the gas, my idle will drop down to 1200-3000 RPM's. If I push in the clutch and go into a gear, the idle instantly drops to what it's set at, or 900 RPM's.
Either that, or I have found that I can do what you guys say and (in a sense) "kill" the high and incorrect idle by putting load on the engine at a low RPM and letting off.
I was actually going to update that thread yesterday, but I found a bandaid that worked for me. However, I would really like to get to the bottom of this...
My bandaid: Set your idle-speed to a high 1200RPM's or so by using the throttle-plate screw. Then basically take out about 20-25% of the fuel at 1000RPM's via an SAFC or something, this will basically kill the ability of the motor to idle that high... Therefore everytime the motor wants to "hunt", or have it's annoying "high" idle--it basically can't and is forced to drop down to a normal idle-speed.
There's more random data to my "problem" I could share, but I don't know if you guys have a similar thing... I'm thinking more about that transmission neutral switch that was mentioned several times in the other thread.
11-09-06, 11:41 PM
#28
Yo jreynish,
The reason I think our problems are similar is because occasionally if I try to rev my engine while it's in gear (or slowly drive in 1st gear from a stop), my engine RPM will want to rise will my acceleration, but since the car is in gear (which kills the higher RPM), the engine will HUNT or basically be stuck in limbo between the two...
As soon as I take the car out of gear, the car can rev cleanly between 1000-2000RPM's (the only problem area).
It sucks because this problem is so hard to describe perfectly, and I've literally never read a thread where someone described this or a similar issue until now...
The reason I think our problems are similar is because occasionally if I try to rev my engine while it's in gear (or slowly drive in 1st gear from a stop), my engine RPM will want to rise will my acceleration, but since the car is in gear (which kills the higher RPM), the engine will HUNT or basically be stuck in limbo between the two...
As soon as I take the car out of gear, the car can rev cleanly between 1000-2000RPM's (the only problem area).
It sucks because this problem is so hard to describe perfectly, and I've literally never read a thread where someone described this or a similar issue until now...
11-09-06, 11:56 PM
#29
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11-10-06, 09:41 AM
#32
(Terraplane)
Well that's three of us with the same problem.
I have tried backing off on the dash pot, no change.
Today I turned in the BAC screw, no change.
Checked clutch switch. Locks out at start.
My Rtek is telling me I have no codes. I have also repaired the neutral switch and 5th gear switch, no change.
This morning I checked air flow at 1200 and 840 RPM. The Rtek showed no change.
Here are some of my theories;
Mechanically when we load the engine, we are torqueing it on the engine mounts. The engine tries to raise on one side. Is there a mechanical bump/wear point in the linkage that the torque/position change is over coming?
Are you guys running a cone filter?
Does the improved/less resrictive air flow actually hold the flapper position to high idle so when we load the engine the flapper moves to the rest position? This was not measurable on my Rtek.
I have tried backing off on the dash pot, no change.
Today I turned in the BAC screw, no change.
Checked clutch switch. Locks out at start.
My Rtek is telling me I have no codes. I have also repaired the neutral switch and 5th gear switch, no change.
This morning I checked air flow at 1200 and 840 RPM. The Rtek showed no change.
Here are some of my theories;
Mechanically when we load the engine, we are torqueing it on the engine mounts. The engine tries to raise on one side. Is there a mechanical bump/wear point in the linkage that the torque/position change is over coming?
Are you guys running a cone filter?
Does the improved/less resrictive air flow actually hold the flapper position to high idle so when we load the engine the flapper moves to the rest position? This was not measurable on my Rtek.
11-10-06, 05:17 PM
#34
Ok I finally got this thing to work like it should!!!!
Here is how I did it, I replaced the Intercooler with a connecting pipe from the elbow to the TB and the elbow from the charge pipe with the Release Valve (BOV) on it. Then I bridged the connector and disconnected the BAC I also turned the BAC idle adjust screw so it was all the way closed I then Adjusted the throttle plate adjuster screw so that the engine idled at 500 rpm.
I then readjusted the TPS with the lights method.
I then opened the BAC idle adjust screw so that my idle was 750rpm
I then Stoped the car reinstalling the Intercooler properly.
I then removed the check connector ground.
And pluged in the BAC
After a quick drive my surging seems to be gone. FINALLY!!!!
I will report back after further driving to confirm it was working. I hope this helps the rest of you follow my procedures and I assume you should be able to get the same results as me.
Here is how I did it, I replaced the Intercooler with a connecting pipe from the elbow to the TB and the elbow from the charge pipe with the Release Valve (BOV) on it. Then I bridged the connector and disconnected the BAC I also turned the BAC idle adjust screw so it was all the way closed I then Adjusted the throttle plate adjuster screw so that the engine idled at 500 rpm.
I then readjusted the TPS with the lights method.
I then opened the BAC idle adjust screw so that my idle was 750rpm
I then Stoped the car reinstalling the Intercooler properly.
I then removed the check connector ground.
And pluged in the BAC
After a quick drive my surging seems to be gone. FINALLY!!!!
I will report back after further driving to confirm it was working. I hope this helps the rest of you follow my procedures and I assume you should be able to get the same results as me.
11-10-06, 08:10 PM
#35
I was going to suggest trying different methods of idle control compromises since you still have the BAC as a variable. But yeah, I was gonna suggest closing the BAC to get the car to idle low, then use the throttle-plate screw to turn the idle back up. Like I said, my bandaid was turning the throttle-screw UP, but killing the fuel via the SAFC to get it to idle low... Like I said, this makes it impossible for the car to idle at 1200+ RPM's--simply because there's not enough fuel.
yankeetratr, interesting idea with the AFM--however with my particular problem, it's directly related to the car being put into gear. Maybe since my AWS, thermowax and everything else are removed (including all solenoids), my ECU doesn't know what to do and thinks my car is running cold all the time? Maybe a bad thermosensor (or whatever) so the ECU is always going into "high-idle" mode when letting off the gas? I don't know. NZ also said in my other thread that the ECU wants the car to idle high when letting off the gas, so that it doesn't stall out, before dropping down to normal... Whatever, I guess I'm fine with my bandaid.
yankeetratr, interesting idea with the AFM--however with my particular problem, it's directly related to the car being put into gear. Maybe since my AWS, thermowax and everything else are removed (including all solenoids), my ECU doesn't know what to do and thinks my car is running cold all the time? Maybe a bad thermosensor (or whatever) so the ECU is always going into "high-idle" mode when letting off the gas? I don't know. NZ also said in my other thread that the ECU wants the car to idle high when letting off the gas, so that it doesn't stall out, before dropping down to normal... Whatever, I guess I'm fine with my bandaid.
11-10-06, 09:37 PM
#36
(Terraplane)
Some times mine will stop a a light in high idle, then go down to normal. Other times no. One person told me the ECU was learning but I've never heard this about RX-7 ECU's.
So I guess its another BAC, TPS, ISC adjustment sequence. I was suspicious of the BAC after the ISC is removed. My idle goes up too, but thays normal if the screw is adjusted out. I wanted to disable the BAC and adjust the idle set screw first but the ISC is supposed to diasable the BAC anyway.
I think I will try closing the BAC screw and use the ISC just to be sure. I too use the IC by-pass pipe.
Disable BAC via ISC and close screw. Could even disconnect the connector.
Adjust TPS via lights.
Set idle knowing BAC will be used to raise it slightly, say 750 RPM.
Remove ISC and see if idle does not raise.
Open BAC screw to 850 RPM.
Whoo hooo or #^*/!.
The odd part still remains, if you load the engine to lower RPM's, isn't the BAC supposed to raise idle on load!
So I guess its another BAC, TPS, ISC adjustment sequence. I was suspicious of the BAC after the ISC is removed. My idle goes up too, but thays normal if the screw is adjusted out. I wanted to disable the BAC and adjust the idle set screw first but the ISC is supposed to diasable the BAC anyway.
I think I will try closing the BAC screw and use the ISC just to be sure. I too use the IC by-pass pipe.
Disable BAC via ISC and close screw. Could even disconnect the connector.
Adjust TPS via lights.
Set idle knowing BAC will be used to raise it slightly, say 750 RPM.
Remove ISC and see if idle does not raise.
Open BAC screw to 850 RPM.
Whoo hooo or #^*/!.
The odd part still remains, if you load the engine to lower RPM's, isn't the BAC supposed to raise idle on load!
11-11-06, 12:26 AM
#37
alright so my problem returned. it started again but less frequently and much less of a hunt only about 200 rpm change now... so i will try setting the thorttle plates for the idle to 700 rpm then try it out that way. Hopefully that will work.
11-13-06, 05:48 PM
#38
alright have you guy's checked your timing, mine was off by 8 degrees I corrected it that upped my idle by 200 rpm I then reset my idle speed and tps. Haven't had a problem yet. Driven for two days.
Hope this Helps in the futur for anybody with the same problems!
Good Luck
Hope this Helps in the futur for anybody with the same problems!
Good Luck
11-14-06, 01:06 AM
#39
Originally Posted by jreynish
alright have you guy's checked your timing, mine was off by 8 degrees I corrected it that upped my idle by 200 rpm I then reset my idle speed and tps. Haven't had a problem yet. Driven for two days.
Hope this Helps in the futur for anybody with the same problems!
Good Luck
Hope this Helps in the futur for anybody with the same problems!
Good Luck
11-14-06, 03:16 PM
#40
Hunting Idle Troubleshooting steps.
Alright to make this painfully simple for futur people that will have a similar problem and do not want to read the three pages.
HERE IS WHAT YOU SHOULD DO TO FIX HUNTING IDLE!!!!
1) ENSURE YOU HAVE NO VACUME LEAKS, if you have some FIX THEM.
2) Set the Throttle Position sensor as per the Factory Service manual links to cette manuals available in the FAQ of the second Generation Section.
3) If the above has not worked check your timing with the timing Light with the engine AT OPERATING TEMPERATURE and the idle speed MUST BE LOWER THAN 999 RPM. If the Timing is not right reset the timing. This will most likely affect your idle speed so you will have to do do the following step to ensure proper opperation.
4) If the Above has not worked then close your idle adjust screw on the BAC valve or on the top of your intake if N/A and then unplug your bac valve and set the check connector so that the engine does not attempt to change the Idle on you. And set the idle to 750 RPM without the help of any idling assist, so you are adjusting the throttle plate screw. For you turbo Guy's you will have to build or use a pipe to bridge the two couplers where the intercooler would usually sit so that you can adjust the Throttle Plate screw while the engine is running. DO NOT ATTEMPT to adjust the idle without the pipe being in place or intercooler as you will not acheive your goal. Now that your idle is at 750 RPM unasisted, you will plug in your BAC valve and take out the Check connector ground and reset the TPS as per the Factory Service Manual. After successfully setting the TPS then start the car and adjust your BAC idle adjust screw to get the car to idle properly so that it idles smoothly. Reinstall the Intercooler.
5) If the above have not worked then Your throttle Body might be dirty Take the throttle body off the car and seriously degrease it and clean the bores, the throttle plates, the cams, and everything so that it is sparkly clean. Reinstall the Throttle Body and reset the Throttle Position Sensor.
6) If the above steps have not worked then you May have a bad Throttle Position Sensor, Check it as per the Factory service manual, if bad replace and reset Throttle Position Sensor as per Factory Service Manual.
7) If the above steps have not worked then Check your Mass Airflow Meter as per the Factory Service Manual replace if required.
8) If the above steps have not corrected the hunting idle then check your Coolant Temperature Sensor (the one on the back of the Water Pump housing with a square two prong plug on it) as per the Factory Service Manual, if Bad replace.
9) If the above steps have not corrected the hunting idle then Have your alternator tested, If bad replace.
If you follow the steps outlined above you should have fixed your hunting idle. If Not then you must have not done one of the steps above properly. As far as I can tell and my research has shown these are the only things that will cause a hunting Idle. Hopefully this will help the multitude of people that have a similar problem.
Good Luck
HERE IS WHAT YOU SHOULD DO TO FIX HUNTING IDLE!!!!
1) ENSURE YOU HAVE NO VACUME LEAKS, if you have some FIX THEM.
2) Set the Throttle Position sensor as per the Factory Service manual links to cette manuals available in the FAQ of the second Generation Section.
3) If the above has not worked check your timing with the timing Light with the engine AT OPERATING TEMPERATURE and the idle speed MUST BE LOWER THAN 999 RPM. If the Timing is not right reset the timing. This will most likely affect your idle speed so you will have to do do the following step to ensure proper opperation.
4) If the Above has not worked then close your idle adjust screw on the BAC valve or on the top of your intake if N/A and then unplug your bac valve and set the check connector so that the engine does not attempt to change the Idle on you. And set the idle to 750 RPM without the help of any idling assist, so you are adjusting the throttle plate screw. For you turbo Guy's you will have to build or use a pipe to bridge the two couplers where the intercooler would usually sit so that you can adjust the Throttle Plate screw while the engine is running. DO NOT ATTEMPT to adjust the idle without the pipe being in place or intercooler as you will not acheive your goal. Now that your idle is at 750 RPM unasisted, you will plug in your BAC valve and take out the Check connector ground and reset the TPS as per the Factory Service Manual. After successfully setting the TPS then start the car and adjust your BAC idle adjust screw to get the car to idle properly so that it idles smoothly. Reinstall the Intercooler.
5) If the above have not worked then Your throttle Body might be dirty Take the throttle body off the car and seriously degrease it and clean the bores, the throttle plates, the cams, and everything so that it is sparkly clean. Reinstall the Throttle Body and reset the Throttle Position Sensor.
6) If the above steps have not worked then you May have a bad Throttle Position Sensor, Check it as per the Factory service manual, if bad replace and reset Throttle Position Sensor as per Factory Service Manual.
7) If the above steps have not worked then Check your Mass Airflow Meter as per the Factory Service Manual replace if required.
8) If the above steps have not corrected the hunting idle then check your Coolant Temperature Sensor (the one on the back of the Water Pump housing with a square two prong plug on it) as per the Factory Service Manual, if Bad replace.
9) If the above steps have not corrected the hunting idle then Have your alternator tested, If bad replace.
If you follow the steps outlined above you should have fixed your hunting idle. If Not then you must have not done one of the steps above properly. As far as I can tell and my research has shown these are the only things that will cause a hunting Idle. Hopefully this will help the multitude of people that have a similar problem.
Good Luck
Last edited by jreynish; 11-14-06 at 03:25 PM.
11-18-06, 09:15 PM
#43
(Terraplane)
It was the timing!
Finally checked it today and found it was about 5 degrees advanced. It hadn't been checked since the start-up.
Set it to factory specs and did the idle adjustments. ISC, Idle screw, BAC, TPS and timing recheck. I can't believe it was 10 degrees off!
Took it out for some runs and the idle drops to my set point after it settles down at a light. No more 1200rpm idle so far.
Seems like I found at least 20hp in getting the timing right.
Finally checked it today and found it was about 5 degrees advanced. It hadn't been checked since the start-up.
Set it to factory specs and did the idle adjustments. ISC, Idle screw, BAC, TPS and timing recheck. I can't believe it was 10 degrees off!
Took it out for some runs and the idle drops to my set point after it settles down at a light. No more 1200rpm idle so far.
Seems like I found at least 20hp in getting the timing right.
04-07-07, 08:32 AM
#47
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tryed shooting you a Pm but your box is full! well i am going to be starting in on fixing my idle prob and going to be useing your info here to do so. Do not think it matter much but i am running a NA car and not turbo.
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