VIDEO - Still crappy idle, no response to idle adjustment??
07-27-07, 09:21 AM
#251
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Is it safe to assume...
....that if I disconnect my ISC/BAC and I still have a cycling, rolling idle that this then proves that the ISC/BAC has nothing to do with the issue?
I would like to eliminate this as one of the possible causes of my idling issue.
Thanks,
Andrew.
I would like to eliminate this as one of the possible causes of my idling issue.
Thanks,
Andrew.
07-27-07, 07:13 PM
#253
If your idle is around 1100-1500 rpm, hook up a timing light and see if the timing jumps back and forth along with the rolling idle. Anything that allows the engine to idle above 1000 rpm will allow the timing to fluctuate. Look for vacuum leaks first and then get the idle speed to 750.
07-27-07, 08:10 PM
#254
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Another quick question...
The idle will in most cases return to 800 - 850. Sometimes it will sit around 1100 when I first pull up at lights if it doiesn't drop I can make it do so by switching the fans and A/C on - electrical load. BUT under both these conditions whether it be 1100 or 850 the rolling idle is still there.
I'm gunna have to take off the UIM and check everything out again.
I've sprayed carb cleaner around without seeing any change. Not sure I understand the propane or compressed air method of locating vacc leaks.
This may be a dumb question but if I leave the intake off just before the trottle body can I start and run the car? I realise this will now not be using filtered air but I just want to be able to see it in operation. I also figured this would have no effect on idle, as idle seems to be measured from the throttle onwards not before. Of course I'm talking about a series 6 FD here and I'm no expert.
I'm gunna have to take off the UIM and check everything out again.
I've sprayed carb cleaner around without seeing any change. Not sure I understand the propane or compressed air method of locating vacc leaks.
This may be a dumb question but if I leave the intake off just before the trottle body can I start and run the car? I realise this will now not be using filtered air but I just want to be able to see it in operation. I also figured this would have no effect on idle, as idle seems to be measured from the throttle onwards not before. Of course I'm talking about a series 6 FD here and I'm no expert.
07-27-07, 11:59 PM
#255
There should be no need to remove the UIM if you suspect that you have a vacuum leak. Grab a propane torch (unlit obviously) and put it near your air filter while the engine is running poorly at idle. Open the propane valve very slowly and watch how the engine responds. If you have a vacuum leak somewhere, the engine will smooth out. Quickly move the torch a couple feet away and see if the engine runs like crap again. If it does, start aiming the torch and propane near the LIM and UIM gasket areas, and especially around the fuel injector/ oil injector areas and the intake duct hoses from the throttle body outward. If the engine responds the same way in these areas as it did at the air filter, you have found your vac leak. Fix these leaks first and then we can re-evaluate your idle concerns.
It would also help a great deal if you could show us a video like Greenbudd did. Borrow a camera or camcorder from someone and upload a link.
It would also help a great deal if you could show us a video like Greenbudd did. Borrow a camera or camcorder from someone and upload a link.
07-28-07, 08:37 AM
#256
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Thanks for your help. I'll try it tomorrow.
I have confirmed another fact today...If the car is idling at 800 - 850 and I slowly increase the accelerator pedal it will always drop back down when I take my foot off so long as I don't reach that critical 1200 rpm point. Once I hit 1200 rpm it would appear that the ECU kicks in and increases revs of it's own accord (as I believe it is supposed to do). If this happens the revs only ever drop back to around 1000 - 1100 until an electrical load is applied - All little steps but at least I've managed to confirm something further today!
I'll try the propane approach tomorrow.
I have confirmed another fact today...If the car is idling at 800 - 850 and I slowly increase the accelerator pedal it will always drop back down when I take my foot off so long as I don't reach that critical 1200 rpm point. Once I hit 1200 rpm it would appear that the ECU kicks in and increases revs of it's own accord (as I believe it is supposed to do). If this happens the revs only ever drop back to around 1000 - 1100 until an electrical load is applied - All little steps but at least I've managed to confirm something further today!
I'll try the propane approach tomorrow.
12-04-07, 05:35 PM
#259
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[QUOTE=RooBoy;7180459]Thanks for your help. I'll try it tomorrow.
I have confirmed another fact today...If the car is idling at 800 - 850 and I slowly increase the accelerator pedal it will always drop back down when I take my foot off so long as I don't reach that critical 1200 rpm point. Once I hit 1200 rpm it would appear that the ECU kicks in and increases revs of it's own accord (as I
************************************************** ***********
At approx 1100-1200 rpm the ECU advances the timing from -5L and -20T to both L and T to approx 12degrees before TDC. The advancing of the timing by the ECU increases the rpms.
I more or less know this by watching a Palm attached to a RTEK2.0 and seeing the timing at -5 and -20 ATDC below 1100rpm , and the timing for both lead and trail going to approx 12* BTDC when just above 1200rpm.
I have confirmed another fact today...If the car is idling at 800 - 850 and I slowly increase the accelerator pedal it will always drop back down when I take my foot off so long as I don't reach that critical 1200 rpm point. Once I hit 1200 rpm it would appear that the ECU kicks in and increases revs of it's own accord (as I
************************************************** ***********
At approx 1100-1200 rpm the ECU advances the timing from -5L and -20T to both L and T to approx 12degrees before TDC. The advancing of the timing by the ECU increases the rpms.
I more or less know this by watching a Palm attached to a RTEK2.0 and seeing the timing at -5 and -20 ATDC below 1100rpm , and the timing for both lead and trail going to approx 12* BTDC when just above 1200rpm.
12-04-07, 10:02 PM
#261
Try This.
polito Racing,
I'd try what was suggested in this thread. Scrip and Hailers know their stuff and we able to help me resolve my idle and inspired me to learn tons of crap about my car.
I'd try what was suggested in this thread. Scrip and Hailers know their stuff and we able to help me resolve my idle and inspired me to learn tons of crap about my car.
I would have never guessed "township". I guess I learned something new today. Man that's quite a commute for ya! I guess you drive your Volvo to work or the GXL?
Ok. I duplicated the hunting idle on a '88 TII that I have at work. I manually held the throttle at 1100-1200 rpm and watched the timing. It advanced 6 degrees from base timing and back and forth until I released the throttle. So basically, anything holding the idle that high will cause the bouncing, whether it be thermowax, vacuum leak, tight cable, dashpot, BAC screw, or whatever. It doesn't have to be strictly a bad tps as so many on here have suggested.
Bottom line is: The idle speed must be kept at or under 1000 rpm with the tps set correctly to prevent the bouncy idle. So, in my opinion, when other people have a bouncy idle complaint, the diagnostics should start with:
(1) A visual inspection of the throttle lever to insure that it contacts the stop screw (by using a mirror and flashlight or temporary removal of the intercooler)
(2) If a gap is found between the throttle lever and stop screw, inspect thermowax and fast idle cam position adjustment, dashpot function and adjustment, and throttle cable slack.
(3) With the throttle lever against the stop screw, perform vacuum leak test using the propane method or compressed air method and make associated repairs.
(4) Set timing to spec with engine below 1000 rpm.
(5) Adjust A/F mixture screw (if equipped) to obtain smoothest idle
(6) Adjust BAC screw (if equipped) to obtain 750 rpm idle (or your preferred speed at 1000 rpm or less) and re-adjust A/F mixture screw if required.
(7) Adjust TPS per FSM and re-adjust idle speed if necessary.
Ok. I duplicated the hunting idle on a '88 TII that I have at work. I manually held the throttle at 1100-1200 rpm and watched the timing. It advanced 6 degrees from base timing and back and forth until I released the throttle. So basically, anything holding the idle that high will cause the bouncing, whether it be thermowax, vacuum leak, tight cable, dashpot, BAC screw, or whatever. It doesn't have to be strictly a bad tps as so many on here have suggested.
Bottom line is: The idle speed must be kept at or under 1000 rpm with the tps set correctly to prevent the bouncy idle. So, in my opinion, when other people have a bouncy idle complaint, the diagnostics should start with:
(1) A visual inspection of the throttle lever to insure that it contacts the stop screw (by using a mirror and flashlight or temporary removal of the intercooler)
(2) If a gap is found between the throttle lever and stop screw, inspect thermowax and fast idle cam position adjustment, dashpot function and adjustment, and throttle cable slack.
(3) With the throttle lever against the stop screw, perform vacuum leak test using the propane method or compressed air method and make associated repairs.
(4) Set timing to spec with engine below 1000 rpm.
(5) Adjust A/F mixture screw (if equipped) to obtain smoothest idle
(6) Adjust BAC screw (if equipped) to obtain 750 rpm idle (or your preferred speed at 1000 rpm or less) and re-adjust A/F mixture screw if required.
(7) Adjust TPS per FSM and re-adjust idle speed if necessary.
01-14-08, 01:20 PM
#263
I have not read the hole post so I don't know what the other guys have said but I can maybe tell you why your idle is bouncing.Air bypass solenoid valve made mine bounce its the valve between the intake manifold and the intercooler right next to the BAC.Look up ways to test it.Hope that helps.
01-14-08, 02:28 PM
#264
^^ Thanks man, but I resolved my idle months ago. It was due to the Fast Idle cam not be set properly and the idle being held around 1,100 rpms - anytime your idle is stuck around 1,100 rpms the ECU advances timing and the idle will bounce. This was actually repeated two posts above yours, but thanks anyways.
Hailers even reposted this a few post up too:
At approx 1100-1200 rpm the ECU advances the timing from -5L and -20T to both L and T to approx 12degrees before TDC. The advancing of the timing by the ECU increases the rpms.
I more or less know this by watching a Palm attached to a RTEK2.0 and seeing the timing at -5 and -20 ATDC below 1100rpm , and the timing for both lead and trail going to approx 12* BTDC when just above 1200rpm.
Anyways, my idle has been fixed. Hopefully others will be helped by the info in this thread.
Hailers even reposted this a few post up too:
At approx 1100-1200 rpm the ECU advances the timing from -5L and -20T to both L and T to approx 12degrees before TDC. The advancing of the timing by the ECU increases the rpms.
I more or less know this by watching a Palm attached to a RTEK2.0 and seeing the timing at -5 and -20 ATDC below 1100rpm , and the timing for both lead and trail going to approx 12* BTDC when just above 1200rpm.
Anyways, my idle has been fixed. Hopefully others will be helped by the info in this thread.
02-04-08, 11:56 AM
#265
Well I just got done reading this thread (took forever haha) and its full of good information. I've been trying to get my S5 T2 swapped first gen to idle right for quite some time this thread has given me a good understanding of how it all works. Hopefully I'll follow the same steps and have success.
Hey Greenbud I'm like 30mins from Green township, I'm down in Long Valley, on the other side of Hackettstown. Wonder if I've ever seen you at rotorfest?
Hey Greenbud I'm like 30mins from Green township, I'm down in Long Valley, on the other side of Hackettstown. Wonder if I've ever seen you at rotorfest?
02-04-08, 09:42 PM
#266
Well...
^ I've actually never been, I've seen the sevens coming and going but I never actually made it to Rotorfest myself. This year I'll have to go, though I heard they weren't sure if they were gonna have it again or something??
Anyways, I'm glad you've found this thread helpful. Here's what I've been up tp since the idle was fixed -
'87 TII Overhaul - From Bouncing Idle to Engine Refurbishment
And what it currently looks like:
Anyways, I'm glad you've found this thread helpful. Here's what I've been up tp since the idle was fixed -
'87 TII Overhaul - From Bouncing Idle to Engine Refurbishment
And what it currently looks like:
02-05-08, 08:39 AM
#267
Yea not sure whats happening with rotorfest this year, but some other guys are organizing a meet at Englishtown similar to Rotorfest, but bigger, and not complete rotary exclusive, so if your car is up for it you should try to make it. I'll probably be there with one of the 7's..
Nice work on the car btw! If you care to check out my build here's the linke for the T2 powered FB, its almost done, but I haven't updated the thread in a while: https://www.rx7club.com/1st-generation-specific-1979-1985-18/project-83-s-restoration-t2-swap-update-624258/
This thread has been a great help, and hopefully I can get the idle under control on that thing once I have time.
Nice work on the car btw! If you care to check out my build here's the linke for the T2 powered FB, its almost done, but I haven't updated the thread in a while: https://www.rx7club.com/1st-generation-specific-1979-1985-18/project-83-s-restoration-t2-swap-update-624258/
This thread has been a great help, and hopefully I can get the idle under control on that thing once I have time.
12-03-09, 12:29 PM
#268
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I just read this entire (now 11 page) thread. A copy of it should be in every 2nd gen's tool box. Something that this thread has that many others are missing is a GREAT* set of photos, graphics, and videos to help those of us who are visually inclined. My personal gratitude to all who contributed! (now I just need to find a similar thread for an NA FC that has such photos so I know what I'm reaching for on the back side of the engine. Are there just more turbo's out there then NA's?)
Again, Great Job! I vote sticky on this one!
Again, Great Job! I vote sticky on this one!
12-05-09, 12:38 PM
#270
my car idled and sounded exactly liek taht when the thermowax was adjusted way wrong, i let a freind borrow my upper intake manifold for a few months, then when he returned it i thought it was fine, but he had messed with all the screws, so when i installed the engine it did this and i coudlnt figure it out for the longest time!
12-05-09, 02:02 PM
#272
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my car idles like that a little after startup. after coming down from 3k. and after warming up it goes down to like 750-800. and stays there... the only problem i see with mine is that the neighbors hate me because of it. and its loud haha. but like i care!
ive had this fluctuating idle on two of the fc's. no issues other than that.
is it bad for anything when it does that??
ive had this fluctuating idle on two of the fc's. no issues other than that.
is it bad for anything when it does that??
12-06-09, 05:25 PM
#273
There are a few possible things I can think of. Either the TPS bracket bolts and/or adjustment screw locknut aren't tight enough to hold the adjustment, or the TPS is going south. Inside the TPS is a carbon (conductive) strip and a "wiper" that moves across it to send the voltage signal to the ECU in a linear fashion. As the TPS ages the carbon flakes off resulting in erratic "glitches" in the signal and inconsistency near the closed throttle position. Also if the coolant t-stat isn't allowing the coolant to stay hot enough for the thermowax to fully extend, you might have set the volts at just above closed throttle. I have also seen a couple t-wax units fail from wax leakage. Less wax =less extension of the plunger.
12-06-09, 05:36 PM
#274
Since this thread was written I have experimented with various TPS voltage settings on a few different 7s to see how it affected idle stability. I have found that while there are a few possible causes for the bouncing idle, the single most likely root cause is the ever-so-critical TPS adjustment. I noticed that the closer I set the voltage to 1.0 volts, the more likely it will have a bouncy idle. If I set the volts to .75 to .85, there is no bouncing at all. I know several guys on the forum like to use the resistance method but I prefer to use the voltage method per the FSM. Just my .o2 cents.
