Low, Lumpy Idle At Stop Lights/Signs.
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Low, Lumpy Idle At Stop Lights/Signs.
1997 Civic EX, stock D16Y8. A/T. 160K miles. 3x3 ATF drain and fill done 10K miles ago. No known transmission issues.
My car has developed this recent issue (along with a/c issue..separate post) in which when the transmission is in gear and simultaneously braking (stoplights) it feels like it's lurching forward but, isn't. The rpms drop to roughly around 350 to 450 rpms and the idle feels lumpy/pusling. When in park or neutral and not braking the engine idles smooth and around 600-650 rpms. Google search came up with this very similar (thread) issue but, without a follow-up or fix: http://honda-tech.com/honda-accord-1...dling-1029288/
Here's another related post: http://honda-tech.com/how-tos/a/hond...jerking-376509 Other than this issue the drivetrain is perfoming well. I plan to start by:
1) Inspecting spark plugs and spark quality.
2) Change fuel filter (no record of last replacement).
3) Remove and clean throttle body and IACV.
4) Inspect throttle cable
5) Have battery tested
6) Clean shift solenoid screens
All suggestions welcomed.
My car has developed this recent issue (along with a/c issue..separate post) in which when the transmission is in gear and simultaneously braking (stoplights) it feels like it's lurching forward but, isn't. The rpms drop to roughly around 350 to 450 rpms and the idle feels lumpy/pusling. When in park or neutral and not braking the engine idles smooth and around 600-650 rpms. Google search came up with this very similar (thread) issue but, without a follow-up or fix: http://honda-tech.com/honda-accord-1...dling-1029288/
Here's another related post: http://honda-tech.com/how-tos/a/hond...jerking-376509 Other than this issue the drivetrain is perfoming well. I plan to start by:
1) Inspecting spark plugs and spark quality.
2) Change fuel filter (no record of last replacement).
3) Remove and clean throttle body and IACV.
4) Inspect throttle cable
5) Have battery tested
6) Clean shift solenoid screens
All suggestions welcomed.
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Checked oil about an hour ago and it was low by 3/4 quart. Added correct amount, drove for 20 minutes and it seems to have helped the issue but, not claiming to have solved it this point. My son has been using my car a lot lately while I worked on his. I guess the little turd didn't feel an obligation to check oil level even though he knows there's a known, very small oil pan gasket leak and rear main seal leak (a quart between oil changes)
Is it common in 6th gens for the idle to drop from 650 rpms while in park to 450 or so when in gear and brakes activated?
I still plan to do the above mentioned maintenance to (hopefully) obtain peak performance.
Is it common in 6th gens for the idle to drop from 650 rpms while in park to 450 or so when in gear and brakes activated?
I still plan to do the above mentioned maintenance to (hopefully) obtain peak performance.
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In gear, hot, idling.........If you kick on the AC--- does the idle stay the same RPM or does it drop?
Does it roll up and down 550-650 as the compressor repeatedly clicks on and off?
Idle should not drop below 650 (IMO).
(use a real tach or a scantool, not the tach on the dash)
If running the AC, it should kick the compressor off whenever the idle RPM drops below 600.
Is your IAC on the back of the intake manifold, or under the throttle body?
Is the IAC able to open all the way? (rotary valve type)
Clean throttle body
Clean IAC
Clean IAB screw passages (assuming it has a big ol screw for this, count # of turns IN to bottom out before removing it so you can put it back where it started),
you may need to reset minimum air rate with the screw
and you will need to relearn idle after adjustments and/or cleaning.
Does it roll up and down 550-650 as the compressor repeatedly clicks on and off?
Idle should not drop below 650 (IMO).
(use a real tach or a scantool, not the tach on the dash)
If running the AC, it should kick the compressor off whenever the idle RPM drops below 600.
Is your IAC on the back of the intake manifold, or under the throttle body?
Is the IAC able to open all the way? (rotary valve type)
Clean throttle body
Clean IAC
Clean IAB screw passages (assuming it has a big ol screw for this, count # of turns IN to bottom out before removing it so you can put it back where it started),
you may need to reset minimum air rate with the screw
and you will need to relearn idle after adjustments and/or cleaning.
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being low by 3/4 qt won't (rather, shouldn't) cause a problem like that.
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That's why I use convenient laywer terms like "seems" because I don't want to sound definitive. Maybe the added oil (proper level) helps lube the cams and valves a bit better which smooths idle some?
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Is the IAC able to open all the way? (rotary valve type). Clean throttle body. Clean IAC. Clean IAB screw passages (assuming it has a big ol screw for this, count # of turns IN to bottom out before removing it so you can put it back where it started). You may need to reset minimum air rate with the screw and you will need to relearn idle after adjustments and/or cleaning.
Is that the screw that the FSM says not to adjust because it's done at the factory or is the TPS that's not to be adjusted per FSM? I've felt for a long time now that the base idle should be 100 or so rpm's higher. Maybe at some point a prior owner, for whatever reason, adjusted it and mistakingly set it to a manual transmission specs instead of A/T specs.
I just finished up some repairs on my son's '07 Mazda 3 and I'm a bit auto repaired out. Here's the thread if you care to take a look: http://www.mazda3forums.com/61-power...et-breach.html Mazda and Ford thought it was a good idea to out the PCV valve behind the intake manifold.
Last edited by Wankenstein; Apr 8, 2016 at 10:55 PM.
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IACV is on back of the intake manifold.
Anyway....
FIRST Unbolt this IAC and scrape all the carbon buildup off of the filter screen. That may solve all of the low idle problem.
Is that the screw that the FSM says not to adjust because it's done at the factory
or is the TPS that's not to be adjusted per FSM?
It is set to be at 0.49v @closed throttle, and 99% are dead nuts on that number when I scan them. If it's off by just a few hundredths of a volt it can screw up the idle program.
I've felt for a long time now that the base idle should be 100 or so rpm's higher.
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D16Y8 idle spec
USA M/T 670
USA A/T 700
Canada M/T and A/T 750
All specs are +/-50 RPM
USA M/T 670
USA A/T 700
Canada M/T and A/T 750
All specs are +/-50 RPM
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I checked for vacuum leaks about 8 months ago by taping off TB intake and blowing cigar smoke through brake booster vacuum hose. At that time no vacuum leaks. I will do it again within the next two days.
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As a side note: I posted a thread about 3 or 4 months ago concerning ignition timing. Previous owner(s) etched in a notch on the top of the distributor base and one on the cylinder head. I lined those up and did an ECU re-learn and it's been that way since I did a TB change last summer. I purchased an old-school $5 timing light from a guy on Craigslist. He mailed it to me and it doesn't work. I purchased one form harbour fright and that plastic piece of crap broke n the first 5 minutes of use. It's possible that the ignition timing may not be optimal until I hit it with a timimg light and jumper connector near passenger door.
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It's possible that the ignition timing may not be optimal until I hit it with a timimg light and jumper connector near passenger door.
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With compressor engaged idle bumps up about 100 rpms for a second or two and then drops back about 50 rpms and steadies. This happens while parked in idle and when in gear and brake depressed. I guessed at my TB location and try to go on memory as I was at work the other night when you asked it's location. It is indeed located underneath the TB. My ride is a US made Civic A/T: 700 +/- 50
The low, lumpy idle when in gear and braking is now, I'm finding out, an intermittent issue. It did it a few times yesterday and today when driving to work it wasn't present. I'll start by removing and cleaning the TB, IACV. If still present will try adjusting idle screw: counting turns as you suggested. Will also do a cigar smoke through vacuum line test. I purchased this: http://www.harborfreight.com/fuel-pu...ter-93547.html yesterday and plan to hook it up to the intake and use the guides (links) on this page: http://www.crankshaftcoalition.com/w...gine_diagnosis
All this auto work is cutting into my Master's golf tournament and beer time.
Last edited by Wankenstein; Apr 10, 2016 at 07:35 AM.
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That IAC does not have a screen then,
Low+lumpy, intermittently.....Is it just a low RPM issue, or does it misfire when it does this?
Low+lumpy, intermittently.....Is it just a low RPM issue, or does it misfire when it does this?
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It's hard to tell if it's due to a minor misfire or low rpm or possible transmission issue. The cluster's rpm gauge stays steady at idle other than when compressor is intially engaged.
I guess I'll know more after the insepcting, cleaning and testing I do today. Is it possible that an ignition coil or igniter in early failure could cause this type issue?
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Even though there isn't a screen would it benefit from cleaning it with throttle body or brake cleaner?
Is it possible that an ignition coil or igniter in early failure could cause this type issue?
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Just finished up:
1) Replaced fuel filter
2) Cleaned throttle body: there was a bit of grime but, mostly clean and flap closed fully.
3) Cleaned IACV: Some carbon build up. I removed the magneto (or whatever it's called) so I could spin it side to side to clean as thoroughly as possible.I used a small flat-head screwdriver and covered it with a rag (to avoid scratches) and brake cleaner. It's fresh and clean as an Irish spring now.
4) Intake manifold body is very clean and no grime build-up
5) Tightened throttle cable: it was pretty loose
6) Tested it with the vacuum gauge at idle/operating temp: Reading stayed at 21 In HG vac (green = good motor) I'm in mid-west Florida and just a few feet above sea level.
7) ECU re-learn
Results: No change but, may still be relearning idle..only went for 10 minute test drive. Doubt that re-learn will make a difference.
My friend forgot to bring his timing light. I did not adjust idle screw yet but, may soon. Also, did not check spark yet.
1) Replaced fuel filter
2) Cleaned throttle body: there was a bit of grime but, mostly clean and flap closed fully.
3) Cleaned IACV: Some carbon build up. I removed the magneto (or whatever it's called) so I could spin it side to side to clean as thoroughly as possible.I used a small flat-head screwdriver and covered it with a rag (to avoid scratches) and brake cleaner. It's fresh and clean as an Irish spring now.
4) Intake manifold body is very clean and no grime build-up
5) Tightened throttle cable: it was pretty loose
6) Tested it with the vacuum gauge at idle/operating temp: Reading stayed at 21 In HG vac (green = good motor) I'm in mid-west Florida and just a few feet above sea level.
7) ECU re-learn
Results: No change but, may still be relearning idle..only went for 10 minute test drive. Doubt that re-learn will make a difference.
My friend forgot to bring his timing light. I did not adjust idle screw yet but, may soon. Also, did not check spark yet.
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but, may still be relearning idle..only went for 10 minute test drive.
You have to wipe ECM memory, then let it idle (HOT) for 10 minutes with zero extra electrical loads.
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I forgot mention that I checked the ATF in a parking lot that appeared to be level. Engine at operating temp and ran through gears prior while driving the ATF was just above the high fill mark. When I initially checked (several times) after the 3x3 drain and fill I did on it last year the level always fell in the middle of the low-high fill marks.
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NO loads. No lights, no windows, no defroster, no AC.
In park or neutral.
If the radiator fan comes on during the learn period, you have to add that much more time to the period.
I forgot mention that I checked the ATF in a parking lot that appeared to be level. Engine at operating temp and ran through gears prior while driving the ATF was just above the high fill mark. When I initially checked (several times) after the 3x3 drain and fill I did on it last year the level always fell in the middle of the low-high fill marks. Check ATF with the engine OFF on all real Hondas, and at operating temperature.
Fluid expands as temperature increases (because physics!) so the level will be higher when the trans fluid is actually hot.
It takes a good bit of running/driving to get the trans fluid up to operating temperature. It is much slower to heat than the temp gauge on the dash. You can wipe the dipstick with your fingers to kinda guess at how hot or cool the fluid really is.
In park or neutral.
If the radiator fan comes on during the learn period, you have to add that much more time to the period.
I forgot mention that I checked the ATF in a parking lot that appeared to be level. Engine at operating temp and ran through gears prior while driving the ATF was just above the high fill mark. When I initially checked (several times) after the 3x3 drain and fill I did on it last year the level always fell in the middle of the low-high fill marks.
Fluid expands as temperature increases (because physics!) so the level will be higher when the trans fluid is actually hot.
It takes a good bit of running/driving to get the trans fluid up to operating temperature. It is much slower to heat than the temp gauge on the dash. You can wipe the dipstick with your fingers to kinda guess at how hot or cool the fluid really is.
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followed the procedure you stated above and previously and let idle for 20 minutes to be sure. I don't want to premature celebrate (cause women don't like that) however, it seems to be idling better. Will know over the next day or two if it solves the issue.
Check ATF with the engine OFF on all real Hondas, and at operating temperature. Fluid expands as temperature increases (because physics!) so the level will be higher when the trans fluid is actually hot.
It takes a good bit of running/driving to get the trans fluid up to operating temperature. It is much slower to heat than the temp gauge on the dash. You can wipe the dipstick with your fingers to kinda guess at how hot or cool the fluid really is.
It takes a good bit of running/driving to get the trans fluid up to operating temperature. It is much slower to heat than the temp gauge on the dash. You can wipe the dipstick with your fingers to kinda guess at how hot or cool the fluid really is.
If it reads a bit overfilled again should I use a baster and remove some?
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If it reads a bit overfilled again should I use a baster and remove some?
A half quart over is actually pretty common......many people just dump in 3 full quarts at a change not realizing it only takes about 2.5.
(including an old timer Honda mechanic I used to work with)
What about the AC thought in the other thread?
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Just barely over "high" full mark probably less than half a quart. No problems to date other than it shifts slightly hard but, as I understand it that is very common for 6th gens and especially for EX models.
See other thread..lol
See other thread..lol
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I'm getting a good vibe over the ECU re-learn that you suggested. I probably didn't do it right months ago and it may have manifested into the low idle situation. On my drive home it didn't once idle low. Hopefully it stays this way... I'll update in a few days.
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Low idle reared it's ugly mug again today. Next course of action is check ignition timing with light. Adjust idle screw.
Checked ATF on flat surface today: 20 minutes of driving prior, with engine off ATF level is in the middle of low/high mark. With engine on ATF was slightly higher but still within spec.
Last edited by Wankenstein; Apr 11, 2016 at 01:40 PM.
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Someone left a rather broken 97 coupe at the shop today.... we all kinda freaked out that someone would bring a car that old to a dealership for anything other than a recall.
Among some other things....It needs an idle relearn after un-f**king a throttle problem, but someone has the radiator fan wired to run all the time--- so it cannot learn idle.
Among some other things....It needs an idle relearn after un-f**king a throttle problem, but someone has the radiator fan wired to run all the time--- so it cannot learn idle.
