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Car Forum / Honda Cars / February 20081990 Honda Accord Idle fluctuation
My 1990 Honda Accord 2.2L started to have idle fluctuations yesterday. The RPM will fluctuate between 1700 and 1000 RPMs when the car is stopped. The fluctuations don't seem to be noticeable when the car is in gear. What would cause this? I searched for vacuum leaks but couldn't find anything. I recently did a tune-up. Please help! A strong candidate: Top off and monitor the cooling system. It cools certain engine control sensors. If they are not fully immersed, then the wrong signal gets sent to the engine control computer. You should do a proper purge of air from the system as well, though its said over time the air will vent itself. I prefer going through the roughly half-hour, fairly easy, idle purge procedure described in the owner's manual and Factory Service manual. > My 1990 Honda Accord 2.2L started to have idle fluctuations > yesterday. The RPM will fluctuate between 1700 and 1000 RPMs when the > car is stopped. The fluctuations don't seem to be noticeable when the > car is in gear. What would cause this? I searched for vacuum leaks > but couldn't find anything. I recently did a tune-up. Please help! > A strong candidate: Top off and monitor the cooling system. It cools certain engine > control sensors. If they are not fully immersed, then the wrong signal gets sent to the [quoted text clipped - 3 lines] > air will vent itself. I prefer going through the roughly half-hour, fairly easy, idle > purge procedure described in the owner's manual and Factory Service manual. The coolant system is working properly. Any other ideas? paul.liner@gmail.com wrote in news:9ae279a7-d778-48cd-8328-5e54960c13e2 @s12g2000prg.googlegroups.com: > My 1990 Honda Accord 2.2L started to have idle fluctuations > yesterday. The RPM will fluctuate between 1700 and 1000 RPMs when the > car is stopped. The fluctuations don't seem to be noticeable when the > car is in gear. What would cause this? I searched for vacuum leaks > but couldn't find anything. I recently did a tune-up. Please help! I'll bet the fluctuations are only when the car is warm. If so, it's a stuck Fast Idle Thermo Valve. There is a way to test for that.  SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ Yes! the fluctuations are only when the car is warm. How do I test for a stuck Fast Idle Thermo Valve? Thank you, Paul > I'll bet the fluctuations are only when the car is warm. > [quoted text clipped - 5 lines] > > The Unofficial Honda/Acura FAQwww.tegger.com/hondafaq/ Paul Jr <linerjr@gmail.com> wrote in news:43771d97-174b-4f42-ba99- 20527fb1aaf4@a39g2000pre.googlegroups.com: >> I'll bet the fluctuations are only when the car is warm. >> [quoted text clipped - 3 lines] > Yes! the fluctuations are only when the car is warm. How do I test for > a stuck Fast Idle Thermo Valve? The Fast Idle Valve is a round, sort of tower-like thing to the left (driver's) side of the intake manifold, between the "PGM-FI" logo and the valve cover. It has two screws on top of it that hold a sheet-metal cover in place. With the engine fully warmed up and the idle fluctuating, remove the two screws and the cover of the Fast Idle Valve. Feel the valve seat area with your finger. If there *is* air flow (suction), the valve is stuck open. You will probably find that once you cover the valve seat with your finger the idle will settle down. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ I finally got around to trying to fix this again. I removed the 2 screws and sheet metal cover to check the Fast Idle Valve. I didn't feel any suction or airflow and couldn't get the idle to settle down by covering the valve seat. Thanks for your help Tegger, but I guess the Fast Idle Valve is not the culprit. Does anyone else have any other suggestions?? Mostco, the coolant is full. TE Chea, your link no longer works. Is there a way to test if the throttle angle sensor is bad? Thanks, Paul > I finally got around to trying to fix this again. I removed the 2 > screws and sheet metal cover to check the Fast Idle Valve. I didn't [quoted text clipped - 4 lines] > > Mostco, the coolant is full. ------------------- The rad has to be full as well as the reservoir. How full is the reservoir, just a puddle in the bottom ? ? (that's called empty) On a 1990 I think the system has to be 'burped' (manually), but it won't work if there's no coolant in the reservoir to displace the air. 'Curly' > > I finally got around to trying to fix this again. I removed the 2 > > screws and sheet metal cover to check the Fast Idle Valve. I didn't [quoted text clipped - 14 lines] > > 'Curly' Both the reservoir and Radiator are full. I will try burping it, but I really doubt that is the problem. It was working fine for awhile before this problem started. Paul Jr <linerjr@gmail.com> wrote in news:867dd06e-9649-4f55-8b5f- 213d00fa97f9@d21g2000prf.googlegroups.com: > I finally got around to trying to fix this again. I removed the 2 > screws and sheet metal cover to check the Fast Idle Valve. I didn't [quoted text clipped - 10 lines] > Thanks, > Paul Another air-related suggestion: When the car is warm and the idle is fluctuating, remove the air cleaner pipe to the throttle body. Can you progressively cover the throttle body with your hand to the point where the idle settles down? What happens if you unplug the EACV? That's the idle air control valve behind the throttle body. Sometimes a stuck-open EACV causes fluctuating idle. And did you check the coolant in the rad, not the reservoir? SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > Paul Jr <line...@gmail.com> wrote in news:867dd06e-9649-4f55-8b5f- > 213d00fa9...@d21g2000prf.googlegroups.com: [quoted text clipped - 29 lines] > > The UnofficialHonda/Acura FAQwww.tegger.com/hondafaq/ Yes, if I can cover the throttle body enough to set the idle down. I unplugged the EACV and the idle jumped up to a fast idle and the check engine light came on. I had to restart the car before the idle would settle down again (actually fluctuate again). Does this tell you anything? Is the EACV the culprit? Yes, I check the coolant levels and "burped" it also. I am very confident that there isn't any air in the coolant system. >> Another air-related suggestion: When the car is warm and the idle is >> fluctuating, remove the air cleaner pipe to the throttle body. Can [quoted text clipped - 8 lines] > > Yes, if I can cover the throttle body enough to set the idle down. Bingo. You have a major air leak somewhere. > I unplugged the EACV and the idle jumped up to a fast idle and the > check engine light came on. It is normal and expected that the CEL would illuminate when the EACV is unplugged. > I had to restart the car before the idle > would settle down again (actually fluctuate again). So the idle fluctuates even though the EACV is unplugged? Hmmm. > Does this tell you anything? Is the EACV the culprit? You have large amounts of unwanted air entering the system. Before anything else is done, you need to check each and every one of your many vacuum hoses, including the ones inside the EGR control box on the firewall. You also have an Air Boost Valve. It is at the opposite end of the intake plenum from the throttle body. With the engine idle fluctuating, disconnect the Air Boost Valve's vacuum hose and plug the port in the valve with your finger. If no settling of the idle, this part is OK. Chek all the bolts/nuts that hold on the intake manifold and other intake parts. Loose intake parts will leak vast amounts of air. > Yes, I check the coolant levels and "burped" it also. I am very > confident that there isn't any air in the coolant system. If the coolant is right up against the bottom of the rad cap, then the level is fine. Your focus now is to find that air leak. If you are 110% certain you have eliminated the possibility of any air leaks, then -- and only then -- we try readjusting the idle speed screw. What are these three digits of your VIN (represented here by x's? JHMCBxxx (No personal information is in those three digits). SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ > >> Another air-related suggestion: When the car is warm and the idle is > >> fluctuating, remove the air cleaner pipe to the throttle body. Can [quoted text clipped - 58 lines] > > The UnofficialHonda/Acura FAQwww.tegger.com/hondafaq/ Sorry, I didn't write that very clear. When I unplug the EACV that idle jumps up to about 2000 RPMs and stays there. I was trying to say that if I plug the EACV back in, the idle wouldn't calm down and fluctuate again until I restarted the car. So is it my EACV that is the problem or an air leak somewhere? My VIN is HGCB714 I really appreciate your help, -Paul > Sorry, I didn't write that very clear. When I unplug the EACV that > idle jumps up to about 2000 RPMs and stays there. I was trying to say > that if I plug the EACV back in, the idle wouldn't calm down and > fluctuate again until I restarted the car. > > So is it my EACV that is the problem or an air leak somewhere? You should find a hole in the sidewall of the throttle body just before the throttle plate. This will be the EACV air intake port. With the EACV UNplugged and the idle high, is there suction at the EACV port? With the EACV unplugged, there should be NO suction. > My VIN is HGCB714 That doesn't seem like an accurate VIN extract. CB7 is the Accord with the 2.2L SOHC. The next two digits are supposed to describe trim level and transmission, but my docs say "14" is invalid. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ replace the PCV valve, and clean the Mass Air Flow (MAF) sensor, remove the idle screw and clean the assembly with carb cleaner if that doesnt fix it then check the Idle Air Control Valve and adjust the Fast Idle Valve, excerpt: "its the cylinder on the driver side of the intake manifold, with the triangular cap with 3 screws. pull them out and take the cap off, and twist the outer white ring clockwise until its as tight as possible, and close it back up." http://www.honda-tech.com/zerothread/1704468 > My 1990 Honda Accord 2.2L started to have idle fluctuations > yesterday. The RPM will fluctuate between 1700 and 1000 RPMs when the > car is stopped. The fluctuations don't seem to be noticeable when the > car is in gear. What would cause this? I searched for vacuum leaks > but couldn't find anything. I recently did a tune-up. Please help! bi241@scn.org wrote in news:d75aec50-7389-41a3-aed1-b6f2395e5594 @d27g2000prf.googlegroups.com: > replace the PCV valve, and clean the Mass Air Flow (MAF) sensor, This car doesn't have a MAF. > remove the idle screw and clean the assembly with carb cleaner > > if that doesnt fix it then check the Idle Air Control Valve and adjust > the Fast Idle Valve, You can't "adjust" the Fast Idle Valve. It gets stuck open on account of neglected coolant changes and results in a massive air leak when the car is warm. > excerpt: "its the cylinder on the driver side of the intake manifold, > with the triangular cap with 3 screws. pull them out and take the cap > off, and twist the outer white ring clockwise until its as tight as > possible, and close it back up." The Fast Idle Valve on this car has two screws, has no white ring and is non-adjustable. SignatureTegger The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ | What would cause this? Mine had this problem, cause was throttle angle sensor ( a variable resistor ). See www.autozone.com/servlet/UiBroker?UseCase=RG001&UserAction=processModel&Paramete rs=001 > My 1990 Honda Accord 2.2L started to have idle fluctuations > yesterday. The RPM will fluctuate between 1700 and 1000 RPMs when the > car is stopped. The fluctuations don't seem to be noticeable when the > car is in gear. What would cause this? I searched for vacuum leaks > but couldn't find anything. I recently did a tune-up. Please help! -------------------------- Before getting too far into it, how full is your coolant reservoir? You said you did some work on it. Did you make sure the cooling system was full to the MAX mark afterwards? I think it's mentioned in your owner's manual. 'Curly' |
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