So I cleaned the IACV… only took like 20 minutes. Was very dirty, sprayed it out with brake cleaner and lot of black stuff came out. Put it back on and idled around 400 so I adjusted the idle some got it up around 800. Drove it around and drives a ton better. Doesn’t hang up high in between gears it drops back like supposed to. Only thing is now when I pull up to a stop light once I get around 5mph it all of a sudden jumps rpm’s to 1300-1400 and then waits a second and comes back down. Then slowly goes back and forth from 700-800. Not nearly as harsh as before but still happening. Gonna try and check all lines this weekend for vacuum leak anything other suggestion still?
D16a6 surging/hanging/hunting idle problem
So I’ve seen a lot of posts about this but no actual answer. My 89 si has always done this but it stopped for a while and has recently came back with warmer weather. It’ll warm up and run fine but then when inbetween gears shifting up or down idle gets stuck around 1800-1900 and doesn’t come down until the car stops rolling for at least a second or two. Then sometimes it’ll idle down to 800 like normal. But other times it will start surging and dropping back and forth between 800 and 1900. Sometimes gets stuck even at stop lights up high and won’t come back down until I tap the gas. I’m cleaning the IACV this weekend and also going to check throttle body gasket and probably replace it as well. I have two ecus have tried both and know they’re good and don’t do it with other cars. I’ve also purged the coolant as well or got all the air out of it. Doesn’t ever overheat or anything either. New exhaust gaskets also. Saw where someone said all those things have done it. Just checking if there might be any other suggestions???
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I think you need to give the EACV a really, really, really good cleaning. They get gunked up with carbon deep inside the valve and the typical cleaning efforts still leave plenty behind to foul things up.
Lay the valve on it's back. Fill it with carb and throttle body cleaner. Let it soak for several hours. Poor the cleaner out. Repeat until the cleaner doesn't have the faintest hint of tint after several hours soaking. It helps to power the valve a few times now and then during soaking. This helps to agitate and flush deposits away from the seal surfaces and deep inside the valve. As a final test after several hours of soaking poor the cleaner onto a clean white paper towel to see if it leaves any tint.
I find it takes several days to a week to get the valve completely cleaned deep inside. After the first few flushings I'll let it soak for as much as a day at a time. It does take topping off a few times over the day because of evaporation.
Make sure you clean out the groove that captures the seal. If the seal is not reasonably fresh replace it.
If your seeing 400 RPM your tach is probably reading low, I don’t think the engine will idle stable that low. 400 RPM is actually the end of travel for the gauge. The needle comes to rest on a peg there. It’s very common for a CRX tach to read low as it ages. Use an external digital tach for setting idle. Some timing lights have a tach built in.
Mike
Lay the valve on it's back. Fill it with carb and throttle body cleaner. Let it soak for several hours. Poor the cleaner out. Repeat until the cleaner doesn't have the faintest hint of tint after several hours soaking. It helps to power the valve a few times now and then during soaking. This helps to agitate and flush deposits away from the seal surfaces and deep inside the valve. As a final test after several hours of soaking poor the cleaner onto a clean white paper towel to see if it leaves any tint.
I find it takes several days to a week to get the valve completely cleaned deep inside. After the first few flushings I'll let it soak for as much as a day at a time. It does take topping off a few times over the day because of evaporation.
Make sure you clean out the groove that captures the seal. If the seal is not reasonably fresh replace it.
If your seeing 400 RPM your tach is probably reading low, I don’t think the engine will idle stable that low. 400 RPM is actually the end of travel for the gauge. The needle comes to rest on a peg there. It’s very common for a CRX tach to read low as it ages. Use an external digital tach for setting idle. Some timing lights have a tach built in.
Mike
Okay well yeah hanging idle came back anyways. Now revs up to 3k and continues to do it while in gear. I’ll be in 5th at 35mph foot of the gas and car is speeding up. Do you think throttle body could be sticking also? I’m probably gonna take it and the intake off entirely and try to deep clean all three this weekend hopefully fixes it.I think you need to give the EACV a really, really, really good cleaning. They get gunked up with carbon deep inside the valve and the typical cleaning efforts still leave plenty behind to foul things up.
Lay the valve on it's back. Fill it with carb and throttle body cleaner. Let it soak for several hours. Poor the cleaner out. Repeat until the cleaner doesn't have the faintest hint of tint after several hours soaking. It helps to power the valve a few times now and then during soaking. This helps to agitate and flush deposits away from the seal surfaces and deep inside the valve. As a final test after several hours of soaking poor the cleaner onto a clean white paper towel to see if it leaves any tint.
I find it takes several days to a week to get the valve completely cleaned deep inside. After the first few flushings I'll let it soak for as much as a day at a time. It does take topping off a few times over the day because of evaporation.
Make sure you clean out the groove that captures the seal. If the seal is not reasonably fresh replace it.
If your seeing 400 RPM your tach is probably reading low, I don’t think the engine will idle stable that low. 400 RPM is actually the end of travel for the gauge. The needle comes to rest on a peg there. It’s very common for a CRX tach to read low as it ages. Use an external digital tach for setting idle. Some timing lights have a tach built in.
Mike
Sticky throttle body should be easy enough to see. Another thing with 3k idle is the vacuum line going from the intake to throttle spigot, if that is pulled off it is suppose to go to around 3k. Is that vacuum line cracked?Okay well yeah hanging idle came back anyways. Now revs up to 3k and continues to do it while in gear. I’ll be in 5th at 35mph foot of the gas and car is speeding up. Do you think throttle body could be sticking also? I’m probably gonna take it and the intake off entirely and try to deep clean all three this weekend hopefully fixes it.
Taking off intake manifold can be a Pia, coolant loss, new gasket etc. And cleaning that will not fix your idle issue. You should be able to clean throttle body on car as well. If plate stops on stop, it's not sticking, if not going to stop, then it's sticking.Okay well yeah hanging idle came back anyways. Now revs up to 3k and continues to do it while in gear. I’ll be in 5th at 35mph foot of the gas and car is speeding up. Do you think throttle body could be sticking also? I’m probably gonna take it and the intake off entirely and try to deep clean all three this weekend hopefully fixes it.
I'd say clean the throttle body, lube the throttle cable, inspect vacuum hose going to the dash pot valve, lubricate the throttle body linkage as well.
My Dx was having similar issue but it was staying up in rpms.
I disabled the dashpot vacuum advance linkage to throttle linkage and it started idling perfectly again. After some time I put it back again and it all cleared off on its own.
whatever it was I suspect was a cleaning spot that needed maintenance. Probably the throttle body or a solenoid controlling the dash pot. In any case most likely vacuum problem caused by grime or a bit of dust.
I would strongly start looking at the dash pot valve or FITV( if equipped).
Don't forgett to make sure throttle cable is sliding smoothly as well.
Gl
My Dx was having similar issue but it was staying up in rpms.
I disabled the dashpot vacuum advance linkage to throttle linkage and it started idling perfectly again. After some time I put it back again and it all cleared off on its own.
whatever it was I suspect was a cleaning spot that needed maintenance. Probably the throttle body or a solenoid controlling the dash pot. In any case most likely vacuum problem caused by grime or a bit of dust.
I would strongly start looking at the dash pot valve or FITV( if equipped).
Don't forgett to make sure throttle cable is sliding smoothly as well.
Gl
If you haven't already, you will need to bleed the cooling system.
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