Problems with the SR20det, is this a safe way to clean the IACV?

[jerryscherry]

05/05/2013
I noticed when i pump my brakes at idle, my vacuum will drop to like 10-15, and will slowly go back up as soon as i stop pumping it. Possible vacuum leak in BMC or Booster? i recently did a z32 front brake swap, using stock bmc and stock booster

Updates 05/04/2013
replaced CTS and o2 sensor, didn't really do much, gonna do a boost leak test next, i noticed when i turn on my car, the rpms go to like 800 rpm immediately, isn't it usually supposed to go higher right when u turn on the car and drop back down? maybe im running pig rich..


Updates 05/02/2013 Part 2

When i unplugged the MAF, the car idle fine..., last time we did the same thing, unplugged the MAf, car idled perfect. Friend had an extra sr20det maf, we plugged it in, started running rough again when plugged in. So don't think its a MAF problem, unless both of our MAF's are fucked. Why does it idle well if i unplug the MAF o.O?

Updates 05/02/2013
Recirculated BOV about a 2-3 weeks ago, seem to run alot better. when going into neutral, during cold starts, idle drops arn't as violent, still dips a tiny bit when cold, when at operating temprature, it is almost non existant, motor is still a tiny bit shaky but not as bad.

Installed z32 front brakes past sunday (rotors calipers pads, using stock 240 BMC).

Next day, car randomly stalled out when coming to a stop (putting car to neutral, rpms dropped and stalled out) parked the car, reved the car, each time the rpms would drop pretty low, like almost stalling after letting off the gas, almost like a rich condition. Car smelled worse than usual, (running test pipe). Drove to school, and it seem the problem disapperead. Hit boost, let the bov go off, put it in neutral, rpms go to normal idle. parked the car, revved it in the parking lot, rpms drop normally, no low idle.. weird figured the problem went away on its own.

Drove to work next morning, didnt have the problem. Got off work, drove for a bit on the freeway, got off the freeway, came to a stop, put car to neutral, same thing,, car stalled out. The symptoms are almost the same as running a VTA BOV (but mines recirculated). Pulled to a gas station, got gas, turned the car on, car seemed to run rough. Smelled worst than usual, sounded like the car was misfiring a bit? Idle would be at 800-900, but would drop to like 200-500 every like 10 seconds. I drove off, i did a semi 1st, 2nd gear pull, seeing if it would stall out when i put it in neutral, problem seemed to correct itself AGAIN like the previous day at school. Got home, did the same thing, revved the car, idled perfect, no drops. Drove the car later that night, no problems.

WHAT THE HECK is this random problem.

I plan to change out the CTS, since i bought one, and next probably the o2 sensor? Not sure if its been changed since the swap. Any other ideas? my Vacuum reads -20 at idle, unless the idle drops.. then its like around 15-18 when the idle drops.

sound like o2 sensor problems? would anything change if i disconnect the o2? Why does the problem come randomly...then correct itself..

Updates 04/15/2013

took out the IACV to clean it, wasn't even that dirty, but cleaned it regardless. Cleaned TB, checked TPS, it was off so set it correctly. Timing was off a tiny bit, so corrected that. Adjusted idle. After doing everything, car idles a bit better, isn't at idle, vacuum went from 15 at idle to 18-20 at idle. But idle still seems to drop a bit and rough idle at stop lights but not as bad. i am planning to recirc my bov to see if that helps, but i don't think that should affect my idle when im at a stop light, only after shifts etc.

However, still during cold starts, engine is hesitant/chokes from 1-2k rpms until engine warms up.. then it runs fine. could it be a CTS?

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How TO: Clean a redtop IACV valve with carb cleaner : SR20DET Forum (rear-drive) (http://forums.nicoclub.com/how-to-clean-a-redtop-iacv-valve-with-carb-cleaner-t251731.html)

seem that some ppl have trouble starting their motor after using this method or not being to start at all !

but it seems you can pull your EGI fuses and crank it and it helps?

i just don't want to try this method and end up with a car i can't drive LOL. any thoughts?


My car starts up fine, and idles pretty good while cold.. but it tends to bog for a bit between 1-2krpms and then clears up after, only during cold , once it warms up, it drives fine. But when im at the stop light , car will idle at around 1-1.1k rpm, very smooth, but after a few seconds at a stop, idle will dorp down to like 800, sometimes drop to 600 and back to 800 and engine will idle really rough. if you tap on the gas, it will go back to 1100 and stay there for a few seconds then go back down and rough idle.

also during cold starts, when you come to a stop or shift to neutral for the first few minutes of driving, idle will drop very low, it even stalled once, but usually itll drop really low and then correct itself.

I changed spark plugs gapped at .030 or .032 i forget which one, fuel filter, fuel pump,

what i suspect right now is either CTS, IACV, Check Timing, Vacuum/boost leak.

any other ideas? stock sr20det, stock cat,stock ecu, stock exhaust, stock ecu, cx racing FMIC, freddy bov vta, stock sr20det maf

another weird thing, my car doesnt stall out with the VTA BOV. i know it did on my ka24de-t, but for the sr20det it doesn't o.O? my bov is placed on the hotpipe. is there a reason for the car not stalling out? thought the unmetered air would make it run rich etc and cause it to stall.

any thoughts?

[Kingtal0n]

well, at the risk of turning a simple issue into a technical one, I can tell you two things about atmospheric bypass valves :

#1
If the valve is open at all, you are right to guess that has to do with air, but that is air that has already been metered, and is now leaving the closed system. So you are metering air, and injecting fuel for that air, but the air is gone, so that is how you wind up richer than you should be.

#2
There is a minimum rpm for this to occur. If the engine rpm is above 1800-2200 rpm ( I am NOT sure the exact number it could be 2400 or 1500 but lets say 1800)... if you LIFT your foot from the throttle above that set rpm, the ECU goes into "fuel cut" mode, almost instantly. In other words, if you boost the engine then shift, it doesnt matter if the bypass valve is venting metered air to the atmosphere because the ECU cuts all the fuel regardless. Now, it does not cut INSTANTLY, so often there is a short period of rich behavior. Not to mention once the rpm drops below that set rpm, there is no longer any fuel cut, so it will run super rich if the bypass valve is open at that point.

So to fully understand why your vehicle doesnt stall with an open bypass, you need to determine if the bypass is hanging open below that fuel cut rpm. if the bypass does not open at all from idle-1800rpm, for instance, it probably will never run rich and cough and sputter. It sounds like you may have a boost/vacuum leak, the most commonly overlooked problem with sr20det engines IMO. depending on where the leak is, it may raise your idle intermittently.


Now, on to your initial question, YES it sounds like the IACV needs to be replaced. I would not try cleaning it, you CAN but for best results I would just change it since replacement IACV are usually very cheap. You should buy a cleaner one, and Clean THAT one really good, then swap them out. IMO.

If I was unclear about anything or you require further explanation or more examples I would be very happy to provide them. gl

[jerryscherry]

well, at the risk of turning a simple issue into a technical one, I can tell you two things about atmospheric bypass valves :

#1
If the valve is open at all, you are right to guess that has to do with air, but that is air that has already been metered, and is now leaving the closed system. So you are metering air, and injecting fuel for that air, but the air is gone, so that is how you wind up richer than you should be.

#2
There is a minimum rpm for this to occur. If the engine rpm is above 1800-2200 rpm ( I am NOT sure the exact number it could be 2400 or 1500 but lets say 1800)... if you LIFT your foot from the throttle above that set rpm, the ECU goes into "fuel cut" mode, almost instantly. In other words, if you boost the engine then shift, it doesnt matter if the bypass valve is venting metered air to the atmosphere because the ECU cuts all the fuel regardless. Now, it does not cut INSTANTLY, so often there is a short period of rich behavior. Not to mention once the rpm drops below that set rpm, there is no longer any fuel cut, so it will run super rich if the bypass valve is open at that point.

So to fully understand why your vehicle doesnt stall with an open bypass, you need to determine if the bypass is hanging open below that fuel cut rpm. if the bypass does not open at all from idle-1800rpm, for instance, it probably will never run rich and cough and sputter. It sounds like you may have a boost/vacuum leak, the most commonly overlooked problem with sr20det engines IMO. depending on where the leak is, it may raise your idle intermittently.


Now, on to your initial question, YES it sounds like the IACV needs to be replaced. I would not try cleaning it, you CAN but for best results I would just change it since replacement IACV are usually very cheap. You should buy a cleaner one, and Clean THAT one really good, then swap them out. IMO.

If I was unclear about anything or you require further explanation or more examples I would be very happy to provide them. gl


is that method i posted, a good/safe way to clean the iacv? with the carb cleaner etc.

also is this AAC valve the same as a IACV? it seems a lot cheaper than other places.

S13 SR20DET AAC Valve (http://www.phase2motortrend.com/sraacva.html)

compared to Frsport... http://www.frsport.com/Nissan-OEM-S13-SR20DET-Idle-Air-Control-Valve-AAC-IACV_p_1123.html

[Kingtal0n]

I dont like that method. the danger is, anything liquid in the intake plumbing can potentially hydrolock the engine. If you choose to do that method, I would let the engine sit overnight before attempting to start it, with the hole open of course so whatever you put in can evaporate. And still, there is no guarantee it will all evaporate. If you are dead set on doing that a safer alternative would be to remove all the spark plugs and crank the engine over a bit then give it an hour or two then crank it some more, looking for liquid of any kind. disable the CAS (unplug the cam sensor) so that fuel is not injected when cranking. That way if you see any liquid you know it was the carb cleaner.

#2 carb cleaner is not effective enough of a solvent to remove a heavy buildup in most redtop IACVs. You would want something stronger for best results. no to mention, once you dislodge all of that buildup, where is it going to go? Inside your engine? on your pistons? on the cylinder walls? in your turbine? No thank you! I would take the iacv off from the engine, and clean it there where you can get to it, soak it in a tub of solvent or something, let it dry completely then reinstall.

#3
I would just buy a used IACV and clean it, because those new ones are so damn expensive. If you can afford it then go for it, but there are other places I would like to spend $150+ than that. Heck you could buy three used IACVs for $100 if you are careful and patient, clean them all and try each one in turn.

[jerryscherry]

bump for updates

[jr_ss]

Did you recirc your BOV? Most likely its leaking causing your low idle. Stick your hand over the discharge of your BOV, can you feel air escaping? Does your idle get noticeably better?

Gap your plugs at .028, that's a good middle ground for your engine.

[jerryscherry]

Did you recirc your BOV? Most likely its leaking causing your low idle. Stick your hand over the discharge of your BOV, can you feel air escaping? Does your idle get noticeably better?

Gap your plugs at .028, that's a good middle ground for your engine.

yeah tried that already, no air comes out, and idle doesn't change, but i am going to recirc, probably getting a slight rich condition.

[idc101]

how do you know if your tps is good?

[KoukiMonsta]

how do you know if your tps is good?

you search the forum and learn how to test it.

[jerryscherry]

bump for new problems 05/02/2013 :(?

[jerryscherry]

replaced o2 and cts didnt do much

[jerryscherry]

bump , noticed when i pump my brakes my vacuum drops to like 10-15

[jr_ss]

You're using vac when you pump the brakes, so it should drop some but 10-15" is a large gap.