Thread: s14 sr20det missing/rough idle but smooth over 2k rpm

Hey guys im new to the forum and new to sr20det motors i have searched many forums and cant find a good answer so if this has been answered before please let me know.

So i just picked this car up a few weeks ago and it has a really rough/missing idle it will sometimes intermittently smooth out for a minute or 2 but for the most part has a missing idle but once over 2k or so it smooths out hold boost just fine no problems accelerating but when i come to a stop it has a lopping idle and it runs very rich and on start up has light grey smoke and if i drive with the windows down i will get choked out sometimes i did a compression test it was 166 on all 4 plugs look good i tryed swapping out my coils one by one with a friends to see if that was the problem but did not make a difference i cleaned the IACV many times no change i also notice the my vac is around 16 to 17 but i have checked all my vac lines also i noticed that if i advance my timing all the way up it gets smoother but idk it thats just because the idle goes up witch the high the rpm the smoother the engine is the only thing i can think of is maybe a leaky injector or vac leak in the intake mani please let me know what you guys think

Could be a lot of things, Vac leak, double check all vac hoses and connections on the manifold. Leaky injector, could be someone took the CAS out at one point and didnt put it back in right. Try to see if you can borrow a timing light or buy one and check what your base timing is at, during idle.

Is this an s14 motor or s13 motor, the title is decieving.

Thanks for the reply and yes its an s14 black top notch back zenki sr20det and is the cas the crank angle sensor? if so where is that located? again thanks for the help!

The CAS is crank angle sensor which is what you were adjusting to adjust timing. Its not a one way goes in type deal like the fwd sr's. You have to align the motor at TDC compression stroke on #1 and then it goes in a certain way aligning the dots on the housing and drive gear. If someone did not put it back in right then your timing could be off.

However if its running rich and low vac. Id say small vac leak somewhere. Search for that first. Could be a split wastegate diaphram, same with the bov depending on model, cracked hose, missing plug on unused ports. Its not a very big leak since your vac is still 16-17 so im gonna guess small vac port uncapped or cracked wastegate diaphram.

O ok thanks yeah that makes sense with the CAS also i forgot that i tryed running my BOV open and alot of air was being pushed out not in at idle and it ran alot better but when i hook it back up it runs rougher so im not sure about that. and i replaced all the caps but i will check all those again.

Thats your problem. The bov whether its aftermarket or stock is too soft and is open at idle causing air to escape that has been metered by the maf sensor. I bet you if you plugged you hand over it while at idle, it would run better. Time to either adjust the spring setting stiffer if its an aftermarket one or get rid of that stock one for an aftermarket one if your wanting to run it open.

Well its recirculating and runs like crap with the missing and what not but when i ran it open it ran alot better but noticed alot of air coming out and also fluttering when i shift and if i put my hand over the bov witch it stock it ran worse take my hand away and it ran better? kinda weird but thats what it does.

ok so i noticed that my idle sits around 1400 rpm and its kinda smooth but after warming up the idle will go up and down when its at 1400 or so my vacuum is around 18 but when it dips down to 900 the car sounds like its gonna stall out running hella bad and the vacuum goes to around 10

Im having the same problem on my sr20de that is. My idle starts to lope around but when i give it throttle it sits nice. My MAF was messed up too so i regrounded it and now the throttle is fine but the idle is still off alittle and sounds like its coming to a stall but doesnt. My intake manifold sounds extremely loud (sucking noise) this could be a leak. I havent checked