Subarutex Posted July 7, 2004 Share Posted July 7, 2004 OK... here is some background on the mods: Custom fuel system/fuel rails/regulator = 34psi Delta cams 670 ones Spider intake WRX Turbo WRX IC/BOV to atmo. Apexi SAFC to help with tuning Ok, here is the problem. On cold start up, the car doesn't like to idle. It will kind of idle, then sputter out. Even when it is running in an idle state... the rpm's are all over the board. Between 0 and 1200rpm. Usually sits at 1000, then lugs down and quits. I'm not sure if it dies because of too much fuel, or too much air. However, its not uncommon for the engine to flood if I try to restart it after it dies like this. So... how should I go about fixing this? Timing is set at 25deg. It just screams otherwise except for idling. Should I back off the timing a bit? Turn the fuel pressure down? The SAFC is zero'd out for now. Just trying to get the idle down before i do precise tuning. Let me know your thoughts, ideas, suggestions. I need to get this sorted out so I can start turning up the boost. I'm at 7psi now, i'd like to run 15psi... Quote Link to comment Share on other sites More sharing options...
All_talk Posted July 7, 2004 Share Posted July 7, 2004 WRX IC/BOV to atmo. Though I dont have direct experience with them (yet), its my understanding that BOVs venting to atmosphere will cause idle problems with systems that use MAF sensors. The BOV opens on low manifold pressure and some cars are low enough at idle to open or partly open it. When this happens you loose some metered air and the fuel ratio go rich. Temporally plug or disconnect the BOV and see if it makes a difference. Gary Quote Link to comment Share on other sites More sharing options...
archemitis Posted July 7, 2004 Share Posted July 7, 2004 ya, thats like a bigass vac leak right? unless you have a map sensor. could it be a combo of the high pressure regulator, and a vac leak from the bov. what type maf? flapper or hotwire? Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 7, 2004 Author Share Posted July 7, 2004 I'll check the BOV. Although, I ran the previous engine with no problems with the BOV vented to atmoshpere... Could be the combo of that and the cams yeilding less vaccum at idle. Good thoughts. Keep em coming! Quote Link to comment Share on other sites More sharing options...
archemitis Posted July 7, 2004 Share Posted July 7, 2004 ya muscle car guys have alot of problems idling with big rump roast cams, and they usually bump the compression to help, idle and low end. this boosted eclipse my cousin had, idled reely crappy and ran rich as hell, but when he floored it, idle didnt mean crap. if its the same disty as mine, vac opperated, with a flapper air meter, it could be your distributor causin problems too... maybe Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 7, 2004 Author Share Posted July 7, 2004 Mine is hotwire maf car. Yeah, i'm not looking for a purring idle... i just want a steady idle i can count on not dying at lights. Quote Link to comment Share on other sites More sharing options...
archemitis Posted July 8, 2004 Share Posted July 8, 2004 another thought, morganm, just had some problems with idling, and staling, and it tourned out to be his alternator/regulator. his dash lights also did funny stuff tho. does your air fuel guage, go all the way to the rich, or even off the scale at idle? i had a bad disty and it made my rpms go up and down, 500- 1200 sometimes could just be big cams and low compression. maybe thats where the ajdustable cam gears comes in. anybody with exp. out there!? sounds like it must awesome at stock boost even. how does the blowoff sound Quote Link to comment Share on other sites More sharing options...
garner Posted July 8, 2004 Share Posted July 8, 2004 ya muscle car guys have alot of problems idling with big rump roast cams, and they usually bump the compression to help, idle and low end. Yeah, what about the cams? I understand that a low idle (800 rpm or so) is not possible with Delta cams but what kind of idle speed are people getting? I have sort of the same issue. My brat runs now (Whoo Hooo!) but at cold start up, it won't idle. Once warm, I can just turn the key, no foot on the loud pedal and bang, starts just like my Impreza. Do you have a A/F guage installed in that bad boy? I'd be interested to see what kind of mixture it shows cold and hot. Mine dances all over the place in cold starts then settles in to the rich side of stoich. Any obscure messages from the ECU? garner Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 8, 2004 Author Share Posted July 8, 2004 Well... I'm shooting for 1000rpm for my idle. Even that high it lopes a touch (when i can get it to idle) I have an a/f guage. However, since it reads off the 02, that has to be hot to read accurate, it doesn't say a whole lot. In fact, the readings are pretty stoic till i rev it. But, i don't have a traditional guage, i have a digital readout. It gives me the theoretical value computed from the input voltages it gets. So... when you guys say stoic... thats 14.7 to me. Full rich is something like 10, and full lean is like 20. Once warmed up, i usually read 14.7 at idle. Non-boost i usually see 14.1. Under boost I get anywhere from 12.5 to 14.1. Depending on weather usually I guess. Its almost time to invest in a wideband o2. Quote Link to comment Share on other sites More sharing options...
garner Posted July 8, 2004 Share Posted July 8, 2004 I have an a/f guage. However, since it reads off the 02, that has to be hot to read accurate, it doesn't say a whole lot. Doohh, good point, I forgot about that little detail garner Quote Link to comment Share on other sites More sharing options...
WJM Posted July 8, 2004 Share Posted July 8, 2004 I had the SAME issue on my RX with the cams and a Gen 1 Mitsu BOV venting to the atmosphere.....i did not had quite the mods you had, but still...i know. My GL-10 has it venting now cuz i have not re plumbed it since the plumbed up intake pipe broke.... Anyhow, with the BOV on my 1986, the flapper door...it will idle surge...after running some time, say after running at speed and the computer seeming to "get used to" the BOV...it will settle into a somewhat stable idle. I used ot ahve it set at 1000...it usually settles around 850-900. However...I got really tired of the surging idle, cuz otherwise the car was great. and I wanted to disable the BOV at speed...say 3600 RPMs crusing on the I state....the manifold is at vac, while the turbo to Throttle body is under presure...that means the BOV is open, creaing a VERY rich condition, a high BOV whistle sound, and power loss, and NO MPGs. So my solution was 10 ft of vac line, and a plastic small engine fuel shut of valve from NAPA. I route two lines to the cock pit, and plumbed to valve in. So...from the manifold, to the cokcpit and valve...valve is either on or off....then the line goes to the BOV. Upon start up...off...smooth idle. Upon street driving or low speed stuff, valve on...highway crusing or long idling (autocross grid, traffic, pakring lot, warm up...etc...) valve off. Under boost it will leak on the highway...so i just elt 8 lbs of boost get into the line, by opeing the valve and it shuts and stay shut. The valve is not air tight completely, so if the BOV line is at atmos. pressure, or more...and the manifold is at vac for a long time....like 15 inches or more.....or is it less since its vac??....the pressure will very slowly bleed out...so i have to "reset" it every once in a while. But ive never had that issue at idle when the bov line was at amos/boost and the manifold line was at idle vac. Anyhow, on the RX....is woudl idle surge really bad...so i just maxed out the idle adjuster screw in the throttle body. idle didnt matter as long as it stayed running. i was just experimenting. The cams and BOV venting did make some drivabiliy issue...idle and some odd situations of severe bucking under certin loads....but all i cared for was under boost, and it was...well....GREAT!! This was a MAF'ed RX....an 89 to be exact... Long story short.....woops too late!!....do what I did with the BOV and see how that works. About the cams...are those the 677-260 ones, the mild cam? or the other profile thats way bigger, and pretty much a race only cam? I know there are two...and I got the 677-260, and mild one. Quote Link to comment Share on other sites More sharing options...
gravelRX Posted July 8, 2004 Share Posted July 8, 2004 Tex, Do you have the Autometer gauge? Mine sits at stoic until it gets warm also. I've got the 260 grind and idle is around 900-1000. It has a chunky, lopey, nervous idle. Took me quite a while to get the idle somewhat square with my car. The FSM says to set the timing at 700. Hell, mine won't idle at 700. What's a guy to do? I ended up timing mine by ear and then checking it with the light. It reads around 29-30 but that's at 900-1000. What does your boost/vac. gauge read at lower RPM? Garner, Just to add and get a comparison my a/f gauge once it gets hot, is constantly searching the lower lean to mid rich. If I get into the boost it reads rich, but doesn't go full rich. Coming down the mountain with my foot off the gas I can get the lights to go completely out to the lean side. Sorry I'm not more help Tex. Jay Are we discussing the same gauges? Quote Link to comment Share on other sites More sharing options...
WJM Posted July 8, 2004 Share Posted July 8, 2004 Oh, on timing: My dizzy was...believe it or not...MAXED out...andit ran great with no detonation on 93 pump gas. i never used a timing light, so i dont know for sure what it was....i stopped using a timing light a long time ago on this engine...i just know where to set it somehow... Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 8, 2004 Author Share Posted July 8, 2004 The trick is... it used to idle. Not very well, but better than it does now. Perhaps it needs more timing. I messed around with the BOV. Didn't really make a difference in the idling. RIght now the neg. terminal is off the battery to reset the computer. I'll go back out in a bit and mess with it. I'm going to try playing with timing... idle screw, and looking for inconspicious hidden vac. leaks, probally in reverse order. I have an Apexi Turbo Timer installed on my car. It has a function to act as a digitally numerical A/F gauge. SO thats what I use. Vac. gauge is between 10-15 at idle and low rpms. Quote Link to comment Share on other sites More sharing options...
WJM Posted July 8, 2004 Share Posted July 8, 2004 those vac numbers look the same as my RX did...so....must be up to the ECU then. Yes, try more timing....little bits at a time. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 8, 2004 Author Share Posted July 8, 2004 More timing? or less timing? I originally set the timing at 25 deg. My dizzy is maxed out at that. I spose I can pick it up and turn it a tooth. I guess what my question is... will more timing help idle? Quote Link to comment Share on other sites More sharing options...
WJM Posted July 8, 2004 Share Posted July 8, 2004 On a "sealed" engine....aka STOCK...running up the timing will increase idle speed. And I tihnk the crank sensor runs off the dizzy, so i dont know if the whole one tooth thing would work...ive never tried it tho. So...go for it! Yes, More timing....that is the answer LOL Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 8, 2004 Author Share Posted July 8, 2004 Well, last night I got it to idle pretty good. Although at about 1100rpm. Mostly by adjusting the idle screw. This morning however, it was hard to start. Took me three tries to get it to fire up. And then... it didn't want to idle for a couple of minutes. I dunno what its problem is... Quote Link to comment Share on other sites More sharing options...
calebz Posted July 8, 2004 Share Posted July 8, 2004 On a stock Turbo motor(non spider) theres the Aux Air valve that kicks up the RPM for cold idle.. and the fast idle thingy for when the AC is on.. (which is basically a controller vaccum leak I believe).. I don't know how that stuff may or may not apply to your modded motor, but just trying to throw some stuff out there to think about. Quote Link to comment Share on other sites More sharing options...
garner Posted July 8, 2004 Share Posted July 8, 2004 On a stock Turbo motor(non spider) theres the Aux Air valve that kicks up the RPM for cold idle.. The Aux air valve is the do-dad that allows air to bypass the trottle body when the valve is open correct? My N/A spider has one, don't know about the rare turbo spider. The Aux air valve is supposed to help in cold start ups so it is worth looking into. Perhaps try disconecting the hose from the side of the intake to simulate the valve being in it's open possition? If it starts and idles well from a cold start, there's a good chance the Aux Air Valve is not opening when it should (cold starts). garner Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 8, 2004 Author Share Posted July 8, 2004 Well... that doodad (the AAV) has been removed from my car. And the nipple on the spider capped. I too have thought of this. Last night, i tried taking the cap off the nipple. Car died. Tried to rev it, car died. Then, i plugged the AAV in, but didn't hook it up, trying to see if it was opened or closed. Couldn't determine if it was open or closed. However, thinking back on it, my method of testing was wrong. Tonight I shall try hooking the AAV up to the intake, plugging it into the harness, and see if I can feel the vac. from the end thats supposed to be plumbed back into the plenum. When i got it to idle last night... its very possible the motor was warm, or close to.. thats why it worked. How cold does and engine have to be to be considered a cold engine? Quote Link to comment Share on other sites More sharing options...
garner Posted July 8, 2004 Share Posted July 8, 2004 However, thinking back on it, my method of testing was wrong. Tonight I shall try hooking the AAV up to the intake, plugging it into the harness, and see if I can feel the vac. from the end thats supposed to be plumbed back into the plenum. When i got it to idle last night... its very possible the motor was warm, or close to.. thats why it worked. How cold does and engine have to be to be considered a cold engine? That would be a better way to test.... With the nipple on the spider open, perhaps that's too much of a vacuum leak... I don't actually no which way the valve works, perhaps it is normally open and in cold starts it closes to richen the mixture? That actually makes more sense. The problem with that theory is that you had the nipple on the spider plugged which would replicate the valve being closed and the mixture being rich... try your test and keep us posted. I would think that a cold start would be colder than a July day or evening in the PNW but I don't know what the engineers consider cold... garner Quote Link to comment Share on other sites More sharing options...
All_talk Posted July 8, 2004 Share Posted July 8, 2004 The cold start/Aux air valve doesn’t really affect mixture as it bypasses “metered” air after the MAF, its really like holding the throttle open a bit, the mixture enrichment for a cold engine comes from the water temp sensor. The Aux air valve works just like a electric choke with a bi-metal spring and heater element, the rotary valve is open when cold and closed when warm. I believe the valves mounting position on top of the thermostat housing is to stabilize the temp and perhaps to ensure eventual opening in the event a heater failure. Its been 50 to 60F at my house in the mornings and my RX starts on the aux air valve, but its not full open like it was in colder temps (start up idle speed is less). Gary Quote Link to comment Share on other sites More sharing options...
Subarutex Posted July 8, 2004 Author Share Posted July 8, 2004 Thanks Shadow. That was very informative. When it was removed, i was under the impression it was some sort of emission device that wasn't needed. So, i'll reinstall in the factory position. I'm guessing this can't suck air from atmo, it has to be metered air. So'll plumb it in somewhere between the MAF and the throttle body... not sure where exactly yet. Probally off my IC tubes somewhere. Quote Link to comment Share on other sites More sharing options...
88targarose Posted July 8, 2004 Share Posted July 8, 2004 If you've only got a narrowband gauge (since it's reading off a stock O2 sensor) it's nowhere near accurate. They're more eyecandy. Calling one accurate is like calling the french a dominating world power, it's just not correct. Quote Link to comment Share on other sites More sharing options...
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