ok..so its been 4 months now that ive had my HS turbo setup.. heres what i got running. Full HS turbo kit, 370cc injectors 240sx maf, nismo fpr at stock spec, idle, timing.. all set to stock values. i have a techtom cmx100 hooked up.. at idle. my duty cycle says 1.2, my maf voltage is about 1.2. water temp is about 180. vacuum reads about 18 .. sometimes 20 on really cold days. fuel pressure is set as per the service manual.
now heres the problem.. this has been happening more often now then before.. sometimes it happens first thing in the morning.. sometimes after sitting for a few hours.. and sometimes after driving around for awhile.. there is no set time for occurence. the car begins to idle erraticly.. coming down almost till it dies then comes back up. a/f gauge reads Rich, maf voltage hits about 2.5 and there is a distinct smell.. not like fuel though..but its a sharp smell.. if you try to drive the vehicle.. it sputters, bucks .. but once boost hits.. it seems to die down ... untill you come to a stop. and starts over... this will persist for a few min... if left to idle.. it will out of no where.. begin to idle out .. and idles back to normal. and it may not happen again for a week.. or it could happen again that night.. there is no consistency. nothing that i know that triggers it. its annoying. i do however feel that the car is not as fast as it was one the install was completed. i went to make an appointment for my dyno run. (jan 16 woo hoo) my friend asked the tech and he said that my ecu is no good. and stated that his tt 300zx won't idle. now i can understand that if my car won't idle at all..but the car runs perfectly..it idles fine when its being good. i am out of ideas. is it possible that the ecu is bad? what about maf? i just getting to the point where this is more of a pain in the ass rather then a fun car to drive. any help id appreciate it.. or if you want some more info. i can say thatmy friend had my car today doin a constant speed of 80.vaccuum was at 10, a/f v was about 3.10 duty cycle said 32.0.. and it began to show some syptoms...then stopped and the car was spinning tires with no problem.
please help
If it is doing this at idle does the vacuum change? Also how do the plugs look? Does it seem like it is running really rich when it does this?
ECU is fine, ignore your friend....
yes.. when the idle becomes erratic the rpms dropped and the vaccum drops or goes closer to 0. during that period. i just changed my plugs. they looked fine.. had normal carbon diposits on them .. did smell like fuel. there was a grayish hint to the top of the plugs.. all 4 looked the same.. all plugs were replaced.. and gapped at ~0.025.. when the car does act up.. yes it does seem to be running rich.. duty cycle does increase, maf v increases to about 2.5 - (service manual says it should be between 1.0 and 1.7) my a/f gauge is in teh green which means rich...like i said.. it happens at different points.. never under the same conditions. thats why its confusing. it happend today when i first started teh car.. it happend last week after driving around for an hour. during acceleration it bucks ans sputters. the car sounds like its choking...but if you reall slam on the gas.. it sputters, boost comes on and it takes off.. but if ou stop and let it idle it'll go back to the rough idle for a few min.. and then with no warning or adjustments.. it'll just idule back to normal and run perfect again. i dunno what else it could be.. tehre are no engin codes i keep checking for that. i know it was the ecu.. i mean if it did it all the time or constantly i would worry about the ecu.. but it doesn't sometimes it can go for a week with no problems. i just don't know where to begin to diagnose the problem now since i added the nismo fpr
i also forgot to add one thing.. this happened about a month ago..and has happened only once but while idling the car was leaking gasoline from teh gas cap.when i shut the car off.. and opened the cap.. gas spewed out..it eventually stopped.. and hasn't done that again since.
How is your fuel pump and which one are you using? I would pull it out and inspect it. It sounds like a fuel pressure issue.
im guessing its fine i mean you can hear it when the car starts. i got the walboro 255lp one as per ur recommendation. i just installed the fpr from nismo.. so i know that my fuel pressure is ok.. i haven't seen the pressure yet when it acts up though. i'll have to do that next time it happens.
is there a possiblitity that i could have a boost or leak somewhere after the maf . i have check evertying else.. except do a pressure test on the piping.
as for the fuel pump..wouldn't it happen more often if it was that. its like the ecu.. they tech where its goin to get dynoed didn't touch my car he just said it sounded like the ecu. but if that was the case.. i would be able to know at exactly what psi or what speed or u nder certain conditions it would cause the idel to become erratic. but i don't. theres on consistency. it has happened at so many different times theres no info i can go by. it can happen first start in the morning.. or just idling at a light. or after a hard run. or normal driving conditions.
my next step was to go with the cobra maf, 50lb injectors and new fuel rail to be safe and not having to worry about maxing out maf. but i can't if i don't find out myissue im having
when last did you change your PCV valve? I had very similar problems and changing the PCV valve solved this issue. Also check all of your EGR plumbing...
__________________ Silver '96 200SX SE: fresh '98 GA16, I/H/E, JWT Turbo Clutch & Flywheel, Motor Mounts, Prokits & GR-2s, 11" FastBrakes, 18" OZ Cronos Parts sitting in the closet: Hotshot GT28RS turbo kit, 3" SS Exhaust, JWT ECU, S14 MAF .... I'm hungry can I bum a couple $?
when last did you change your PCV valve? I had very similar problems and changing the PCV valve solved this issue. Also check all of your EGR plumbing...
honestly i think i changed the pcv valve when i installed the kit.. igave my car a full tune up.. as for the egr from what i could see it looked fine.
to be honest.. id like to remove that dam egr completely. is there away to remove the egr completely without harming the motor?
ive noticed in some pics that my bov is installed reversed.....yet it still works.. is that ok?.. could an incorrectly installed bov cause problems to my car. would it even make a sound if installed wrong?
ive noticed in some pics that my bov is installed reversed.....yet it still works.. is that ok?.. could an incorrectly installed bov cause problems to my car. would it even make a sound if installed wrong?
The bosch BOV will work both ways, although I would flip it around.
What exact fuel pressure are you running with and without vacuum?
When this issue occours does the coolant temp. fluctuate?
You can remove the EGR completely without harming the motor. The only issue is that you will throw a CEL. JWT can try a resistor trick on your ECU which should keep the CEL from coming on because of the EGR. I have this done and it has worked perfect on my car. I removed the EGR completely, I didn't just block it off.
The bosch BOV will work both ways, although I would flip it around.
What exact fuel pressure are you running with and without vacuum?
When this issue occours does the coolant temp. fluctuate?
You can remove the EGR completely without harming the motor. The only issue is that you will throw a CEL. JWT can try a resistor trick on your ECU which should keep the CEL from coming on because of the EGR. I have this done and it has worked perfect on my car. I removed the EGR completely, I didn't just block it off.
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i have the turbo xs bov that recirculates. my fuel pressure at idle without vaccum is 43...with vaccum its about 36.
i haven't checked the coolant temp. but i'll make sure to check that out next time it occurs. my concern is also the smell that comes from the car.. i can't describe the smell.. its pretty sharp though.. not like fuel..though
The bosch BOV will work both ways, although I would flip it around.
What exact fuel pressure are you running with and without vacuum?
When this issue occours does the coolant temp. fluctuate?
You can remove the EGR completely without harming the motor. The only issue is that you will throw a CEL. JWT can try a resistor trick on your ECU which should keep the CEL from coming on because of the EGR. I have this done and it has worked perfect on my car. I removed the EGR completely, I didn't just block it off.
as an update i checked the coolant temp when it acted up tongith and coolant temp stayed normal.. it was about 177 when driving and when it was sputtering at idle it was about 184 which is normal for my car so i have seen.
I asume you already checked/cleaned all ecu/engine related electric connectors...
no i have not.. today i i replaced my plug wires.. i had some cheapo replacements on there. i checked compression.. compression was ok that was a concern of mine. fuel pressure is still perfect as per service manual. cleaned the iacv. tps checked out ok.
now.. what i find to be intersting is this...at idle i'll see the a/f hit green meaning rich.. that gives me a heads up that its about to occur.. it will stay there for a min and the car will begin to bog down.. rpm doesn't rise hirght. it starts to sputter like it wants to die. there is a smell like ive said before.. now what i don't understand is this.. if maf uses a hot wire and as the air coming in. cools this down.. in wich it uses this difference in temp in the form of a voltage for the ecu to determine what the width of the pulse of the injector should be.. then why at idle while th rpms ar dropping .. the maf voltage fluctuates from 1.7 to as hight as 2.5. that would indicate that more air was coming in. or it THINKS air is coming in. so my next question.. could the maf be damaged..fuel pressure doesn't fluctuate thought when this occurs.. it stays at about 36psi.. and thats in the threshold of 32-38 as my haynes manual says with vaccum attached. now im trying to figure out if there is some defect wit the maf or somehow if theres an electrical issue giving the ecu this hight maf voltage.
sorry for the long post lol. but ive been reading up in the haynes manual
should i try replacing the maf and its electrical connector? if so..where can i get it cuase its like over 200 bucks for just the maf
Have you figured this issue out yet? Are you saying
Quote:
the maf voltage fluctuates from 1.7 to as hight as 2.5
at idle?
My MAF voltage is around 1.3 at idle, if yours hits 2.5 I'd say that's definately the problem.
Fuel pressure should differ depending on vacuum/boost level. It should increase about .5 PSI per -1 in/hg or 1 PSI per pound of boost (1in/hg is equal to about .5 PSI). So at idle your fuel pressure should be constant, as vacuum should be constant.
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2008 BMW 135i
96 Sentra GXE
Boost is addictive
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Last edited by aminidab : Jan 21st, 2006 at 10:04 PM.
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