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Unstable idle, car almost stalling at low speeds, need help

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Old Jan 12, 2009, 08:12 PM
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I attempted to work on the areas as I described above. When I raised the baseline timing to 8* the load devreased by about 10 at idle. The crazy thing is though, my LTFT and STFT are all screwy again. I don't get it. The car still was hunting at a rolling stop. It goes way rich 10.2 and tries to stall with the RPM going into the 500s.

I retuned it back to near stock and the fuel trims are still all messed up. GRRRR just when I thought I had them perfect.
Old Mar 25, 2009, 11:14 PM
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I haven't driven the car for a while. A week ago or so I removed my AEM intake and put stock rubber piece on. The problem is 90% gone so far. Once in a while if the car is cold RPM will drop while turning the steering wheel or turning on the heat. Dont know whats up with that now, but at least doesnt stall anymore.
Old Mar 27, 2009, 07:02 AM
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The main issue with hard intake pipes is they screw up the engine idle MAF Hz value. This in turn does not allow the LTFT low to adjust accordingly, thus, problems with idle.

So the fix is to get your MAF to read below 40Hz in order to get the LTFT low to adjust. This is accomplished by smoothing the air flow after the MAF. Any hard pipe that is larger or has bends right after the MAF cause the major MAF Hz reading. I found that by putting a 3" rubber coupler on the MAF outlet side will smooth the flow enough to get the Hz value to idle at around 35Hz. Thus, the LTFT low will adjust and voila....no more stalling.
Old Mar 28, 2009, 09:11 AM
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I was having the same problem when i got new injectors and tuned i was running a gt30r set up with 780cc and while tunning the same thing was going it would almost stall and regain itself... it could be a number of things on why the idle is acting up like for one alot of time after market B.O.V. might be the problem also, if u have any leaks in ur exhaust...
mmm...and if not that, you also have an idle adjuster on the throttle body that you could mess around with...all u need is a small phillips screw driver....and u could higher the idle or lower it ....
Old Mar 29, 2009, 07:21 AM
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that screw is supposed to be set at 850 rpm when SAS mode is activated in EvoScan. To adjust idle, adjust the tune, and possibly ISCV steps. The problem is either at the MAF (fixed by scaling, smoothing, or different intake setup) or a faulty ISCV.
Old Apr 6, 2009, 03:00 PM
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Im having a similar problem, when the car idles in neutral its fine and it drives fine when in gear, but when I press the clutch in the idle drops to 500 RPMs or less and sometimes the car dies. Im pulling my hair out to find info on what could be wrong.
Old Apr 14, 2009, 08:28 PM
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i drive a subaru wrx 06 but i just bought a evo 8 but there is a problem i switched out the stock turbo. dropped in a stage 3 and hks ssq blow off valve. rebuilt the engine. bigger cams and everything. but the engine makes a spitting sound a about 6k rpms when am full throttle. i checked for boost leak , faults spark plugs n everything. i need help fast plz.
Old Jun 7, 2010, 06:42 PM
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so to re-activate this: touringbubble tried almost everything (it was my car he was fixing, for which i am eternally grateful) including swapping MAFs with his car (his idles fine), but the problem, while diminished, persisted. in fact, i had my evo tuned three times now by chris black (AMS in Chicago), switched back to stock rubbber, different (cone) filter and coupler.

all i get is BAD, unstable idle, overcompenstates to 2200 on occasion, but does not die anymore. it was so bad the powersteering would cut out in parking lots, i had a few scary moments trying to avoid grandma in her buick....

since i am unwilling to part with cossie m3 grind, the "solution" is to throw a TON more money on the problem and go to speed density, new intake piping, aem ems, methanol and start de novo.

i will report the results (august), but since my approach is rather radical i am not sure if i can contribute much. in the meantime i think it would be of value for y'all to post if any definitive solutions have been found for the many cars affected thus far...

pk
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