Welcome to the SR20 Community Forum - The Dash.
Register
SR20 forum logo

Thread: aac valve causing bogging

+ Reply To Thread
Posts: 1-10 of 20
2008-07-06 00:54:57
#1
aac valve causing bogging
when i start my car and try to rev it, the rev bogs and drops rpm, but when i re it slowly the rpms go up smoothe could this be the idle air control motor?
2008-07-06 21:29:13
#2
no, here try this. Unplug the iacv. Then start the car with just a lil throttle (it won't start otherwise) and see if you have the same problem. Double check for any vacuum leaks and check tps voltage to see if there are bad spots in the signal.
2008-07-06 23:03:56
#3
im having a weird problem that im really having difficulty solving, first my problem was a partial throttle acceleration studder, i tried setting the tps to .38 closed and 4.03wot, helped but still didnt solve it, so i was also having bad cold start studder and hesitation/flooding causing the hesitation. So i remembered i hadnt switched my jdm coolant sensor to my new usdm one when i swapped the motor, i didnt think that had much affect, but i switched it and set my tps voltage to .45 closed 4.16 wot, partial throttle hesitation gone. Nice and smooth,

Now my main problem, This only occurs in 1st gear. My setup is as follows.

Calum basic ECU 370's 4bar, Z32 maf in blow through setup. Now here is the thing, ever other gear is perfect, 2nd just burns the tires like crazy, 3rd gear spins the tires till 70-75, 4th and 5th are smooth, all gears accelerate smooth with no hesitation, no bogging, no misfire, no detonation. Im running 12psi of boost but the initial spike is around 19psi. T25 setup, i know i know poor t25, but ive been running this setup for a while, this just started to occur a couple weeks ago.

No matter what i do in 1st gear when i punch it, it starts to want to just burn the tires then it just cuts out, to the point where it almost feels as though the engine shut off then kicks back on bucking and misfiring through 1st but bam hit second and the tires go up in smoke it will pound off the rev limiter with no problems and go hard. Its only f'n first gear. What the Hell.......Im almost thinking maybe a maf problem. im gonna redo the ground for it and also run a grounding wire from the battery to the intake manifold where i have all the other grounds including my MAF ground. But its weird as hell. I cant lauch the car from a stop because once load is put on the motor and it starts to make boost it cuts out, bucks, hesitates to the point it feels like the motor shuts off, then it kicks back on and goes being the car is still in gear. Any ideas. Weird problems popping up lately, Oh and ive been running the Calum Ecu for a while with no problems, this just started a couple weeks ago out of the blue. I dont have any boost leaks so dont ask, im smarter than that, all couplers are good. Unless my MAF has just all of a sudden busted a huge boost leak somewhere going up through the sensor. but i doubt it because i would think it would affect all the gears not just one.

I know it must be fustrating for you to because you just got your car tuned like crazy it was running like a champ then you started having all these bogging and hesitation issues one right after the other. Cant figure this out.
2008-07-06 23:22:05
#4
well my car is just transending through prolem after problem and no letting up. i just got a newer aac valve replaced it and now it ides WORSE than before! now it idles at 3k rpm instead of 1500rpm

ive replaced:
distributor cap
rotor button
fuel presure regulator
aac valve
spark plugs
coolant temp sensor

iv checked:
fuel pressure getting stock fuel pressure at acc on and engine off and stock fuel press wih engine on.
the engine idles fine
i pinched the return line and my fuel pressure jumped so i assume my fpr and fuel pump are fine
i hold fuel pressure with engine on and with engine off it drops off after a while but holds non the less

ive checked the tps sensor, lowest i can get it is .55 otherwise the tps doesnt jump in volts or anything like that

when i put it into gear and let out on the clutch the car just falls straight on its face it makes no sense, i have checked everything, and EVERYTHING checks out, i dont know what its deal is, when its at idle and i try to rev it, it bogs, but if i let it rev up SLOWLY it goes up fine, whe i try to rev it up fast, it just cuts out, and bogs and all that.

im beyond MAD, i have done more and more and more with no recourse of it running better, i mean i has came a long way from not starting without gas, and running really rich, and all that **** and missing....but there is just something else that isnt right thts why its running like this but i cannot figure it out
2008-07-06 23:28:12
#5
i had that same problem before i finally fixed it with the correct tps voltage. The slow reving would be fine but full throttle rev it would sputter then rev up quick, it would fall on its face though so in a way its not the same thing. I have no clue about the 1st gear crap. haha
2008-07-06 23:37:30
#6
well i havetried to set the tps however, the lowest i can get it to go is .55 insead of the .44.... i dont see how it idles so well, but then when you go to drive it, it just straight stops it makes me so mad, i have SOOOOO much money invested in this car, and have only driven it about 5 miles with it ACTUALLY running correctly!
2008-07-06 23:39:59
#7
and im gettng -20in hg on my boost gauge too, that is the confusing part, its not likei am seeing weak vacuum i am seeing better than average negative vacumm, i just dont it.

ive checked the following sensors and configurations on my aem ems
tps
map
fuel injector pulse
intake air temp
timing degrees

ive pulled the fuel injectors and rail off and checked for leaking fuel injectors with the acc off, ive checked the injectors with stock pressure on, and no leaks.. i am pretty certain that the injectors are fine, the acc on pulse, pulse looks fine, with the engine on the fuel pulse looks fine,

i mean i am getting to the nitty grityy considering the aem ems lets me look at and configure EVERYTHNG on the engine, and ihave replaced and checked and reconfigured anything that needed replacing or configurng and i STILL havent gotten the problem
2008-07-07 00:33:47
#8
hmm, i wonder if a tps could be bad but not give bad readings? i because i put the old aac valve on and it was idling lower, and i moved the tps around and it wasnt really making a big difference in the way the ar was idling, altho when i moved the tps where i thought it was at the lowest possible voltage at idle, the car was actually able to drive SOMEWHAT, itwas really bad, but it was actually driving ok, unlike before??

i lso unplugged it and it didnt really make a difference in the way the car idled i donno
2008-07-07 01:49:15
#9
or maybe something in the wires, unplug it and check the pins and make sure all your wires are good and tight, give them a little tug and make sure none of them break. Thats a spot where there can be quite a bit of movement on the wiring causing some of them to eventually break inside the insulator had a buddies car that acted was the same thing. found the tps signal wire was almost broken.
2008-07-07 03:35:12
#10
Maybe the maf took a dump. IT is def an a/f problem. are you hitting -20 vac at idle? cause if you are and you have cams then you have way too much vacuum.
+ Reply To Thread
  • [Type to search users.]
  • Quick Reply
    Thread Information
    There are currently ? users browsing this thread. (? members & ? guests)
    StubUserName

    Back to top