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Thread: aac valve causing bogging

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Posts: 11-20 of 20
2008-07-07 03:39:03
hell yeah that is, all the motors ive had in my car with my s4's at 750 lopey rpms im only pulling like 11 hg according to the guage. all my motors have been that way, at 1000 rpms im up at around 16-17, under decel i go up to around 25 hg so i know all the motor is fine. but yeah if you have cams and are pulling 20 hg at idle depending on what the idle is that is alot. My buddies t25 setup on his jdm he with stock cams pulls 19-20 hg at idle but thats with stock cams again.
2008-07-07 23:31:59
well, i think i may have fond a good part of the problem, i am hesitent on what to do about it yet ,but

i was looking at m map sensor voltage and i was only getting .9xx less than 1 volt and i read the aem map sensor voltage specs and i should be getting 1.64 volts with acc on and engine off, i went into the engine compartmnt and squeezed the clam where the map is tapped into the tps, and the volts jumped up to 1.64 volts and and the map psi started readng right. i tried driving the car and it actually was running better i could actually get it in 1st and take off without it falling on its face.

i think that the map sensors positive feed isnt vey strong, i mean its seing voltage but its not clamped on there really tight... i was tihnkng of cutting the line alltogether and sliceing the tps an voltage volt together for a solid line, insteadof one of those tapping plastic sources that dont actually cut the line just taps into it.

this could be alot of my problem ALTHO i am not 1005 aout that, but the map sensor not getting correct voltage will definitly mess things up, obviously lol

did also get my tps sensor to adjt to .43 which is better and coser to stock than prvious .47v

what do you guys think?
2008-07-08 04:10:06
I think for your setup you should keep that TPS from seeing too much over 4.15V. When my computer saw over that amount the car would pull timing. The car would be faster at part throttle than at full throttle. I adjusted the TPS and the problem is solved.

Def fix the map sensor problem though. I really really hope it works out for you.
2008-07-08 08:41:10
yeah i would never trust those clamp things, pieces of crap, just splice it and be done. Guarantee that will solve probably all your problems, Those dont get good connections worth the crap and i will never use them on any of my wiring, always tap and splice using butt connectors in the bay and solder in the cab. Solder tends to not like heat very much so i wont use it in the bay. Nicely crimped and proper size butt connectors work well and always have.
2008-07-08 19:53:55
i think that fixed my problem, i have yet to actually completely cut into the tps power to splice in the mp sensor power, HOWEVER i took off the clamp, and i cut back the wire some more, from the looks of it, the clamp was BARELY tapping into the tps wire for the map sensor, obivously it was tapping in some, but not a 100% power connection, hence the .9v with the clamp on it before and now i am seeing the correct voltage 1.64 with acc on and engine off.

i am still seeing a slight hesitation ALTHO i am running some fouled spark plugs in the engine now as the getting this problem fixed ouled yet another set of bkr7e's

BUT i was actualy able to drive the car and go into boost, well small ammount of boost but was able to go into boost (i just drive it around the parking lot to see how it felt so you really cant go full on into 17psi in a parking lot lol. but the car did;nt die, ;fall on its face, had the slight hesitation, but it seems pretty solid.

i think once i really tap into the wire all will be well, i also got a new aac valve so i will have to install it an see how the idle goes

i am stil getting the slight bog, nothing like before, but when i FIRST start the car, the engine revsup completely fine, no bogs or hesitation, then about 3 mins later i get the sligh bog not sure if thats becuase my tps is set to .43 or what, i will have to get a multimeter and see how that gos i would be able to adjust it better with a multimeter than rely on my laptop and look at the screen then adjust ect.

and to address the -20ing i have 1500rpm idle, and the asc valve onit now is shot, so adjusting the idleisnt possible, that is probly the eason for the higher inhg with a cammed motor
2008-07-09 01:26:36
i deided the onlyway to full know eather or not that was the problem was to actully drive the thing full on (today i renewed my plate as they expired becuase the car wasnt running ect) so i put some gas in it and drove it 100miles lol, i didnt purpsly drive that far i got ****ing lost at irst i was all like wow ts not drivin half bad, then i got really far out on the highway and was like, this problem coud rear its ugly head and i would be ****ed lol. it actually did start driving like **** again and i poped the hood and the ****ing map sensor wire was loose again, i clamped it down harder and the hesitation and weird issues went away...the 15.00 atometer boost gauge i bought from a local guy is ****, t doesnt work, and my grddy type swas opening up during boost, mind you i didnt take it past 5000rpm and i hadthe greddy opening during boost (not pusposely but i forogt to adjust it) but that ****r was flying....i definitly need new sparkplugs beucase it is still having a hard start/missing and i knowthe spark plugs are bad so i need to invest in some new ones.

basicl what i gathered from the ride is

A: my clutch cable is streched out from the stage 4 clutch
B:m clutch cable needs adjusting
C:spark plugs are fouled
D:has missing and hard start could be from C (most likely)
E:boost gauge is junk (good thing i was justusing that as a temp i have a greddy BG)
F:greddy types needs major adjusting so its not letting out metered air

G: car is majorly fast and i didnt even mearly hit 5k and i definitly didnt hit full boost so its just making methat much more eager to get this on the roll
2008-07-09 01:48:54
what you mean you clamped the map sensor wire down more?

you have GOT to properly setup your idle tables, there are many.

There is no metered air with a MAP sensor so the greddy type S can leak at idle slightly

you need to spend a lot of time in the aem forums and dig into many different cases similar to yours and make adjustments

2008-07-09 01:50:43
Originally Posted by GT2871RBLUBIRD
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!

This doesn't apply to you, we don't measure this like stock ECU does man. You can't take what they say about the stock ECU and apply it to your standalone EMS. The TPS reads 0-100% and you use the configure option in the EMS software to set the range. read the manual on how to do that.

2008-07-10 00:45:54
i adjuste my clutch cable, i thik its still pretty shot but it was a little better

i put in the newer aac valve and it seems like its making a bit mor of a difference as when i adjust the screw the idle moves i need to set my idle now.

i also adjusted my throttle cable it was a bit loose

the car runs really good now, hits boost full on, i put in my hks sqv as my greddy type s is a PITA and i think it going to be sold here soon lol, i wasnt getting any hesitation, runs really good

the new problem i am having which i tihnk is minor, but when i go to start my car it cranks then acts like it wants to start then it doenst and just keeps cranking, i have to give it gas a few times for it to start. i pulled the NEW spark plugs and they are already blackish.

my fuel setup is as follows:
stock fpr (my nismo took a **** and wouldnt adjust anymore)
msd 72lb injectors
walbro 255lph fuel pump
JWT fuel rail
fuel pressure gauge

I AM seeing STOCK fuel presure with acc on and engine off. and am seeing around 38psi with the engine on...do you think that the fuel pump is too much for the stock fpr? tested the fpr, i am seeing a tad over 3bar with the vacuum line off, i pinched the reurn line and the fuel pressure jumped, so the fpr and the fuel pump are in good working order.

what could be the deal? i have pulled the fuel injecors numerous times to see if they are leakin they arent

any thoughts?

i am really making great progress i think with my car, i just need to get that staring issue fixed..i tested the coil its good, pulled all the spark plu wires with engine on, and getting good park, seeing good fp with engine off seeing good fpr with engine on, ect

i also have my spark plugs gapped to .28
2008-07-10 19:59:21
i think i chased down YET ANOTHER BUG. i believe my coolan temp sensor is bad, i went intomy aem ems and the coolant temp sensor is reading below the normal voltages for nmal operation temps, i started the car and it was aready reading 180 degrees and thats not right, also the coolant temp needle didnt move on my cluster andi know it should have moved with a 180 degree reading...i also ooked at my timing and i see that my car pulled the timing down.

this cold be the cause of my car not starting right away and cranking and causing my plugs to fail becuase th temp snesor sening the wrong voltages and making the ems haver unproper fuel trims for starting

i wonder how the coolant temp sensor could have gone bad that fast tho? i have correct coolant level, the sensor isnt thatold at all its maybe 100 iles old? i did buy it at autozone?not the best?
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