Boosted_StinkyNuts

Hmmm were do I begin. Stats first: OBDIIA Y8, P06 converted to P28 and converted to 5speed w/ datalogging, Precission 440s, adjustable FPR(static psi 40), TBO3(.48/.52), Deltagate(7psi), yadda yadda yadda.... Im sure this is enough info so far. Anyways, Im still having the same ------- problem ive had for the past 2 months now and recently found a new lil quirk. Ive been getting idle surge like a **** at initial start up. 90% of the time when I start my car it jumps to 23XXXrpms and stays there for a few minutes then begins to move back and forth between 23XXX and 15XXX till car reaches optimal engine temps. After that, car runs sweet. Ive been thinking its the IACV Maybe My first Q is should I block it off and do I need to on a Y8. I thought this was only on Y7s? Is this the answer? Also, I recently hooked up the laptop to my ecu to see if I could maybe find the prob and huh, I noticed the TPS was reading funny? @ idle its reading 10% and sumtimes jumps to 12%? Could my TPS be fucked and do I just need to adjust it? I havent hooked up a multimeter yet but has anyone else had this prob? I even stays at 10% after the car is running @ nominal temps? I know for sure the ECU is fine Ive already tested it on 1 z6 and another Y8. Any answers thanx guys.

NCHATCH

TPS should definetley NOT be reading 10% at idle with the throttle closed, you may need to simply get a multimeter or voltmeter and reset the tps per the manual, its not hard to do, mine was off after i switched TBs and i had to re adjust it,

J-MAN

i have a y8 and am running crome on it. at first it was the same thing 23-2500 then down to 1500 then back and forth until it warmed up. somehow it fixxed its self for a little while but then it came back. i was looking through crome to see if there is anything that would make it run rich until it was warmed up but didn't see anything except this. think maybe the startup box migth have somehting to do with it but don't want to mess with it until i know for sure.

leed

In my experience with 450's (close enough to your 440's), the TPS enrich or Throttle tip-in (CROME) works out just right at around .45-.50. This is what I have observed via the WB. The other settings seem just fine where they are at.
As far as your idle is concerned, Id almost call that normal for an Uber bin, the high cold idle atleast. Uber p74/75 based bins activate high idle via the IACV. The 1500-2000 weirdness could potentially be large irregular a/f's as it sweeps through those cels. Just a guess.
Wouldnt hurt to set your tps with a voltmeter though. .5v at key-on, throttle closed. If your TPS has never been removed, 99% of time its perfect already.
Both CROME and Uber Dlog datalog slightly diff. TPS values relative to each other, and I wouldnt be supprised if it was ok. The condition you describe wouldnt normaly occur with a slight TPS mis adjustment.

good luck with it.
Dave

J-MAN

i will take the WB to it again once i get time and see if that will help the weird idle. what effect would it have on the cold idle if i was to change the "startup" box in the table above? would i need to retune the whole map or would it just effect the cold idle?

0b00st0

10% in Uber is fine. The calculation for the TPS percentage comes straight from the hex values. Its supposed to be 0.5V when the throttle is closed. So 0.5V / 5.0V = 10%. CROME makes the percentage from 0.5 = 0% and 4.9x = 100%.

As for the idle surging during warmup. Try disconnecting the purge solenoid. Uber overwrites some ---- and messes with that solenoid output.

Tom-Guy

Wrong. Well, not really, it's just that the stock 9-10 value in UD is not fine if you are ---- retentive like I am.

TPS based fuel cut in UD is at any TPS value smaller than 15. This leads to a nasty on/off throttle buck, which I sidestep by adjusting the TPS sensor. The bigger the injector, the worse the bucking tends to be. With 440/450, yours in noticeable, I'd guess.

Yup!

hebijake

sometimes there's a wic valve or something on the mani that sometimes causes prob's..

Tom-Guy

FITV. Fast Idle Thermo-Valve. It bypasses air when engine is cold to create the high cold idle, and is supposed to shut as the coolant warms up. If it doesn't because it is broken/coked up/comes unscrewed it keeps bypassing air once engine is warm and the TPS closed fuelcut goes into effect. Exact same thing as a big vacuum leak.

This is a different symptom, as the surging occurs once the engine is warm, and not as it is warming up like discussed previously in this thread.

J-MAN

and where would the FITV be on a Y8?