rb25det idle and timing issues

[platez808]

so i have an rb25det series 2 in my s13 hatch. i've been having issues trying to set my idle and thus having also having trouble trying to set the timing. Just to fill everyone in i guess i should post my mod list

rb25det sII
wiring done by myself
stock maf
stock cas
stock ecu
stock intake mani
stock turbo/turbo manifold
splitfire coilpacks
ngk iridiums gapped to .8
new ecu temp sender
replaced iacv using one pulled from sentra at the junkyard
avcr boost controller
safc II
new electronic boost/vac, oil pressure, water temp
wideband afr gauge
3in downpipe with qtp electronic cutout valve hooked up to stock exhaust

i've checked for vac/boost leaks and i'm pretty sure its all good. i boost consistently to 14psi and shes fun as hell to drive, but it sucks at idle.

keep in mind that i try to go by the instructions set in the FSM. so i let it heat up and the idle drops as it should. then i turn the car off, unplug the tps, then turn the car back on. Then i turn the screw on the iacv which does affect the idle to a certain degree. At the highest it will go from 1200rpm and will lower consistently to about 750. Then it wont go any lower for a few turns. Then at a certain point it just drops to the low 600s and high 500sand it idles erratically, going up and down repeatedly. So i would just set it to where it would stay kind of consistently at 750ish. I also set the timing so i would be right at stoich at idle (my timing gun was acting up) But when i would drive it around when i would put it in neutral the idle would drop dangerously low and then bounce back up if it doesnt die on me (it dies probably a 1/4 of the time.)

So now i tried going at it again and now when i unplug the tps it wont stay on at all. and this time around i can't get it anywhere near stoich (stays around low 12s to high 11s) at idle even when it's at 15degrees btdc at 750rpm

The tps and maf check out fine (i'm pretty sure) according to the voltages and the readings on my AVCR and SAFC2. like i said i replaced the ecu temp sender.

any suggestions? i was thinking maybe i need a brand new iacv but its a special order item here in hawaii and pretty damn expensive. lmk what you guys think. thanks ahead of time.

[Infinitiguy19]

Try cleaning the Idle Air Control Valve and the rest of the intake if your up for it. The IACV (Solenoid) doesn't really fail but the body of it does get dirty on the inside.

[Darius]

Try keeping the TPS plugged in. I can't set the timing with it unplugged or it surges up and down like you described.

[robbie2883]

Try keeping the TPS plugged in. I can't set the timing with it unplugged or it surges up and down like you described.

+1...i actually unplugged my IAC motor and was able to set timing like that

[platez808]

thanks for the input guys

Try cleaning the Idle Air Control Valve and the rest of the intake if your up for it. The IACV (Solenoid) doesn't really fail but the body of it does get dirty on the inside.

what i've done already was clean the rb25 one but had no luck. then i went to the junkyard and snagged one from a sentra, cleaned it and bolted it on, it was little bit better, but not anywhere near perfect. I've thought about taking the whole intake mani apart but the thought of sourcing gaskets and what not from here in hawaii.. bleh.. you get the picture

so i have a few updates..

i had a feeling that the maf wires (thanks to a repair made using unshielded wire after the maf wires drooped down onto the exhaust mani, melting the wires, creating a short and frying the ecu) were a part of the issue. So I took the shielded wire from my friends old harness that i had laying around after doing his SR swap and I wired in a z32 maf that i picked up cheap locally. I replaced the wire all the way to the ecu just to make sure that none of it was unshielded. I didnt forget to change the settings on the SAFC2 to accommodate the z32 maf. I also picked up another stock ecu just to rule out the ecu as a problem. Then i checked the fuel pressure and it was on the dot.

Started her up and right away it seemed to run a lot better, so right off the bat i know the shielded made a difference. Right at start up it was running at stoich AFRs, but as it warmed up it got progressively leaner. By the time it was fully warmed up, the AFRs were hovering way lean around 16s. I put the settings on the SAFC2 back to stock but still really lean. So i started messing around with getting the idle down. I unplugged the IACV and got it down to 700rpm and set the idle to 15degrees, but still no luck.

So I just figured that because the z32 maf, even with it hooked up to the SAFC, would still need to be tuned (or am i wrong??) and i wasnt up for it. So I went about wiring the stock maf back in. But of course, I was getting the same exact AFRs, with no change to the timing and idle from before. So I figured I would see what it would take to get the AFRs back to stoich and i ended up having to add 11% to get it there.

I'm kinda lost now. I have a set of ngk bcpr7es-8 waiting to be put in but i doubt that will make any difference.I'm kinda starting to think my CAS or belt is off, but i'm thinking positive and hoping that i'm just overlooking something that you guys can help me out with haha. again thanks for the input. lmk what you think now.

[IBoughtAS13]

16 is not rich, it is lean.

[platez808]

16 is not rich, it is lean.

haha.. thanks for catching that.. in my defense i said right before that "progressively leaner" and i just slipped up.. i'll change it.. hahaha

[platez808]

Alright some more updates.

I took of the upper timing cover and everything looks to be in order in terms of the condition of the belt and all the marks lining up. I decided to put the new plugs in and it idles a lot more consistently at stoich, but it still bounces up to around 15.2 and back to stoich every once in a while.

I took if for a drive and it was running really lean (or at least in comparison to what I know it should be running if things were "right"). At partial throttle it would go down to the low 13s for about a second then work its way back up to around stoich. At WOT, the afr's would go down to 12s max for a second then it go up to the mid 13s and by then i would let off the gas because it'd either be missing or i was just paranoid about blowing something. It hit full boost at 13psi easy but the power would cut out around 4500-5k.

Am i right for thinking that its running way too lean?

I dont know whats going on and i feel like i'm running out of things to check. Right now i'm looking to get my hands on another walbro and see if it fixes the issue. Any ideas??