Really Dumb Air Regulator Question

[rico05]

Mine is not working. It won't open, so on cold start, I am running grossly rich still. Once the car kicks over to open loop, there is a NOTICABLE change in idle and revving the engine. So my issue is there any way that the regulator can be eliminated? I was under the impression that a flased EPROM eliminates cold-start mode regardless, so could I possibly reflash (planned to do this anyway) and block off the nipples on the coldpipe and intake mani for this? The only problem that my car still has is the crap when cold, and since I have eliminated every other issue but the air regulator (I even pulled it apart and cleaned it....to no avail) and it is really wearing down my patience! I am tired of having to warm my car up, drive it really slow for 5 minutes, then give it hell for a sec to get it to run right

[datsunboy]

I can't see why a flashed ROM would remove ECU control of the air reg???.....have never heard about it before either....

But.....maybe it does....I have never seen anything in ROM Editor that allows you to adjust anything to do with the warm up process.

[float_6969]

If you want to have a working one, you can pick it up from an SE-R. That's what I was using on mine. The one that came with my clip didn't work either. I've never heard that flashing the EPROM will eliminate the cold start, but I won't say that it won't do it either.

[biosehnsucht]

automatic FWD SR's have direct replacement parts.I actually bought a new one from nissan..

flashing the rom should have nothing to do with that.. the ECU doesn't even control the cold start air regulator, that just gets 12V power when ign is on, it has a wax gizmo that heats up and closes off the valve inside as it heats up - its that braindead simple, sadly.

perhaps its possible somewhere to modify the period of time before the ECU goes to closed loop operation and uses the O2? I don't know where you'd find this value however.. if only it would just use the FICD/AAC to raise idle at cold start and not the stupid air regulator, and smartly control it until warmed up..

[rico05]

datsunboy: I have "heard" that flashing a ROM ususally eliminates the cold start and limp mode, and most shop tuned EPROMS (Holsham, Norris, et al) run only one map....although there are ROMs I have seen from Oz and the UK have usuer switchable daughter boards that feature a separate ROM with another (usually more aggressive) set of maps.

I think I will poke around and see about replacing the unit some more (I have looked in jyards and eBay, no luck) but since I am considering alternative management currently...

Also, could anyone with non standard ECUs step in and mention your cold start setup. Dee, Korey, etc...lets hear it!

EDIT: Damn bio....you posted while I was typing LOL.Good call on the operation of the regulator, but the issue is more the fuel and ignition situation. As I understand, in warmup (like limp mode) the ECU will run more fuel and retard the timing. The way that the car feels when cold is if say I rev under 3500RPM or pull over 10inHg, the car will bog and sputter. Once it is warm, it runs AMAZINGLY. Revvs like mad and pulls hard (3" off the turbo, T25G, bigger IC really do pay off ), so my ONLY issue is cold start. I just want to pull fuel and add timing to get it to run better when cold. But if a new regulator is that easy to find....So off of a B13 SE-R SR20 then hunh?
Modified by rico05 at 6:53 PM 7/29/2005

[biosehnsucht]

something's wack on mine that I've cranked the FPR are to fix - at cold start it wasn't putting in ENOUGH fuel, as in you couldn't small ANYTHING from the exhaust, no richness at all, cold start should be rich, since the cat isn't working yet, and you need more fuel to atomize anything combustable since it won't atomize properly.. so I just managed to limp it alive and adjust the FPR until it was happy.

so it runs pig rich until it starts running off what it thinks its doing from the O2 sensor, which is still very rich..

in fact the car was almost impossible to start when this started happening and it was undrivable until warmed up, because there wasn't enough fuel actually mixing with air to burn..

suspecting it might have been the water temp sensor telling the ECU it was already warmed up, I tried swapping the KA one in but that was no change.. I have bought a new one I haven't installed yet (just to elminate it for sure), along with various other bits (gaskets to rebuild the FICD/AAC, new air regulator, new o2, got my cleaned injectors and I have a RB MAF just need to chip and program an ECU for the combination..)

as for the "one map" thing, they just put the same map in both the low and high octane fuel and ign map positions, "eliminating" the 2nd map by duplicating..

[Not_a_sr]

im not running a air regulator on my stock ecu this time around. i took it out blocked off the ports that fed it. cold start even when its 100deg out. cant drive it till its around 60deg C.

side note. today i finnally turned my fans off got up over 100deg C and the temp gauge never went past half way..

[biosehnsucht]

do you mean you can't drive until the water temp is around 60, because its undrivable, and that it goes through cold start even if 100deg outside?

it'll always go through coldstart for some X minimum of time (not sure what) before going semi-closed loop and using the water temp to continue enrichment as long as necessary until it hits whatever its predetermiend 'warmed up' temperature is, and O2 once it senses its warmed up and goes truely closed loop ... or so is my understanding, which means a bad water temp sensor for the ecu can cause weird things i.e. rich or lean conditions.

[onevia1800cc]

so what you could say is a bad water temp sensor cause alot of backfire and extreme richness?mmm.........nico is definatly a trove for info makes me proud to be a member

[biosehnsucht]

almost anything can cause fueling problems

vacuum/boost leak (intake piping, manifold gaskets, TB gasket, hoses..)water temp sensormafo2 sensorknock sensor (i.e. nonworking/not present)overcooling the engine so it doesn't warm up (no thermostat + koyo radiator would be effective at causing that ROFL)overheating (no / not enough / air in coolant, etc)15 year old stock FPR w/ a 255lph high flow walbrotiming (bad cas or mistimed, etc)bad spark (ignitor, coilpacks, plugs, timing, etc)injectors (stuck, clogged, etc)fpr (not enough or too much fuel)

I'm sure other things could cause it that I'm forgetting lol

too many things to **** up hahah

[rico05]

I have operational (ie Clean, working, tested) MAF. No vac leaks (all new lines). New coils (Well, 2), a fuel pressure gauge (36psi at idle), brand new OEM water temp sensor a year ago, and new plugs. The only things I can think of are the regulator and the timing. I have set timing by ear, but since I don't have a gun (and I am poor) that is the best that I got. Looks like that new body peircing will be put off yet again until after I buy a timing light and air regulator from Nissan.

BTW, my issue is ONLY cold start. Like I said, once warm, it is 100%. And no ECU codes either.

[biosehnsucht]

IIRC stock fuel pressure should be 36.3 relative, at idle it should be something less (vacuum).. easy way, hotwire the fuel pump relay boss to connect the fuel pump to on and put car to on (not start) so it doesn't auto off after a few seconds, and adjust FPR to 36.3; then turn off, unhotwire fuel pump, test. it may be running richer at cold start because the O2 isn't working yet and it isn't compensating.

see here

[float_6969]

I don't have a FSM in front of me (I'm at work), does the FSM give a "range" that is considered OK, or is it supposed to be exactly 36.3 relative?

[biosehnsucht]

well it says 36.3 in at least one place, but its not like it has to be exactly 36.

if you look at th SXOC thread the stock FPR on a stock pump was more than that (of course its years old), but if he set it to 36.3 at idle that would be around 6-8 psi too much fuel pressure at idle.. and until o2 heats up it can't compensate because it doesn't know

[onevia1800cc]

BTW, my issue is ONLY cold start. Like I said, once warm, it is 100%. And no ECU codes either.

ok i'm having the oppisate happining to me. on cold start its fine then it gets bad i also have no codes,i'm leaning twards the o2 sensor, Will an autozone carry the correct one plug wise????