Search the Community
Showing results for tags 'lean'.
Found 5 results
-
Just wanted to share a fix to an issue I had. Car would get terribly lean when boost was ramping up, in my case 3800-4000 rpm. AFR's went to 19 for that moment, not good at 20+ psi!! I'm using the stock rail and had an Aeromotive FPR mounted to the passenger side front fender of the engine compartment, with 2.5 feet of vacuum tube to it. Took me a while to find the solution and it was in part due to a post I read, can't recall who it was, who had the same issue but never fixed it technically. He happened to replace his stock rail with a Perrin and it fixed his issue. All this got me thinking why Nissan put the FPR on the rail in the first place. I thought I needed a fuel damper but Nissan never used one originally, so....I moved the Aeromotive FPR back to the oem FPR location, and have a 8" vacuum line now. Now that it's there, acting as a damper as well (like Nissan intended), you can guess what happened, cars runs great now. Thought I'd share since I see so many people mounting it in the same place I did.
-
OK, So heres what im dealing with right now. My rb20 is having some weird issues running, Idle is good at a 14.7 AFR but under load/driving is where I get problems. Upon initial acceleration or low rpm`s the engine has little power and runs like its missing a cylinder or two with afr`s dipping into the 10`s then as boost comes on it runs normal for a bit like it should with afr`s towards 12-13`s and as the rpm`s raise and I hit full boost it will sputter and pop as it leans all the way out untill my wideband cant go any higher (18+ afr`s). So far I have checked everything manually and also through nistune and I still cant figure it out. Here is my current setup: Stock RB20DET and stock turbo Z32 MAF Nistune chipped ECU RB26 444CC injectors (and resistor wired into the harness) Walbro 255 fuel pump Nismo FPR AEM Wideband I have checked the timing and its at 15 deg. Fuel pump has good power and ground. All injectors are opening/closing. All coilpacks work (I pulled them with the plugs and spun the CAS to double check). ECU dosent pull any codes. Fuel pressure isn`t dropping off. TPS voltage is good. Plugs look good and are gapped to the reccomended .8, The MAF readings look linear and accurate from what I can tell through nistune. If I go into nistune and bump up the fuel it just runs richer in the lower rpm`s and still leans out and pops. The only things left I can think of is a bad MAF, Low voltage to the pump under boost, A bad ignitor for the coilpacks, or possibly a bad CAS or something. Any help would be greatly appreciated because I dont know what else I should check at this point lol.
-
Well my car has been at the point where I can actually drive it around for a while now but I have some gremlins which make it kind of sketchy and I want to try to pin down what my issue(s) is/are. Background of the car: 1976 280z, l28et swap Stock engine setup and ECCS, z31 coil, EGR deleted and blocked off, pop off valve removed and plugged. New battery. Alternator tests good. Brand new CHTS. New aftermarket FPR with a pressure gauge. Brand new O2 sensor. My issue lies in air/fuel ratio... I have a wideband gauge which I know isn't precise but can at least give me an idea of what the car is doing. Startup is difficult, and I'm under the impression that it's because the mixture isn't rich enough for easy fireup. Idle upon startup shows lean. Idle is also a bit high at ~1100 rpm. Not sure if that could be the cause, but I haven't been able to find any indication of idle adjustment on the L28ET throttle body like people have mentioned. The odd thing is after driving the car around and letting it warm up, idle AFR shows normal with a bias towards rich, which seems to be as it should be. Things get weirder, and this is why I think I have some kind of issue with grounds or something. Driving around normally, I can turn my headlights on and the mixture will go from slightly rich to slightly lean. Driving around with the headlights on indicate that it has a permanent issue of running lean with the lights on. I've had a heck of a time finding any indication of what could cause this specific issue, both looking through the FSM and google. I'm hoping someone on here can give me assistance since at this point I feel I'm in over my head. Thanks in advance, Pac_Man
-
I've been doing some tuning of my Mikuni 44 set up as of late with the assistance of a wide band o2 sensor, and I have learned a few things that may be helpful to some others. Generally, I recommend determining these in the order listed: Pilot Screws: One bit from Honsowetz in the How to Modify Your Nissan Datsun OHC Engine which is a very specific instruction: run your pilot screws 1.5 turns out. I have mine set at 1.5 dead on, and the engine likes the 57.5 pilots at that setting. AFRs are where they should be for idle and low speed operation. The engine runs well in both of these conditions. Mains (Fuel Jets) and Air Correction (Air Jets): This bit came from TonyD... and that is stay out of the pump nozzles when trying to determine what the engine wants for main and air jets. Accelerator pedal movement may engage the pump circuit and if it does, this will throw fuel into the mix from that circuit. This will "mask" what is happening with the main circuit and you won't know what is what. According to the Mikuni manual, accel pumps are in play from 0 to 30% of throttle. So use inputs like 50% or 100% and ignore where the 0-30% is most likely occurring. Since the pump circuit has a known volume... and the duration of the fuel "injection" from the nozzle is specific to each nozzle, you could time the length of the injection duration if you are so inclined. Then you could ignore that time duration (from throttle open) in your Wideband AFR (Air Fuel Ratio) plots. Pump Nozzles: This one came from my engine builder. Know that sometimes wideband o2 sensors/loggers may show you rich readings when actually the engine is lean. This can occur when there is any engine misfire condition. The rich reading is resulting from a chain event of the flame going out too early, and the subsequent passing of remaining unburnt mixture through to the sensor. When you open the throttle quickly, if the engine is sluggish, but doesn't misfire, and your wideband shows rich, you are rich. However, if the engine misfires, and your wideband shows rich, you could be lean. Regarding this last one, I think that is what I am currently experiencing. I will be testing that theory out soon. As I have changed the pump nozzles from 50 to 45 to 40, I am fairly certain that I have been experiencing a more prevalent misfire when applying large throttle inputs (I haven't been doing much full throttle yet and there has been a fair amount of time involved from when I swapped nozzles one to the next to the last). I was going smaller and smaller because of the rich readings I was getting on the wideband when "throwing large throttle inputs" at the engine. Last tuning session, I was getting a large amount of misfire for the first couple of seconds of full throttle... even when in first gear. I am going to switch back to the 50's next and see if that situation improves.
-
Hi im new to this forum but just the other day I got my first 280z. When I bought the car I knew it would be a project but I thought mechanically there was nothing wrong the previous owner swapped a new l28e and a new 5speed with 50k on both. With that being said I was doing a speed run the other day and after taking my z to 100 the power curve seemed shaky like after 80mph I would get bursts of highter power and then a lull of power. Now the problem hasgotten much worse, when I get upto 4000rpm it feels like the car is fuel cutting and randomly while I drive I just get what feels like complete fuel starvation. I think it might be either the afm or the tps but I was wonderin if anybody else has had this problem. There are new wires and plugs, new fuel filter, and injectors, and from what I can tell decent fuel pressure. I also started the car and it seemed like one of the cylenders want firing... maybe somethin to do with ignition timing? -thanks
