GabeDiaZ27

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.

I should have my twin scroll manifold coming shortly from Cindertrackfabrication, I`ll let you know how good it is when I get it.... not sure when that will be though as it has already been about 5 months over the 2-3 week time frame I was told. Cant say anything about the quality yet but I can say for sure they have terrible costumer service with no updates, no time frames, and even being told it was "almost ready" then later told it was just started on.

So I recently installed a Bee-R rev limiter on my rb20 and had a question. If you know how to install these there is 4 main wires to hook up. Power, Ground, and two others (one green and one yellow) for the signals. anyways I just cut these wires from the ecu and connected them directly to the bee r unit. so far everything has worked fine as far as I can tell. Recently though I have read not to cut these and connect them directly to the bee r but rather splice into or "Piggyback" onto them or at least onto the signal ones. Can anyone who has installed one of these please verify what I should do? I tried it both ways and couldent tell a difference, Thanks!

Sorry only saw that second post for a second. Ok yeah Ill check all the ignition stuff tonight and try to see if I can get further on this

Its running stock boost pressure not anything more, and I have a walbro 255 pump and a nismo fpr. The problem isnt that there is a lack of fuel the problem is that as more vacuum is introduced to the fpr via manifold vacuum it lowers the amount of fuel pressure on the regulator. The engine should be loosing vacuum and go to 0 then into positive pressure as boost comes into play. The vacuum should be highest at idle then drop so more fuel is added as the rmps rise. I just dont know why my vaccume is low at idle then raising with the rpms

Ok so recently I have been plagued with some rb problems. The engine will behave fine but when under boost the engine will bog/stutter kind of like a rev limiter or two step kind of deal but it wont rev much higher than maybe 4k-5k rpm. when there is no load on the engine (in neutral or clutch in) it will rev fine but not while in gear. So I did a lot of trouble shooting and found the cause of the problem, as the engine revs up the vacuum is INCREASING and causing my FPR to cut the fuel down to around 20 psi or so. From my understanding as the rpms rise the vacuum is supposed to DECREASE and go into positive pressure as the boost comes on but it seems that the opposite is happening. Im no master mechanic so I am just wondering what is causing this. could it be a timing chain slipped or something? Im honestly stumped and I cant find much info on this so I need some help or at least a way around this, Thanks in advance.

OK. I have a pretty good deal on a Bee R rev limiter and I don`t want to miss out because I really want one! But sadly I don`t even know if I would be able to use it I have a 1977 280z with the stock L28...only thing is, is that I am running a Holley 4 barrel setup. with that being said I don`t have any of the old EFI stuff or even the ECU so what I am asking is if there is any way to hook up the rev limiter instead via ECU? and if so how would I go about that? I have been trying to look this up but no one seems to have done this before so i`m kinda lost. Thanks- Gabe

I FOUND THE ISSUE!!!! the needle and seat for the primary was stuck shut! I broke it loose and broke it in general but I put it back together and it fired right up, but also shot some fuel out the top because it is broken. So I just need a new needle and seat. Thanks Miles and NewZed for the help and the links to help me find what was causing the issue!

I checked both of the fuel level sight plug hole things and one was a little high and I managed to lower it to the correct amount but the other one (the one closest to the fuel port) had no visible fuel in it and I tried to raise it but that didn't seem to work. So I guess there is a clog or something in the carb?

OK so I just got done putting my 4 barrel conversion all onto my car piece by piece, nothing crazy just a Holley 390 cfm carb on a arizona-z-car intake manifold. I used a self regulating K&N fuel pump to the carb. all the wiring is done and everything is in order but my car still wont start. If I spray carb cleaner into my carb my car will fire right up then die out shortly after (2-3 seconds). What could it be? I am getting fuel for sure at least all the way up to the carb that is. The carb was a used one off someone else`s RUNNING 280z but he did say it sat for awhile before I had bought it. With the way it acts if I spray carb cleaner in it I would think its a fuel problem but being relatively new to carbs I don't want to mess it up trying to tune something I know nothing about. If anyone could help me out that would be great because im 9 months into this project and its finally time to drive it and I cant wait! I appreciate any help at all, Thanks! -Gabe

Ok guys I found a 4 barrel setup for $450! You can close this now

Yeah I have been looking into carbs for a while now and even if the problem is something else it would save me a lot of time to know that the air/fuel mixture is already correct. almost every single connector in the EFI system was severely corroded. The connectors for the fuel injectors were so bad that if you wiggled them they would go out on you. The carbs have been an upgrade I would have made either way but because of how troublesome the EFI is on my particular car I am switching now, and yes I am aware of the fuel pump and other things...believe it or not I do research a lot I didn't install the distributor on my car it was already installed but I will look into that! I probably will have to get some work done to it anyways if I can afford some triple webers, I think if I read correctly you have to get it modded to allow the webers to run perfect.

I have some stock 280z wheels?

Hi I am looking for a carb setup for my 280z. A 4 barrell or triple setup in good condition is what im looking for. Preferably the entire setup (carbs,Intake manifold,Linkages) so that I can get it all at once but if you have just a manifold or carbs in good condition that is fine too! I have $900 to spend on this MAX. You can reply here or txt me at 972-955-0116 or email me at gabediazz27@yahoo.com Thanks!

Alright guys I have decided that I am going to do the switch to carbs. I have had it planned out for awhile now but wanted to fix the efi first but because of all the trouble and cost I am going straight to the carbs. I will post in the parts wanted section but if any of you guys have a setup [triples or 4 barrell] I will gladly buy it off of you for a reasonable price. Thanks!

Ok I will look into it...I honestly have no clue as to who rebuilt the engine as it was already in the car when I had purchased it. Its practically brand new though. I have read that it says you can troubleshoot the problem via the 30 pin connector for the ecu? I will do all the test but is it a good way to find the problem or is it unreliable? It sounds like the most effective way to solve this.

Alright so we kinda got the car to run properly. Here is what happened. First we checked the injectors and took them out to make SURE they were actually working properly, and they were. Then we checked the distributor,wires,spark plugs, and timing, and they all were good. Then we checked for compression and all my cylinders had about 170-180, Good. Then we adjusted the valve lash to correct specs so those are good. with all of this done the car still wouldn't run properly. We then today decided to take off the afm again and run some test, we made some adjustments and then closed the circuit on the water temp sensor because I thought it may be bad which is why it started smoking yesterday...BOOM the car ran properly for the first time since I had bought it! I let it run for awhile more then turned it off for a minute or two to move our other cars out of the way so I could drive it but as soon as I started it up again it had problems. so now the problem is that the car revs barely over idle (800rpm) then just kind of bogs down for the rest of the way. I am at a completely lost now I am going to replace the water temp sensor and check the AFM AGAIN but that all I can think to do. I am pretty sure it is related to the AFM or some computer thingy but that's all I know for now. I will update soon with info but if anybody has had a similar experience please share!

Sorry for my lack of info. Each individual injector is firing but cylinder #1 doesn't seem to be working properly. I am getting spark on all cylinders and each injector is firing, but cylinder #1 can have the injector unplugged and it wont effect the car at all. I will look more into vacuum leaks and the valve lash tomorrow. I'm sorry if I don't make sense sometimes but its a little hard for me to explain what is happening in words, I may take a video soon if the issue continues. Thanks!

We checked for vacuum leaks with a proper vacuum gauge. Unless that isn't sufficient enough then there are no vacuum leaks that I have been able to find. I have been looking through the FSM but I simply don't have enough time or money on my hands to go through every single thing in my car to check for a potentially small problem which is why I have decided it would be better to ask some people with more experience than me. As I said before all of the injectors are good and firing, your can easily hear them working and I have used a set of noid lights to insure that each was getting the correct power pulses. I even bought a new injector only to find that the other ones are in as good condition as the brand new one.

yes I have checked for spark and I am getting it on all plugs. The injectors are all firing correctly but they still seem to be acting up. The engine actually seems to run BETTER with injector #1 unplugged!?!?! The only other thing I think I should note is that the engine seems to not rev over around 3-4K I have a bad tachometer but I can definitely tell its not revving nearly high enough....All these weird problems has me thinking about switching to carbs!

Ok guys so here is an update. the car is not running much better than before but I noticed that if I unplug the injectors one at a time #1 has no effect when unplugged meaning that Cylinder #1 isnt firing right? I noticed the problem and bought a new injector, distributor rotor and cap and new plugs but the problem is still there. The wires are fine too. What could the problem be??? I think this issue is a big part of my problems so I would like to get this out of the way first. Any help is greatly appreciated guys! Thanks!

Hi sorry for such a late response my phone was having issue with the website or somthing of that nature and wouldn't let me post! ok so the timing is at 10 if I remember correctly, I installed a fuel pressure gauge that reads out to be about 28 psi then spikes up to 36 psi when reved. yes it is fuel injected. there are no vacuum leaks whatsoever I also and went ahead and replaced the fuel filter. also another thing I noticed is that when the hose to the top hat thingy on the fuel rail (I forgot the name) the fuel pressure stays at 36psi also I had thought the injectors were bad but they looked to be in good working order. when you start it up it runs as if it weren't firing on all cylinders then it will steady out to a normal idle. if you give it gas slowly it will rev up but if you give it gas fast the rpms completely drop then the engine will rev up but sputter in the process.