Pochie45566

Okay, I so was pretty sure that my BCDD was gone so I ordered a block off plate, used silicone gasket maker, and installed the block off plate. When I start it now, the idle immediately goes to 1750 rpm and cannot be brought back down. the AFR is reading 11.5 so Im pretty sure its not a vacuum leak, that and it would take a pretty obvious vacuum, leak to raise it 1000 rpm. Am I supposed to block off any vacuum lines for the BCDD? What's going on? It has to be getting extra air from somewhere!

The spring has been replaced in the past and while examining the linkage that is attached to the throttle body I can see the whole assembly moving and closing, when the RPM is hanging the throttle plate is shut.

yeah, I made sure that the whole linkage was working, I could take the throttle body out to make sure but the linkage has full range of motion and the spring is working well. It sounds like the linkage is sticking to me also but I don't see how that could be happening. I have tried pushing the throttle linkage back down while the rpm's are hanging and it does nothing so it seems like it isn't throttle related. BCDD developed an internal vacuum leak maybe?

Sorry for the confusing language, im not very good at describing these issues lol. When I start the car the idle is at normal, but once I press the gas pedal the rpm's will not come back down, they will stay up until I turn off the car at a stoplight or something. I dont see any split vacuum hoses and they have all been replaced in the last couple years.

since I was driving home when it happened, I just had to keep the car in gear and put my foot on the brake. It was pretty horrible but luckily I was about a quarter mile from home. the idle doesn't drop down by itself at all

1978 280z stock EFI I'm having a weird issue that when the engine is revved, the rpms do not go down once the gas pedal is released, the RPM's kind of just stay where they are, around 3k. I am posting because I have gone through the forums and checked off a lot of boxes, the BCCD has been unplugged, could it still be leaking air? after testing with a vacuum gauge I think that there isn't a vacuum leak, that would need to be an obvious leak also. The throttle linkage is working smoothly and the throttle plate is closing. Im just trying to think of what else could have this effect? I have an AFR gauge hooked up and it is running at about 15 when at idle and stays around there when the rpms are hanging, which I guess is quite lean. Is it possibly an EFI thing? But it needs the extra air to Rev higher? Im just trying to figure out where that is coming from if the throttle plate is closed. Anyway, I would love some ideas on this issue. Thanks.

yeah the rheostat is all the way up. The taillights and dash lights went out all at the same time so they have got to be connected in some manner. Is the troubleshooting protocol here to just trace it back to where im losing voltage or what is the process here? I have never done anything like this before so im kind of in uncharted territory. It is interesting that the fuse for the taillights was blown but when I replaced it they still didn't come back on.

okay so with the light switch off I have 12.4v and with it on I have 11.8V. Is that a significant drop?

I replaced the headlight switch to no avail! the fuse for taillights was blown, but I have replaced it and nothing changed.

Hello! my first time searching for electrical gremlins so I have come to get some advice on the best way to start troubleshooting this issue now that I have checked off the basics. a while back my taillights and dash lights went out, my side markers are also not working. My headlights went out shortly after that. I checked the fuses to find that they all have continuity, and pulled off the steering column cover to find the red wire going to the headlight switch had come loose. After soldering that back on the headlights resumed working but the rest of my lights still do not work. I have read that the green wire on the switch is in control of these interior and tail lights, however I have already replaced the whole headlight switch and it did not change anything. Are there some common things I should check? Places I should measure with a voltmeter? let me know. Thanks!

Hello! When I test my AFM air temp sensor, it comes back at 170 ohms, which is way too low. I looked through my spare parts and I found an old AFM with part number A31-622 420 Would this AFM work in my 78?

Yup! thanks for the help guys!

problem solved! I guess my spark just wasn't strong enough. I did test for spark and it was there but it mustve been weak. I pulled the distributer cap to find a small amount of moisture and the points had been corroded. Cleaned em off with a file and she started right up.

well bad news friends. I drained some of the gas from the fuel lines and let it settle. No water in the gas. What next? Efi diagnostic?

Smart! There is a drain plug on bottom of gas tank I think? I will maybe drain 1/2 of the tank and fill back up. How would I get the existing gas out of the fuel lines? Maybe pull the line going to the injectors then crank it over?

I tested the spark by pulling spark plug boots and holding screwdriver 1/8th inch from the block and it had spark there. Im not sure if that means a whole lot, but spark is present. that ignition module is under passenger size dash correct? I will try squirting fluid in through vac hose tomorrow. Im confused on why the car was running fine when it was cold.

It is pretty high humidity here in Oregon. I got like 1900 Ohms which was pretty close to what the EFI manual wanted. I tried unplugging it and starting the car but that didn't work either. I did try squirting some carb cleaner into the intake manifold through the line connecting the cold start air valve into the manifold but it didn't start doing that either.

I filled up the tank before I left it and I put a fuel stabilizer in it. How could I go about testing? I pulled the efi harness and tested the coolant temp sensor according to the manual and it checked out. I was thinking water in the lines too. How do I go about getting it out lol

Hi, I didn't drive my z for three months, so I put a car cover and tarp on it and let her set for a bit. I came back to a very moldy Z car. Lesson learned, she's going in the garage next time ?. I cleaned up the mold and started her up, started like I never left as was running great. I let her run for about 10 minutes, and then the idle started to get lumpy and it was surging. I went on a drive around the block and it had very little power and consistently wanted to die. I parked it and tried to start it back up and now she won't start at all. I have gone through the EFI bible a good bit, tested all the injector circuits, tested the water temp sensor, cold start system. I checked for spark by putting a screwdriver in the boot and holding it near the block. I have 36 PSI of fuel pressure. I checked some of my relays, I think they are working. I wasn't sure which one was responsible for what but most of them seemed to be clicking. When I hold a screwdriver on the injector I do not hear it click, so I presume they aren't firing? I also pulled the plugs and they did look like they had a good bit of carbon on them, but my z has always run a bit rich. I'm not sure what to look for next. Any ideas?

I followed every component check in the efi manual and used their charts to determine if the component was functional or not. Heres a screenshot of the test i used to check idle functionality of the TVS i have no backfiring, misfire, or hesitation that is common with late timing. but I will grab a light and check it.

The injectors? When pulled they have no buildup. They have a green ring around the outside. Not sure that you are looking for there. What is TVS? I have checked the TPS. I checked every component check in the EFI bible related to running rich. They all appear fine. I get 11-15 MPG and am running NGK r plugs

Previous owner did new fuel lines and new injectors, and I don’t have any reason to believe there are any leaks. But I do always keep a fire extinguisher in the back haha. The black spots are just behind the exhaust pipe tips. I am using ngk r plugs. Also on WOT sometimes black smoke comes out the exhaust. I appreciate your help, I’m just a bit confused on what steps to take next.

It had always smelled like gas, got bad mileage, and leaves black spots on my driveway. I did put fresh plugs in then go drive and they were black. Im just simply more motivated to fix this issue now that the nice weather is out and my garage isn’t freezing? This is not a sudden problem, I’m sorry I described it to be that way. Zedhead, I’m getting around 11-15 MPG

It runs well now, just smells like gas and gets horrible mileage but I will try unplugging the sensor and seeing what happens. Should I set my AFM back to stock? Yes the filter is in good shape. Pretty sure is Nissan factory. Could be from a different car though. I have no idea. Any way to check?

yes i compared them to the chart and they are all within spec, the CSV does not leak. i pulled it out and started the car and let it run, no gas came out. I have a working afm with the factory setting mark and when I set it to that it just runs even more rich. What steps should i take to check to determine why my plugs are getting carbon fouled if it may not be the mix? I should add that I leaned out the AFM a lot. It does not idle correctly now so I set it back. And this was not an all of a sudden issue, it’s always run pretty rich.