78blackpearlz

Thats a good idea siteunseen. Im gonna go pick up both of them when i get out of class tonight.

Sorry for the wait guys been busy its finals week, But I did have a few minutes the other day and got to take a look at the z. I listened to all the fuel injectors, checked to make sure the AFM was still plugged in tight, checked all vacuum lines and wires, then pulled my plugs and found out it is running extremely lean. When I pulled the plugs they where white as could be. I am waiting till tomorrow to get paid then I am going to go and pick up a fuel pressure tester and recheck it. Hopefully tonight I will be able to check and see how the fuel looks dirty. I did have the fuel tank cleaned and coated when I first got the car however. It has gotten to the point where I can no longer drive my car. I know I shouldn't have driven it at all but had to with it being my only car and having to go to school and work.

Ok not a great picture but its the best i could get.

It does not have an egr anymore and i looked at where the port is plugged at and its starting to crack around the edge. I took a picture but on the mobile site it wont let me upload it so as soon as i can i will. Fastwoman, just to make sure i am understanding you correctly, you are saying that the vlave springs might be sticking open slightly on some of the exhaust valves?

Ok everyone thank you for all the help. I really appreciate it. Zed Head, I thought the ignition was a part of the issue but now that the ICM has been replaced everything in the system is at most a year old now minus the switch. I will double check all of the wires, cap, and button to make sure they are all seated correctly in the morning and I will read the EFI bible until I know it by heart. FastWoman, you mentioned the valve sticking open and it kind of made me feel stupid because it dawned on me that my I do have a slight valve tick to it. So I did some research and found another post on here where you had commented telling the valve clearance for the 280z's and it helped a lot because doing some more research I learned that it is recommended for the valves to be adjusted on them every oil change. And to answer your question about it being an afterfire, yes I am totally sure it is. I am pretty sure i have scared some people while driving down the road because it sounds just like a gun shot. I do have one question though, if the exhaust valve is sticking open will adjusting the valve help or is there something else i need to do? I want to do this anyways because it is long past due. I do not believe it has ever been done to my car and i hate to say it. Sorry about the late reply.

Well I can say for certain its definitely not the cat because it was taken off long ago. But if that was the case wouldn't there be some sort of smoke coming from the exhaust?

I wont complain about detail you have helped me a lot here and I've learned a lot from you and a lot of other people on here. By in the heat I mean from about 85+ degrees in Alabama so its a very humid heat. No offense taken, but I don't pedal to the metal it. When it decides to do it I let the gas out and push the clutch down and coast it till it decides to run again. Engine temperature effects it but it will do it with the engine not at running temp which on mine (because I've noticed a lot of people have different temps on their Z that it runs at) is just below half around 170-180 I assume. I have had the tank cleaned it was actually one of the first things I had done when I got the car around 4 years ago. The tach will hold steady at the rpm of the engine. I have noticed that all the gauges hold steady when it is happening (always paranoid when driving so I watch my gauges like a hawk) But little more info one the issue, while driving back and forth to work that it has gotten better since replacing the ICM it doesn't do it near as much or near as badly just under load it still will. Thanks again for all the help.

Ok ill try to describe it the best I can. When I drive in the heat my car will try to stall almost like all the power from the engine is just gone. It used to only do it coming from a complete stop but lately it has started doing it from first to fifth gear but from third and up it will only do it if I give it a little extra gas. But when the car almost stalls it will have a backfire from the exhaust ( technically an afterfire I think) with no smoke. After the afterfire the car will come back to life and take off like a rocket. But soon start to sputter until I get to a cruising speed and do not have to give it much gas. I hope all of that makes sense. But I do want to run another fuel pressure test on it. I ran the test last summer trying to figure out the same issue so I don't recall the exact numbers. I did do a tune up about a month or two ago (plugs, wires, cap, and button). I did have the clutch replaced the winter before this issue began but I talked to an ASE certified mechanic and he couldn't think of any way the clutch could be causing the issue but I trust you guys a little more about these things so I figured I would add that in there. That's about all there is. I do have one other question though, is it possible to have a partial failure in the fuel pump. I ask because during my test drive yesterday I noticed the fuel pump was whistling not its normal humming and when I got in my car to go to work yesterday morning it was doing its normal hum all day and I never had an issue with the hesitation I guess is the best way to say it.

well guys I got lucky and got the new ICM early and installed it today... Unfortunately, my luck ended there however.. Put in the new ICM and took it out for a test drive and it drove really smooth for about a minute and backfired horribly then drove smooth again. So I was hoping it was just one last pop to end it all so kept on going and it drove smooth for a little while but started to do it again just not as bad.

Yea I am trying my best to keep everything as stock as possible which is proving to be a bit of a challenge. But I did find a new one its not an OEM part because they don't manufacture them anymore. I got lucky and found one on rockauto for $120 when everywhere else wants $200+ for them. I read a lot about the HEI "conversion" with it and just decided for some reason to go with the ICM. And I'm hoping this isn't to much of a "plug and play" since my z is a daily driver and it gets a little hairy at times with this one.

Alright guys I pretty much just said screw it and went ahead and ordered a new ICM since it seems to fit the best. It should be here Friday hopefully, I'll post the results as soon as i can. Thanks again guys for the help.

Thank you for the help. My tachometer does actually jump or it will just stick in place and wont work right again till I shut it off and wont work right till it has slowly settled back to zero. I didn't realize that the ICM could effect that, but now that I think of it, it makes sense.

This one has been the toughest issue so far for me of all cars I've diagnosed. I've even talked to two master mechanics and spent a lot of time researching with no results.

I have run a fuel pressure test on it and everything was alright. It was a little while ago so I don't remember the exact results. I guess I should have mentioned that my car had begun to do this towards the end of last summer and as the temp outside lowered the problem went away and I got caught with other issues and this one slipped my mind.

ok guys gonna be a bit of a long post but here we go.. My Z has started to run extremely rough, whenever it gets up to running temp it will start to sputter and backfire from take off and will also seem to die out but suddenly come to life after the backfire and take off. The only thing I have been able to tell is that it only happens when the temperature outside is hot because in the mornings when I go to work the car will drive perfectly. I was talking to a friend about the issue and showed him what it was doing and he mentioned that a vehicle of his had done the same thing and he replaced the ignition control module and it solved the issue but I wanted to see if there where any other possibilities out there. thanks.