Guest livewire23 Posted February 4, 2003 Share Posted February 4, 2003 well, since my last bout of posts, I've managed to massage my 1977 280Z into running on all cylinders. I've even taken it around the neighbourhood a few times, and it runs real nice. But that is only half the story. Every now and then the engine just craps out on me. It'll backfire (not the loud type, but a slightly softer burp through the exhaust. Is that called misfiring?). It also has this really annoyinh problem with bogging down. It'll start up fine on all 6 cylinders, but when i rev the engine, it acts like its choking and actually loses RPMs. If I do anything more than tap the gas, it will completely stall. This makes it impossible to drive, as you can imagine. The car also hunts and surges while idling. It idles at around 1000rpm, and then it will surge to around 1250. The car is very shaky, and the engine tone changes ocassionally (really wierd). Furthermore, it is backfiring through the intake a lot. I pulled out the CSV to see if it was working, and there was definate backfiring through the hole that was left in the intake. As far as I can tell, these problems are not occuring only during cold starts, in fact, if anything they are more prone to occur when the car is warm. My list of things to test is as follows: Pickup coil in the distibutor Air Flow Regulator Timing However, im not certain how to test the first two, and I dont have a stroboscope yet, so i'd rather not test the third. Basically I want to know what order i should test in, and if any one thing is more likely to be causing the problem than the rest of the stuff. ps. I know testing the pickup coil involves testing the resistance of something, but i dont know where to find that something. ----------------------------------------------- end of technical problems. *********************************************** on a side note, i've been looking at the value of my car, and realizing that its more than I payed for it + money i put into getting it running. So I'm looking at possibly selling it, and putting the profits into the next Z I get. Turns out that was what my mom thought I was doing anyway... . I think if I look hard enough I should be able to find another 280Z with a straight body for around $500. Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted February 9, 2003 Share Posted February 9, 2003 I don't konw a d***ed thing about fuel injection (never had an FI car), but since no one else has taken a whack... this sounds like simple fuel starvation. I know- not simple with FI . You have spark, or it wouldn't run at all. You're having problems when you try to load the engine... sounds kind of like the ultimately plugged fuel filter, tank pickup filter (do Z's have them?), or a bad fuel pump. I'd check fuel delivery, then try the high tech guys for computers, injectors & the like. Luck. Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted February 9, 2003 Share Posted February 9, 2003 Oops, cancel the above- just found your earlier topic. Is it fair to assume that you don't have a plugged exhaust? Quote Link to comment Share on other sites More sharing options...
Guest livewire23 Posted February 10, 2003 Share Posted February 10, 2003 exhaust... hmmm... now there is an issue. It spits chunks occasionally. Big black chunks of hot unidentifiable stuff. Is a 77Z supposed to have an O2 sensor? I looked all along the exhaust downstream, and saw no O2 sensor. I was looking because I got a very good book on FI, and according to my symptoms, I figured I might have a faulty O2 sensor. I'll detach my exhast from the manifolds back, and see what changes. Other than the exhaust note. I just got a new fuel filter, the old one was definately plugged up a bit and full of ugly yellow nasty fuel that stains concrete. However, the problem still exists. There is definate fuel starvation going on, and Im on my last legs trying to figure out why. I've fixed the surging problems, and it doesnt seem to run rich at idle any more. Quote Link to comment Share on other sites More sharing options...
denny411 Posted February 10, 2003 Share Posted February 10, 2003 If your car has a catalytic converter, what you are seeing from the tail pipe could be pieces of platinum covered in soot. It sounds like a plugged converter to me. Quote Link to comment Share on other sites More sharing options...
Guest livewire23 Posted February 10, 2003 Share Posted February 10, 2003 I'm real pissed at pep boys right now. I hooked up my air compressor to the fuel pressure regulator to see what kind of pressure it held before bleeding some off, and the old unit I had was holding about 5 psi more than the replacement one I got. Its probably not a big difference, but all this time I've been thinking that I may not have enough fuel delivery, but I ruled out the pressure regulator becuase it was brand new. Stupid POS, they'd better take it back and gimme back my money. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 10, 2003 Share Posted February 10, 2003 I've spent many a day beating the gremlins out of my 76'. What that sounds like is your AFM. there's tests you can run w/ a voltage regulator, but pretty much if you take the Aair flow meter off, and the flap inside isn't smooth operating or sticks, or if the inside is really carboned up, then its time for a new one. I had many anomalous firings (ie afterfires) through the air filter and i swapped this part (159$ MSA) and they went completely away. Also started great in the cold after that. I would definately take a peek at that at this age those boxes start to take a **** . Good luck Aaron Quote Link to comment Share on other sites More sharing options...
Guest livewire23 Posted February 10, 2003 Share Posted February 10, 2003 my AFM is in pretty immaculate shape. Not sticky at all. In fact, the only damage is the valve being slightly bent from all the backfires blowing through it. Quote Link to comment Share on other sites More sharing options...
Guest livewire23 Posted February 12, 2003 Share Posted February 12, 2003 took off the cat, and voila. It was completely empty. LOL!!! Someone was trying to cheat. haha. But back to the story. After putting in the old pressure regulator, and tightening the AFM spring, the car is street drivable. IT consistently revs to 4500rpm in first, 3750 in second, and around 3000 in third. Or somewhere in that range. However, its not going to break any speed records with such horrible power dropoffs. So now I have three choices. Continue fixing the engine. Fix the brakes and upgrade the suspension. Finally scrap this engine and go 7m or L28et. Im thinking #2 is the most pressing of the 3, especially since I have brake jelly instead of brake fluid. Quote Link to comment Share on other sites More sharing options...
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