Posted December 25, 201014 yr comment_339814 Hello. let me start by saying i love my z but right now i would have no problem taking it to a feild, setting it on fire and just walking back home. The car ran great until it randomly started loosing power no biggie just some clogged injectors. I put the car in storage for 1 yr when i had to move from TN to GA. I went back with a car trailer and got my beloved z car. brought it back as soon as it was off the trailer i was under the hood. I pulled my fuel rail and injectors no squirt.no go juice at all. so i drained the tank put new fuel line from back to front. new filters and a new fuel pump as well. I aslo decided it was time for new air sensor, thermotine switch, AFM, and injectors seals and the injector blocks. replaced them and she fired up and sounded good but was idling at 2000 rpm. and when i pressed the gas pedal i would sometimes get a back fire through the intake. so we played with the distributor timing and got a nice clean rev top to bottom. We then proceded to get in and go for a run put it in reverse and she studdered back and nearly died several times. we then tried to go up my drive way it studdered and luged up it and started to pick up power near the top of the drive way so i backed down and tried again same thing happend. me and my friend are trying to figure this out but i figgured i would talk to the people who have owned a few of these cars. My guess is the vaccum advance on the distributor or nasty tank but the gas was clean no sediment and have great pressure on the rail. this car is an enigma i have both the fsm and the efi bible. can i please have some ones oppinion on what this might be. if you need i could shoot a video and post it her of what it does and sounds like. thanks for taking the time to read this andy help would be greatly apreciated. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/ Share on other sites More sharing options...
December 25, 201014 yr comment_339816 Hey wee, welcome to the board. This post is likely in the wrong spot for a lot of help, it perhaps should be over on the car forums portion. My first advice is to go over there and read through the electrical posts and see if you can find a few answers for some of your symptoms. Same for the fuel section. I had most of the same issues with my 77 and found bad gas to be a major player, but my air mass meter (amm) was not working correctly also and it would be just plain powerless. It sounds like you are saying it doesn't have power when it has a load against it. Be sure you have all of the vacuum lines in place. It really sounds like the timing might be a bit retarded as well. I'd open the distributor cap and spray the rotor and all of the assembly, including the inside of the cap, with WD 40. See if the vacuum advance mechanism moves freely. Beyond that, unplug and replug all of the electrical connectors, including the ones at the ecu and check for corrosion, cleaning if necessary. These cars get cruddy connections, especially having sat in humid conditions. And by all means, let us know what you find so that the next guy can lean on your experience.Good luck! Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-339816 Share on other sites More sharing options...
December 26, 201014 yr comment_339840 I had the same problem with my 77. I had taken stuff off the motor shortly after purchase to clean it all up and put it back and had the miss and shudder going on. I retraced all my steps (or so I thought) to no avail. Started the expensive resort of it must be this, nope, must be that. Replaced fuel line, filter, plugs, wires, dizzy, thermotine, injectors. Got the fsm and efi bible, bought a fuel pressure guage, injector tester, etc. I finally got around to the afm, found a used one. When taking the old one off(that I had removed to clean) I noticed when I put the ground wire back on, I had grounded the other end back to the afm, not to the frame mount. Duh, put the new one on and it ran great...just a thought, check the ground to the afm Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-339840 Share on other sites More sharing options...
December 26, 201014 yr Author comment_339845 thanks guys. ill retrace my steps and perform the vaccum advanced test to see if the plate moves like its supossed to. Im a 2 stroke mechanic so 4 stroke is a bit confusing to me. Ill have my friend come over monday and we'll replace all the vaccum lines and make sure every thing is in the right spot as well as do the vaccum tests. sory if i posted in the wrong spot just signed up today not sure how every thing works yet. my bad Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-339845 Share on other sites More sharing options...
December 26, 201014 yr comment_339848 Did you set the timing with a timing light ? You can't set it by ear, it will be all off as soon as you step on the gas. Set it for 10-13 btdc at 800rpm and report back.What exactly is your fuel pressure at idle ? What is it at 2000 rpm?Got a vacuum gauge? What is the vacuum reading at idle ? Can you put the idle at 800rpm ?I wouldn't just go replacing a bunch of stuff. you will likely spend a lot of time and money and still wont solve the problem which will add to your frustration. This problem shouldn't be that hard to figure out if you take a methodical approach and use the proper gauges and tools. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-339848 Share on other sites More sharing options...
December 26, 201014 yr Author comment_339861 I orderd an adjustable fuel pressure regulator from jdm but the gauge doesnt seem to work. The last time i took the timing light to it it was set to 10 degrees. not really sure where its at now that we messed with it. I am having my mechanic come over monday to help me replace all the old vaccum lines then well probly test with the origional fuel regulator that origionaly came with the car instead of the jdm one and test the vaccum advance on the distributor. ill let every one know what we find out on monday. thanks every one merry christmas Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-339861 Share on other sites More sharing options...
December 26, 201014 yr comment_339871 Yeah, I would definitely put the original FPR back on. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-339871 Share on other sites More sharing options...
December 28, 201014 yr Author comment_339999 Ok guys I got a timing lite to it today and we set the distributor to 10 degrees. when we started it up it pured at 700 rpm and reved great very little intake popping. but we noticed that the timing was off one tooth when we took the valve cover off. and the timing chain had a little play cause the tensioner wasnt adjusted all the way. so tomorow were going to pull the rest of the cover off and correct the timing chain and re time the distributor and that should fix the problem. let yall know tomorow. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-339999 Share on other sites More sharing options...
December 28, 201014 yr comment_340016 Have you had the chain off? not sure how it would have gone one tooth off? If your tensioner is not keeping the slack out of the chain, I believe the tensioner will need to be replaced. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-340016 Share on other sites More sharing options...
December 28, 201014 yr comment_340026 Chain stretch could make the timing appear to be a tooth off. You might need both a chain and a tensioner. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-340026 Share on other sites More sharing options...
December 28, 201014 yr Author comment_340060 no i once took the car to a local auto shop to have a tune up performed and the mechanich said he timed it but upon closer inspection he did a horrible job. The car revs great in neutral and park but when i put it in reverse or drive and press the gas it will cut out and try to die and when i let off it goes right back to idle no prob. the thing we noticed about the timing was the cam sprocket and mark on the alignment plate were off at tdc on cyl#1. so once thats corected im hoping that will improve the situation. adjusting the timing back to factory settings. as well as every thing else back to factory settings as what the fsm says. thanks guys ill let you know how the timing job goes tonite. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-340060 Share on other sites More sharing options...
December 28, 201014 yr comment_340061 Rather strange that a mechanic would remove the cam cover and screw with the chain/sprocket just to set the timing............. Link to comment https://www.classiczcars.com/forums/topic/38046-78-280z-from-hell/#findComment-340061 Share on other sites More sharing options...
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