ZCar Forum banner
Status
Not open for further replies.
1 - 4 of 4 Posts

·
Registered
Joined
·
381 Posts
Discussion Starter · #1 ·
I have a '76 280Z, which my dad gave me for my birthday. He had it since '76 hav ehase never needed to or has rebuilt the engine in it the current milage is about 199,432!!! The trouble that I am haveing are a ciouple of different things, I need to know when do I know when to change my TIMING CHAIN. I do not think it has been changed yet.

I am also have ing problems with missfiring!!! On Saturday, I tested each one of my spark plugs, which was very electricfing experience. The way I check it was I turned on the car and pulled out one cord of the plug at a time. I foud that the 4th plug was missfiring. I changed it and it still did it. The cable was producing electricity but it still misfired. Could there be somthing blocking or cloging the valve which lettes the full into the cylender or some thing like that. Also when I am driving down the road I will see my RPM needle go up fast then with fall again. does any one know if this has to do with the missfiring problem I am having?

Thanks
Tom
 

·
Registered
Joined
·
107,695 Posts
Tom, if you are getting good spark on number four, chances are you arent getting compression (stuck valve, or rings gone) or the injector isn't providing any fuel. Run a compression test on all of your cylinders and see that they are within specs and close to each other. The timing compnonents in these L series are extremely tough, but 200K.. might not be a bad idea. But if your going there, niether would a head job, rings, rods, and mains. Injectors are fairly easy to change, if it sat up any amount of time they might be clogged. Good luck and remember, whenever a car runs rough or not at all... there's usually a problem with fuel, fire, or compression, you just have to find which one. TC
 

·
Registered
Joined
·
107,695 Posts
Dear Tom and Tim,
I too suffer (apparent) missfiring with my '78-280Z (208K miles). The symptoms occur only when the engine is warmed up (cold idle is fine). The symptons are a noticeable, almost severe, stumble upon part-throttle acceleration. The car sounds like it is backfiring through the throttle body. If I rev the engine up to 4500-5000 rpm or drive at Interstate highway speeds briefly, the missfire and stumble will cease. But when driving around in city traffic, the missfire always occurs. Otherwise, the engine runs and pulls strongly.

I've tried different brands and grades of gas, to no effect. Also used Gumout FI cleaner, to no effect. The spark plug wires, distributor cap and rotor are new within the last 2k miles. The plug tips are clean and the correct color, but there is engine oil residue around the outside plug base and threads.
Could it be that the plugs are fouling up because of the stop and go urban driving? (Tom, you did not mention what type of traffic you normally drive in)
Appreciate any info from other injected Z-owners.
 

·
Registered
Joined
·
107,695 Posts
Ok guys. Here we go down the wonderfull road of systematic engine diagnosis (groan). Tom. Hold a screwdriver on each injector (also to your ear) and listen for a click-click-click coming from each one. Make sure your injector harness is clean, that the connectors arent corroded. You might want to have the compression checked if this doesn't find a problem. Jeff, your car is either running lean, or the Airflow meter is bad. Easiest way to fix this is check for a leaking vaccuum hose, or rot in the connections between the airflowmeter and the throttle body. When your car is cold, it is dumping in gas to richen the mix, thereby negating the extra air drawn in (vacuum leak). When it warms up , however , the engine leans out, and with the vacuum leak, it won't idle (too much air, not enough gas). Check it out. If it comes down to it, listen for hissing under the hood, lol. If ya'll need more help feel free to email me at the said adress. Lynn
 
1 - 4 of 4 Posts
Status
Not open for further replies.
Top