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Need help finding a gremlin in 280z turbo


J Taylor

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I was riding down the road the other day and the Z died, out of the blue. I coasted to a little side street and tried to re crank it to no avail. The motor sounded really weird...like it was had no compression(same as it sounds when you turn it over with all the spark plugs out). I turned it over a few more times and it started sounding normal again(could hear the exhaust pulses out of the exhaust again) but still wouldn't crank. I got a ride back to the house and grabbed the compression tester. Came back and tested the compression and it was perfect on every cylinder. Put plugs back in and it cranked right up but was missing on a cylinder or 2. I drove it back to the house running really rough and busting up bad around 3000 rpms. Been trouble shooting for a couple of days now and can't seem to figure it out. I would really appreciate some input on this if anyone has any suggestions.

Thanks,

JT

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I would start with the usual suspects. Put plugs in it. Make sure the rotor is not broken or that the cap is carbon tracked. Put you're ohm meter on the wires and make sure they are OK. Stick a fuel filter in it. Check ignition timing. Make sure you haven't gotten some water logged gas somewhere, etc.

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v8dats: that could have been the reason it was cranking the way it was at first. I have had problems with my starter lately.

 

Mike: I have replaced the plugs, checked the cap, rotor, changed distributor(crankangle sensor), etc. My next step is going to be some gas treatment. I know my old 55 ford pickup would act up kinda like this after it would ran a bunch....would get some water in the tank somehow. A botle of the stp gas treatment would always clear it up. I doubt this is the case unless I just might have getten some bad gas or something. Anything else I should check?

JT

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Guest super280z

J, my 79zx did the same thing to me about 2 years ago. sad thing is, i never figured out the problem. i started the motor swap before it got fixed. hrmm.. let us know what it turns out to be cause that one's still got me stumped. sorry for the pecemistic word,

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Guest the_dj

My car had its worst problem after it developed a leak after the mass air flow sensor. Check the MAF to make sure it works, and then make sure there are no leaks in the intake line after it. I'm sure you'd be able to hear a leak after the turbo...maybe between MAF and turbo? Just a guess.

 

DJSS

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Guest LAYTON

have you tried changing the lil black ignition modaul on the dist.? that little bas@#%rd had me pullin my hair out for a week just after i dropped in the motor i rebuilt just weird timing i guess but it would do that crap and also would get warm ,die then rfuse to start till it cooled off but it progressively gave me a hard time then it just started doin it consistantly after changing alot o stuff thats what it was.

just a possibility good luck

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Guest Tim78zt

JT, I would look at two other things too:

Fuel pressure regulator (with a fuel pressure guage) and

injector relay wiring (on my 78 the perp was the jumper wires right in front of the battery on the black relay box). Not sure where this wire is located on your car, but mine had 2 white plugs with big white wires. I wiggled these wires and it would restart every time, but this problem also went away when I did my engine swap, eliminating this wiring connection.

Oh, one last thing, look at the connector to your water temp sensor. If it is corroded get it completely shiny clean.

 

Good luck!!

 

Tim78zt

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JT what electronics system are you using? Which year?

I'm very familiar with the `82-`83 turbo system, so let me know.

If you you're not running the `82-`83 turbo setup I have everything except for the harness to do the swap.

Also have everything to do the Z31 Turbo swap except for the harness.. There is a `84 turbo here with a pretty much complete harness that I'm thinking about grabbing.

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Guest LAYTON

hey tony

do you have a extra dist drive gear for the 82/83 zxt dist. and a zxt air flow meter

those are the only things im missing for a complete zxt swap for my 240

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Guest sabum

Ditto to the leak in the intake system. I also had that problem with stalling a few years back. Ended up being the airflow meter. Also make sure there is no moisture in the Throttle body position sensor (connector). Good luck with it... those type problems are a bear.

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I have a working 280zx turbo air flow meter. I don't have another distributor drive gear though. Sucks that they are different huh?

Email me and let me know how much the AFM is worth to you, and if you'd like for me to bead blast the case. I did have to pay for it at one point so it is worth its value to me.

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Above are all good suggestions, but you need to do your basic troubleshooting to narrow down your search for the source of the problem. Is it a fuel delivery problem, ignition, or both?

Troubleshooting Algorithm: Start with rule-out ignition: when the problem occurs, take the coil wire out of the cap, place a phillips screwdriver in the wire terminal and rest it on a metal surface of engine/compartment so that the metal of the screwdriver is about 1/4" gap from the suface (valve cover or one of three strut mount bolts works well), you want to place it so that you'll see the spark while you're cranking, i.e., through the windshield and below open hood edge. Should be a thick spark with some blue in it. If there's a spark but it's thin, orange and weak the problem could still be ignition. If there's any spark, then replace coil wire and repeat with a spark plug end of a plug wire. If there's good spark there and the car's not firing; problem is in fuel delivery. If feeble, or no spark at plug wire end and coil wire end, then check coil wire with ohmmeter, should be about 1,000 ohms resistance per inch of coil wire. If bad, replace and retest for good spark. If you've narrowed it to the electrical side, then make sure the distributor shaft is turning when you turn the engine. If so, try a replacement ignition module and go on from there. Test the primary and secondary circuits in the coil to see if they pass re specs. If ignition passed, troubleshoot fuel system. If you had spark but plugs were soaked with fuel, replace them or spray electric motor or brake-cleaner on them and let them dry then install. Crank it to see if it runs. If it does but is rich, pinch off the fuel line (vise grips with a rag works) near the fuel filter and run till stalls to dry cyls out. If dumping fuel, then it's probably AFM or temp sensor, possibly pressure regulator or ECU. If plugs were dry with spark, pull output line off fuel filter and cautiously place into container. When cranking, there should be brisk fuel flow. If none, check input line to filter, if flow, replace filter. If none, then check fuel pump relay for power output to pump (green wire on your car), if present, check same wire at pump, if present; replace pump.

If you had good fuel flow at filter output line and plugs are dry with good spark, then the easiest way to proceed is with fuel injection test devices like sold by J.C. Whitney. Plug the tester light into an injector harness terminal. If no signal, then suspect AFM, ECU or harness to it or ignition trigger signal to it. Confirm that it would run if it had injector signal by hooking up injector testor to injector, activate it (pulses at speed you select), and crank engine which will try to run on one cylinder.

Hopefully, before getting too far through this algorithm you isolated the problem by testing and eliminating components rather than the "shotgun" approach of replacing expensive items which weren't at fault. Having done it both ways; this way is better. DAW

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The #1 rule to finding problems? Check the easy stuff first.

 

Your problem doesn't *sound* like a fuel supply problem. Fuel pumps tend to either work, or not work (most of the time, but not always). Fuel pressure regulators will cause excessive fuel consumption, but I've never seen one cause a no start condition.

 

It also doesn't sound like a plug wire issue. Plug wires don't usually cause a no start condition (unless you have a coil wire that may be breaking down).

 

It also doesn't sound like a mechanical issue. It'd have to be one helluva intake leak to cause a no start.

 

Do Z's have a "limp in" mode? In other words, does the Z ECU have premapped tables in the event that a sensor fails (or is disconnected?)

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J Taylor, the purpose of testing the spark at the coil wire, then at the end of the spark plug wire is not to see if you have a bad plug wire that's causing the car not to start. A thick blue spark at the coil wire and a thin orange spark at the plug means there's some breakdown in that segment of the secondary ignition, e.g., deterioration of the underside of the center of the rotor letting the voltage ground to the top of the distributor shaft. You can see this if you dissasemble and inspect. Testing is faster. DAW

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