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280ZX Surge


jusjofok

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So I recently took a two hour trip with my NA 82 280ZX and it developed a surge in it about half way through the trip. It started as just a stutter running at 80 and progressively got worse, by the time I got to my destination it would barely maintain 60 up hills and buck when accelerating. I checked fuel filter and pump pressure and didn't find anything wrong, free flowing through the filter and had 34lbs running jumping to 40 when I open the throttle. On my return trip the car would maintain 80 but surge on the hills. Any ideas what would be causing this? My definition of a surge in this case is a slight drop in RPM (maybe 50-75 rpm) and a lack of power.

Help would be greatly appreciated.

Thanks

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So I got some new information I am hoping will help diagnose the problem.

I have been driving the car as normal since the trip when it started the surging and it seemed to be running ok except for a surge on occasion. Last night it started with the surging (more like cutting out) again and wouldn't rev over 3500. It would run up to 3500 and wouldn't take any more throttle after that, I could coax it up with very slight throttle increase but not more than 200 or 250 rpm. If I rev the engine in neutral or with the clutch down it revs to 5500 easily. I experimented a little by accelerating in 1st through 3rd and it won't rev past 3500, just stops pulling, no pops, no backfires, just stutters and stops pulling.

So what do you guys think?

Thanks

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I had the same problem a couple of years ago and it turned out that my MAF was clogged so the car couldn't breath. Get some MAF cleaner from an auto store and clean the bejeezus out of it. There's also a sensor in there, either a nub or a wire/filament on the intake side that if it's broken, opens a world of problems.

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I eliminated a couple things yesterday, I pulled the exhaust down from the manifold and drove it thinking it was the catalytic converter, it still did the same thing. It has been getting a little worse too, now it won't run up past 2500. I could tell one thing with the exhaust off, when it reaches its limit the exhaust noise quits so I am thinking it is shutting spark off for some reason. I also pulled the AFM to take a look at it, it appears to be fine (didn't check as per FSM), I pulled the cover and it didn't have any corrosion at all. I checked the connector on the temperature sending unit, it looked fine.

Keep the ideas coming please!

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Tony D, I did search and the connector issue was the first thing that I came up with and did suspect. I recently had most of the connectors disassembled (about 2 months ago) when I replaced the head gasket and the connectors all looked good with no corrosion. They all mated correctly. Also in my experience when you have a bad connector you can wiggle the bad connector with the engine running and it will change rpm or stutter or miss or do something, this engine didn't falter when connectors were wiggled.

I did do a throttle chop when it cut out and pulled over and removed a plug, it showed extreme lean. I then checked fuel pressure again which was ok, checked volume and found it took 10 cycles of the key to get about half a 20oz bottle of fuel, took off fuel line behind the damper to eliminate it and still very little flow, removed pump and had a great siphoning effect from the pickup in the tank, replaced the fuel pump and all is well. I can now fill a 20oz bottle in a few cycles of the key and no more cutting out.

Thanks for the help guys.

Justin

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