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Discussion Starter · #1 ·
So a little background so everyone knows the car. 77 280z owned since 2001. Stock L28 block and head, Isky stage 2 cam, MSA header, custom 2.5 inch exhaust, custom cone Intake, areomotive FPR set I belive 4psi higher than stock (dyno tuned), MSD ignition. Last tune up was a year and a half ago. Plugs, wires, valve adj, oil change, diff/tranny service, etc. I only drive about 250 miles a year so nothing has really changed since then. Except 2 months ago the 3rd injector hose started leaking. Got a clamp on it as a temp fix while I ordered pallent fuel rail and new injectors. Still waiting on the injectors to come in. But the car has been running strong with no issues. Drive it every 2 weeks around the same loop here in town

So today on my drive, it's 104 out at 9 am. Drive 2 miles down the road, hitting some lights along the way. Driving normal. Hit the fwy and get on it a bit but nothing crazy. Half way on my loop I'm just cruising. Get off the fwy and more surface streets. No problem. I'm about 1 mile from home at a light. As I accelerate the car hesitates and stumbles. I'm easy on the throttle realizing what's happening. I shift into second as as I come on the gas there is a 1 Second delay and then throttle kicks in. So the car bogged and then accelerated. Immediately pulled over. Car is idling fine. Don't see anything out of place. Get back in and limp it home. I notice if I accelerate it hesitates and then stumbles. If I hold a steady speed it runs fine, but if I try to accelerate further it stumbles. Got it home. Checked for vac leaks, sensor connections, fuel injector connections, plugs, wires. It all seems fine. Turn the car on. Idles fine but if I throttle up you can hear the intake gulp like it always does, fuel gage goes up like it always does, but it hesitates a second before acceleration and then will stumble if you cont accelerating. If I hold the throttle steady it will run fine. Injectors are all clicking. Any thoughts? It's just odd one second it's fine and next it's not. I'm handy to a point so I can check some stuff but others will require I take it to my mechanic. Problem is he is 45 minutes away so trying to avoid a tow
 

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I would drive it again when its cooler to see if it was just it being 104 outside and not a mechanical issue.
 

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Discussion Starter · #4 ·
Well my ohm meter is busted so will have to wait until I get a new one.

I did check the car again today. Still acting up. When cold it was running a bit rough. After a minute of warming up it idled smoother bit still stumbles on acceleration
 

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Get some seafoam spray to spray into the intake and some bg44k for your tank and see if that helps. If not your intake injectors and valves will be clean.
 

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Discussion Starter · #6 ·
So an update. Checked the temp sensor and thermotime switch, injectors, cold start valve, air regulator, throttle position sensor, fuel injectors, plugs, wires, vac hoses. All seems well.

I noticed after taking off and putting back on the gas cap that the car ran better. The hesitation off/on throttle is gone now. Bought a new cap but didn't change anything. Ran fuel cleaner through with new 91 Oct gas.

So currently what I notice. When idling it sounds fine. When accelerating there is loss of power and it feels like rapid surging in the throttle rather than smooth. The exhaust tone is also much deeper now and you can hear a vibratory sound that matches what I feel in the throttle. The car is drivable but doesn't feel/sound right. Any other guesses?
 

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Are you smelling any gas fumes?
 

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You should put in some BRAND NEW ngk plugs, run it for a few days and pull them. see if the air fuel mix looks right based on plug reading.
 

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Discussion Starter · #9 ·
No gas fumes or change in odor
 
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