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Discussion Starter · #1 ·
I went ahead and put PREMIUM gas in my 82 280zx turbo, it runs fine until you floor it. At around 3750 rpms, its start bucking a little, kinda like if you pushed the gas incosistenly, but sutle. If you try to ask it for more, it starts making a popping sound. Again, its not very loud, is it a misfire? causes?

Won't go past 4k, in neutral, it revs fine to 4500+ rpms.

It seems to be a high load situation since it happens if you floor it going up a hill. This started today after not driving it all weekend.

ARRGH, THIS CAR IS DRIVING ME INSANE!

Help much appreciated,
Mario
 

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check afm and gas tank afm could be messing up that can make it pop and surge like that so can a rusty gas tank or cloged fuel filter or cloged fuel pump filter easy test on afm is open it by hand and rev it up but keep in mind high rpm's at idle is alot less pressure needed than high rpm's under a load like takeing off or heading up a hill or just driving in gen
 

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Discussion Starter · #3 ·
Take offs good, just happens in second, don't know about third, as that is close to 90mph.

Checked connectors, added pint of seafoam to tank, drove it hard, and it seems to have stopped. I went to a store, was gone for 15 mins, and it does it once on the way home.

Could it be heat/fuel related?

The gas was from a chain gasoline store, but there tanker truck got held up. They ran out of normal so they were selling premium at same price.

Could it be sludgy old gas?

Thanks
Mario
 

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Have you tried cleaning the connectors to the ECU? Try unplugging and plugging these several times to remove any dirt and corrosion. Spraying some electrical may help. I find I need to do this to my 81 turbo once a year, same symptoms, will not gain speed after a certain point and will backfire through the intake (popping) indicating that it is running lean.
 

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I'm currently having the same problem and trying to track it down. Started last week out of nowhere. I was driving at 75mph on the freeway in 5th gear when it started doing it. Pulled off the road and parked. Turned off the car while I called a classmate I wasn't going to school as I feared I might get stuck down at school which is 60 miles away and a tow is very expensive at that distance. Five minutes later I decided I would try to get the car home. Started it up and it ran fine all the way home. Drove it all weekend and it was fine. Let it sit Monday. Then Tuesday before school I filled up with gas from the same station near my house that I've been using for 2 years now. Drove down to school fine. Later that day I start the car and warm it up. Right when I turn out of the parking lot I get on it a little as there is a car coming. Right in the middle of the turn the car acts up and bogs, then kicks back in and takes off like a bat out of ****. Acts up for about 10 mins while driving at low speeds, under 45mph, then stops and runs fine the whole way home. The next day it was fine too. So far the only thing I have found that links the two incidents together was that both times before it happened I filled up with gas right before. The first time it happened I had filled up with gas the night before and the second time I filled up with gas that morning. I've heard it could be bad gas or moisture in the gas from condensation from temp changes as in my area it is now cold at night but hot during the day. However, like I said I've been going to this same spot for a long time and have never had a problem. Also my fiance goes to the same place and doesn't have any problem with her car. We both use 91 octane as that is what are cars are set up to use with our mods. Anyway I'm running a control test tonight and tomarrow. I filled up at a different gas station so we'll see what happens tomarrow when I drive. So far I've replaced the cap, rotor, plugs, fuel filter, and cleaned all electrical connections which didn't solve the problem since it still acted up on me the second time. Like the others have mentioned it could be rust in the gas tank coming through the lines blocking fuel but my fuel pressure gauge on my adj. FPR never showed a lower reading when I was having a problem which to me would indicate fuel psi is good. The only other thing I can think of is a bad AFM but I'm not to sure how to test it. The only way I know of is with an OHM meter but I've heard that even that can be inaccurate in how the AFM is working. I've also heard that it could be the AFM flap inside that is sticking which I haven't checked yet; I'm waiting to see if it's possibly bad gas. Being that this is an intermittent problem it's going to be hard to diagnose. I'll keep you updated and please do the same.
 

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lol this might be funny but, i had this problem the other week and it was from moisture getting into the dizzy, a hose from the TB to the Thermostat housing had a slight crack in it which dripped on the fan and was putting moisture into my dizzy.....


Worth a check ;)

Mat.
 

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Well after driving today no problems. I guess it could be bad gas I was getting. Now I have to run a second control for the experiment which means next time I fill up I go back to the original place I've been getting gas to see if the problem happens again. If so then that clearly makes it bad gas but if not then the problem lies elsewhere.
 
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