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Loss of eng pwr at 4000 rpm. 81 zxt


luvmy280zxt

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Ok, Ive asked b4 about this problem and a few people gave me sum ideas. Tried them all and it worked 4 a bit. Am now almost over my budget and need a no Shizzle diagnosis!!! On start the car run's good. Its when i start driving. When in 2nd gear at 3000 rpms the car shudders bad. In 3rd it shudders at 4000 rpm. and i loose power unless i shift and give it gas. There are a few times while in idle ill rev up the eng and between 3-4000 rpm and it will shudder and ill hear a backfire from both the intake (NEW MAF) and exhaust. I've done a complete tune up!! Is there any connections I need to check? Also....dum question but, where exactly is the MAF located. LOL

 

Thanx a lot!!

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  • 1 month later...

If your car is backfiring that is a surefire that something is causing your fuel air ratio to be screwed up. More towards the rich than lean. Check to see if your dizi is centered and doesn't have an advance or retard, if its backfiring and hesitating at certain rpm's especially the rpms when boost kicks in I'm thinking that the a/f ratio is REALLY rich, which would mean the timing is retarded. I hope that helps a bit.

 

 

1981%20Datsun%20280ZX%20%2833%29.jpg

 

Maf is located right up against the drivers side front of the engine bay on near the core support. I'll find a pic of one or take one tomorrow whichever comes first. It's the silver box in front of the charge pipe.

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Maybe a little off topic, but TexasZX is that your Z's engine bay? That's sweet. I love the use of blue on the valve cover, with the wires, and is the J-pipe Blue as well? That's really cool.

 

To go along with HowlerMonkey I'd say to try this out. I had a very similar problem. Car ran great all the time, most of the time I was just low speed driving to work so I never noticed this problem. Then I got on the freeway and once I started to get under boost or up to higher RPM generally over 3000, it may have been closer to 3500. The car would start popping and just losing power like it didn't have enough fuel. This drove me nuts for a while. I remember pulling out the MAF and checking the boots, and checking the clamps on the boots, and making sure the J-pipe connection at the turbo was connected, checking vacuum lines, etc. Everything was fine. I unplugged the ECU connectors and plugged them back in. The problem was gone. Then next thing I knew it came back again. I reached down and shook the wiring at the ECU. Problem went away. I cleaned the ground connections to the intake manifold and this seemed to help. After a while the problem came back.

 

The problem was related at least in my case to 2 ground wires on I think it's the bottom ECU plug? Anyway it's two black wires one over the other. They run separate and then into a metal crushed connector where they connect to a real big wire and two other black wires. These our the main ECU grounds. It just seems like this type of connection was fine at the time, but over time gets corroded or the wires must start to move a bit. I tried to use crimp connectors, but the one wire is so big it's hard to do it properly. So finally what I did was to just take the 5-wires. Twist them all together really well and solder them together. This finally got rid of my problem.

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