92 240sx bogged in hot weather

[Anomaly]

I have a strange problem. My 92 240sx (with the KA) seems to loose alot of power during warm days. In the winter when its cold, the car pulls hard, in the summer it feels slugish. Im estimating about 10-15% loss. I know, because of the air pressure in the winter, you do notice more power but its only like 2%. This is something different. The only mods i have are high-flow intake. Any thoughts? Thanks

[navysnail]

what kind of fan are you using?

[rogoman]

You may have a vacuum leak in the intake system after installing your high-flow intake.

To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. A good place to connect to is the charcoal canister. There should be three hoses connecting the carbon canister. Two of the hoses go to a purge valve that's built into the canister. The second larger hose off the purge valve should be your vacuum line. With the motor fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be around 21 InHg.

If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.

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[Anomaly]

Well, i only installed a high flow filter. nothing else. I did not mess with any of the vacume tubes. Also, I have the stock radiator fan. I will note that the car does not seem to overheat. I was thinking this could be a problem with the MAF or the intake temp sensor. It seems like the car is detecting warm air entering the intake and slowing down the timing advancement, or something to that effect. Even if I get the engine nice and warm, if it's cold out, I don't experience any loss in power. If its hot out, the power loss is huge.