heat soak? car feels weaker when hot

Hey guys,

Ever since I got my headers, cams and AA tune installed, when the car heats up, and I mean in 25+ degree celcius weather (85-90farenheit? lol), I feel a significant loss in low end power.

The headers are ceramic coated, but have peeled a bit so some parts are exposed. I'm also running a Dinan CAI. Anyone have an idea of what this could be? Is it heat soak? The engine bay does get pretty hot, but I'm not sure if its hotter than before the mods. Is there a way the tune can be the culprit (somehow?)

Any suggestions as to how I can keep temps down are appreciated. (air scoops maybe?)

Thanks.

It is probably caused by heat soak of your inlet air temp sensor. If the inlet air temp sensor is heated while sitting still for a period of time, it will indicate to your ecu that the air going into your engine is much hotter than it really is. When the ecu gets this info, it will retard the timing in order to prevent detonation. This is a bigger problem for cars like the e39 M5.....but it happens to all FI cars. Try insulating the MAF sensor, where the IAT sensor is, and see if the problem goes away.

Thanks for the advice. Any suggestions as to how to insulate the MAF?

One other thing to consider is the oil temp. Years ago I never ran an oil cooler and when we'd go to tracks like Homestead or Phoenix, the car would start to lose power after the first 30 minutes. When we'd come in for a pit stop, the car would start pushing water out of it within 30 seconds of sitting in the pits. The first thing I did was remove the whole electric fan and shroud. That helped but the problem was still there. Once I installed an oil cooler, the problem went away. now the oil runs around 230 F instead of 290 F. I did notice that on the dyno, the power did drop off once the oil temp went above 240 F.

As for the intake temp sensor. If you have a MS 43.0 ECU, then the sensor is in the intake manifold. If you have a MS 45.1, then it's in the MAF.

I do suggest buying this Thermo Tec Aluminized Adhesive Heat barrier for the shielding for the CAI. Then buy Thermo Tec Aluminized Wrap (about 1.5" wide) and wrapping the complete intake boot all the way to the throttle body. It works and lowers the intake air temps. Only takes about an hour and $100 (Jegs carries the stuff). I would put a few long zip ties around the boot once you are done. This will keep the wrap in place over the long haul.

One other thing. Get the Stewert High volume water pump and use the stock pulley. The stock pulley is small and will allow the water pump to deliver enough volume at low rpm's to keep the head cool.

Also, put in a new radiator. While the radiator is out, clean out the condenser with a water hose. You'd be amazed the amount of garbage that gets stuck between the condenser and the radiator. If the air flow is cut off, that just means a less efficient cooling system.

^thanks, that's great information. I'll look into these options.