Any idea what would cause me to loose low-end (i.e. below 2 500 RPM) power after about 20 or so minutes of driving time? I don't really have any numbers, but the ***-dyno is noticing a loss of power. This is an L98 car, so it's supposed to have a lot of torque down low--and it has plenty, esp. when it's running after having cooled down fully. But after it heats up, the acceleration is sluggish even in 2nd gear with the throttle down 3/4 of the way or so. If I push in the gas enough to trigger a downshift, it'll wake up--but that also puts the engine in the middle RPM range (+3 000 RPM).

Just wondering... Thanks for any input.

 

im gonna say its probably the tranny and not so much your engine
thats how mine was this summer before I installed the tranny cooler

 

All cars are this way. When your engine heats up so does the intake and air filter assembly. This in turn adds heat to the intake charge thus reducing its density. Also, when your car is cold it is most likely running in open loop which adds fuel and timing.

 

I had that same thought about the transmission... Although, why would you have needed to install a transmission cooler? I thought these came stock (unless I'm confusing the two metal lines that run up to the radiator with something else).

As for this being "normal" with all cars: I do realize that, just due to physics, extra heat would cause a decrease in performance. However, this seems like a more dramatic decrease than should be acceptable. I can almost break traction in second gear if I gun it when I'm within, say, 10 minutes of starting it. After it's at operating temperature, however, there's not much of a difference between 1/4 throttle and 3/4 throttle. It just kinda slowly lugs on until it hits about 2 500 RPM, and only then does it feel like I've got a V8 under the hood.

 

In regards to being in open/closed loop operation: Is there any way for me to force the computer to remain in open-loop operation even when it's hot? I'm interested in seeing if the performance decrease is due to what you're saying.

 

You could still have a problem that is associated with closed loop. You could have a sensor whose output to the ECM is inaccurate casuing poor performance. Is the car in good running condition? Has it had a tune-up in the last 50k miles or more? You can program the chip to stay in open loop but that is merely a band aid some chip tuners use to bypass the 02. Have you checked the simple things like a fouled plug, cracked plug wire or clogged air filter? It is not uncommon for these cars to feel sluggish in the heat. A good comparison of power between cold and heat soak would be to take your car to the track. You can run it when it has sat and then run it after you have let it heat up. Compairing the times could confirm a problem or put your mind at ease.

 

the stock cooler is apparently just enough to keep your tranny from killing itself, but not very helpful in the heat
and you live in TX? sooo i dunno im just saying
thats where my power was going, torque convertor slipping more?? or the tranny itself?? i dunno but it sure feels better now
it felt the same as your describing pretty much

as for my engine its running around 170ish or below almost all the time (before and after the tranny cooler)