When my A/C is on, the engine has more inertia--it is more resistant to revving, but overall power delivery is about the same. There's no way the A/C will use any more than 5-10 horsepower tops. In a wide-open acceleration run, I'd wager that there is almost no difference in 0-60 or 1/4 mile time...

 

This has been true for just about every car with AC since they were first available.

 

In stop-and-go driving, I feel the a/c -- the engine revs less freely and it does actually require a bit different shifting technique. On the highway at speed, I don't notice any difference because it takes relatively little torque to maintain hwy speeds.

 

My TSX doesn't seem to care what my right foot is doing. I don't think there is a provision for disengaging the A/C at WOT... if it does, then that feature is broken on my car. My friend's '03 TL-S doesn't disengage the A/C either.

There have been a number cars though that would disengage the A/C for a few seconds when the throttle is first depressed off idle, and then for around 10 seconds or so at wide-open throttle.

 

Sounds like you need to pick up the Helms manual and turn to page 21-54 to troubleshoot your compressor clutch problem. It definitely turns off at WOT, no 10 second delay.

 

Based on what I'm doing I'll turn the A/c on & off.

 

It would be neat to correlate TPS reading with AC clutch power to see if the "lag" people are talking about is actually due to the clutch taking too long to disengage the compressor (which I kinda doubt) or just the lagginess inherent in the adaptive DBW subsystem.

 

I've noticed that when the a/c is turned on, it bumps the MAP reading on my Brockway R920 up by about 10-15 Kpa.

 

Doesn't the Comptech ACM that comes with the supercharger kit function as a MAP voltage clamp and prevent the ECU from seeing boost in the manifold? I thought that was one of its functions. If so, then the MAP reading from the OBD2 port is false.

 

Since the car has only 4000 miles, I'll let a dealer tech use that procedure If there is indeed something malfunctioning, it will be the 12th silly defect on the car so far. I figure it is my luck--I happen to buy a car that is allegedly one of the most reliable you can buy, and I have the only one that was built at 4:30pm on a Friday by a drunk and/or disgruntled Honda employee

And I wasn't referring to a 10 second delay... some cars will disengage the A/C for 10 seconds (or some other finite amount of time) when the engine is at wide-open throttle. I cannot think of any modern cars that disengage the A/C indefinitely when the throttle is wide-open... not even the TSX I test drove did that.

With the climate control on full-cold (to rule out normal compressor cycling), my friend's '03 TL-S will keep the compressor clutch energized regardless of throttle position. We tested this one day (with a VOM) because his former Integra would disengage the compressor for a few seconds at wide-open throttle, and we were curious. We figured that Honda deemed the feature pointless... and really it kind of is pointless because a swash-plate compressor isn't going to consume that much power anyway.

 

Actually the Comptech ACM module doesn't act as a voltage clamp until boost kicks in. The reading is accurate until boost kicks in, which seems to be about 100 KPa. At that point then the MAP sensor reading maxes out at 100 KPa, and the boost reading maxes out at .5 psi on the Brockway R920 (even though there can be up to 5 lbs. of boost).

I've been in touch with Brockway engineering and they are actually working on an external map sensor. I will hopefully be testing their prototype.

 

Why would A/C engagement increase the manifold pressure? Does the ECU open the throttle a bit to partially compensate for the drag of the compressor?

 

Yes. Remember, if you lose the TSX ECU, you lose VSA and climate control as well...that is why. One cool thing about DBW is that you don't have to screw around with an idle air controller.

 

I believe the advantage of drive-by-wire throttle from a manufacturer's perspective is the ability to eliminate parts like an idle air control servo, thereby reducing parts and assembly costs.

Speaking of idle control, I hate the way my TSX starts up cold... The RPM spikes quite a bit immediately. Every morning I can hear the bottom end and valve train briefly chatter as it tries to rev at 1500RPM with negligable oil pressure. I'm sure it does wonders for the long-term life of the engine.

I want to experiment with a circuit for the coolant temp sensor... Something that will bring the resistance down a bit upon startup, then allow it to gradually assume the "real" reading.

 

If you haven't done so yet, I suggest you switch to a syn oil vs. dyno oil. I use Royal Purple mostly because of what you are describing. My TSX exhibits none of the symptoms that you have raised. I have in the past had an engine go over 300K miles, most of which was while running Mobil 1. Take a few minutes and hit RP's web site and read up on the "engine start-up" section.