I don't recall this ever being this bad before, but my car is old with alot of miles. '03 with 100,000miles 5AT with original clutch fan.

With this crazy summer heat (Texas 90+deg), I'm getting some power loss or specifically lag from a stop....and pretty much only when I have my a/c on. It feels like the first half of the throttle application is doing nothing. Only when I dig into the pedal will it pop the tranny down and move.

Otherwise, I drove around when it was cooler (below 85deg, before lunch and later in evening) without the a/c and I get really good and normal power delivery from stops just like I would otherwise.

Are you guys feeling the same thing in Texas or is there something with my car?

 

sounds pretty normal to me. It was 99 with 70% humidity yesterday here and I noticed a signifcant power loss. Hot and humid weather will rob performance. Having the A/C on will definitely cause more power loss since the engine has to turn the A/C compressor as well as the alternator's heavier electrical load.

 

It's pretty typical for these motors. They're high compression (ie more likely to detonate), have overly sensitive knock sensors, and flakey ECUs. When the ECU sees ultra high ambient temps, high intake temps, high engine coolant temps, and higher tranny fluid temps, it's going to dumb down the power a bit. Factor in the reduced air density, A/C compressor drag, hard working alternator (if you have e-fans = major electrical drag), and the mechancial fan engaged, your car is going to be down on power.

The air density in Kansas City (1100' asl) over the past few days (upper 90s, 105-112 heat induce) has been hovering in the 88-90% range which is equal to driving at a 4500'-5000' elevation. My G is probably 10 to 15% down on power. Luckily, I can get 93 octane which helps keep the detonation in check. My G is laggy in the ultra hot temps, but nothing like my old modified VQ30 Maxima or modded 94 Z28. Those cars really got pounded by the heat. I'm actually surprised my G runs as strong as it does in this weather.

 

It's been in the 90's here all week. Omaha, Ne. Car is down on power......for sure. Could be worse, could be more humid outside. But to be honest, my 2005 Altima Se-R felt faster.

 

Well, I feel sad because it feels weaker than normal. For example, a 2006 accord I4 auto jumped out faster and sped off faster from a stoplight than my car with a/c on. As I dug into the pedal, all i felt was lag and practically no power until pressed more than halfway into the pedal.

Even my gf's '03 civic ex sedan auto scoots off the line very nicely and NORMALLY even with a/c on.

 

With 100K miles you might need to clean your injectors for max performance.

 

when was the last time you did a tuneup? Plugs, coolant, oil, trans fluid, differential oil, air filter? 100K miles is not that much as long as your doing your routine maintenance.

 

It's been over 30kmiles since I had a good tuneup. Coolant was checked about 2 months ago and some coolant was added. The tank says it is at max currently. Haven't touched trans or diff oil for longer than that though. I was told by several knowledgeable mechanics that it is in most cases a non-issue. But I figure it wouldn't be an issue with normal drivers but since its a G, its driven harder. I should look into that. And btw, the feeling of power loss is not affected by the ecu reset. Before it was reset it felt loss and laggy and even a weeks after the reset it feels loss and laggy. Reminder, this is when driven during the hot part of the day with a/c on.

I ran a k&n dropin but didn't feel that it was really worth it. I swapped it for a paper about 2 months ago. There is/was no diff before or after.

Like I said though, in cooler temps the car drives like it should. Strong off the line and everywhere else.

 

That really has nothing to do with power. It's simply how thier throttles are tuned. With the G, the gearing is pretty deep and the low rpm torque pretty thick, so throttle response is dumbed down a bit in the low rpms to keep the car from feeling really jumpy. That Accord has probably 100wtq right around idle. Your G has around 180wtq. Big difference. Also, the variable cam timing is pretty weak at first. If you're really concerned about getting a jump into traffic, apply more throttle.

 

I understand what you are saying DaveB but it is very noticeably different when it is say hot or cool outside...just like with almost any car. I don't know if the throttle is more relaxed in hot weather or if its just heat soaks OR something wrong...but its a really crappy feeling. It's very sluggish off the line in this heat.

I feel that the civic simply has that pep off the line and in the throttle/pedal in both hot and cold weather. It doesn't matter...the car reacts very similarly. The G35 does not...noticeably at that.

 

It's pretty normal really. It's why I LOVE the fall. Cool, dense air leads to more power.

With the heat and humidity, the air contains less oxygen and your power level goes down.

A/C plays a role too. Some cars you never feel the A/C on at all, others you do. When mine is on, i can feel the performance difference. The A/C robs crank HP, but also creates more load on the engine creating more heat soak reducing power even more. Even if you turn the A/C off, the power loss will still be there until the engine cools slightly (highway driving usually does it or just sitting)

It's why i hate driving a fast car in the summer


But your car could have some mechanical issues. Tough to judge if the power loss you speak of it what I notice with mine through the net.

 

very slight. I mainly notice at 100 degrees and a full tank of gas on D. But if I'm off VDC and on manumatic---this G still goes very strong (particulary on 1/4 tank!). I only have 52kmi for a car that's 3 mo. shy of being 7 yrs in service--not bad. I'm getting the coolant, oil/filter, ATF and diff. fluid, air filter in couple weeks so that should help. I've done the belts recently too.

 

Might want to consider cleaning the TB and MAF.

 

Well, just the other day, my a/c compressor belt tore off. Now the car feels as quick as it should and used to be in this crazy Texas heat-it helps somehow not having to rotate another mass.

I believe my power loss or "from-a-stop-lag" is from the compressor....or fraying belt somehow. I should mention that after I made this thread, I noticed that I was getting some odd metal to metal sounds from the engine area when I turned the a/c on. Then finally, the other day as I was driving, i heard a very distinct and loud "metal on metal" or "metal pinging and ratcheting noise". Thats when I just turned the a/c off. Upon getting home, I sat in the driveway taking turns with the a/c on and off and there was no other weird noise from the engine area. The air stays warm and never gets cold and I found the a/c compressor belt torn away under the hood. I will have to check it out with my dad to see if the compressor is shot or anything else.

Does anybody know if the compressor can make these noises in a normal situation or a situation like I had? OR are metal pieces being sucked into the compressor-ruining it?

 

well if the belt never was replaced, it probably broke due to mileage and age. Definitely inspect the compressor and tensioner when you put on a new belt. My compressor makes a metal clacking and slight squealing noise from time to time, moreso in the winter. Once its warmed up it goes away though, i think they are just naturally noisy in our cars.