loss of power when really hot

[4x4Dude]

Well as you can see on my profile i live in AZ. Its been around 115 or so the past few months and i have noticed that since i bought it....I'll start her up after sitting all night and she will accelerate just fine and run great, but as soon as the engine is on and running for a while in the heat i'll step on the gas from a stop and she feels like she has no power. This only happens during the day when its really hot outside. At night time she will run just fine. There are some moments with hesitation, but i'm afraid to even think about what that could be.

She will eventually accelerate just fine and level out, but from a start in gears 1 and 2 she feels like a fat kid trying to run a marathon. no power whatsoever.

I've heard it might be spark plugs, or maybe the wires, but the guy i bought it from just did the 100k tune up at about 95k when i bought it. so the plugs were just changed out. help please!!

I love my car but i've had nothing but enginge issues with her since day one! The thing that kills me is that none of this stuff happened on my test drive when i went to go buy it from the guy who obviously didnt tell me everything about the car!! :shootout:

 

[4x4Dude]

Well, i think i found part of my problem. One of the clamps for my intake was loose and was letting air in past the mass airflow sensor. So i tightened it up and hopefully that will make it a little better.

 

[ELVATO]

115? Wow, that's hot.

Although it's probably something else, my guess is that it's might just be the heat. More heat, less oxygen, so less power.

Apparently, this issue becomes really noticeable when you have a boosted engine (which I know you don't have, just throwing it in there FYI.)

 

[4x4Dude]

Thankfully we only have another month of hot weather. It needs to get cooler already!!

 

[green03]

depending on your factory calibration it may be pulling alot of timing to keep it from pinging when the air temperature gets really hot.... this will kill the power....
glad I've only seen 105 degrees here in TX.....LOL

Matt R

 

[sweetstangchic]

Well I know for me in Vegas I have the same problem, 120* + and if I sit the car for awhile it sounds like the fan is on REALLY high and no HP whatsoever, but after a few minutes it does fine. Expy's and 120* weather dont mix....

 

[pronstar]

Sitting in traffic will make it worse.

Even in the heat, if you can get a little bit of airflow going it helps prevent heatsoak.

But high temps = teh suck for power no matter how you slice it.

Things feel much worse with forced induction.

 

[Grasshopper]

I don't know if this is accurate, but I've heard that the stock torque converter lockup settings in the EEC are responsible for the apparent lag in 2nd gear. I've noticed it in our Expo. I would think that performance would go down if the tranny and converter are running hot.

 

[AvroAero]

Well this is mentioned in the manual so check it out. If the computer detects the engine running to hot, like in the event of collant loss, it shuts down 4 of the 8 cylinders and uses them to circulate air throughout the engine. Obviously, as the manual says, this will cause a loss of power. Although I don't remember 100% but I'm pretty sure that it won't cause the check engine to come on. Although logically I would think that should cause it to flash or something.

 

[ELVATO]

Originally posted by AvroAero
Well this is mentioned in the manual so check it out. If the computer detects the engine running to hot, like in the event of collant loss, it shuts down 4 of the 8 cylinders and uses them to circulate air throughout the engine. Obviously, as the manual says, this will cause a loss of power. Although I don't remember 100% but I'm pretty sure that it won't cause the check engine to come on. Although logically I would think that should cause it to flash or something.

I thought that only happened when the engine was overheated. This, you would be able to tell with the temp gauge in the red zone. Also, it says that the engine would run very rough, but it would probably run you for 50 miles till you made it to a mechanic.

 

[AvroAero]

Could be. Although it depends how the computer figures out the temperature. It could be also from the MAS measuring incoming air to the engine and not only the oil temperature. Or some other temperature sensor in the engine bay. The temperature gauge on the dash is oil temp only.

It may be a mild form of it, I'm not sure. Just the symptom and the cause seemed to tie together.

Or maybe the computer is just limiting how much you give it until theres circulation on the engine. But I don't think they're programed that sophisticated.

 

[green03]

The cooling failsafe mode turns off cylinders and air cools the engine in the event of overheating. You would definitely know if this was going on..... What is being experienced is the timing being retarded due to air intake temperature....... This is less pronounced with a higher octane custom but you have to run good gas in it...
Matt R

 

[4x4Dude]

Ya, this has been happening less since i bought it as i started putting the expensive stuff in when i gas her up now. It still happens but to a less degree. Thanks for all the input guys, and i'm just glad my engine isnt going to blow up lol

 

[green03]

did you reprogram for the premium? If not you aren't getting the full benefit of the good stuff. You would pick up some mileage that would offset the cost of the premium fuel....

Matt R

 

[4x4Dude]

I didnt know you had to reprogram for premium? What is the best reprogramer for the money? I've never thought about getting something like that before, but i've heard they can be extremely beneficial.

 

[4x4Dude]

Something like this?

http://phoenix.craigslist.org/pts/405652612.html

 

[green03]

That's a pretty good deal. I write custom programs...... but for 200 bucks that one is a pretty good deal. Programming for premium lets you take advantage of the better octane, otherwise there won't be a performance increase with the better fuel.

Matt R

 

[AvroAero]

Is there a way to unlock programers? I have the same one that 4x4dude showed.

 

[green03]

you usually have to find the truck that the tuner is married to and put it back to stock before the programmer is available for use again on another vehicle. Sniper does it a little different you can program many vehicles by purchasing "bullets" for each vehicle alot cheaper than buying the hardware all over again.
Matt R

 

[AvroAero]

Well mine locks itself to the vin of the vehicle, but the one 4x4dude showed said it was unlocked. so either you can unlock them, or it was just never used.