LT1 runs better cold...Is this normal

[wrd1972]

My LT1 seems to have a lot more power when its cold, like befor the temp guage hits normal operating temp. Why is this and is it normal.
Does it indicate a problem.
Thanx

[Blevyou know]

Mine used to also (before i sold it) I would think it's simply beacuse the cooler air being ran through the throttle body is more dense at the cooler temp. Once the engine heats up and the throttle body heats up the air, making it less dense therefore less air.?! I maybe wrong.

What part of Kentucky are you from?

[TraceZ]

There are a coupe things you can do.

1) bypass the throttle body coolant lines
This will keep the TB cooler and allow for cooler intake air into the motor.


2) Relocate or bypass the IAT sensor with a cheap 4.7K ohm resistor from Radio Shack.
The IAT sensor gets heat soaked and gives falsely high readings. You can relocate it to a cooler part of the intake track less open to heatsoak or you can bypass it with a resistor and fool the PCM into thinking it is cooler outside all the time. Adding the resisor requires running higher octane to avoid detonation from the increased timing advance.

[Jeff_in_Atl]

There are a coupe things you can do.

1) bypass the throttle body coolant lines
This will keep the TB cooler and allow for cooler intake air into the motor.


2) Relocate or bypass the IAT sensor with a cheap 4.7K ohm resistor from Radio Shack.
The IAT sensor gets heat soaked and gives falsely high readings. You can relocate it to a cooler part of the intake track less open to heatsoak or you can bypass it with a resistor and fool the PCM into thinking it is cooler outside all the time. Adding the resisor requires running higher octane to avoid detonation from the increased timing advance.

#1 is good.
#2 I don't agree with the resister trick.

[wrd1972]

I already have the coolant bypass and I relocated the IAT sensor more downstream on my Cold Air Induction tube where it goes through the frame.
I dont think I will do the resistor trick.

[Jeff_in_Atl]

I don't see in your signature, do you have a 160 thermostat?

[TraceZ]

#2 I don't agree with.

dont agree with which part of #2?

relocating the IAT further from the engine is definitely a good idea. The way GM located it, it is subject to radiant heat from the motor. How dumb was it on GMs part to mount a temperature sensor for incoming air so close to the engine that it gets competely heat soaked?

some people do disagree with the resistor mod. This mod will not do anything to improve WOT, but it does improve part throttle response and make the engine feel more powerfull under normal driving conditions. From what I've been told over the years it basically gives the engine more timing advance sooner.

[Jeff_in_Atl]

dont agree with which part of #2?

relocating the IAT further from the engine is definitely a good idea. The way GM located it, it is subject to radiant heat from the motor. How dumb was it on GMs part to mount a temperature sensor for incoming air so close to the engine that it gets competely heat soaked?

some people do disagree with the resistor mod. This mod will not do anything to improve WOT, but it does improve part throttle response and make the engine feel more powerfull under normal driving conditions. From what I've been told over the years it basically gives the engine more timing advance sooner.

Sorry I was editing my post but you got it first.

I don't agree with the resistor trick because it depends on the air temperature as to whether it helps or not. When it's cold outside it will make it worse. The O2s should compensate for it anyway.

I think tricking the computer is poor way to adjust performance rather than doing it with the software.

[wrd1972]

Yup, got the 160 degree stat

[Injuneer]

Just how much difference do you see in performance, after it heats up? Things like coolant temp and throttle body temp are going to make a difference, but just barely enough to "feel". If its anything more than that, you need to look at things that can be temperature sensitive.

O2 sensors fit into the equation, because when they are "cold" the PCM stays in open loop, and limits the adjustments to the A/F ratio. Under any sort of operating loads, its only looking at the long term fuel corrections in Cell 18, and that is a "synthetic" Cell, arrived at by a calculation using the "normal" Cells. After the O2 sensors warm up, the PCM goes into closed loop and starts looking at a whole set of long term fuel corrections. If the O2 sensors are producing "bad" data (e.g. they are faulty, or there are exhaust leaks or misfires) the long term corrections can get all screwed up and the car can lose major power under some operating conditions.

Also need to look at things that may break down when they get hot - IC Module (look for Shoebox's cooling mod), Opti optical sensor, coil, wire insulations, etc.

Also might have a problem with the coolant temp sensor. If it is giving false low temps, it will screw up the A/F ratio under most loads.

So.... its a matter of whether its just a change you can barely feel, or whether its a major loss of performance and/or smoothness when things heat up.

[Jeanius]

Which is better, a 160 or 180 degree thermostat?

[wrd1972]

Its a very small difference but just enough to notice, like turning the AC on then off kind of difference. It has new O2's and shoeboxes cooling mod to the ICM.

[Canadian WS6]

I have the same problem with my car. It is a fairly noticable difference, if it is plugged into a scanner will this tell me if one of my sensors is worn out.

[brynnda]

Which is better, a 160 or 180 degree thermostat?

you live in california, do a 160. if its gets below 35* dont run your car, its not good

[Injuneer]

you live in california, do a 160. if its gets below 35* dont run your car, its not good

Why would it be a problem when temps are below 35*F? From a cold start, up until the coolant temp hits 160degF, there is no difference between a 160* and a 180*. And 160* is only the beginning of when the 'stat opens.... it still isn't fully open to about 180*. And at anything other than highway speeds, the coolant is going to be showing closer to 200* no matter which 'stat you have.

Remember, the LT1 coolant temp only looks low because the coolant is hitting the heads first, and then continuing through the engine where it continues to pick up heat. Watching my oil temp gauge, the oil always reaches a temperature sufficient to drive off water and other harmful contaminants.