Thaik

Hi,
As the title suggests, I notice that when I'm driving on the highway and I'm trying to reach high speeds like anything above 60MPH, the gas pedal is hard to depress, the engine is sluggish, I really have to depress it really far into order to get some feedback from the engine.

My car is a manual and this happens in 5th gear, I have to downshift to 4th gear in order to get accelerate from that speed.

When I say cold winter, I'm talking about -20 C and lower (about -4 F and lower).
When it's warmer, the car has more power and is easier to accelerate.
It is so bad when I try to accelerate that I can see my fuel gauge needle dropping constantly, don't know if it's the needle or if my engine is really drinking all that fuel.

Anyone had this issue?

scooty

Wait till the car is at operating temperature before you try to floor the gas in the winter, and then wait some more to allow time for the oil to reach proper temp. It just takes a while, so be patient.

The engine actually produces more power in cold weather because the air is cold and dense. It just has to be at the proper operating temp.

The reason your car feels slow is because it is! At 60mph in 5th gear you really are not in the power band. Down shifting to 4rth is what you'll have to do to accelerate.

Also, if you have the heat blowing through the windshield defrost vents then the AC compressor is running, even if the heat dial selector is all the way hot. This puts a load on the motor and decreases performance.

Check your tire pressure as well. Its not uncommon to loose some air pressure in the winter.

Thaik

You might right about the operating temperature because I currently have some problem reaching operating temp on really cold days even after 10-15min of driving.

Whenever I open the heater to full heat and the fan the medium speed (right in the middle), I can see the temperature gauge moving down when Im idling.
It goes back up when I turn off the fan or when I start to drive again.

I guess theres something wrong with my thermosthat, not totally broken, but not working the way it should. I think the valve open way too soon.

About tire pressure, before it got cold, I put them at 30PSI, but with the cold, I guess the pressure decreases.

scooty

It was -10 F here this morning. I was about 20 minutes into my daily commute before the engine reached operating temp. And that's in stop and go traffic.

I keep the heat dial on full hot and I keep the fan speed low until it heats up. This helps a bit.

Check the coolant level in the rad. It might be low. How cold is it?

scooty

Oh and BTW did you get your front end clunk sorted out? I had a broken engine mount and replacing it helped, but I still get a clunk every now and then.

Also, I hear clunks when I rock the steering from side to side, like the rack is loose or something. But it isn't. I grabbed the steering rack from under the hood and yanked as hard as I could. It felt very solid.

Thaik

It was -10 F here this morning.
See? I think I really have a problem, here it has been only -4F during these previous days and I'm having difficulties reaching operating temperature.
The problem is that it takes kind of longer to warm up compared to before, and what bothers me the most is that the needle of the temperature gauge keeps fluctuating while heating up.
It goes down when I idle, it goes up when driving on the highway or simply keeping the engine revved up longer.

I think it has something to do with my thermostat. Because I swapped the engine for another used one and I didn't change the coolant passage (where all the coolant hose come together). I kept the one already on the new engine.

About the clunking noise, no, really, haven't found it yet
When the engine is turned off (no powersteering) and I'm wiggling the steering wheel from side to side, I really can't hear a CLUNK CLUNK CLUNK.
It's really noticeable, but when I grab the inner rods, I don't see or feel and looseness.

I kind of hear it too when making long turn, like when merging on the highway.
It does it on speed bumps when the front wheels aren't hitting the bump at the same time.

scooty

Something is definitely up with your cooling system. I've never seen the temp gauge needle fluctuate and I have a blown head gasket! albeit its in the very early stages.

What kind of coolant are you running? Do you have the right mixture?

Make sure the cooling system is bled properly. Check and monitor coolant levels in both the radiator and over flow. Look real close for any coolant leaks.

If you don't have an OEM Honda thermostat, get one.

The other 2 things you can check are the radiator cap and the coolant temp sensor. Do you have any check engine codes?

Thaik

Everything seems to be in order now.
I think that because the new engine, before being swapped in, has been sitting too much time doing nothing and I guess the thermostat was kind of sticking inside.

Now the needle is moving up gradually and stays stable.
I have no CEL related to that.
I have what I can call a "coolant temperature tester", sorry I don't know what exactly it is called.
But when mixing the coolant, I mixed a little more coolant that water, and the coolant can sustain temperature down to -35C (-31F).

Radiator cap and coolant are good.

If there is really something wrong with the thermostat, I can still replace it with the one in my old engine.

Also, thank you for your concern.
Anything new with that popping noise of yours?
Still haven't diagnosed that yet, kinda lazy here XD