Bad Gas Milage and Cooling Questions

[JDMMA70]

Been about 6months so far since I last asked about this. In that time I've swapped Heads and fixed all boost leaks. So even after all of that im still only managing 10.6mpg. Fuel Injectors Balanced.

Now to help out here's what I haven't changed yet. Fuel Filter, shims on the head (valve tick), and cold start injector. I can't think of what would cause me to get this bad of milage, and im not racing around everywhere. The mods on the car are as follows 3" Exhaust, Intake, 20G Turbo, Boost controller (5psi Low, 11psi High).

For my cooling question, ever since I swapped heads, and did a coolant flush, the car takes forever to warm up. Even after letting the car idle for 10min and driving it for another 15 it still isn't at full operating temp (going by the stock gauge). My guess is maybe the guage sender sensor is going out? Or maybe a wire? Or could it be my fan clutch is working to well (if that's possible). I've had the fan clutch on my car for about 7 1/2 months now and only above 60mph (like on the freeway) does it disengage (gets quiet). On cool nights on my way home from work; outside temp is 58'F, I can hear the fan "wooshing" at 40mph with the windows up. Now maybe im not used to having a new fan clutch but im so used to having a quiet one. However even after having it on the car for 7 1/2 months its still really tight when cold, you can't get it to spin if at all, tapping it will only move it less than an inch. Maybe this also attributes to my bad milage?

So is there such a thing as over-cooling? Or is the sensor on the t-stat housing bad? As far as I can tell the gauge still works its just really slow.

Help would be appreciated
Thanks for the time of those who read this

~JDMMA70

If I missed anything please let me know so I can fill it in.

 

[CyFi6]

Sounds like your thermostat could be bad(stuck open) or maybe there isnt one in there? If your car runs cold, it richens the A/F mixture, which would cause your mileage to go down significantly. First thing i would do is verify temperature at the thermostat housing after driving around a little bit. The thermostat is supposed to aid in quick warm up times and also regulate operating temperature. If your fan clutch is new, i wouldnt worry about that much, your thermostat should be restricting coolant to the point where even if the fan was locked on it wouldn't matter.

 

[zachm611]

i would check for a tstat. my car didnt even have one in it when i first got it. also does it seem like your fan clutch is always on or does it only come on when your car is warmed up. i know on hot days here in the desert i sound like a semi driving down the road. the fan clutch is annoyingly loud when its on whoooooo but it does a good job cooling :] good luck.

 

[Pantaloon007]

According to the stock gauge, my car warms up in approx 5 miles/5 min of driving. You are most likely missing a t-stat and your cold start injector isnt turning off. Otherwise a wideband would really help you figure out whats up. I doubt your fan could keep your engine so cold that it never gets out of warm-up. I know you said your injectors are "balanced", but are you sure they are not stuck open?

 

[jdub]

The cold start injector functions when coolant temp is low and the starter is engaged. Once the motor is started, it's impossible for the CSI to remain on due to the way it's wired. However, the CSI can be mechanically stuck open and cause a rich condition, but that has nothing to do with coolant temps.

 

[Nick M]

The cold start injector functions when coolant temp is low and the starter is engaged. Once the motor is started, it's impossible for the CSI to remain on due to the way it's wired. However, the CSI can be mechanically stuck open and cause a rich condition, but that has nothing to do with coolant temps.

Yep.

And he may have a working thermostat that is rated too low. With a fan clutch that doesn't get quiet within 30 seconds, it will be noisy.

I think the problem with milage is driving habbits. Pull DTC's.

 

[sneakypete]

did you change the water pump?
small chance this may be your problem... but i changed the water pump on my girlfriends es300, never checked the part number. turns out the guy at the parts store got me the wrong water pump (for a v8 lexus). it flows alot more than it should. her car barely got close to operating temperature.
-pete

 

[Nick M]

did you change the water pump?
small chance this may be your problem... but i changed the water pump on my girlfriends es300, never checked the part number. turns out the guy at the parts store got me the wrong water pump (for a v8 lexus). it flows alot more than it should. her car barely got close to operating temperature.
-pete

That would not matter. The thermostat controls the minimum operating temperature. If it is closed, you could have a 40 gallon per minute pump on there, and there would be no place for the heat to go without convection.

 

[sneakypete]

very true

 

[Keros]

If your milage was crappy before the engine work, and it's still crappy now... might I suggest a quick look at the brakes. On the possibility that the milage issue and cooling issue aren't related, make sure your brakes aren't dragging.

Lift the car and make sure the front wheels spin freely. The rear will require some judgement because of the drivetrain fighting you.

 

[JDMMA70]

Thanks for the reply's and advice guys, I bought a new thermostat since it seems to be a quick and easy plus never hurts to change. I will try jacking my car up to see if the wheels move freely. Um as far as the CSI I don't know there's a way to test it to see if its stuck open or not. Im actually sitting in my car now letting it warm up. I started the car at 4:10 and its 4:20 now and it still hasn't gone past the first tick on the gauge.

Thanks for the advice again I will try it.