Light Surge at Steady Cruise
 

I'm just curious what it could be :confused: probably no big deal...(this is in the Integra, BTW)...

It's more of a power draw, then surge.

At highway speeds (60 mph for the sake of discussion), something is cycling on and off that acts like a really weakened version of an A/C compressor kicking-on.

At constant throttle, FE drops very slightly, speed drops, and the feel of a faint "nudge" occurs -- I'm talking hardly noticeable. Then after 30 seconds, another slight bump, the power returns, FE increases and things are back to normal -- that is until it happens maybe 2 minutes later. It happens up hills, down hills -- usually at highway speeds during full TC lockup. No CEL, and the car otherwise operates the same as it always has...

It started about 3 weeks ago. Around the same time as a radiator-block installation. This may have no connection between the 2.

Theories: Since I have no idea, I'll throw out some guesses. Is it the thermostat opening and closing, causing more of a coolant pump load? I don't hear it, but would it be the electrical load of a cooling fan translating back to the alternator->belt->onward? Changes in pressure in the auto-trans / slippage? (let it not be that one...) And yes, the A/C is off :p

Thanks guys...

RH77

Did you not just replace the t-stat? Do you have any other parameters. If it's the cooling fan you should be able to tell by where the water temp is. I've got mine blocked completely and if never comes on in cruise. The highest temp during a climb is 209 and the fan comes on at 211.

The stat was changed over a year ago -- so nothing really recent there. I noticed during the summer that coolant temps would be reported as 216-224F from wherever the sensor is located. The fan would kick-in at 220+, but never went higher than 224. Temps aren't close to that now -- 215 at the most, but 200 at cruise. Lowest ambient has been 15F with freezing rain. On a side note, big time ZR+ tonight -- accumulations up to an inch of ice! :eek:

RH77

Is it possible the cooling fan on high speed could cause enough of a draw that you'd notice the extra engine load? The fact that this started when you added a grille block is a little too coincidental.

One way to tell might be to watch your SG2 voltage parameter. See if it changes when this event happens.

That's what I was thinking but the water temps are 20 degrees below when the fan kicks on. :confused:

I'll monitor the Voltage display during this event. I have noticed that once coolant temps get up to normal, they stay there -- and TC lockup is aggressive (finally) -- even in outdoor temps 10-15F ambient. I also altered the air intake to draw from the engine compartment for Winter. FE hasn't dropped a whole lot, which is a shocker.

Another hypothesis is a knock sensor of sorts, but I don't think it's equipped as such. IATs aren't high enough either.

Honestly, the only inconvenience is a slight drop in power (especially on hills), which has to eat into the FE bottom line. Aside from that, I'm picky about vehicle operation and the slightest abnormalities. :rolleyes: It's so faint, a non-hypermiler may not even notice it unless you monitor the numbers and feel closely for the vehicle's nuances. I just want to better understand the operation. The biggest obvious problem is a leaky valve cover gasket (stinky burning oil underhood) and lack of transmission maintenance. Christmas to New Years = little work in my field, finally! Time for maintenance. And the cold temps are perfect working conditions (better than the heat, IMHO). :)

RH77

Could it be something with the heater operations? Next time it starts doing it turn off the environmentals and see it it continues. Shrug.

It's got me stumped. It's more of an inconvenience or challenge.

The ice wasn't so bad in our part of town, but the airport got quite a bit of ice. We'll see what happens...

At any rate, I'll hook-up the data logger on the Teg to crunch numbers tonight.

RH77

Do you have A/C? It could be coming on as part of the defrost setting. And you'd definitely feel the A/C kicking in.

For sure it's not the A/C -- when that engages, the clutch is quite loud and there's a considerable loss of available power. I've tested the situation with any possible heat/air in the off position and the air selector to "vent". It requires the A/C button to be engaged as well. I tried the A/C during this condition and it was more pronounced than the mystery condition.

RH77

It looks like it's time to sell the teg and get an insight, :turtle:

Welp, that settles it... To the Toyota dealer! :p

I choose not to afford a newer car right now. The Teg's runnin' great (knock on wood). It's pretty durable too -- more on that later.

RH77

Might it be the alternator?

I'm leaning to something electrical. I may pull the plugs on the cooling fans to rule those out, but with the EOC lately, I'm concerned of alt/batt issues. It feels just like the A/C but very subtle. On really windy days (most of the time here) I can't discern it from wind buffeting -- but I noticed it with the tailwind today (and yeah, negative wind chills). Took forever for the TC to lock.

-RH77

Yup
 

I'm pretty confident that it's the alternator. After some randomly noted occurences, that seems to be the culprit:

When it was super-cold out, I moved the blower from "1" to "2" and noticed the draw (it was on an uphill climb, so very noticeable).

The vehicle is equipped with an "Electrical Load Detector" that fools with alternator demand (I expect -- from the shop manual, the ELD is an input into the ECU that regulates the output from the alternator, and cyles the input back to the ELD->ECU through Batt Voltage). It may be causing the cycling action when the battery voltage depletes and is consequently restored. I noticed a Sine Wave of sorts on the data logger, which could explain the behavior. To test the ELD, one of the sequences is to turn on the headlights for draw. I drive with them on constantly (I know -- it's a safety issue for me) -- but that may just be enough for it to rob enough juice for this situation.

Since it's noticeable, should there be any cause for concern (i.e. alternator bearing wear)?

RH77

I'm inclined to think that it is normal. The alternator doesn't need to run steady. Maybe it's just a sign of how in tune you are with how the energy is consumed moving you around?

Thanks!
 

Thanks :) I get pretty picky with anything unusual about the car -- mostly to keep it running well/efficient for as long as possible.

When The Rad Was Out And In. Look At All The Lines And Hoses. If It Sarted Then, Something Happened Then. Use A Hose Or Starting Fluid To Look For Leahsd. Put One End Of The Hose At Your Ear And Move, Or Have Someome Move The End Around Lies Ect. Run The Moter Up And Down If Uot Heard Nothing At First. It Sounds Like Running Lean Or Timing.

Alternator voltage
 

Looks like this may have died. I have a, 2010, Chevy Cobalt. I have never liked the High Battery Voltage of 15 volts. I also believe in the lights on 24/7, safety. I have heard about a Smart Alternator. Some ideas seem good, but they may have off-shoots that are not expected.

If the alternator put out a regulated 13.8 V. As the battery reached charge, the current should drop off, as apposed to a Constant Current, which the battery would have to absorb and give off as heat, and possibly boil or "gas".

I used to drop the battery to the headlights with a 6A diode in the ground lead, to reduce the Lamp voltage, and increase the life. Have been thinking of putting in TWO in series to reduce the voltage by 1.4 volts. 0.7 volts drop on each diode.

I find it hard to see a real advantage to varying the Alt Volts.

I CAN understand an advantage between the Ears, behind the eyes.