Letting a TDI idle... good? bad? really bad?

MarylandJetta · Dec 31, 2009

Hi All --

I'm new to TDIs but not to VWs/Audi. Just got a 2010 Jetta TDI and absolutely love it.

So I have a question. Where I live the power goes out occasionally and I was thinking of getting a fairly beefy (750 watt) digital inverter so that I could, in a pinch, run some minor electrical items off the car. Would it be bad to let the car idle for 30 or 60 minutes at a time while doing so? I know that big rigs will be left idling for hours or days; is that kind of treatment really bad on a TDI?

Joe_Meehan · Dec 31, 2009

I doubt if it is going to hurt the engine, but it might cost you a new alternator. It is not really engineered for that kind of work.

MarylandJetta · Dec 31, 2009

Joe_Meehan said:
I doubt if it is going to hurt the engine, but it might cost you a new alternator. It is not really engineered for that kind of work.

Hmm, that's a good point. Hadn't really thought about that. Thanks.

mohawk69 · Dec 31, 2009

Have you considered moving? Just kidding. I saw a small Chinese junk generator for sale at harbor freight for less then 200$. I think it was even two stroke. Even better, watch CL and pick up a used, name brand, suitcase type generator cheap. That would be far better then letting a new car idle.

VeeDubTDI · Dec 31, 2009

It won't be able to power that large of an inverter at idle. Fast idle, yes... regular, no.

MarylandJetta · Dec 31, 2009

mohawk69 said:
Have you considered moving? Just kidding. I saw a small Chinese junk generator for sale at harbor freight for less then 200$. I think it was even two stroke. Even better, watch CL and pick up a used, name brand, suitcase type generator cheap. That would be far better then letting a new car idle.

Philosophically I'm against buying Chinese-made junk -- I'm a big believer in paying more for good stuff.

But I'll admit I've considered the generator route -- and it probably is the best thing to do -- but I was hoping to avoid having something that noisy. Plus I don't really want the damn thing cluttering up my garage the 99.9 percent of the time that it wouldn't be in use.

Rich

NB_TDi · Dec 31, 2009

VeeDubTDI said:
It won't be able to power that large of an inverter at idle. Fast idle, yes... regular, no.

We have a Weiner.

MarylandJetta · Dec 31, 2009

VeeDubTDI said:
It won't be able to power that large of an inverter at idle. Fast idle, yes... regular, no.

Well, that settles it.

Thx.

stevekris · Dec 31, 2009

You need to check out small inverter generators. They are not much bigger than 2 six packs. You can hardly hear them running and they weigh nothing. Thanks Steve

TDIJetta99 · Dec 31, 2009

VeeDubTDI said:
It won't be able to power that large of an inverter at idle. Fast idle, yes... regular, no.

that's not true at all, and a 750 watt inverter is pretty small by the way... mine powered 2 750watt inverters for several days idling when we had our outage.. It won't keep up with both going full tilt, but how often are you pulling max current from the inverter? I ran almost an entire tank of fuel through mine just sitting there idling.. Neither one of the inverters ever shut down from low voltage, and my alternator is still working..

Lee_Taylor · Dec 31, 2009

This is what you need...... http://www.otherpower.com/fuking.html Made in India by "craftsmen" ho, ho, ho.

NB_TDi · Jan 1, 2010

TDIJetta99 said:
that's not true at all, and a 750 watt inverter is pretty small by the way... mine powered 2 750watt inverters for several days idling when we had our outage.. It won't keep up with both going full tilt, but how often are you pulling max current from the inverter? I ran almost an entire tank of fuel through mine just sitting there idling.. Neither one of the inverters ever shut down from low voltage, and my alternator is still working..

Well you sort of just talked in a circle.

PDJetta · Jan 1, 2010

Lee_Taylor said:
This is what you need...... http://www.otherpower.com/fuking.html Made in India by "craftsmen" ho, ho, ho.

I just love the engine manufacturer's name (no need to curse your engine):

"This page is a brief one about my new Fuking diesel engine..."

--Nate

TDIJetta99 · Jan 1, 2010

NB_TDi said:
Well you sort of just talked in a circle.

really? please explain... I was running an average of 850-900 watts of stuff plugged into the 2 inverters.. they weren't going at full tilt, but it was more than a single one can handle. It ran the 2 refrigerators, my PC, 1 television, and my laptop charger intermittently.

My TDI sat and idled for almost an entire tank of fuel and neither inverter shut off due to low voltage.. That's talking in a circle?

turbocharged798 · Jan 1, 2010

A lot of people say that it is really bad to idle a TDI. I really don't believe until I see more proof.

If you are going to idle a TDI for extended periods, I would look into a high idle kit.

TDIJetta99 · Jan 1, 2010

turbocharged798 said:
A lot of people say that it is really bad to idle a TDI. I really don't believe until I see more proof.

If you are going to idle a TDI for extended periods, I would look into a high idle kit.

who makes one for a TDI? I know Jeff can tune them to idle high, but it's not something you can turn on and off easily...

NB_TDi · Jan 1, 2010

TDIJetta99 said:
really? please explain... I was running an average of 850-900 watts of stuff plugged into the 2 inverters.. they weren't going at full tilt, but it was more than a single one can handle. It ran the 2 refrigerators, my PC, 1 television, and my laptop charger intermittently.

My TDI sat and idled for almost an entire tank of fuel and neither inverter shut off due to low voltage.. That's talking in a circle?

Sorry but I call a HUGE BS. That's 75A, over too because the car has to run some things.

You're lying.

TDIJetta99 · Jan 1, 2010

NB_TDi said:
Sorry but I call a HUGE BS. That's 75A, over too because the car has to run some things.

You're lying.

say what you want, my food didn't spoil when the power was out for 4 days.. Does your fridge run 100% duty cycle? mine doesn't, neither does the freezer in the garage..

what does the car have to run other than the ECU, cluster, and the fans once in a while? everything in the car can be turned off other than that..

The inverters shut off at 11v, so for all I know it could have been sustaining 11.5 and I would never have known anything unless one of them kicked off..

Maybe instead of calling BS, maybe ask a few questions about how I set everything up and you'll take back your BS claim.. It wasn't as simple as opening the hood and clipping 2 inverters on.. I'm not an idiot..

jasonTDI · Jan 1, 2010

mohawk69 said:
Have you considered moving? Just kidding. I saw a small Chinese junk generator for sale at harbor freight for less then 200$. I think it was even two stroke. Even better, watch CL and pick up a used, name brand, suitcase type generator cheap. That would be far better then letting a new car idle.

1100w peak 900 running on sale for $179. Yes, 2 stroke.

jasonTDI · Jan 1, 2010

stevekris said:
You need to check out small inverter generators. They are not much bigger than 2 six packs. You can hardly hear them running and they weigh nothing. Thanks Steve

Honda i2000 is $999. 2000w. 58db rating at load. They can be strung together too for bigger applications.

jasonTDI · Jan 1, 2010

Lee_Taylor said:
This is what you need...... http://www.otherpower.com/fuking.html Made in India by "craftsmen" ho, ho, ho.

I have a client that has one of these and runs a 10K head on it pulling about 7000w max with no issues. Not that brand of listeroid though, a better one. I save the shop oil/diesel for him in 55 gallon barrels.

jasonTDI · Jan 1, 2010

NB_TDi said:
Sorry but I call a HUGE BS. That's 75A, over too because the car has to run some things.

You're lying.

With the VCDS check the car at idle with a fully charged battery and a good alt the car is using 30-35% of it's output sitting there. You can max out all the systems in the car and still be in the 70-75% range. That's all the heated seasts cranked, rear defrost, brights, monsoon cranked, blower maxed out, cooling fans running etc.

I get rebuild spec sheets with EVERY alt that comes through and they all make at least 75-83amps at idle and peak out about 140-147amp at 4500 rpm.

That said it is clearly possible.

RoundHouse · Jan 1, 2010

TDIJetta99 said:
really? please explain... I was running an average of 850-900 watts of stuff plugged into the 2 inverters.. they weren't going at full tilt, but it was more than a single one can handle. It ran the 2 refrigerators, my PC, 1 television, and my laptop charger intermittently.

My TDI sat and idled for almost an entire tank of fuel and neither inverter shut off due to low voltage.. That's talking in a circle?

How many hours did it take to empty the tank?
and whats the tank capacity?

In other words whats the fuel consumption per hour?

It aint good for it, but a fast idle isnt going to hurt it, especially a modern computerized engine.

Ive left EFI gas engine vehicles running for hours & hours.
Left my 18 wheelers running at a fast idle for 3 days straight.

Long as it doesnt have any unburned fuel, which an EFI diesel will not have as long as its at operating temp.

TDIJetta99 · Jan 1, 2010

it averaged about 4 hours on a gallon of fuel and it holds about 16 gallons of usable fuel.. I filled it up beforehand and added 5 gallons of fuel twice over the 4 days it ran.. I had 1/4 tank left according to the gauge when the power came back..

I probably would have been better off using a generator, but I don't own one, the inverters were all we had. Good luck buying/renting a generator AFTER te power goes out haha..

turbocharged798 · Jan 1, 2010

TDIJetta99 said:
who makes one for a TDI? I know Jeff can tune them to idle high, but it's not something you can turn on and off easily...

Dieselservices.com used to make one for A4 ALH tdi's. I see they have now been discontinued. I believe that one you could be able to turn on and off.

I was thinking, you probably could somehow hook up a resistor with a switch into the go peddle to make the engine think you are pressing the accelerator.

Heck, you could use a pot tied into the accel. and dial in the amount of idle speed that you want. That would be sweet.

Hmm...maybe I should try this.

DeliveryValve · Jan 1, 2010

The issue I would be concerned with prolonged idling is having the variable vanes on the turbocharger get crusted up with carbon & soot causing it not to work properly. Turbos are expensive.

.

AndyBees · Jan 1, 2010

Use of inverters

Most good inverters will shut-down if the DC voltage drops below a predetermined level.

The 120 Amp alt will handle the 750 inverter, especially if you are not "taxing" it all the way up to the max...... lights, PC, some TVs, stero, etc., will be just fine. Refrige ... no!

My Vanagon with a 65 Amp Alt has handled, the AC, the electric fuel pump, the Brain Box, the spark ignition, driving lights, radio, CB radio, a DC operated ice box and a 750 Inverter to operate CamCorder, charge CamCord batteries, charge Camera Batteries, etc., 6 of the 7 trips to Alaska and return without any issues!

Ski in NC · Jan 1, 2010

A typical fridge is 5 amps at 120vac. That's what mine draws, checked it. So that's 600watts. An inverter is not 100% efficient, so it's amp draw at 12v will be more than 600/12=50 amps. Probably more like 60amps.

I doubt a tdi alternator can put out 60 amps at idle. Alternators are rated at 120 amps, but that is at an rpm well above idle. Typical alternator can put out around 25% of max at idle, that's 30 amps.

That must be one efficient fridge!!

jasonTDI · Jan 1, 2010

Not an issue with ULSD.

Fast idle on an alh? Press the brake and the go pedal at the same time. Or rig it to do it. 1200 rpms. Honestly it'd make little difference other than to heat the motor too much. The oil pressure would difference would be minimal with hot oil.

TDI's burn .3-5L per hour at idle.

AndyBees · Jan 1, 2010

Correction on my Vanagon Inverter... it is a 700 Watt!

EDIT

Yeah, this is another "don't idle" your TDI because the engine will be damaged. Well, that debate has been going on for months and months.

7 years ago, I was trapped in a traffic jam/pile-up on the expressway in a cold snow storm for almost 7 hours ... Yes, my TDI idled the entire time. It still performs super today!

Letting a TDI idle... good? bad? really bad?

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