Hard Start / No Start - Is your intercooler frozen? Check Here!

[Jack Frost]

The only way that I can see a vacum existing inside the IC is when it is plugged (or nearly so) with frost with the motor running.

But that would make the vacum a symptom of the problem but not the cause of the problem.

In any case, there will still be water inside the IC once the frost has melted.

 

[bsalbrig]

Now all we need is members bsalbrig and conan to take the bet and we can wrap this up. I think bsalbrig made a comment about being underwater and blowing bubbles. So, I take that as he believes there isn't any suction in the coldside intercooler hose. Get those bets placed so I can make the club $50 bucks and we can end this discussion and maybe even learn something.

dweisel

I get on here to see that I have been called out....

I never stated there isn't vacuum in the post IC pipe even though I do believe there isn't or is such an insignificant amount it cannot cause a problem as you state. I also didn't make comments of being under water blowing bubbles....not sure where that is coming from. There could be the possibility of when the turbo is trying to catch up with the engine's demands that a very small amount of vac could be created.

No tricks like taking your pressure after the anti-shudder valve or blocking off the intake.

Sounds like you wouldn't take this bet unless you knew you were going to win........


That being said I will take you up on your offer.

 

[dweisel]

There is no way a pressurized hose is going to suck up two cups of water through a slightly sloppy o-ring, unless the car is underwater. Does not the IC have positive pressure on both sides? It'd be blowing bubbles even if it was underwater.

bsalbrig, my apoligies. That was conan that made the ''blowing bubbles underwater'' statement. Sorry.

I suffer from Dyslexia and fight it everyday. I knew it wa either you or conan and transposed your names. Sorry again for the mix up,but it did get your attention and get you to place your bet. lol. Now if conan would chime in. We could get things wrapped up in short order.

 

[dweisel]

The only way that I can see a vacum existing inside the IC is when it is plugged (or nearly so) with frost with the motor running.

So,Jack. Can I get you signed up on the $20 bet donation for the club. 6 members would total $120 for the club or one $120 donation from me if I'm wrong.

dweisel

 

[MayorDJQ]

So what explains the numbers/info that I logged? IMO, it shows there's no vacuum.

A question for the science folks: Does a pressure drop across the IC necessarily mean there's a vacuum? If there's 15psi on the "hot" side and 10psi on the "cold" side, does that mean there's a vacuum?

 

[bsalbrig]

So what explains the numbers/info that I logged? IMO, it shows there's no vacuum.

A question for the science folks: Does a pressure drop across the IC necessarily mean there's a vacuum? If there's 15psi on the "hot" side and 10psi on the "cold" side, does that mean there's a vacuum?

No, vac is measured from atmospheric pressure.

 

[bsalbrig]

If the test does show there is some vacuum on the intake it will be only for a very short time and a very small pressure.....Not enough to pull water past the seals that are on the pipes.

 

[Conan]

Sorry, not betting. I can see how there might be vacuum at times in the IC, but I just can't buy that a sloppy seal would allow fatal amounts of rain to get sucked into the pipe. If the seal was that sloppy, you would have a massive boost leak. I like the EGR theory, but don't know enough about how these things work to bet on it.

 

[GraniteRooster]

I'll jump in and take Dweisel's bet in place of Conan - I agree with the above comments that no substantial vacuum exists for any significant portion of normal driving. And therefore, Loose seals sucking in water are not the cause of this problem.

If liquid water did get sucked in it would be entrained in the airflow and get carried through the cylinders anyway.

Ice accumulation in charge air cooler & ductwork followed by subsequent melting of accumulated ice are the cause of this - as described in Post #1.

 

[MayorDJQ]

The prevailing theory of too much moisture from the LP-EGR seems to be the best explanation. If humid atmospheric/intake air were the problem, then the problem would exist on earlier generation TDIs, as they all have I/Cs.

If the hose connector on cool/outlet side of the I/C is loose enough to allow water to be drawn in under a very, very light vacuum--not that I agree a vacuum is created--then 22PSI of boost should be more than enough to blow out the water from said loose fitting. Plus, any moisture pulled in by this vacuum should wind up getting pulled downwind into the combustion chamber, since that's where the vacuum is coming from. It wouldn't go upwind into the I/C.

I'll jump in and take Dweisel's bet in place of Conan - I agree with the above comments that no substantial vacuum exists for any significant portion of normal driving. And therefore, Loose seals sucking in water are not the cause of this problem.

If liquid water did get sucked in it would be entrained in the airflow and get carried through the cylinders anyway.

Ice accumulation in charge air cooler & ductwork followed by subsequent melting of accumulated ice are the cause of this - as described in Post #1.

I said the same thing several pages ago, but no one commented on it.

 

[740GLE]

My guess is that right at start up there is a vacuum, how small it is who knows. Right at start up there is no way the turbo is creating any boost, meanwhile your cylinders are trying to suck air in. Thats why many people see this issue when starting up.

As for data logs with VCDS, if the MAP can't spit out a voltage that the ECU can decode to being a vacuum, then nothing will be spit out to a graph showing a vacuum.

Like others have sugested, only way of knowing is if there is a boost/vacuum guage dirrectly connected to the intake, and monitor this gauge when cranking over the engine. The gauge scale needed to see the slight vacuum created at start up might be the hard part.

 

[VeeDubTDI]

This thread is turning into a steaming pile of fail. I say we ban dweisel.

 

[MayorDJQ]

My guess is that right at start up there is a vacuum, how small it is who knows. Right at start up there is no way the turbo is creating any boost, meanwhile your cylinders are trying to suck air in. Thats why many people see this issue when starting up.

As for data logs with VCDS, if the MAP can't spit out a voltage that the ECU can decode to being a vacuum, then nothing will be spit out to a graph showing a vacuum.

Like others have sugested, only way of knowing is if there is a boost/vacuum guage dirrectly connected to the intake, and monitor this gauge when cranking over the engine. The gauge scale needed to see the slight vacuum created at start up might be the hard part.

Ok, I could see there being some vacuum at start up, but if it's so slight as to need a very small scale, would it be enough to draw a slug of ice or water uphill into the combustion chamber? And would it be enough to hydrolock?

As to the sensor issue, why would the MAP sensor not be able to indicate a vacuum? If there's a vacuum, it wouldn't be an absolute vacuum. When I did my logging, the barometric pressure was reading 1009.8, as measured by VCDS via a sensor somewhere. Would a MAP reading of 900 indicate a vacuum condition, as 900<1009?

I'm still getting hung up on how a tiny vacuum leak would not allow boost leak under much higher pressures.....or to just let the crap drip out when the engine is off.

 

[VeeDubTDI]

The VW MAP sensor can absolutely measure a vacuum. It reads ABSOLUTE pressure, so atmospheric + manifold gauge pressure. Anything below atmospheric pressure is... A VACUUM!

And it will measure it accurately!

Shock and awe, friends... shock and awe.

The only time you will see a vacuum is on initial cold start before the turbocharger speeds up.

 

[GraniteRooster]

The VW MAP sensor can absolutely measure a vacuum. It reads ABSOLUTE pressure, so atmospheric + manifold gauge pressure. Anything below atmospheric pressure is... A VACUUM!

And it will measure it accurately!

Shock and awe, friends... shock and awe.

The only time you will see a vacuum is on initial cold start before the turbocharger speeds up.

Thank you for injecting rational thought back into the discussion.

 

[Drivbiwire]

The fix....DRIVE THE CAR HARDER and clear out the intercooler.

Lugging a diesel will always lead to accumulation in the intercooler.

A good solid blast of full throttle will prevent all of this from occurring.

Do this once or twice a day or after extended periods of idling.

Idling will also cause this accumulation to form in the system.

 

[VeeDubTDI]

That is not a practical solution to the problem. Only a temporary band-aid, if that.

 

[GraniteRooster]

The fix....DRIVE THE CAR HARDER and clear out the intercooler.

Lugging a diesel will always lead to accumulation in the intercooler.

A good solid blast of full throttle will prevent all of this from occurring.

Do this once or twice a day or after extended periods of idling.

Idling will also cause this accumulation to form in the system.

This is NOT the fix to the problem - it is not driving style related. It is a thermodynamic problem where ICE coats the charge air system - more RPM and airflow will NOT blow through ice stuck to the intake surfaces.

 

[dweisel]

This thread is turning into a steaming pile of fail. I say we ban dweisel.

Geez............I just got back from a ban and you're wanting me banned again! lol. I still don't have the right to edit.

dweisel

 

[VeeDubTDI]

Just sayin'...

 

[dweisel]

Was picking up some parts today at a dealership. I stopped in and talked to the Service Manager. First I asked about the water/ice in the intercooler. He said VW is aware of the problem,but he has not heard anything about a fix. He attributed the problem to temp variances and condensation. I also ask how many hpfp failure they had done. 4 complete fuel systems and 1 pump only replacement.

My PC is down right now. As soon as it is up and running I'll get this all wrapped up.

dweisel

 

[dweisel]

Please explain how there is a vacuum in the charge air system on the TDI. What about the intercooler creates a vacuum on one side of it?

My guess is that the intercooler is on the suction side of the turbo. When I asked the Service Manager today,about why most of the water ends up in the coldside hose. He said: ''it doesn't have enough SUCTION to pull it up.'' Hmmmmmmmm,did he say suction???

dweisel

 

[MayorDJQ]

My guess is that the intercooler is on the suction side of the turbo. When I asked the Service Manager today,about why most of the water ends up in the coldside hose. He said: ''it doesn't have enough SUCTION to pull it up.'' Hmmmmmmmm,did he say suction???
dweisel

The intercooler is in the suction side of the turbo?? What?! As in before the turbo? Pleae tell me that's a typo.

 

[740GLE]

wow? really dwesel?

trusting the dealer for info?

 

[tcp_ip_dude]

My guess is that the intercooler is on the suction side of the turbo. When I asked the Service Manager today,about why most of the water ends up in the coldside hose. He said: ''it doesn't have enough SUCTION to pull it up.'' Hmmmmmmmm,did he say suction???
dweisel

Your credibility just took a big hit. The above statement clearly establishes your lack of understanding of the function and purpose that an Intercooler serves in turbocharged engine.

 

[dweisel]

Your credibility just took a big hit. The above statement clearly establishes your lack of understanding of the function and purpose that an Intercooler serves in turbocharged engine.

Credibility??? I've got no credibility! Never said I understood the inner workings of the turbo and especially not the high pressure/low pressure EGR. I'm still going to say there is suction in the intercooler hoses. If I'm right...............I guess its you that looses and credibility.

dweisel

 

[MayorDJQ]

The VW MAP sensor can absolutely measure a vacuum. It reads ABSOLUTE pressure, so atmospheric + manifold gauge pressure. Anything below atmospheric pressure is... A VACUUM!

And it will measure it accurately!

Shock and awe, friends... shock and awe.

The only time you will see a vacuum is on initial cold start before the turbocharger speeds up.

Then I'm confident with the results shown on the logs I made. As I mentioned when I posted the graphs, I'll send the log files to anyone who wants to look at them or make the graph look nice.

Your credibility just took a big hit. The above statement clearly establishes your lack of understanding of the function and purpose that an Intercooler serves in turbocharged engine.

Bingo. If you put a gauge on the tube from the air filter to the turbo, there probably is a slight vacuum, but if water is getting sucked in there, we've got bigger things to worry about than condensation in the I/C.

 

[bhtooefr]

The fix....DRIVE THE CAR HARDER and clear out the intercooler.

Lugging a diesel will always lead to accumulation in the intercooler.

A good solid blast of full throttle will prevent all of this from occurring.

Do this once or twice a day or after extended periods of idling.

Idling will also cause this accumulation to form in the system.

Based on the description of the problem, it's sounding like an effective version of your fix is to always drive the car at maximum boost, to get the charge air heated up as quickly as possible.

So, block heater to get the coolant hot, then, as soon as the engine has oil pressure, get it in gear, and go for WOT. When not using WOT, shut down the engine and disengage the transmission, to prevent airflow through the intercooler.

Which, quite frankly, is ridiculous.

 

[bsalbrig]

Credibility??? I've got no credibility! Never said I understood the inner workings of the turbo and especially not the high pressure/low pressure EGR. I'm still going to say there is suction in the intercooler hoses. If I'm right...............I guess its you that looses and credibility.

dweisel

When do you plan on testing your theory?

 

[danham]

I just re-read the CR self-study guide and though I can't make any wise pronouncements about this whole issue, it does strike me that the number of ways "they" can mess with intake air pressure is mind-blowing, so normal, common sense knowledge about the behavior of intake air in a turbo system is no longer good enough.

Basically the take-home for me is that the system can use various valves and signals from way more intake air temp/pressure sensors than I knew existed to alter conditions in both EGR loops, the intercooler loops, and the turbo to meet a variety of performance and emissions situations, including cold starts, very low engine load and other conditions which may well apply to our present problem.

-dan