Prevent engine runaway with the strap on mod?

[indysoto]

Would this work? Put a flat tiedown strap with cleat around egr intake, If runaway; then pop hood and pull strap tight?!(thereby pancaking the rubber pipe, thus closing the system?)

 

[slamhouse]

The engine will likely rev to its death before you can get to the strap, and regardless of cutting.g off intake supply, once it chokes and dies, fluid will still be in the cylinders and result in possible engine damage.

 

[40X40]

Can you exit the car and pull that strap in less than a second?

The engine can severely overspeed in about a second if it not kept in check by driveline load.

If you suspect runaway, let off the throttle, leave the car in whatever gear it currently is in and hit the brakes. Steer to a safe location, turn off the key, DO NOT PRESS IN THE CLUTCH OR CHANGE GEARS, if the car does not die when you turn off the key, kill it by locking up the brakes.

Never shift and never push in the clutch during a runaway.

Diesel 101. Instruct your family.

Bill

 

[TurbineWhine]

Would this work? Put a flat tiedown strap with cleat around egr intake, If runaway; then pop hood and pull strap tight?!(thereby pancaking the rubber pipe, thus closing the system?)

That is the function of a properly functioning anti-shudder valve in the EGR. Having said that, I have a race pipe. Brakes and gears will work for the manual transmissions. Its only a problem for the automatics.

Basically, by the time you get an automatic stopped, the hood open and enough nerve up to reach into the bay of a Diesel engine turning upwards of 6000 RPM, the engine will run out of oil (runaway fuel) or hydrolocked and stopped on its own.

If you own an automatic, its probably a good idea to keep a functioning EGR in place. If you are an attentive TDI owner, you will notice increased oil consumption that is your clue the turbo is possibly nearing end of life and should be checked for its health status. Turbo failure is the primary cause of Diesel engine runaway.

TW

 

[indysoto]

Can you exit the car and pull that strap in less than a second?

The engine can severely overspeed in about a second if it not kept in check by driveline load.

If you suspect runaway, let off the throttle, leave the car in whatever gear it currently is in and hit the brakes. Steer to a safe location, turn off the key, DO NOT PRESS IN THE CLUTCH OR CHANGE GEARS, if the car does not die when you turn off the key, kill it by locking up the brakes.

Never shift and never push in the clutch during a runaway.

Diesel 101. Instruct your family.

Bill

Great to know thanks Bill! TW My ECM Egr is within Factory Spec on the high side... 380mm was the high side if I remember correct

 

[KLXD]

I doubt it will squeeze enough to cut off the air.

Be a man, whip out your knife, slice the hose open and put your hand over the inlet.

 

[duwem]

Diesel pulling trucks and tractors are required to have air shutoff devices. Most are either butterfly or guiltine type. The antishutter valve has a butterfly in it. Maybe a cable to it or a a switch to the solenoid that actuartes it?

 

[KLXD]

Turning off the key supposedly closes the ASV until the engine stops turning.

 

[Birdman]

That is the function of a properly functioning anti-shudder valve in the EGR. Having said that, I have a race pipe. Brakes and gears will work for the manual transmissions. Its only a problem for the automatics.

Basically, by the time you get an automatic stopped, the hood open and enough nerve up to reach into the bay of a Diesel engine turning upwards of 6000 RPM, the engine will run out of oil (runaway fuel) or hydrolocked and stopped on its own.

If you own an automatic, its probably a good idea to keep a functioning EGR in place. If you are an attentive TDI owner, you will notice increased oil consumption that is your clue the turbo is possibly nearing end of life and should be checked for its health status. Turbo failure is the primary cause of Diesel engine runaway.

TW

If you would turn your EGR valve into a race pipe, leaving the ASV working you can have the best of both worlds. Takes about 2 hours and saves you the 100$ + you spent on the race pipe, and now you do not have to run around the car like a crazy man trying to shut down a run-away
( BTW I had 2 run aways on my 78 Rabbit not much fun when you do not have the ASV. ) even using the brakes and gears they are not much fun. Last I saw of that car, it had over 300.000 miles and still going strong back in 1989.

 

[duwem]

Turning off the key supposedly closes the ASV until the engine stops turning.

But it only closes for a short time then opens back up again

 

[jcrews]

I doubt the vacuum motor is strong enough to close the valve at high speed. I have photographic proof that it's insufficient to stop runaway - prev. owner's mechanic turned off ign but switched to N instead of standing on the brakes. 4 broken rods and huge holes were the outcome.

 

[turbocharged798]

But it only closes for a short time then opens back up again

ASV stays closed until the engine stops, a member on here proved that by turning off the key while in gear on the highway. He reported that the flap stayed closed until the engine stopped turning.

I doubt the vacuum motor is strong enough to close the valve at high speed. I have photographic proof that it's insufficient to stop runaway - prev. owner's mechanic turned off ign but switched to N instead of standing on the brakes. 4 broken rods and huge holes were the outcome.

Its a butterfly so the load is placed on both sides. That means the net force to close it regardless of the pressure is the same regardless if its a runaway situation or not.

 

[Vince Waldon]

ASV stays closed until the engine stops, a member on here proved that by turning off the key while in gear on the highway. He reported that the flap stayed closed until the engine stopped turning.

Would you mind posting a link to the thread? Wondering how he observed the ASV status on the highway... would like to duplicate.

 

[jcrews]

ASV stays closed until the engine stops, a member on here proved that by turning off the key while in gear on the highway. He reported that the flap stayed closed until the engine stopped turning.

Its a butterfly so the load is placed on both sides. That means the net force to close it regardless of the pressure is the same regardless if its a runaway situation or not.

While true that dynamic torque across a pressure drop will try to close a butterfly valve when partially open, this isn't a seated valve and at high speeds will leak enough when closed, and it is evident the leak is large enough, for run-away to proceed anyway. I know from pushing the valve closed by hand that it takes an awful lot of force (much more than the vacuum motor can provide) to get a good enough seal to stop even an idling engine. Keep in mind that it's there as a comfort item and is not a true control valve.

The point remains that shutting off the ignition alone is not enough.

 

[VeeDubTDI]

Would you mind posting a link to the thread? Wondering how he observed the ASV status on the highway... would like to duplicate.

You can hear the change in engine tone when the ASV is closed. Try it and see.

If you wanted to do a really good test, you would manually operate the ASV during over-run at highway speed (with the ignition ON) and monitor MAF data via VCDS to see how much air still gets through it with it closed.

 

[Vince Waldon]

I think the key here is there is likely a difference in behavior between the ASV doing its thing in the driveway at idle vs on the highway at full bore burning oil from a destroyed turbo.

Monitoring the MAF is a good suggestion... I suppose a boost valve where mine is (downstream of the ASV) would show vacuum while the ASV is closed at highway speeds as well.

 

[duwem]

At the end of the day I think we would need real world experience to know for sure if the asv actually would stop the engine during a runaway. Engine will continue to run with very little air.

I had a single cylinder lawn mower diesel engine I put the injection pump control rack in incorrectly and it kept running even after taking the air filter off and emptying a fire estinguisher into the intake.

 

[Vince Waldon]

FWIW my runaway was about 5 seconds long... by the time I figured out that I had taken my foot of the gas and the car was still accelerating it was over...bent rods and all. No time to turn off the key to activate the ASV, no time to think about engaging a switch or tugging a lever...all done except for the smoking turbo and the impending engine rebuild.

 

[TDIMeister]

Have a functioning anti-shudder valve and turn the key to off.

Edit: Well, it didn't work for Vince, but maybe one could implement some logic in the ECU coding that if it sees an implausible RPM rise for the amount of fuel injected, then shut off fuelling and choke the engine using the ASV automatically if it detects this implausibility.

 

[VeeDubTDI]

How would you differentiate between that and over-run or downhill acceleration?

 

[TDIMeister]

Vehicle speed sensor.

 

[VeeDubTDI]

So it would only work if you were in neutral and your speed didn't match what the ECU thought it would be?

 

[whitedog]

I have shut down a run away by manually shutting the ASV. I think that with what others have said about it not working, combined with what I saw, I can conclude that sometimes it works and sometimes it doesn't.

 

[robnitro]

Perhaps the ECU can be set up to shut the ASV when revs rise above 6000 RPM, or whatever engine speed that is above the max the tune is set to?

It may also be that when the ASV is called for, it doesn't get enough vacuum to hold it closed. My old N239 (ASV solenoid) was quite leaky when actuated, due to old age. I used an old N75 as a replacement, which works fine for the ASV. You can check the asv solenoid seal by applying 12v to the pins, covering the hole that goes to the asv, and sucking with your mouth on where the vac feed goes.

Also, it may be that in runaway conditions, the engine produces so much blowby that the vacuum pump (which pumps air into the crankcase) ends up not making much vacuum! That is why I have my vacuum ball linked to the N75 AND the ASV solenoid vac feed. Of course, both of those along with the vacuum ball are isolated from the vac pump and brake booster by the factory check valve (black and white part on the vac lines).

 

[Birdman]

But it only closes for a short time then opens back up again

You can hear the ASV close after the engine stops running and you can run an engine output sensor test with the VCDS and hear it.
I know from the 2 runaways on my old 78 rabbit (with an after market turbo) that you can really feel the car start accelerating quickly when the engine starts sucking oil.
The first time mine runaway I was going uphill on the PA turnpike and looking in the mirror I could only see black smoke from the tailpipe, behind the car. There was so much black smoke that you could not see the hwy behind the car.
The 2nd time I was on flat highway and as soon as I felt the car start to take off I killed it. Both times on a 8000 mile trip out to the west coast and when I returned home I fixed the problem that caused the early 77-78 diesels to runaway.
I would have to believe that if I could tell that a 60 HP engine had started to runaway that it should be much more noticeable in our higher HP cars. But since I have not been unfortunate enough to encounter this I can't say for sure.
I do know that on the big diesel engines like I had on a Yard Tug boat in the Navy that they all had shut off valves on them to stop a runaway and they did work. The 2, V-6 engines on my boat were larger then any VW car or truck I have seen. And you did not want to be the one responsible for letting one get away from you. Each piston and rod were over 6 feet tall. The shut off valve on those were manully operated and was on of the first things they would show you how to do when training you on starting a running the engines.
Now that i have the ASV pump, as soon as it cools down a bit I will mod my old EGR valve into a race pipe and use it to replace the DK race pipe that was on this car when I bought it 2 years ago. Any little edge I can get encase of a problem I will take. And since I did the same mod on my old 01 IMHO I believe that making a race pipe using the EGR is as good as buying the 100$ race pipe and a lot cheaper.

 

[Vince Waldon]

- a TDI runaway often starts when the turbo is under duress... passing, on an on-ramp, etc, so difficult to distinguish initially. In my case the turbo went as I was on an on-ramp and the car was already accelerating briskly. I realized the engine was running away only after I had entered the freeway and taken my foot off the go-pedal.

- I have no problem believing that removing the air of combustion will stop a runaway... be it a sock down the intake manifold, your hand, or holding the ASV closed manually. The two questions that have never been fully answered to my satisfaction are:

1) how long does the ASV actually stay closed when the ECU cycles it? Some reports say forever, some say it only cycles closed for a couple seconds and then resets, which is why it is open whenever you look at it, and in particular when you next go to start the car.

2) assuming that the ASV does in fact try to close and *stay* closed when you turn off the key does the vacuum dashpot connected to the ASV have enough power to toggle the valve closed under duress... ie when the engine is gulping huge amounts of air?? There may be a difference between shutting off the air of an engine sitting in the driveway idling vs. the air being gulped by an engine turning at 4000 RPM burning large amounts of air and melting its pistons. On the other hand, it may make no difference to a butterfly valve.

Ah life's mysteries! When I get half an hour I am going to try to definitively answer #1 by replacing my boost gauge with a vacuum gauge. The line is tapped into the intake manifold so downstream of the ASV, and I would expect to see vacuum on the highway the entire time the ASV is closed.

#2 would be difficult to duplicate other than to try the ASV during an actual runaway... and in this thread we've already heard from someone who states a customer of theirs tried this, with no joy.

My personal theory at this point: the ASV is a reliable anti-shudder valve, not a reliable anti-runaway valve. How "not reliable" ?? Dunno, but I'm not going to count on it.

 

[VeeDubTDI]

There's a pretty easy way to test! Get going down the highway with moderate load/acceleration, turn the key off and see what happens!

It's not rocket surgery.

 

[Vince Waldon]

There's a pretty easy way to test! Get going down the highway with moderate load/acceleration, turn the key off and see what happens!

It's not rocket surgery.

Under normal circumstances, turning off the key will turn off the engine's fuel and ECU and the engine will turn off and and the car will slow down....true dat.

During a runaway turning off the fuel and the ECU has no effect...the engine is running without them on its own fuel supply aka engine oil.

So, not sure how turning off the key on the highway and "seeing what happens" helps understand how the car will behave during a runaway? You're artificially turning off the fuel supply...so not a valid test IMHO.

 

[VeeDubTDI]

It will tell you whether or not it starves the engine of all air or not. I don't see how oil flowing through the intake would change the sealing properties of the ASV - if anything it would make it seal tighter.

Yes, the engine will still burn the oil that is in the manifold, BUT the point is to determine whether or not the ASV is capable of starving the engine of air for an extended period of time.

IF the ASV is not capable of blocking airflow completely, then it is a completely ineffective method of controlling or ending a runaway.

 

[witchcraftz]

You could make rig a CO2 extinguisher which would be hooked into your MAF, run a wire with a handle to the drivers side. In case of a runaway, pull the cord and the CO2 will kill the engine without any permanent damage.

Kind of like a NOS setup, but with CO2 instead.