Car Shakes at 160 km/h: Sudden Jerk, No Power?

More power. The engine remains at approximately 3,500 revolutions per minute and doesn't go any higher (even going downhill). Restarting the engine (quickly restarting the engine in the middle of the highway requires some courage). After that, the speed was limited to 120 km/h and then to 100 km/h, so I took my foot off the accelerator and let the engine's torque intervention system guide me within those limits. Okay, after that, the car (Passat 35i B4, 1Z) could barely reach 120 km/h (only after a lot of effort) and didn't want to go any faster. So far, so good. Then the federal road ended, and I drove up a hill at 60 km/h, letting the torque intervention system roll me towards a traffic light. After that traffic light, the car's acceleration was suddenly normal again. What could this be? I suspect it's the solenoid valve for the turbocharger pressure regulation (unfortunately, the car doesn't have a turbocharger pressure sensor). I assume that the 1Z has a limp-home mode. But how does it manifest itself? No warning lights came on on the instrument panel. Unfortunately, I also don't have a VAG Com or an adapter.

Best regards, WarLord.

Building adapters...

To access the error memory, you have to carry the PC to the garage since you don't have a laptop.

Best regards, Rainer.

Okay, so take it to a VW dealership and have them read the error codes. Before you start replacing any parts, that's the first step.

P.S.: Yes, the driving performance is very close to emergency mode. It feels like you have a trailer from a tractor-pulling competition attached, or like you're driving into a tsunami...

or a tsunami acting as a headwind...


hm... but with a waterfall, it usually stops immediately .

@warlord
A self-made adapter costs at most 10 euros.

CU Gremlin.

@DocSnydor

'Hmm, it's strange that the engine didn't have its normal power after the restart (it only regained power later, after I got off the B road and started driving again). You also have a 1Z engine, right? How does the limp mode manifest itself? Does the preheating indicator blink?'

@Gremlin

I know, I want to build one too.

@Everyone

I drove the same route this morning again, and the car ran without any problems up to 4,200 RPM (which is almost 200 km/h according to the speedometer).

Best regards, WarLord.

...I've had enough of that now, because the 1Z turbo engine simply isn't suitable for a T3 Syncro.
That's why the wastegate valve shaft has often seized on mine.

Then the pressure is no longer correct, and the engine control unit (ECU) switches to emergency mode, which is why I could only manage 90 km/h with the bus, which corresponds to the values you mentioned.

However, you can always reset the engine control unit (ECU) and accelerate again by simply letting off the gas. This works well for a few seconds, but then the limp-home mode kicks in again. That's probably why your acceleration seemed okay; if you don't have a boost gauge, you wouldn't notice it. I haven't encountered this problem in the city either.
A reset doesn't do anything different; it only helps with more serious problems, where the engine control unit (ECU) is trying to save the engine from imminent failure, such as when there's a complete loss of the speed signal.

The day before yesterday, I replaced the turbocharger's electronic wastegate valve, and that was the problem this time. High pressure – emergency mode. It had also been failing intermittently before. Maybe you're experiencing something similar, or this could be the first sign of a problem.

Perhaps another sensor is malfunctioning, and the emergency program might be the same. It's best to read the memory.

Regards,
Dirk.

Okay, so today I was at a friendly VAG mechanic (who, as usual, was talking nonsense - why do they always talk nonsense to me? Do they not like me?). He said: '00575 017 - Intercooler pressure control difference, intermittent fault.' Then he also mentioned: 'Let's do a boost pressure measurement.'

3050/min 1825 mbar 1856 mbar 89% (What exactly do these values represent? Are they revolutions, setpoint, actual value, or duty cycle?)
3020/min 1836 mbar 1866 mbar 90%
3000/min 1836 mbar 1836 mbar 88%

LMM is still within specification (827 mg/H at 928 mbar, 1754 mbar, 100%).

How does it look? Does that apply to the solenoid valve?

Best regards, WarLord.

Intermittent error: Intake manifold pressure control differential.

Sporadically: this can mean many things. A stuck wastegate valve or the wastegate itself can both occur sporadically. In my case, the two different causes were indistinguishable in the symptoms, even though the lambda sensor reading didn't show any abnormalities.
It wasn't until the 'lid' simply wouldn't open anymore (even after longer trips) that I started investigating further.


Then, let's talk about boost pressure measurement:

3050/min 1825 mbar 1856 mbar 89% (What exactly do these values represent? Are they revolutions, setpoint, actual value, or duty cycle?)
3020/min 1836 mbar 1866 mbar 90%
3000/min 1836 mbar 1836 mbar 88%


The pressure readings are perfect, and I'm not sure what the percentage number refers to.


LMM is still within specification (827 mg/H at 928 mbar, 1754 mbar, 100%).

How does it look? Does that apply to the solenoid valve?

Well... it might be possible, but it also might not be. Probably yes. The exchange will cost you 30 euros, and it's a quick process. If it fails, you'll have a spare part or something you can sell on eBay (would you sell it to me? I'd like to have a spare, as I sometimes go on longer trips).

The other way would be more complicated; you would have to try to get ceramic paste onto the bearing surface of the flap shaft using a small syringe or similar. Depending on the engine bay pan, this can be complicated, but it's cheaper and might be necessary anyway. In any case, you will then know what it looks like down there .
Using a small adjustable wrench, approximately 14mm, you need to move the flap lever against the spring (apply pressure on the handle of the wrench away from the clutch) until the flap becomes noticeably easier to move. This may take a few minutes of fiddling.

However, I would estimate the probability of an electrical defect at 70% and a mechanical defect at 30%. Perhaps the owner would allow a test drive, but typically they are reluctant to allow this, especially with electrical components, because it's difficult to trace the cause of a defect.
Alternative approach: Disconnect the valve, apply 12V, and listen to see if it clicks. You might need to apply a vacuum to one of the terminals, as that could provide the counter-force to the magnetic field. Also, you can measure the resistance, although I don't know the specific value, just something that makes sense. 1kOhm would be ridiculous. However, it's possible you won't hear the intermittent fault this way, so trial and error is the only option.


Regards,
Dirk.

The valve is making a clicking noise, and it's quite loud. The problem is that it only happens sporadically and it's not predictable. Sometimes the car accelerates normally on the highway, but then there's a loss of power (which can even happen below 100 km/h, I've noticed). However, it hasn't been happening for the past few days. But I also noticed something else: After the car was accelerating normally on the highway, I could really feel the turbocharger kicking in again (that proper boost at around 1,500 RPM). That feeling is slowly disappearing, and I no longer feel the turbocharger's boost. However, the acceleration seems normal, as far as I can tell.

Best regards, WarLord.

After driving on the highway, I noticed again how the turbocharger kicks in (meaning the proper boost at approximately 1,500 revolutions per minute). This feeling slowly fades away, and I no longer feel the turbocharger's boost. }

Well, that definitely smells like freshly machined or hanging metal.

CU Gremlin.

Wastegate?

Best regards, WarLord.

'At the very least, I would take a closer look at that thing, and if necessary, use a crowbar.'

CU Gremlin.

At the very least, I would examine that thing more closely, if necessary, with a persuader...

Conviction iron? Hammer? By the way: Is it possible to see the wastegate shaft from the outside? Does any exhaust gas leak from there, or do I even have to remove the turbocharger to check it?

Best regards, WarLord.

Hi!
What you see from the outside is: a metal can from which a rod extends, with a ball joint at the front. This ball joint sits on a pin, which is attached to a metal lever. This lever is welded to the top end of the wastegate shaft.
That's why you can't change or disassemble anything there; it's the biggest pain in the neck about the whole thing. There's a tiny bearing point that gets stuck, and in my case, it led to me having to buy a new charger for 400 euros (because I didn't know about the ceramic trick yet).

The sliding surfaces (a bushing at the top, the edge of which is visible from the outside, and a hole in the casting at the bottom) can become coated with carbon deposits, get clogged with dirt, or in winter, with salt, which then corrodes the bearing surface, causing the shaft to bind.

You don't necessarily have to disassemble anything, it depends on the version. However, the mechanism is usually covered by the intake manifold, so you'll need long fingers to feel around from underneath/the clutch side.

Unfortunately, I don't know whether exhaust gases are escaping or whether air is being drawn in due to Bernoulli effects. I fear the latter, because the outer bearing area doesn't appear to be coated with soot.

As a first step, you could try cleaning the electronic valve with a cold cleaner or WD-40 and carefully blowing it out. Mine was either already blocked or I damaged it in the process; in any case, I no longer had any overpressure afterwards, but the engine could not maintain the correct fuel map, resulting in limp mode. So, you should try to get a replacement before you rely on the car.

Regards,
Dirk.

@ Dirk-16

Does your NEW solenoid valve also make a noticeably loud rattling noise?

"Mine (on the 12/95 1Z) rattles noticeably, so I'm wondering if it might just pop out on its own."

m;

Hi!
Unfortunately, I can't say for sure, but I'm pretty certain it's broken, so I stopped paying attention to the rattling noise.

Are you sure you're not holding the EGR valve? The turbo valve has a yellow-chrome metal bracket, while the EGR valve is completely made of plastic, at least in models manufactured in 1994 for the Golf 3.

The turbo valve shouldn't rattle if there's nothing to regulate, and if you give it so much gas while stationary that it needs to regulate, you definitely won't hear the valve anymore ! I guess you were holding the EGR valve!

Regards,
Dirk.