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Discussion Starter #1
Hello from Norway, Olso



Been having a strange behavior in my car for a vile now, and it’s starting to irritate me!



Whether I’m driving slowly in 40 km/h or going fast on the highway I can’t relay on the car to boost up, some times it’s just like driving without turbo.



For inst. When I’m driving slowly on flat ground, I can suddenly get a boost, and then in a couple of minutes I’m getting a power loss, all with an even pressure on the gas pedal (that will say not moving the pedal at all). This goes on in cycles, all the drive.



The strange thing I have notice the last days is, when I get a power loss, the instrument light dims down. Also I’m getting a ticking noise (like from an old clock) in the coupe, from somewhere behind the glow compartment. The noise comes and goes.



I have tried shutting the AC off, but don’t seem to help.



The wastgate is OK, the solenoid is OK, the bypass is OK and the turbo is OK (obesity, because when I get boost the boost is OK)



Can someone please help?



Terje Moe
 

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The ticking sound would likely be the evaporative system purge valve, which is attached to a bracket inside the engine compartment to the passenger side strut tower. The ticking is the ecu cycling the electrically controlled valve. You can confirm this by waiting for the engine to warm up, then stopping the car with engine idling, and placing your ear against the right side (passenger side) fender. The ticking should be very noticable.

The instrument panel lights dimming is probably an intermittent electrical problem, perhaps a loose or corroded battery cable, intermittent connection at the alternator etc.
 

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I concur that the ticking sounds like the evap purge valve. Perhaps the extra draw of the evaporative purge valve is just a little bit too much for the battery or alternator. The purge valve operates, the draw occurs, the alternator kicks its up a notch and draws that much more from the engine (robbing the engine of power). I say this because when I operate something mundane such as a window, my headlights will dim slightly too.

Strange that the power loss occurs when the extra gas vapor is being introduced to the throttle body. I wonder if when the ECU opens the purge valve it compensates by lowering the gasoline volume flowing through the injectors to keep the engine speed constant? If their is a break in one of the evap purge lines, allowing the vapor to leak, and the ECU is lowering fuel input, it may create a low spot of power during purging times. Plausable?
 

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The amount of power used by the solenoid operated purge valve is normally very small, compared to something like an electric motor used for a window or the seat.

The ecu is supposed to adjust to the amount of extra hydrocarbons burned in the engine. The amount of hydrocarbons purged from the charcoal canister is largest after refueling. It drops quickly after that, and after a few trips it is next to nothing. Most of the time, the evap purge system does nothing, but the ecu cycles the purge valve anyway.

The electrical connector at the purge valve can be disconnected, and the valve will stay closed. That will make the ticking go away, and isolate the evap system temporarily until reconnected. If there is a break in the hose from the evap purge valve to the throttle body, disabling the purge valve will not help, but that hose is accessible, and can be inspected for cracks or breaks.

There are at least three versions of the evap system in use on turbo versions of the engine. The original EVAP, Enhanced EVAP (from mid-1996), and ORVR from 1998 on. The way the system is used by the ecu also changed first with the OBDII requirements in 1996, then with the T7 ecu. The changes are phased in gradually on 40% of the cars, so cars made after those dates can have the older version. Some non-turbo versions are the same, some are different, not sure which ones.

The car would be better off without the evap system. Unfortunately, the EVAP system is also used to test the fuel tank integrity for leaks, which is a very useful feature for the environment as well as for the safety of the car.

A two stage test is run, first for a large leak, then for a small leak. If the fuel tank fails on two consecutive cold starts, the CEL is lit. Therefore you cannot get rid of the evap system completely, but on models where disconnecting the purge valve does not give you a CEL, you can disable part of it.

Obviously cars in the US have to comply with government emissions regulations, but it is truly too bad owners in other countries are stuck with this too.
 

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Discussion Starter #5
Loss of power in regular cycles

Hello



Thank you guys, I will look into the evap system hoses, and see if I can find a leek. Dos the ticking mean that the valve are malfunction. I find it a bit strange that the valve can take that much power from the engine, but certainly, if it cut the fuel of.



But what about the cycles, it comes and goes roughly every second or third minute, very annoying. Can I test-drive the car when I have disconnected the electrical connector?



Could the ECU act like this, or the APC?



I’m most certain that it’s not the chip or the program, because I have tried different programs and it act the same way, now matter. I even have tried a brand new ECU unit.



Believe me, I have tried everything I now of.



Maybe a shot in the dark, but if there are something that draws power (like the AC) in cycles, is it safe to remove fuses, as a sort of ruling out method? And if so, where should I start?



Thank you



Terje
 

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I meant to say that the purge valve uses very LITTLE power. The reason to try disconnecting it is to stop the ticking, and isolate any leaks in parts of the Evap system that you cannot reach and inspect easily.

You only disconnect the electrical connector, not the hoses, so yes, you can drive that way, I did it for a couple weeks.

Maybe a shot in the dark, but if there are something that draws power (like the AC) in cycles
The electric radiator fan, but you cannot disconnect it because you need it to cool the radiator. You can run the engine with the hood open, and measure the battery voltage to see if it drops much when the fan starts. But, the fan does not seem very likely to cause your problem. A real longshot.
 

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I am not positive about how the turbocharger control works.

In this case, it seems as if the wastegate is erratic in its operation..
Whether not not vacuum is needed all the time, I do not know...

If a vacuum port is clogged at the throttle body - then no vacuum leak is even possible.
This may be something to at least check..
 

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Discussion Starter #8
Loss of power in regular cycles

Thank you PMI.



I agree with you, and will try to disconekt, but again: Dos the ticking mean that the valve are malfunction?





And thank you earthworm.



I have been thinking about that, it is almost as the turbocharger goes in to a negative mode, sucking ear out instead of blowing in, can that happen? Almost like an engine break on bigger vehicle?



Thank you



Terje
 

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I do not know if the purge valve is defective. When I investigated to try to test mine, I found out that the voltage to open the valve is not DC, but 8 Hz AC. Disconnecting the connector keeps the valve closed, which is what I wanted, I did not look any further.

The turbo has a factory set base boost. I do not recall, but a quick search for "base boost" on this board came up with 0.4 bar. So if the BPC valve were intermittent, that just maybe could cause your problem. The BPC valve needs to be cleaned out with compressed air after a few years, because it fills up with dirt. Mine did that. The only problem is that the usual symptom is overboost and a fuel cut, not what you posted.

The wastegate that is also a possibility, but I do not know how likely.
 
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