First, no power, and now preheating, but it won't start

Hello everyone,

Yesterday, I unfortunately made things worse while working on a friend's car (an Audi 80, model year 1994, 1Z engine).
The engine recently lost power suddenly, it's running roughly, and it can only accelerate up to about 100 km/h.
First, I checked the needle lifter (which was already defective in my case) and performed the 'tapping test.' Unfortunately, the initial result was negative (I didn't experience any skipping). To be sure, I disconnected the cable while the engine was running and wanted to see if anything would change. -> The engine continued to run the same way.
When I turned it off and tried to restart it, the preheating indicator now lights up for about 15 seconds, and the engine doesn't start (not even with the needle lifter reconnected).
Does the motor electronics possibly have a kind of safety function that prevents the motor from starting if two errors occur simultaneously? I've also tried disconnecting the battery for a few hours to see if it would clear the error memory.
Unfortunately, I can't tell you if the engine control unit warning light is on, as the bulb is probably burnt out.
Unfortunately, I don't currently have a way to read the error codes, and most workshops are on vacation until the new year .

I suspect the problem with the loss of power is coming from the mass airflow sensor (Pierburg), but is there a way to get the car to start at least?

Thank you very much, and happy holidays!

Best regards,
Stefan.

Here in the forum, you can find good tips for troubleshooting the LMM (lambda sensor) issue, for example, from Ulf. Try searching for that. Reading the error codes would definitely be the best approach. I also don't think disconnecting the battery for a few hours will really help. In an emergency, you might be able to turn the ignition on and off about 50 times with the plug reconnected. This usually clears errors that are no longer present, but I can't guarantee it! Feel free to correct me if I'm wrong.

Hello,

'That it won't start at all because of the immobilizer would be news to me; it's more likely that you accidentally disconnected something while working on it. Does your car have the same control unit?' If you'd like to swap, let me know.

When working on electronics, always ground yourself by connecting a cable to your wrist. Modern synthetic fabrics create far more tension than a MSG can handle.


Is there a way to check with VAGCOM whether the MSG (Modular Signaling Gateway) is still functioning? Tax signal for ESP? For turbo wastegate, etc.?
simply to check if any further regulatory activity needs to be identified.

Good luck.

To be sure, I unplugged the cable while the engine was running and wanted to see if anything changed.


When the engine is running or the ignition is on, you should avoid plugging or unplugging anything if possible.

Of course, there are situations where nothing happens, but especially when a 'security group' is involved, this kind of action can quickly become very expensive.

Hello & Thank you in advance for the answers you've already provided!

I can't really imagine that anything could break by disconnecting the NHG (Negative Hold). I'm an electrician myself, and I was 'grounded' at the time because I was connected to the car's body. Besides, it still ran and accelerated with the NHG disconnected. With a broken NHG (presumably referring to a specific type of component or device), the effect should ideally be the same as if it were disconnected.
It doesn't seem like the MSG (magnetic solenoid valve) is completely dead (the wastegate valve is still ticking, etc.). The solenoid valve on the ESP (electronic stability program) is also activating...
Unfortunately, I can't test it with my control unit, as I have an older model.

Thank you & best regards - Stefan

Hi,
It doesn't necessarily have to be a case of "New Housing Guarantee." Perhaps the actual cause has worsened by chance, or it may have been exacerbated by the actions taken. Or, you may have inadvertently damaged building components that were not directly involved. Plug unplugged, cable broken, etc.