White smoke, uneven idling and no power!

Hi,

Please check your engine and battery while your car is running. Please wear goggles as you don't want the contents of the smoke getting in your eyes. This will help you find what item or items are shaking and smoking in your car.

Thank you.

Ordinarily, rough running with a raw gas smell indicates a fuel pressure regulator or fuel injector problem, but that usually produces grey or black smoke. The white smoke may be steam, which is more serious.

If the exhaust also smells somewhat like maple syrup (that's what burned engine coolant smells like unless you are running water without antifreeze), or your coolant level is going down rapidly, you probably have a bad head gasket, cracked block or head that is leaking coolant into one or more cylinders. That's what would produce a large amount of steam, and the uneven power production is what makes the engine vibrate strongly. The mixture control system is being all messed up because the coolant in the cylinder is preventing proper combustion - on the one hand the knock vibration sensor is telling the computer that the engine is running too lean, but on the other hand the oxygen sensor is detecting the rich condition. A readout of the engine computer would be interesting to see.

Run the engine as little as possible until you get this checked out. A coolant leak into a cylinder can cause quite a bit of secondary damage.

You may be able to identify which cylinder has the problem by removing the spark plugs and inspecting them. A wet spark plug is confirmation of my hypothesis. If you have a borescope (video camera on a flexible tube or with a fiber optic bundle with a lens on the end), you can peek inside the cylinder through the spark plug hole. Otherwise, pull the head to see where the coolant leak is.

What is year--make--model?
Are you losing coolant? The white smoke may be coolant in the combustion cylinder, possibly caused by a head gasket problem. If head gasket problem, fix that first.

With idle issues, clean/check anything that has to do with idle air system. Any applicable trouble codes?

sounds like injector is leaking letting fuel leak into a cyclinder the smoke is raw unburned fuel then it takes a minute or so to clear the cyclinder

Blown head gasket. Pull the spark plugs. The cleanest one is where it is blowing or sucking coolant. Sorry. White is water/coolant. black is gas. bluish is oil.

please ask them to chk out the throttle body clean it gently with petrol than connect the vehicle to diagnose with tech-2 it will show u the whole engine running process

water getting into cylinders cause of your white smoke

it could be plugs and or high tention leads, causing missfire best way to check these is better at night open the hood of the car, run engine and see if you are getting a loose spark, that will be your high tention leads it could also be that when they get hot, they expand and start reducing the power of the spark to the plugs if you find that these will need replacing, to test spark plugs, get a pair of pliers and preff a pair of rubber gloves, pull the leads off each plug one at a time, if there is no change on one you pull of, that plug needs replacing, continue till you have checked all of them, hope this helps

Blown head gasket for sure if its a petrol engine.

If its diesel then its overfuelling.

The MAF has been a source of trouble for Audi such that the cost of replacement was halved a few years ago.

I am not sure why replacing the MAF would produce white smoke - white smoke being symptomatic of steam from water or coolant ingress into the cylinders or extreme amounts of fuel entering the cylinders. The latter is almost exclusively a diesel problem.

Generally if the MAF is suspected of being the cause of rough running then disconnecting it will cause the engine management to switch to the get-you-home programme. If the engine runs better the MAF is probably faulty..

As a matter of interest, it is necessary when changing parts on Audi that only the correct parts are used. Not only must they look right and be intended for that year and model but the part numbers should also be correct. A couple of digits out isn't close enough...

I am not sure where the idle thingy is on your Audi - the earlier models used a throttle body with the idle/throttle sensor and idle control all integrated in one very expensive lump and that is how I discovered the importance of correct part numbers.
In order to save my customer from scrapping what was otherwise a good car, I took a can-opener to the throttle body and opened it and found two broken wires and mananged to repair them. I needed to do some tricky welding to put it back together. The car went on for another seven years afterwards...

The car made no white smoke prior to the repair but the idle was very erratic...