jay

if there’s lights on the dash indicating an issue then get a diagnostic tool plugged in, lots of BMW’s once these lights are on won’t allow you to start the car for safety reasons probably to protect the engine. BMW specialist or a in depth diagnostic tool to read it before taking any guesses rather than a standard OBD tool, The light comes on for a reason, clearing it won’t do anything other than just come back on and cause more damage more than likely continuing to drive it. the icon with the car on a lift is an indication built in to the car meaning it is due for a service, if it hasn’t been done recently may explain why the coolant light is on too.

let the motor get cold, drain the system, refill it with the correct coolant/water mix to the max level, bleed the system (most important thing to do or this will make it overheat with no obvious culprits). Turn the engine on and let it idle and get up to temp with the hood open and just watch for any leaks underneath too, even a small one may take a while to notice, keep and eye on the temp though and turn off if you need to. If you can’t find a leak then that’s narrowed it down a bit. if you’ve already replaced the water pump and thermostat and are confident that they are functioning as they should I would check the radiator and fan next.

does it start up okay without any issues? if your getting very weak acceleration and starting with a bit of a stumble every now and then on idle I’d check the plugs, fuel system and filter which you’ve already done and air intake first of all. could check for any clogged oil lines, I know you’ve ran sea foam but if there was already a pretty bad blockage then using it to loosen up other deposits may have collected in the same place. compression could also be a tad low, is your oil consumption normal?

any small replacements on the dash check Ebay, Amazon etc… failing that go to the dealer or ask your regular mechanic or a supplier.

if its an auto then downshifting is probably what’s happening, most gearboxes have that difference in ratio. depending on where you are driving it could be normal for it to downshift like if your climbing up a gradient and the engine is struggling or if you are putting the accelerator more than around half way down the ecu will be programmed to downshift. If it is an auto and you have the option for a manual mode try using that and go out for a drive, if you select one gear that’s comfortable for 70mph and go on for a mile or so as long as you have it in the manual mode it shouldn’t change. If this fixes the problem for you then you have narrowed you issue down and can get someone who knows a bit about transmissions to take a look.

Go to Audi dealership, there usually a bunch or arses as soon as you say the word warranty but a car that’s only 3yr old should be covered, be persistent with them. with a car that new they should be able to fix it easily, notorious for complicated electronics especially with all the dashboard stuff they’ll probably be able to reset it or something. my Audi is 2009 and up until a year or two ago they were still parts under warranty on it.

Possibly, you will need to check the engine mounts match if not you can make some so it will mount as long as there’s enough room in the engine bay. you will also need to check the transmission matches up unless you are taking the out too and swapping it, some places can make parts for the transmissions to match on cars if the don’t. most annoying part is usually getting the wiring correct and the ecu, If you have both full cars in working order it will be a lot easier. any engine swap is not an easy task if its not like for like. if you haven’t done it before my advice would be don’t unless its a project car and isn’t going to be driven daily so you have time to get things right.

first thing before you spend any money on the job, if the timing has gone it is possible the valves could of hit the pistons so I would get someone to check that before you throw any money at it (it is possible they will be okay) and yes its best practice to replace the water pump when doing a timing chain job as the new chain will outlast the water pump probably and you will be paying the same labour cost in a years time or so. Oil pump not so sure it will need changing unless its damaged it should be fine as it is. Gaskets and timing chain kit is a given obviously, if its a V6 or an engine with the chain at the rear it will involve removing the engine which is more time and expense, some cars can be done with the engine in if its a single chain at the front by removing the front end of the car, either way a basic car with one chain at the front with no engine removal will set you back around £700 whatever that converts into $, we do a lot of the over here and normally looking over £1,000 for a job with...

if you’ve had the problem from the initial install take it back, usually with aftermarket stereos you have to feed a wire from the stereo into something in the car that tells the stereo your in reverse (usually the live wire for the reverse lights) maybe be been hooked up to the wrong wire, if its flickering I would probably take a guess the link between the car and stereo to indicate this is incorrect and probably loose or not attached securely if its flickering.

if it is a keyless start it may be the signal from the key to the car is weak or there is a problem in the keyless system, not sure about mazda but Toyota and a couple of other models have that,