Vehicle: 2004 BMW Z4 3.0i w/ SMG Transmission
One day, I went to get my engine bay detailed. I pulled up and got the engine bay cleaned and then tried to reverse out but...nada. I was stuck in Reverse. Tried it again and my battery started to drain. I thought it was an electrical issue due to the engine detailing. He did a very good job in avoiding electrics but who knows. Got the car towed home.
The next day, I decided to try the car out. And the car popped into Neutral and started without an issue. Drove it to work. Worked. Went back to my car, started perfectly once again. SMG pump was priming, and no issue whatsoever. I looked online and I was told to change the SMG Relay. I went to BMW and they had NO idea which relay was the SMG relay. They told ME to come back to THEM with the part number. They then sold me a relay. It wasn't the right one. I walked right back in within MINUTES. They tell me that relays are FINAL SALE. I'm like "dude you gave me the wrong relay and I literally tried it out in your own lot!". I had to fight for it and finally after searching forums on my phone, I got the right part number. They allowed an exchange as a form of "good will". Bullocks.
Put the relay in, nada. I asked them for a boost because I don't have any power. They refused because the tech guys were on break. I then called up a mate, and we drove to a local Canadian Tire and bought a new battery hoping this would fix the issue because there was no power to the car. I popped in the new battery and nada. I left the car there over night and decided to try it out tomorrow and borrowed my friends E46 .
That night I did more research and again people point it to the SMG pump or the SMG relay. However, some folks believe it could not be the pump since the issue is intermittent.
The next day, I got to the BMW dealership to pick up my car, and lo and behold the car worked. I decided to drive my car to my local indy for a free diagnosis because BMW wanted to charge me $180+tax. (in hindsight, I should've done so...)
Got to my local indy. He checked the battery and alternator. We noticed that the SMG pump kept priming for no reason with 4-5 second intervals. And we also noticed voltage drops when it primes. Due to the constant priming, maybe the alternator was not shooting enough to the pump. (Hey, what do I know). After replacing the alternator. I drove away. The next day...nada.
Decided to go to the indy next door. They deal with Ferraris, lambos, porsches, maybachs, etc. I'm sure they have SOME idea. They asked for $99+tax for diagnosis. I bit the bullet and got a ride to work.
They called me while I was at work. Explaining that it was due to very low SMG fluid in the reservoir. They told me I need new fluid and I should be good to go. They changed the fluid and retaught the system. They also told me that they were not too familiar with the SMG gearbox in the Z4 as it was very different from the E46. This worried me. $300 later, I had the car out and was driving perfectly for 3 days. 3...short days.
While on the way home from work, the car kicked to N and the tranny light popped up. I was stuck in the middle lane off the exit of a highway, with douches honking and swearing at me as if I planned on breaking down. I turned it off, waited, turned it back on, it kicked into 1st! Put my foot on the gas annnnd...it kicked back to N. Luckily I was on a downhill so I coasted into a parking lot. And called for a flatbed home.
That night, I decided enough was enough. BMW was not helpful. Indy did not know what he was talking about. The high-end place had no idea what they were doing. I called up Mister Transmission. He knew EXACTLY what I was talking about because he has had 2 other Z4's with that issue along with numerous E46's. I made an appointment and got the car towed there.
VERY friendly folk and they knew what they were doing. I did not tell them what I suspected was the problem. They told me they will give me a call, and I went back home (I had a family member give me a ride back).
One hour later, they gave me a call. Explained that they pulled out codes using their DIS and it all related to the SMG Pump and one code about the thermostat. They cleared the Thermostat code but the SMG pump code remained. They asked me for the all clear to replace the pump.
A day later, they call me saying that the car is ready. I was excited but kind of worried due to my previous experiences. I got there, and it actually worked a LOT better than before! The SMG pump was the issue all along and it only cost me $700 to replace with a new one. It used to prime all the time, but I did not know that was not normal as I bought it like that and there aren't any videos or people I know that can show me what a normal SMG priming noise sounds like. I'm incredibly happy, and ready to get on the road again
. I hope this really IS the fix.
P.s. My third party warranty agreed to cover all the costs
tl;dr version: SMG would not kick into gear, indys didn't know what they were doing. I wasted money. Went to tranny place. Replaced SMG Pump. 3rd party warranty agrees to cover all costs. Fingers crossed