Tag: bmw n20

BMW N20 (Z4) No Start When Warm Fix

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BMW Hard to Start Warm

INTRO:

After two years, no help from the dealer or the Indy shop and countless troubleshooting steps, I have finally solved the bad start issue on my BMW Z4. Hey guys and welcome back to the SimpleCarGuy channel! Today, I will go over all of the steps I took to try and solve this problem over the last 2 years, what I’ve learned in the process and how I accidentally solved it.

Quick Preview:

To put a lot of this into perspective, I got the car with a blown engine and swapped in a newer 30k-mile engine in my garage. Since I didn’t use the same exactly engine as I took out, I had to swap a lot of parts in the engine replacement process from the old engine. As a result, I had a few issues once everything was finished, but nothing I couldn’t solve. Except for this bad starting issue. When the car was cold, it would start no problem. However, after the engine was fully warmed up, there was a chance that it wouldn’t start or hesitate while starting. It didn’t help that the car has auto stop and start option and would turn the engine off at each red light.

From the information I have given you so far, what do you think the solution to this problem is? Leave your comments below and NO cheating! Now would also be the best time to hit that LIKE button to support the channel!

Troubleshooting:

Since I believed the issue had something to do with the engine swap, I started troubleshooting some of the more obvious items. I rechecked and retightened all of the ground wires as well as the power wires going to and from the alternator and starter, checked all of the fuses and everything else I could think of. None of it made a difference. To be clear, I never had ANY codes on the car related to this issue.

With the wiring not being the problem, I got to thinking that it must be something to do with the ignition system. The most obvious item that came to mind and something I definitely touched during the swap was the crankshaft position sensor, this sensor tells the rotational position of the crank to the ECU and when it goes back, shows similar symptoms to what I had. Luckily, these are very cheap on eBay, so I swap it out but the problem remained. Similarly, the camshaft sensors monitor the speed and position of intake and exhaust camshaft. ECU uses this information for ignition and fuel control, but after swapping these out as well, I still had the same starting problem.

At this point, I’ve posted on forums, groups and consulted with a few friends and of course everyone gave a different solutions and mostly blamed different sensors that are known to fail on a BMWs. Since I like tinkering with cars, I got right to it! I’ve swapped out the air intake temperature sensor, cleaned and later swapped the mass air flow sensor, tested the coolant temperature sensor on the engine block, unplugged the O2 sensors to see if that made any difference and even looked into the oil pressure sensor as well as checked the oil pressure when the engine was fully warmed up. All was normal, still no codes or any other indication of something being wrong with the engine.

Just to check some items off my list, I smoke tested the vacuum system on the engine to look for any leaks, replaced the vacuum solenoid and even cleaned the PCV valve in the process. Of course the results were still the same.

Knowing that the wires are all secure, the ignition system is operating as expected, most of the sensors on the engine have been replaced or tested and there were no vacuum leaks on the car lead me to believe that it has something to do with the fuel delivery. I started with a big one and replaced the HPFP as I had a spare one from my old engine. The HPFP is one of the common issues on this engine that can cause very similar symptoms. However, even after replacing the fuel pump, the fuel pressure regulator AND testing the fuel rail pressure, my starting situation didn’t change.

Things I’ve Learned:

All of the items I have mentioned so far have had no effect, but replacing the injectors did make a change, just not to how the car started. What I learned was that there were 2 different injector types on the N20 engine, the EU5 and the EU6. Although practically the same, at full throttle, I would get a lean code pop up once in a while. After replacing the newer EU6 injectors with the EU5 Injectors from the old engine, those codes never re-appeared. The reason I’m mentioning this is in case you are troubleshooting a similar issue and didn’t think to look at the injector version.

Dealer:

So, I definitely learned a lot in the process but after all of this time, the car would still be hard to start when warm. Since I couldn’t figure it out, I decided to take the car to a local Indy shop that specializes in German cars. They spent a couple of days troubleshooting the car and at the end told me that it ‘might’ be the Valvetronic servo motor that needs to be replaced. Looking online, it looked like a possible solution, but before I took the engine apart, I brought it to a BMW dealer to check out as well. They scanned the car, logged some data, reset the adaptations on the DME and sent me home. The issue was back before I even got home. Not wanting to pay $200/hour for further troubleshooting, I left it alone and drove the car as is for a while.

Final Fix:

Knowing everything you know now, have you figured out what the issue was? The solution was purely accidental. If you follow my channel, you may have seen a video where I replaced the starter motor on this car. After I removed the old one and got the new one out of the box, I noticed that they were different in size, color and even OE manufacturer. I was sure I ordered the correct starter as I went by part number that came up for my VIN. The reason these two were different is because the starter that was install on my car was for N20 engines that do NOT have the Auto Start/Stop functionality. Someone in the past, installed a starter that technically fit, but was not made for this version of the car. After installing the correct starter and driving for about a week now, I have had absolutely zero issues! This just shows you that you can try 100 different things, but sometimes the solution is hiding in plain sight. I hope some of the troubleshooting steps I talked about help someone fix their cars that have a similar starting problem. For now, I will continue enjoying my BMW Z4 now that it’s 100% issue free. Thank you so much for watching and I’ll see you in the next one!

BMW N20 Problems to Expect – Reliability Report

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Hey guys and welcome back to the SimpleCarGuy channel. So, you are looking at a BMW with the N20 engine and want to know how reliable it is? Well, you found the right video as today we will be talking about the common issues, best and worst years to buy, what to do if you already have this engine in your car and my experience after 2 years with this car.

History:

We’ll start with a little background and history as I think it’s important to understand before we talk about the common issues and problems. I swear this will only take a minute! The BMW N20 engine was designed to replace the N52 and N53 6 cylinder naturally aspirated engines that were among the most reliable engines produced by BMW and used in most ‘common’ BMWs. Even though the N20 engine is a 4 cylinder, it produced similar power figures and powered equivalent models. Of course, this means the engine has been turbocharged, direct injected and used other top of the line technology for 2011 to achieve this performance.

There were a few different version of the BMW N20 engine manufactured from 2011 to 2017 and used in many different vehicles. Europe and other countries have the optional lower power 180hp version in their 320i, 420i, 520i and other ‘something’20 cars, but in North America we only had the 240hp version and that’s the version I will concentrate on in this video since the biggest difference is actually tunning and support components and not the engine itself. So, it mostly applies to both. North America got this engine in the Z4 (point to it), X1, X3 and X4 SUVs, 3, 4 and 5 series and even in the sDrive40e X5 where it was mated to the hybrid electrical motor. So, clearly it was used across most of the BMW range. [Show which cars it was in on the screen like I had the list in the emergency kit video]

Common Issues:

Alright, so what are the common issues then? The worst common issue on the BMW N20 engine has to be the timing chain issues that have been discussed at length. To summarize, BMW has used brittle plastics for the timing chain guides which break or crack after a certain period of time causing the timing chain to get loose and eventually skip timing, eventually destroying the engine. Hopefully it never gets that far and you notice the chain rattle way before that and get the chain replaced. In some cases, the chain tensioner is the culprit behind the loose chain and since it’s very easy to change, it can be a good first step before taking the engine apart.

The second big issue on the N20 engine is the rod bearing failure. This one is even more serious, but luckily not as common as the chain guide issue. If you start hearing a slapping type noise like this, you might be looking for a new engine. While the rod bearings are not impossible to replace, unfortunately, the crankshaft gets damaged in the process as well and to fix the journals on the crankshaft, the entire engine has to be taken apart. If there is any hint of rod bearings going bad on your engine, it’s time to replace those NOW.

With the scary items out of the way, let’s talk about some of the common issues that you can probably DIY or get done without spending a fortune. Just like with the N52 and N53 engines, the valve cover is plastic and has a tendency to crack and/or leak oil. This wouldn’t be a huge problem, but it usually leaks all over the exhaust and O2 sensors, which can be damaged in the process… not to mention the smell of burning oil.

Similarly, the oil filter gasket issue has been carried over from the older engines and can leak. Luckily this one is very easy and inexpensive to replace, but if it’s not replaced, it will leak all over the serpentine belt which can cause some serious engine damage.

We are getting closer to the end of the list, but there are a few more items to mention. As we know this is a turbocharged engine and as such it has a wastegate. Unfortunately, the design of it allows the wastegate flapper to get loose overtime and start making a noise. This wastegate rattle isn’t a huge problem at first as it just makes an annoying noise, especially when you start the car, but the looser it gets the more of an issue it can be as it won’t hold boost and degrade performance of the engine.

This engine is also direct injected as mentioned earlier and produces low emissions, which is great but it also means that carbon build up isn’t uncommon. The injectors themselves are also pretty high tech and can fail causing drive train malfunction messages and stuttering of the engine while driving. Check out this video on how to replace the injectors on this engine in the top right corner or the description.

The last item I want to talk about on the N20 engine is the high-pressure fuel pump. These were a huge problem on the N54 engines, but luckily not as huge of a problem here. They still do fail on these engines but at least they are not as expensive and can easily be replaced in half an hour. I’ve done it on this engine and here is how.

As these engines are becoming older and older, it’s also a good idea to check the coolant hoses for cracks, make sure the chargepipe is not cracked and inspect the vacuum lines for any leaks. The most expensive part of fixing BMWs is the labor, so maybe it’s good to tackle some of the easier projects yourself and learn more about your car in the process.

Best and Worst Years:

So, what issues got fixed over the years and what are the best years to buy then? [put this on the screen] In most cases, that doesn’t really matter, but with this engine there is a big difference. The only N20 engines I would recommend would be the ones build in 2015 and later as they have fixed most of the issues discussed here on those models. They improved the timing chain guides, changed the injectors to EU6 from EU5 and improved the overall reliability. If you are considering a BMW with the N20 engine between 2011 and 2014, I would make sure that all of the issues we discussed have been taken care and the maintenance has been on time, but especially the timing chain replacement.

Longevity:

What can you do?

Now, it may sound bad on the surface and I’ll admit it’s not the best engine in the world, but these engines are in thousands of vehicles and a lot of them have no issues at all or the issues have already been fixed. So, as with most BMWs, if you take care of them properly and do some extra maintenance they will last much longer. A few examples of that would be to check your oil every other fill up and change your oil every 5k miles and not every 10k miles as recommended by BMW. This will help with preventing rod bearing failure. Also, check for oil leaks and take care of those fast before they cause more damage and a lot more expensive repairs in the future. Lastly, if the timing chain has not been replaced on your early N20 engine, get it done before it’s too late!

Personal Experience:

As for my personal experience, I bought this BMW Z4 with a bad engine, but looking at its history, it was maintained by the dealer as per the book. You can follow my early videos on this car where I go through the process of replacing the timing chain, HPFP, injectors, fixing the wastegate rattle and eventually tearing apart the broken engine to reveal the damage done by a spun rod bearing. However, ever since I installed a 2015 engine in this car, it has been running like a dream for the last 2 years.

Conclusion:

All in all, this is not a bad engine, especially after the improvements done for 2015 and newer models and the other issues are only becoming common on engines with very high mileage. A lot of it also has to do with how the engine was taken care, driven and of course some luck on how it was built that day at the factory. With any luck, a well taken care of BMW N20 engine should be reliable and also inexpensive to maintain while providing a smooth, enjoyable and sporty drive. Stay tuned for the reliability video on the N55 and N63 engines in the near future, thank you so much for watching and I’ll see you in the next one!