My BMW 320i engine woes: How I found a solution after a 5 month ordeal

The car was sent to the dealer, they opened the cylinder head and according to their diagnosis all cylinder bores were out of spec.

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Hey everyone!

This is going to be a long post that takes you through the mental agony I faced over the past 6 months in getting my BMW F30 320i LCI repaired. Before getting into details, I would like to make it clear that my 320i ran a custom stage 2 tune and no attempts were made to hide the same from the dealer.

The Beginning - Jan 3, 2023:

On a regular morning, I was taking my car out on a drive and noticed at it was violently misfiring at rpms slightly above idle. As I had driven the car the previous night and had no issues while driving it, I thought it was a simple issue and got it towed to my workshop.

My workshop personnel inspected the spark plugs and they were fouled badly. There was oily residue on the tips of the plugs and it smelled like fuel. I could not understand why the plugs were fouled so quickly especially since they were just replaced 1000kms ago since the old ones had covered 25000kms.

Condition of the Plugs and Diagnostic Codes:

I thought that the tune might be causing the car to run rich and subsequently moved back to the stock tune. The plugs were cleaned and put back. The car ran fine for a few hundred kms but the issue came back.

As I was unaware of what could be causing this issue, I sent the car on a tow truck BMW service centre who said that the catless downpipe installed for stage 2 must be returned to stock and then the car should be sent back to them. I happily obliged, put the car back on a truck and reverted to the stock cat. When the car was sent back to BMW, they replied that the engine must be opened up to diagnose what the issue is. When I asked for supporting evidence to support the opening of the engine, they had no answer but they simply said that the tune has damaged the engine. As I understood from their tone that they were just trying to blame something without understanding the problem, I moved the car back to my shop and continued diagnosing on my own.

Purchasing Tools to Self Diagnose - Mid Jan 2023:

The dealer was extremely unhelpful in talking about data to diagnose the problem. His diagnosis from the beginning was that the piston rings had lost the ability to seal the cylinder and subsequently causing oil fouling of the plugs. While I admit that a broken cylinder is quite possible on a tuned B48, plug fouling on 4 cylinders is highly unlikely since all 4 cylinders do not just fail together. Also, my B48 never ran anything less than 99RON fuel and there has been no case of failure with this engine running >98RON fuel.

As I did not believe in their diagnosis, I went ahead and purchased a compression tester and leakdown tester from toolbuy.com. Although this costed me Rs.15000, I thought it was better than whatever BMW would do blindly opening an engine.

A compression test was performed on all 4 cylinders that showed consistent 225 psi across all 4 cylinders. I also performed a leakdown test which showed less than 5% leakage on all cylinders.

Compression Testing the Engine:

With this testing, I was convinced that the engine was in a healthy condition and spoke to the dealer again. The dealer did not have a response on my findings and insisted on opening the engine.

FORUMS and how they can turn a simple diagnosis into a big problem:

As my agony continued with the 320i, I put up various threads and forums on websites like bimmerpost and babybmw to help me diagnose my issues. I narrowed my issues down to 4 possibilities -

Possible Causes:

• Worn valve seals - No Smoke from tailpipe thus unlikely (Extremely unlikely)
• Worn piston rings - Compression is good. Problem with all 4 cylinders not just 1 thus unlikely.
• Faulty PCV in the valve cover causing fouling - Diagnosis difficult since no direct cause can be identified. (Known B58 issue)
• Faulty Fuel Injectors - Known B48/B58 issue. Extremely difficult to diagnose and unlikely to affect all 4.

As I found the PCV problem to be the most likely (since It would affect all 4 cylinders) I asked the BMW dealer to change it but first, I asked them to test the fuel injectors while they're at it.

Few important threads where I found help with my problems:

• Baby BMW - B48/B58 Injector Failure
• B58 Valve Cover Replacement and other experiences

Where it went all wrong - 5th Feb 2023

I received an affirmative reply from my service advisor at the service centre that they had indeed checked the injectors and found nothing wrong post which they continued with the Valve cover replacement. Note that BMW Jaipur specifically said that they do not suspect its a valve cover issue but I insisted in trying out the same.

Few days passed and the Rs.52000 valve cover replacement did not help. It was an expensive lesson learnt. The plugs were getting fouled after a few kms and I had no idea what could be the problem. As I wasn't willing to open the engine at this stage, I decided to move the car back to my place for a few weeks to think what it could be.

As the car was practically just taking up garage space, I decided to finally give into the service centre's demands after a couple of weeks and approved engine disassembly for further diagnosis.

Engine Disassembly and Results - 5th March 2023

The car was sent to the dealer, they opened the cylinder head and according to their diagnosis all cylinder bores were out of spec. They claimed that the 82mm bore of the B48 of all the 4 cylinders had somehow enlarged by a 0.02-0.03mm and that was resulting in the oil pooling. I did not believe their stories since bores do not just deform on such a well built engine. Note - The B48 block is extremely strong and has a plasma arc coating on the bores. It is built to the same standards as the widely renowned B58 and custom turbo engine setups are producing 500whp with a stock block B48. There are zero known issues with the B48/B58 block and they are only known to fail due to a significant injector failure causing detonation.

Among their many hypotheses, the technicians also suggested that the valves were damaged thus the whole engine needs to be replaced for around Rs.12,00,000. I was present at the dealership when the engine was fully dismantled and I noted that there are no visual signs of wear on any of the cylinder bores. Cylinder 2,3 and 4 are dry but cylinder 1 had oil pooling for unknown reasons. I spoke to my tuner who is a B48 specialist and he too could not find anything wrong in the pictures i shared. The oil pooling according to him was probably due to the disassembly process causing oil to spill out of places. I could not comment on the valves since I lack the experience but so many issues on a fine running engine were not possible.

Few pictures of the engine disassembled:

Note that cylinder 3 and 4 that had the misfires code had not even a speck of oil on them. The dealer did not have an answer for this and blamed the valves for the misfires.

Distraught by the diagnosis received, I turned to a BHPian mechanic in delhi @Viraat13 to help diagnose the issue.

Update - 9th March 2023:

I got the car back from the dealer after paying an eye-watering sum of Rs.72000 with nothing to show for. I tried to approach the people at BMW India but their reply is that they trust their dealers and their mechanics in the diagnosis. The car was put on a tow truck and sent to Viraat's garage in Delhi for diagnosis.

Viraat's diagnosis:

Viraat suggested that it was likely one of three issues that could be creating a problem:

• Worn Valve seals - Only physical verification possible
• Just the oil rings on the piston going bad - No way to test
• Fuel Injector issue - He could not test due to lack of bench testing of such injectors

Since the engine had already been opened by BMW once and returned with the same old gaskets and loosely put together (As I requested), the engine was dismantled by Viraat again. He too did not find anything wrong with the engine per se and suggested that the piston rings and valve seals be changed just to make sure that the engine is fine. Although I was reluctant on changing either of the two parts due to the lack of any compression loss, I went ahead with his suggestion with a couple of caveats:

• Absolutely no honing of the cylinders - The B48/B58 cylinder bores cannot be honed and since they were in mint condition, I asked specifically for no honing to take place.
• The engine should be built to factory spec - I also provided Viraat with all the relevant technical literature from newtis.info for my personal satisfaction

Some pictures from the rebuild:

The Long Parts Wait:

From 9th March to Almost 18th April, my car awaited parts that were simply not available anywhere in India due to the 320i being a limited CBU import. Even though 99% of the parts were shared with the 330i, simple parts such as a head gasket took more than 12 days to source. Piston rings were imported using Ebay UK in a couple of weeks and valve seals were procured in India.

The Story Continues:

On 19th April my car was put back together and on the road with Viraat in Delhi. It drove fine for 200 kms and the misfires came back as usual. Once again, the plugs were fouled.

At this stage, there was nothing except the fuel injectors that hadn't been replaced and they weren't being suspected since the BMW dealer categorically said that he had tested them. In hindsight, I should not have believed him and spent all this money at the dealership and the FNG.

The Final Fix:

Running out of ideas, new injectors were ordered through Sushila Autotechnik for Rs.52000 and after a couple of weeks, they arrived. Low and behold, the car with it's new injectors was fixed.

No misfiring at all, the engine was as smooth as ever and the car was back to brand new. The plugs were not getting fouled, there were zero misfires and the engine felt just like it did from the factory.

Final takeaways and a couple of thoughts:

On 7th May, I drove my car back from Delhi and this 5 month ordeal was finally at an end.

If I had to sum up my experience, this would be it:

The tech staff at BMW Jaipur is not qualified to diagnose any serious issue a BMW. They are here to rip off unaware customers of lakhs of rupees and cannot offer anything to an customer who knows even a little about cars. Their list of lies if put into bullet points would be:

• Engine needs a valve job and that the child parts aren't available for the same thus requiring an engine replacement.
• THEY TESTED THE INJECTORS
• The bore was out of spec causing oil fouling of spark plugs.
• The various theories of bore enlargement, bore damage and piston failure.

Had it not been for my own inclination towards the workings of an engine etc. I would have spent 12L rupees at the dealer for a new engine and the problem would have reappeared since the injectors wouldn't be changed!

BMW India was of no help during this ordeal. I get that they trust their dealer technicians but clearly not all of them are trained/skilled to handle the problems that BMW vehicles have. A faulty injector is one of the leading problems on a B48/B58 engine worldwide and dealers in the UK are well aware of such issues and do the diagnosis accordingly.

Not having basic tools such as a leakdown tester is truly a shame for a dealer. How can BMW expect a customer to pay lakhs in labor to diagnose a problem without any concrete data as to why? The dealer did not even have a simple borescope to check the cylinder condition.

If all that the dealer is good for is using ISTA to diagnose issues and in the absence of which can't go through simple procedures such as injector testing, leakdown testing etc. I question why send the car to the dealer at all for diagnosis. Just get ISTA for free and tell any reliable FNG what to do.

Rare and CBU vehicles can be such a pain to deal with due to the parts availability. A more popular BMW such as a 320d/520d could have been fixed much sooner in my opinion.

Please have access to common diagnostic tools such as ISTA and websites such as newtis.info. These websites saved me from a ton of lies I received from the dealership.

Ending Note:

These five months were extremely agonizing for me considering how much I like to drive and enjoy my car. It has left me with a bad taste for BMWs and especially it's after sales service in Jaipur. Although the recent offerings such as an M2/M340i are extremely compelling, I do not see the brand with the same fascination that I used to before. As a young enthusiast I hope BMW India takes steps to improve it's customer experience as the brand's attractive lineup of vehicles is being let down by such experiences and deterring others like myself from choosing this brand in the future.

On a cheerful note, this 5 month journey has taught me alot about BMWs and cars in general. The sheer lack of knowledge displayed by the techs at BMW has shown me the market potential for specialist garages and I hope to have one in the future to tackle all sorts of engine mods, rebuilds etc. From learning how to use a bore gauge, borescope, compression tester etc. and reading about ring clearances, honing etc. I have gathered immense amounts of tools and knowledge that has prepared me not just for this ongoing project but also other cars that will come in the future.

As to what the future is of the car, with a brand new Bilstein b12 suspension, I am back on the road. Waiting for the break in period to be complete. Hoping to put on thousands of more kms on this beast before I move onto something faster, preferably from Stuttgart

Special Thanks:

Thanks to bhpian Viraat13 for helping me with this repair. Special thanks also to the folks at Mechanix Automotive, Pune for helping me with the diagnosis process.

Check out BHPian comments for more insights and information.