Jay P

Update: So on Sunday I decided to retrace the work that had been done by the mechanic when the spark plugs and coils were changed. The first issue I noticed was that the clips on top of the coils were not properly fastened they were partially loose or partially wonky on one side where it is connected to the coil like it had come out of place. So I removed all the plugs and used electrical contact cleaner on all, sprayed some of the stuff on the wires and their housing and sprayed into where the pins were on the top of the coil. Also swapped all the coils around for good measure. And made sure the clips were properly fastened with the plugs in properly. Best removed the two crank sensors which were a pain to get out, unplugged them, same process of electrical contact cleaner on the pins and plugs and reconnected up. Next removed the plugs from the starter motors and sprayed into pins and plugs. Removed various other sensors which I could reach without disconnecting major parts and cleaned with the spray on the pins and plugs. Started the car up, was still sluggish... Monday drove to work was still slightly sluggish but felt a little responsive. Got in the car at the end of the day, started it up to be met with an EML, hooked up my cheap code reader, two codes both related to throttle position sensor, the misfires were not showing this time. Cleared the codes. Removed my accelerator pedal and cleaned the sensor pins and plug with the same spray. Hooked it back up. Started the car and no codes. Drove home and the car back to itself!! I couldn't believe it. When I got home I left the car to stand still for awhile and got back in for a drive round the block was still fine! Today drove to work and it is still fine! Moral of the long story?? Maybe check the sensors and pins and plugs and make sure they are crystal clean before getting expensive work done on the car next time! Also make sure the coil pack plugs on top are properly fastened with the clip in place and none being loose! Another moral of the story? Make sure to check your mechanics work after him/her!! I hope I'm not getting ahead of myself but I really do hope the issue is now fixed. The car feels great and is pulling strong. Sorry for the essay but had to share the story in case anyone else has similar issues and what they should check.

Update: Had an MOT done on the car just now as I am not in the exempt category 🙄 The guy said the emissions would have been a fail but after revving the engine harder it then passed - so at lower revs emissions aren't good. Could this shed any light on any possible reasons for the misfire? Or isit unrelated? Also something to note, the steering feels heavier than before since I have got the car back. Could this be related in anyway? Feels like not much power assist? Could it be a sensor of some sort that could cause car to misfire if steering isn't working properly? Just a thought As always thanks for the help so far really appreciate it and I'm learning a thing or two too whilst at it

I actually forgot to tell the mechanic to check this. But it seems easy enough so I will have a look myself to see if that pulley is moving as you have described.

Dave, when you say wiring loom is there any specific ones I should be looking at? Or isit a case of checking every single wire in the engine bay?

I have also read online in many forums that sometimes bad cam sensors or crank sensors can cause power loss and misfires and they also sometimes don't show up as fault codes. How can I check that these sensors are working?

Also would it be worth checking the basics again? Like the coils and spark plugs in case they are faulty? They were all changed from the previous mechanic plus one fuel injector which was sticking the rest were fine so weren't changed.

Update: So had another mechanic take a look who has a BMW tool and he read the hexadecimal codes (hexi? / Hexa?) And they are only showing multiple cylinder misfires. I didn't get a picture unfortunately. He also updated the ECU software while he was at it. He checked fuel pressure and flow which was fine @ 3.7bars He checked the O2 sensors all reading fine and he did a back pressure test showing 20.30m/bars He checked the entire air induction system which was all ok. He checked vanos lines and swapped the control valves to see if any differences and all was ok. He is the second mechanic to now say its not an electrical fault and if I want him to further test he will need to open up the engine which of course costs money. On top of the diagnostics which have been done from previous mechanic which I listed above he has done additional tests. I brought the car back and fired it up without any issues. Sounds fine. Runs fine. Fuel consumption is fine. No wierd noises. No stalling or engine juddering or fuel cut off. Can't hear any wierd noises from the engine bay and neither could the mechanic. Drives perfectly fine when driven at around 40-50mph. Slowly pressing the accelerator the car picks up speed but is missing the punchy feeling of immediate throttle response, it's more of a steady pick up in speed. Go over 3500-4000rpms with foot down the car starts to hesitate and misfires and loses power. Engine light flashes then Dissapears after 15seconds approx. Is there anything I can check myself without needing to open up the head? I'm no mechanic but I could possibly check some simple things as a starting point? I have experienced a bad timing chain couple years back because of the metallic horrible sound from the engine and constant EML and limp mode. I do not have this currently. Would a chain tensioner going bad throw up limp mode and a horrible sound? Or would it be more undetectable unless you removed the bolt to check? Sorry for the long message. And thanks for any responses

Hi Dave, He told me has a reader capable of reading BMW specific codes 🤔 I will be questioning him on this if it isn't true! Thanks for the insight.

Hi Dave, The car has 80k miles on it. The timing chain and guides were changed about a year and a half ago. Also they changed one fuel injector which was failing the rest were fine. The mechanic took the air system apart to see if there was any issues there and everything was fine. He checked all the areas surrounding the coolant tank which I had changed to see if anything was out of place and all checked out fine. Wouldn't sensor issues flag up sensor errors on diagnostics? I don't have the ticking sound either to suggest sticking lifters. He wants to take off the valve cover to investigate further but I have asked him not to as I don't want to spend any further money just on the investigation phase. They used a reader which reads BMW codes and only the misfire codes show up. P0300 p0301 p0304 (random misfires, cyl 1, cyl 4) 😥

Quick update the mechanic says his gut feeling is that it's a mechanical fault. He can't find any electrical faults and has checked wiring and the fact that it's driving sluggish even without the EML on/flashing when below 3-4rpms it would indicate a mechanical fault. I guess my next question to you experts is, what are the possible mechanical faults that can cause sluggish power, and misfires with a flashing EML? I will certainly mention the pulley which could be out of place as mentioned by X5smw.

Hi Dave, Interesting suggestion, I will for sure pass that information on to him so he can check the wiring looms for both injectors and coil packs. Is there individual ones for each coil and each injector? Or isit just one for all coils and one for all injectors? I havent looked into that much detail to know. Thanks for the response

Hi All, I need some urgent help as I am starting to lose hope! Have an E46 2006 318ci coupe which has developed a misfire when under load at around 3-4k rpms where the engine light flashes for 10-15seconds and then disappears. Car starts up perfectly everytime no shaking or juddering or cut off or stalling. Drives perfectly fine when below 3-4k rpms. Does feel a little sluggish however. Diagnostics only list random misfires and misfires cyl 1 and cyl 4. No other codes showing up. Changed all coils and all spark plugs. Moved them around into other cylinders to see if those cylinder issues also moved - no resolution Had a fuel injector not working properly which was changed - no resolution Two lambda sensors changed - no resolution Smoke test - no issue with vacuum leaks Compression test - no issues Cat/pre car inspected - no issue with melting from hot fuel from misfiring For background - I had the coolant expansion tank changed recently from which a few days later the misfiring started - any possible connection? Have a minor oil leak - believe it's the sump or the vgc No other issues mechanically. Any advice or ideas Into what else I can check? I don't want to give up on the car but it's been out of action for nearly month now and my mechanic is struggling to find the problem. Thanks for reading

Hi guys, Got myself a E46 318ci 2006 couple months back and just Look forward to seeking support for any issues and reading through this forum and try help anyone with anything also! I will get around to posting pics at some point. Thanks