HELP!! E46 328i runs rough misfire only when hot?

[WANAM5 5]

HI everyone i need some help if anyone has come across this problem before,

My 1998 328i just developed a misfire feels like runs on 5 cylinders and rough idle BUT only when it gets to operating temp? I dont have a code reader and im poor so i thought id try fix my baby myself.

So i checked for split hoses eg air box hose thing and that elbow shaped hose that runs off it no splits thought a vacuum leak sounds plausible as cold start makes eng run richer? hence runs perfect until hot and runs lean causing misfire? thought maybe a blown head gasket but then wouldn't it run crappy all the time and get hot? thought faulty coil or plugs but then again wouldn't the problem present itself even on cold start?

Any help or guidance be much appreciated thankyou

 

[Gaz 1061]

I know you don't want to spend money but a scanner is going to be your most effective solution here. Otherwise you will be spending money on parts that are not needed

[qube 3570]

yep its a blown headgasket and going to cost $5k to repair. Please sell to me for $500 scrap value

[M3AN 4016]

A problem with coils/plugs could manifest only when hot due to thermal expansion. You can check those manually without a code scanner (see Google) but I tend to agree with Gaz, a scanner is a very worthy investment.

 

[WANAM5 5]

30 minutes ago, M3AN said:

A problem with coils/plugs could manifest only when hot due to thermal expansion. You can check those manually without a code scanner (see Google) but I tend to agree with Gaz, a scanner is a very worthy investment.

 

ARRR got ya, yes i see thankyou very much gentleman, hopefully wifey will give me extra pocket money lol out of interest what brand scanner is a worthy investment for a weekend warrior like myself?cheers

[WANAM5 5]

9 hours ago, Gaz said:

I know you don't want to spend money but a scanner is going to be your most effective solution here. Otherwise you will be spending money on parts that are not needed

Bugger thanks Gaz i had a gut feeling i needed a scanner just the tight arse that i am didn't  want to fork out lol

[M3AN 4016]

2 hours ago, WANAM5 said:

ARRR got ya, yes i see thankyou very much gentleman, hopefully wifey will give me extra pocket money lol out of interest what brand scanner is a worthy investment for a weekend warrior like myself?cheers

To be honest I'm not sure what's the best to get but you should be able to get one that supports both the E60 and E46 and I hazard that a basic one will cost less than 100 bucks (I stand to be corrected).

Perhaps have a search around this site, I'm sure it will have been discussed recently.

 

[qube 3570]

see if anyone nearby has one you can borrow?

[WANAM5 5]

23 hours ago, qube said:

see if anyone nearby has one you can borrow?

yes i may have someone in mind! thanks all for your help will report back when i get it sorted Cheers

[Mad_Max 231]

Check the basics first. As @M3AN said, these things suffer from the sealant on the top of the coil packs failing, something that won't be picked up from a scanner. I have also seen a friend's rally car occasionally drop a cylinder at revs, only when turning left - turned out to be the hose from the intake boot to the ICV and manifold that caused that issue - again, something that wouldn't be picked up from a scanner.

Check your spark plugs, not just the condition but make sure they are done up right. If you can identify which cylinder is dropping out, switch coils and see if the misfire follows the cylinder. Also do a compression test, both dry and wet. Check for gasses in the coolant etc. Is there any rattles or ticks coming from the top end?  Is the condition just at idle, at WOT or POT? 

If you want basic diagnostic stuff, a cable and adapter with INPA (BMW specific software) is reasonably cheap, think I paid around $40 a few years ago. Start with the basic stuff first, these things can throw fault codes that don't always point to the exact solution so you may end up throwing a lot of money at sensors and start costing you more than you think only to realise it's a simple solution.

[WANAM5 5]

On 2/22/2019 at 12:02 AM, Mad_Max said:

Check the basics first. As @M3AN said, these things suffer from the sealant on the top of the coil packs failing, something that won't be picked up from a scanner. I have also seen a friend's rally car occasionally drop a cylinder at revs, only when turning left - turned out to be the hose from the intake boot to the ICV and manifold that caused that issue - again, something that wouldn't be picked up from a scanner.

Check your spark plugs, not just the condition but make sure they are done up right. If you can identify which cylinder is dropping out, switch coils and see if the misfire follows the cylinder. Also do a compression test, both dry and wet. Check for gasses in the coolant etc. Is there any rattles or ticks coming from the top end?  Is the condition just at idle, at WOT or POT? 

If you want basic diagnostic stuff, a cable and adapter with INPA (BMW specific software) is reasonably cheap, think I paid around $40 a few years ago. Start with the basic stuff first, these things can throw fault codes that don't always point to the exact solution so you may end up throwing a lot of money at sensors and start costing you more than you think only to realise it's a simple solution.

Hey thanks for your time i really appreciate it! im a tight arse in most cases but in this case i just want to learn about my car! and i feel a great sense of achievement when i fix it! also i keep in the good books with wifey!!

Its far from a mega dollar hotrod like a lot of the cars on this forum BUT its my little car which owes me nothing and this wee BMW im in love with! cause she just keeps on going........until now!

Cheers