Warm start longer crank and misfires

[zbrit00x]

Hey all, having an issue when I hot start ( car was driven up to temps, turned off and driven 30min-2hr later) my cranks are longer.


all coil packs were changed as were the spark plugs to step colder plugs ( issue was still occurring prior on oem plugs), valves blasted about 2k miles ago, a couple injectors replaced after diagnosed ad leaking.

No codes are thrown

I can tell car is getting more fuel than usual. Tips go black after a day and ISTA reports -29% adaptation on bank 2 while bank 1 is .3%

Car runs fine at wot.

Anyone got any ideas?

fuel adaptations and idle now good.

[Dackelone]

I would go back to stock plugs. Buy your spark plugs at a dealer, not some aftermarket ones - they are known to cause issues.

You said you replaced a "few" injectors... one or two... you do know that BMW says you should always replace the injectors in sets of THREE. There are two banks/sets of three.

What codes are you throwing? You might want to check your fuel pressure to see IF one of your injectors is leaking.

I would also look for vacuum leaks. Like the vaccum lines that go to the WG actuators or a cracked valve cover.

Dackel

[zbrit00x]

3 injectors from bank 1, and 1 injector from bank 2, I checked and made sure the index numbers were compatible with what was left in bank 2.

Issue was actually worse with stock plugs and they only had 6k miles on them

No codes are thrown, looked through the Cobb AP, looked through ISTA. Same deal. Haven't logged fuel pressure on start up but at wot lpfp and hpfp are good. Can't remember exact values right now.

I replaced the vac lines by the oil filter housing but will check the waste gate.

I inspected the valve cover and actually replaced the valve cover gasket, thermostat housing gasket and oil filter housing gasket too.

Thanks, keep shooting any suggestions you have to me!

Originally Posted by Dackelone

I would go back to stock plugs. Buy your spark plugs at a dealer, not some aftermarket ones - they are known to cause issues.

You said you replaced a "few" injectors... one or two... you do know that BMW says you should always replace the injectors in sets of THREE. There are two banks/sets of three.

What codes are you throwing? You might want to check your fuel pressure to see IF one of your injectors is leaking.

I would also look for vacuum leaks. Like the vaccum lines that go to the WG actuators or a cracked valve cover.

Dackel

[Dackelone]

Originally Posted by zbrit00x

Thanks, keep shooting any suggestions you have to me!

Bad oil cap/seal? I've seen cars with a bad oil cap seal cause a bad idle. Maybe remove it with the engine running and see how the engine idles ? (be sue not to make a mess with spitting oil out of the VC).... It should idle rougher - bc it causes a vacuum leak.


I would still replace your spark plugs with dealer bought ones. I have just seen too many guys chase their rough idle tail only to be cause by a bad spark plug. I used to work with a tech who was fond of saying.... "Just bc its anew part doesn't mean it's a GOOD part!

I would buy some non flammable(IMPORTANT!) brake cleaner... CRC use to make some... they spary down your vacuum lines with the engine running... IF the engine suddenly bogs down... you've found your culprit!

I kind of feel that it's vacuum related bc you say your cold start idle is fine. Maybe when everything expands when hot you have a vacuum leak somewhere.

Have you ever had your intake valve's carbon removed? Maybe someone did not replace an intake manifold gasket or it went half on? Any kind of work like that done?

Dackel



PS: Maybe MightyMouseTech has some ideas. He's always a good "thinker" when it comes to stuff like this.

[zbrit00x]

Yep valves have been cleaned, issue was happening prior and after to the service. I double checked that gasket too.

I'm thinking its vac related since when I remove the oil cap there is no change in idle. However going over the lines in carb/choke I was unable to find the leak

Looks like I'm going to have to track down a pressurized smoke machine!

Originally Posted by Dackelone

Bad oil cap/seal? I've seen cars with a bad oil cap seal cause a bad idle. Maybe remove it with the engine running and see how the engine idles ? (be sue not to make a mess with spitting oil out of the VC).... It should idle rougher - bc it causes a vacuum leak.


I would still replace your spark plugs with dealer bought ones. I have just seen too many guys chase their rough idle tail only to be cause by a bad spark plug. I used to work with a tech who was fond of saying.... "Just bc its anew part doesn't mean it's a GOOD part!

I would buy some non flammable(IMPORTANT!) brake cleaner... CRC use to make some... they spary down your vacuum lines with the engine running... IF the engine suddenly bogs down... you've found your culprit!

I kind of feel that it's vacuum related bc you say your cold start idle is fine. Maybe when everything expands when hot you have a vacuum leak somewhere.

Have you ever had your intake valve's carbon removed? Maybe someone did not replace an intake manifold gasket or it went half on? Any kind of work like that done?

Dackel



PS: Maybe MightyMouseTech has some ideas. He's always a good "thinker" when it comes to stuff like this.

[MightyMouseTech]

Not adding much new, but it is always harder to start a car that is hot and has sat for 20-30 mins. Fuel can boil in the lines and create some vapor issues. My own car does this, has since new. Often won't start first try when hot. Have to hit start again. Actually happened to me twice yesterday. Very hot here right now.

Maybe priming the fuel pump a second time will help? Get in, press start twice to on without starting. Turn off again and then start it?

You can also try running a different fuel and see if that helps, maybe something without ethanol.

And ya, what Dack said, OE plugs for life!

[Dackelone]

Originally Posted by zbrit00x

Looks like I'm going to have to track down a pressurized smoke machine!

Yea... a smoke machine is necessary to track down a vacuum or boost leak.

Humm... speaking of boost leaks... have you looked at your charge pipe. They always seem to crack/break. Just an idea.

good luck,
Dackel

[MightyMouseTech]

Shit, just read entire post.

That -30% means you have a really bad injector on the bank you only replaced one, it is pissing fuel, you sure you replaced the right one? Should have replaced all three in that bank.

[zbrit00x]

I pulled the plugs and didnt see liquid or smell gas, but I might as well swap the last 2 injectors if it comes down to that.
chargepipe is good, its not the oem piece and if it did snap..I wouldbe more worried lol.

Also as far as fuel.. all we have is 91 piss water :<

[MightyMouseTech]

Originally Posted by zbrit00x

I pulled the plugs and didnt see liquid or smell gas, but I might as well swap the last 2 injectors if it comes down to that.
chargepipe is good, its not the oem piece and if it did snap..I wouldbe more worried lol.

Also as far as fuel.. all we have is 91 piss water :<

BMW only replaces in sets of three, I think that is a good recommendation.

[JEngland]

zbrit00x,
I have an 09 with 39k miles and was having the exact same issues, took it to BMW and they replaced low pressure fuel pump sensor. They said it was to old style so replace with new style. Haven't had a long crank or missing idle since.

[zbrit00x]

I replaced the old one with a new one recently too. Were you throwing any codes btw?

Originally Posted by JEngland

zbrit00x,
I have an 09 with 39k miles and was having the exact same issues, took it to BMW and they replaced low pressure fuel pump sensor. They said it was to old style so replace with new style. Haven't had a long crank or missing idle since.

[twinboost_MD]

reset your adaptations and do the transmission reset. give it a shot, takes 2 minutes

[gabeyts]

Hi everyone, just got my car last month and noticed this issue as well. I am a total noob at DIY maintaince and wanted to know where to start as far as diagnosing and reading codes. Thanks in advance.