[mgorman87]

I recently became proud owner of 2011 328i with ~78,000 miles.

Previous owner(s) didn't do any routine maintenance from what I can tell. Still had original plugs/coils, air filter ,etc.

Car is running much better now after i did my tune up.

However, I still get at start up, whether it's hot or cold, a stumbling of RPM. The whole car shakes and I can hear a "noise" from the engine. This only lasts a couple seconds and then it idles and sits nicely at around 700-800 RPM.

I've been told it could be a vacuum leak, which are common on these cars? or possibly I have dirty injectors.

I have no codes and the car runs fine otherwise.

My concern is this. Is it too late to start using fuel cleaners when I'm sure it's never been done before? I don't want to cause further problems by doing this to try and fix a slight stumbling at start up.


advice is appreciated.

[hassmaschine]

78k isn't high miles, and most aftermarket fuel cleaners are snake oil.

[The Nightman]

No harm in running a cleaner now. Use something containing PEA (Techron, Gumout, etc) as they are actually effective.

As for your specific issue, I would check for oil in the eccentric shaft sensor connector

[nsjames]

Originally Posted by hassmaschine

78k isn't high miles, and most aftermarket fuel cleaners are snake oil.

this.

and for what port injection bosch injectors cost, you could forgo the snake oil and replace them every 100K miles. Probably be about even money.

[W37V]

Originally Posted by mgorman87

I recently became proud owner of 2011 328i with ~78,000 miles.

Previous owner(s) didn't do any routine maintenance from what I can tell. Still had original plugs/coils, air filter ,etc.

Car is running much better now after i did my tune up.

However, I still get at start up, whether it's hot or cold, a stumbling of RPM. The whole car shakes and I can hear a "noise" from the engine. This only lasts a couple seconds and then it idles and sits nicely at around 700-800 RPM.

I've been told it could be a vacuum leak, which are common on these cars? or possibly I have dirty injectors.

I have no codes and the car runs fine otherwise.

My concern is this. Is it too late to start using fuel cleaners when I'm sure it's never been done before? I don't want to cause further problems by doing this to try and fix a slight stumbling at start up.


advice is appreciated.

Just run some techron fuel cleaner and see if anything changes. You lose $5 if they don't work.

[hassmaschine]

Or just run top tier fuel consistently. it already has injector cleaner detergents in the fuel.

[Phil325i]

Cleaner won't cure your issue...which is the classic symptom of failing injector(s) leaking fuel into the cylinders overnight, leading to your symptoms when you start up from cold.

[mgorman87]

Originally Posted by nsjames

this.

and for what port injection bosch injectors cost, you could forgo the snake oil and replace them every 100K miles. Probably be about even money.

I can't find Bosch injectors for my car (2011 328i N52)

They have the BMW ones, but those are $187 each.

[mgorman87]

Originally Posted by Phil325i

Cleaner won't cure your issue...which is the classic symptom of failing injector(s) leaking fuel into the cylinders overnight, leading to your symptoms when you start up from cold.

This doesn't only occur when car is cold.

Yesterday, I drove home from Indiana. It was about 300 miles. I stopped to grab dinner. Car was off for about 10 minutes. When I started it back up, it stumbled and shook and then it was fine.

Is there an easy way to test injectors without pulling them all out?

[mgorman87]

Originally Posted by freedomfries

No harm in running a cleaner now. Use something containing PEA (Techron, Gumout, etc) as they are actually effective.

As for your specific issue, I would check for oil in the eccentric shaft sensor connector

This would require removing the valve cover and replacing the gasket as well right?

[Phil325i]

Originally Posted by mgorman87

Is there an easy way to test injectors without pulling them all out?

Take out the spark plugs one by one and sniff for unburnt gas and inspect for heavy carbon or wetness.

[rjahl]

OP,

When you say "no codes" was that from a generic ODB code reader or a BMW specific tool like INPA? Only those tools will report errors like Vanos solenoids or VVT sensor issues.

Injector cleaner will probably not fix anything.

I've never heard of leaking injectors in the N52 platform, fuel rail pressures are really low when compared to the other motors like the N54. Could be wrong, but 200,000 miles on my N52 and it was always very quick to fire up. Never used injector cleaner, good gas already has cleaners. Only time it acted cranky was when the battery was near the end of life.

Use INPA, read codes, Check Fuel trims and report back.

[mgorman87]

Originally Posted by rjahl

OP,

When you say "no codes" was that from a generic ODB code reader or a BMW specific tool like INPA? Only those tools will report errors like Vanos solenoids or VVT sensor issues.

Injector cleaner will probably not fix anything.

I've never heard of leaking injectors in the N52 platform, fuel rail pressures are really low when compared to the other motors like the N54. Could be wrong, but 200,000 miles on my N52 and it was always very quick to fire up. Never used injector cleaner, good gas already has cleaners. Only time it acted cranky was when the battery was near the end of life.

Use INPA, read codes, Check Fuel trims and report back.

I use INPA. I cleared the stored codes a few weeks ago and none have come back.

As far as the gas goes, based on how this car was treated, I have a feeling that the previous owners only used E87 for 78,000 miles. Since taking ownership, I've been only fueling with E93.

I will hook my cable back up and check fuel trim levels. Does this need to be tested under certain conditions? Or can i just start the car up (cold) and read the values?

[gT-BMW]

to sum it all up if the car has been sitting for awhile then you can use a fuel injector additive. IMO its still useless because if you buy top tier fuel it already has those additives.

btw when you buy fuel from a top tier provider it doesnt matter what grade you buy 87-93 octane have the same amount of detergents. the only different is knock threshold.

[nsjames]

Originally Posted by mgorman87

I can't find Bosch injectors for my car (2011 328i N52)

They have the BMW ones, but those are $187 each.

remans dude.

very seldom does the coil or electrical part of an injector fail.

it's something that dicks up the spray pattern, or the seal on the pintle gets damaged and they leak.

You can pick up a set of flow tested, like new remans from a reputable shop for under $200.

I know, because I did it.

[hassmaschine]

Pretty sure the N52 injectors aren't made by bosch

[shuotong]

You don't lose anything if you tried a bottle of Techron. Most of the fuel additive is snake oil but this one is definitely not.
The fuel quality in China is crap even the fuel filter is a serviceable item at 50000km interval, at the very least many owners have positive result in cleaning the intake carbon buildup.

[tlow98]

I don’t even know how we got on this injector talk. All from “stumbling”.

My car stumbles like that sometimes, too. For the last 30k miles.

Mine also makes a grinding noise seldomly for the past 30k miles - suspect it’s the starter, but again. It’s seldom an issue so I’m kind of in the ‘who cares’ camp.

Scan for codes. If nothing, don’t worry. Injectors rarely fail on the n52.

[rjahl]

Originally Posted by mgorman87

I use INPA. I cleared the stored codes a few weeks ago and none have come back.

As far as the gas goes, based on how this car was treated, I have a feeling that the previous owners only used E87 for 78,000 miles. Since taking ownership, I've been only fueling with E93.

I will hook my cable back up and check fuel trim levels. Does this need to be tested under certain conditions? Or can i just start the car up (cold) and read the values?

I'm a big believer in data logging. I log everything but you can probably get away with watching the fuel trims at idle and high idle. If they hold near normal levels, I'd move on to other possible causes. N52s are not known to have injector problems.


Have you tried running with MAF sensor unplugged?

[mgorman87]

I have not tried unplugging the MAF.
I still need to hook up and read the fuel trim. Still trying to figure out exactly where in INPA I would read this.

The issue only occurs on warm starts after I've driven the car, parked it for more than 5 minutes and then started it again. It does not happen after sitting in the garage over night.

I tried to get a video of the tac and the engine. It's kind of hard to really feel what's happening.

When the tac is jumping around, the car is shaking. This only lasts a few seconds and goes back to normal idle.

I was able to hear a faint whistling sound coming from the engine when it started up and did the rough idle. The whistling stopped after the RPM hit idle levels.

It may just be how the car is and to fix it would be too much. I just don't want this to be some indication of a bigger issue that if addressed now, could save me time and money down the road.

[logantheodorou]

Originally Posted by mgorman87

I have not tried unplugging the MAF.
I still need to hook up and read the fuel trim. Still trying to figure out exactly where in INPA I would read this.

The issue only occurs on warm starts after I've driven the car, parked it for more than 5 minutes and then started it again. It does not happen after sitting in the garage over night.

I tried to get a video of the tac and the engine. It's kind of hard to really feel what's happening.

When the tac is jumping around, the car is shaking. This only lasts a few seconds and goes back to normal idle.

I was able to hear a faint whistling sound coming from the engine when it started up and did the rough idle. The whistling stopped after the RPM hit idle levels.

It may just be how the car is and to fix it would be too much. I just don't want this to be some indication of a bigger issue that if addressed now, could save me time and money down the road.

I've had my 2008 e90 328i for about 9 months now. I've had this issue intermittently since i bought the car. Not really that concerned as no codes are being thrown.

[desertman123]

My car stumbles on cold startup every time, only for a few seconds. But I'm full bolt on

I've replaced CCV hose, have a new genuine valve cover (and made sure the internal breathers are secured upon installation), new intake manifold gaskets, throttle body gasket, no MAF anymore, etc. etc.

Basically everything except O2 sensors that might cause a stumble. It might just be O2 since the catalyst isn't warm yet but these cars use the O2 sensor readings very precisely.