rough start after new injectors

[aquapool]

I just replaced my injectors with the bosch 19# ones in my 90 535i. They were refurbished/ cleaned ones. since installing I am having an issuse with idle right after I start her up. It will idle real rough and bog down for about 30 to 60 seconds. after it clears out she will run fine and idle fine. It only seems to happen after I turn it off and let it sit for a little while. Does not seem to effect it wether the engine is hot or cold. Could I have a leaking injector or possibly an air leak that is letting air into my fuel rail after it sits. no gas leaking out and they all seem to be seeted properly. I attempted to check for an air leak by spraying starting fluid around the injectors while running but no change in idle. Any help from you guys is really appreciated.

[Ross]

Sounds like one or more injectors leaking down. Any smoke?

[bad_manners_god]

I just replaced my injectors with the bosch 19# ones in my 90 535i. They were refurbished/ cleaned ones. since installing I am having an issuse with idle right after I start her up. It will idle real rough and bog down for about 30 to 60 seconds. after it clears out she will run fine and idle fine. It only seems to happen after I turn it off and let it sit for a little while. Does not seem to effect it wether the engine is hot or cold. Could I have a leaking injector or possibly an air leak that is letting air into my fuel rail after it sits. no gas leaking out and they all seem to be seeted properly. I attempted to check for an air leak by spraying starting fluid around the injectors while running but no change in idle. Any help from you guys is really appreciated.


I changed my last week with these exact same ones. The first time I started the car after putting everything back it had a really hard time starting. When it finally started there was no response when giving gas, so I looked at the fuel rail, moved it slightly and fuel started spraying everywhere. I forgot to put the retaining clip back. So I took everything back out again, put the reatining clips back and made sure they were all sitting in their place. Put everything back again and started it up, started up almost right away but little rough idle, so I checked them again, gave the rail a couple taps with a rubber mallet to sit the injectors. Put the 2 screws that hold the rail down, strarted the car. It idled rough for a couple seconds and then settled down.

You should remove the rail again, and make sure all the clips are holding properly and then re-seat them into the manifold with a mallet, put the screws and try again.

[aquapool]

Smells a little rich while acting up but no smoke. I will also pull it out again and reseet them trying the mallet trick. Not so hard to do now that I have had it apart three times already. First two tries sprayed fuel everywhere.

[filip00]

weird.

i just got my injectors cleaned recently, and eversince i have rough idles at cold starts for the first minute, then it gets absolutely normal. what could it be?

[Ross]

BMG's idea sounds good if there are external leaks causing a loss in pressure at start up. Seems probable you would smell gas though. ?

[bad_manners_god]

BMG's idea sounds good if there are external leaks causing a loss in pressure at start up. Seems probable you would smell gas though. ?

Not as much as you would think unless you literally stuck your nose in the injectors and even then, you wouldn't be able to differentiate between the fuel that was released when you disconnected the rail and the fuel that is leaking.

I got lucky when I took out my rail, the fuel shot in a straight line, missing by eye by couple of inches. Thank god.

[upallnight]

Did you guys lube the o-rings before inserting the injector?

[zmuff]

It has been four years since I replaced my injectors with the same ones as you are using, and I had the same issues at startup. After ensuring that I didn't have any visible leaks or other issues I may have overlooked, I took it out on the road anyway. It ran like crap for close to 10 minutes regardless of driving conditions, sometimes it ran worse than others. All of a sudden it just completely smoothed out on its own and has run perfectly since then. All I can guess is that Motronics was trying to figure out what the hell I just did and finally adapted.