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Boris3

1991 318is injector issues?

Question

So, the past few days I've been tackling the leaking plastic coolant pipe on the 1991 318is, and as a while I was in there did the"mess under the intake" mod (short version for those who don't know this is cleaning up the rats nest of vacuum and coolant hoses under the intake, and replacing with only the necessary dedicated lines). Car has been sitting for about a month until I had the time to do this.

So car initially  idled fine yesterday after everything was buttoned up but while revving the engine during the bleed the engine stumbled and threw a CEL. The Peake reader codes were 64 ("unspecified DME output stage") and C9 ("emission (Lambda control))."  Cleared the codes, restarted and idled fine, no CEL, drove it around the neighborhood for a bit max speed 35-40. After about 20 minutes or so car stumbled again (after a 3k+ rev), almost died and then was fine. I made it home, saw the same codes, cleared them and parked it.

This morning went out and drove it again, idled fine, after about 20 minutes in, same stumble same codes. Also smelled a bit of gasket burning so I went back and checked everything and the lower intake manifold nuts were loose. Put everything back together with a better torque wrench, cleared codes, disconnected/reconnected the battery. Tried again. Car idled fine, this time drove it for about a half hour, ran the tach up to about 3k a few times with no issue, ran it up to 4k eased off and car stumbled, flashed the CEL, then shortly a solid CEL, and I limped the car home. This time the reader showed 20 (Fuel injectors, Cyl 2,4), and the 64 code. Cleared the codes, disconnected and reconnected the battery, restarted but still ran rough though only showing the 64 and C9 codes.  Parked it and decided to call it a day.

So next steps?

Car has close to 300k on it and expect this is first time the upper/lower intakes have been off. Bottom inch or so of the runners on the lower intake were coated with sludge with the injector caps barely visible. I cleaned out the runners with what was on had (carb cleaner, brake cleaner, shop towels) and used a soft toothbrush to loosed the crud around the injectors. They weren't leaking but looked to be the originals. I'm wondering if the injectors are indeed the issue for all of the above, and my effort to clean rather than pulling them from the rail and replacing them didn't help. 

Before I start looking for a new set of M42 injectors I was wondering if I'm missing something? Valve cover is weeping near the firewall which is the next project but car wasn't throwing any codes or having any running issues prior to the removing the manifolds for the coolant pipe repair.

On the plus side, the coolant pipe replacement is not leaking.

Insights welcomed!

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Probably not much help, but I would double-check all the vacuum lines to make sure everything is routed right and nothing is pinched.

If you want to try swapping out injectors/ICV/AFM/whatever, I've got lots of spare parts you could borrow.

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Thanks, I appreciate the parts offer.   I had passed double checking and moved into quadruple by earlier today. 😳

All that said, may not need the parts and may have solved it on a suggestion from Dan Frodl to think electrical to the injectors. Turns out the main connector off the injector plug board was correctly plugged into the fitting in the black plastic box over the starter but the connection wasn't tight. Pushing hard on the plug smoothed out the idle.  Just went out and flogged it with no issues. I also had dumped a bottle of gumout into the tank earlier today. I figured couldn't hurt

I'll see how it runs tomorrow.     

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