New Injectors Faulty?

[CycloSteve]

Finally buttoned-up the 2006 B7 2.0T after a ton of work, including:

Timing Belt Service
All Hoses
Radiator
Carbon Cleaning
Alternator
Injectors

Started, and ran a little rough...OK, let it get up to temp, and settle while bleeding the coolant system, and on comes the MIL. Toss on the VAG-COM, showing few misfires on 2, and a lot on 4. Cleared, and logged live; 2 had an occasional one, 4 basically every three seconds. Swapped the coil packs 4 to 3, 2 to 1, and same result with the misfires on 2 and 4. Pulled the plugs, with 2 being black with soot and wet with fuel, and 4 looking more white, so definitely opposite ends of the spectrum. 1 and 3 had nice light tan color. 2 definitely had a wet cylinder looking down the spark plug bore.

Pulled compression and have 160-165 psi across the motor (quite good for 182k miles). So, I then decide to pull the mainifold, and injector 2 was indeed wet, all others dry. So my thoughts are that the brand new Magneti Marellli injectors from FCP are duds, flooding 2 and starving 4. Wiring is supple, both the injector harness and coilpack harness, with zero indications of heat-related breakage (had that in my son's 1.8t in the past). All connectors clean and clicked tight and lightly lubed with dielectric.

Going to take my OEM ones, 2005 mfg date, to a local shop to have them tested/cleaned/recalibrated.

Any thoughts from the AZ braintrust about other items to check while I wait to get my injectors back?

[CycloSteve]

Hmm, the alignment of the injector orifices in the Magneti Marelli are not uniform.

https://www.audizine.com/gallery/data/500/medium/IMG_34411.jpg

Factory ones below all have the same orifice orientation at 3 o'clock. My gut says that this could be part of the issue, as the injectors would not spray where the factory wants them to be biased (center of the combustion chamber).

https://www.audizine.com/gallery/data/500/medium/IMG_34521.jpg

[canadianA4B7]

Alignment is an indication of quality control. If you wish to correct this just remove the tab in photo with a file. Draw a dot on the top of where the odd ball nozzle points and same on one that is good. Re install aligning all 4 and try again. The pin hole in the centre all look to be aligned quite well.

https://i.ibb.co/wdktCdm/IMG-1115.jpg (https://ibb.co/nwGpfwJ)

[CycloSteve]

I simply do not trust the MM injectors, and sending them back. Unfortunately Chinese QC is not great. The resistance is fine, but the delivery of fuel is way off on two of the four. Dropping my original ones off today for service.

[Jayz691]

This is the problem with aftermarket, QC.
Have you talked to FCP about the issue?

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[CycloSteve]

$102 later the original injectors have been rebuilt and flow exactly the same across the board. Installed and the motor is purring like a kitten with zero misfires. Lesson learned; stick with Audi/VW injectors, and skip the aftermarket.

[80sGuy]

.... Lesson learned; stick with Audi/VW injectors, and skip the aftermarket.
Number one rule when dealing with Audi, ESPECIALLY with our B7s! That's how these cars stay healthy and on the road almost indefinitely.
Congrats on the major service. Speaking of TB (and WP), I'm at 98K and planned on doing it soon, hopefully before 105K. Car still purrs like a kitten as I always use the term to tell my wife about our B7.

[CycloSteve]

In the past I have bought factory new Bosch injectors for my B5 and my son's B6. No problems with those whatsoever, as they were 100% the same as the VAG ones, and made in Germany or France IIRC. The newer outsourcing trend to China for these parts does not work. To their credit, FCP is refunding. Sent pictures, including the VAG-COM log file showing the excessive misfires triggering the MIL.

[Jayz691]

In the past I have bought factory new Bosch injectors for my B5 and my son's B6. No problems with those whatsoever, as they were 100% the same as the VAG ones, and made in Germany or France IIRC. The newer outsourcing trend to China for these parts does not work. To their credit, FCP is refunding. Sent pictures, including the VAG-COM log file showing the excessive misfires triggering the MIL.Yeah, sux you can no longer buy Bosch direct for our injectors, they're NLA. I know the S3 ones can't be found anymore, as I've searched extensively. May still be able to find stock one in stock somewhere, maybe not.
They were same quality(they're OE) for half the price. Could get an S3 set for $450 a few years back..

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[CycloSteve]

The issue with your 2006 B7 2.0T is likely caused by the new Magneti Marelli injectors, with injector 2 flooding and injector 4 starving. Since you've already swapped coil packs and inspected the spark plugs, it’s important to check the fuel pressure to ensure it’s consistent. Inconsistent fuel pressure can cause misfires, especially when it fluctuates across cylinders. Additionally, check for any vacuum leaks, particularly around the intake manifold, as they can disrupt the air-fuel mixture and lead to misfires. With your healthy compression numbers, focusing on injectors, wiring, and grounds should resolve the issue. Also, resetting or reflashing the ECU might help if the new injectors have different flow rates. Lastly, verify the camshaft and crankshaft position sensors, as any issues here can affect timing and cause misfires. Once your injectors are tested and recalibrated, the issue should likely be resolved.

FYI, did all of the above a month+ ago, see post 4 and 6. Original injectors balanced and working fine, FCP refunded in full for the MM ones.