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sprinkles08, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 23004
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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Im working on a customers car here. Recently have installed

Customer Question

Hello, Im working on a customers car here. Recently have installed a used engine for them. Car came back in with a check engine light. Had codes for the tumbler flap issue which we have taken care of. Also, i have a p0016 code that was in the history.
After tumbler flap repair it hasnt been driven very far and the p0016 hasnt returned. But we have a missfire on cylinder 1 and occasionally cylinder 3. I have pulled the intake manifold back off and resealed it with new gaskets. Also switched coils from different
cylinders and plugs to eliminate those on cylinder 1. I did reuse the old intake on the new/used engine when I replaced the tumbler flap arm. So we are using her old fuel rail,injectors intake assembly etc. It only seems to missfire once the car warms up.
It acts just like an ignition missfire. It will come and go for 3-4 seconds at a time. Any and all help will be greatly appreciated.
Submitted: 1 year ago.
Category: Mercedes
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

Have the injectors been swapped to other cylinders?

Does it appear the missing cylinders are shutting off completely or just missing?

There was no change at all when the spark plugs were moved?

Customer: replied 1 year ago.
Injectors have not been moved. I was considering swapping back to the other fuel rail. It's not a dead cylinder type of miss. It's random just like a coil or bad plug. I've swapped a few different plugs into cylinder 1 with no change. I checked the timing for the balance shaft gear issues that are known problems. Everything there checked out good as well.
Expert:  sprinkles08 replied 1 year ago.

Have you tested the coil driver at the time the problem is happening? If the coil and plug have been ruled out but it's actually an ignition issue then you have to be losing the coil driver, but that would cause a dead cylinder.

Customer: replied 1 year ago.
No I haven't checked that yet, haven't had to check one that in depth before. Anything in particular you can point me in the direction of checking that would be helpful.
Expert:  sprinkles08 replied 1 year ago.

You can either use a noid light at the injector connector or you could test the driver using a test light either with the connector unplugged or backprobing at the coil connector.

Customer: replied 1 year ago.
I'll check it first thing Monday morning,
Expert:  sprinkles08 replied 1 year ago.

Re reading my post I see that I mentioned checking at an injector in my last post but meant coil. A test light can still be used, a noid light can also be used if you have one that fits the coil connector. A test light would be easier if you don't already have noid lights.

Customer: replied 1 year ago.
2 sets of noid lights no worries there. I'm still somewhat concerned with the p0016 code as well too. Everything ive read mentions when timing is an issue it will also have a p0017 code. I'll put the front of the car back together so i can run it again. I may go ahead and swap the old fuel rail back into it first. And check the driver circuit for the coil too.
Expert:  sprinkles08 replied 1 year ago.

P0016 sets when the intake cam isn't in sync and could be caused by a cam sensor, improper cam timing or a variable valve timing issue. This could definitely cause driveability issues but it shouldn't cause what you're describing.

Customer: replied 1 year ago.
I havent been to far into one of these V8's yet. Are the variable valve timing components a known issue? Some of the BMWs are having issues with the variable timing solenoids getting sludged up and causing run issues. I noticed some sludge on the timing cover when i pulled the cam sensors out. Also, should i possibly consider swapping back to the original intake manifold that came with the used engine? I posted on iatn my issue as well, i had a response about these intakes coming apart internally? I havent seen anything like that before. But Im really wondering if the intake and or the injectors are somehow affecting how the car is running.
Expert:  sprinkles08 replied 1 year ago.

It could be a solenoid issue, a physical cam timing problem or the adjuster assembly on the cam sprocket. If you did see sludge that may not be a good sign.

It isn't unheard of for the intake internals to come apart, once in a while pieces will enter a cylinder. I don't think the intake is causing what you've described though.

Customer: replied 1 year ago.
Reason I ask about the intake is. I'm curious if it possibly caused an issue with the old engine as well. I'll have to verify for sure what cylinder the dealer said the issue was with prior. It may have been cylinder 1 on the old engine as well.
Expert:  sprinkles08 replied 1 year ago.

A blockage in the intake will obviously make a cylinder run rich or something foreign ingested into a cylinder can cause damage and most likely valve leakage, but I wouldn't expect either of these to be intermittent like you seem to be describing. If you have the intake that came with the engine you could put it on and see if anything changes.

Customer: replied 1 year ago.
I'll check the driver to the coil first and let you know what I come up with
Expert:  sprinkles08 replied 1 year ago.


Customer: replied 1 year ago.
I swapped the intake and fuel rail back from the used engine instead of the original engine the car had. It runs perfect now. I'm suspecting something in the intake manifold was the issue. The original engine had a misfire on cylinder 1 as well and some cylinder scoring on that cylinder. Something must have been coming apart inside the intake and caused an issue. I'm going to try and dismantle that intake today and see if I can find anything
Expert:  sprinkles08 replied 1 year ago.

Great, I'm glad you got it fixed!

Customer: replied 1 year ago.
Me too, very odd problem for sure. The customer has picked the car up. I wish I would have swapped just the injector or fuel rail to verify if it was indeed the intake causing the issue.
Expert:  sprinkles08 replied 1 year ago.

I agree it would be a good thing to know for next time but at least now it's out of your hair and you can move onto making money again! The same can't yet be said for the truck sitting behind me as I type this...