[f30jadyn]

I just picked my car up from my mechanic after months in the shop because he had to replace my engine due to OFHG seize. Afyer install of the new engine, he told me the car was misfiring and he couldn’t find the cause as all coils, injectors and spark plugs were replaced. Before the first engine even seized I had him install a CTS intake. I notice a major difference and I feel like the stock motor isn’t holding the boost from the intake and causing it to misfire and jump. Should I take it off or just tune the ecu. Or any other reasons why I would be misfiring on a new engine?? Doesn’t make sense. Also not throwing any codes.

[Billfitz]

A cold air intake won't affect a stock N55 because the stock intake is cold air. Most aftermarket intakes are not. If you can see the filter it's not cold air.

[krith]

It sounds like this new engine may not have been "new." It may have been rather new to the car in question. Find what cylinder is misfiring, then swap parts (coil, plugs, injector) to another cylinder. Does the issue follow the parts? If yes, replace the bad part; if not, something is amiss with this engine. My expertise is not significant enough to say more than that.

To answer your title posting, a cold air intake may 1. Increase the sound of the turbo, as the stock air box is referred to as a muffler. 2. If not a closed box design, it may result in a slight loss in throttle response and pressure.

Eventually, this car will throw a code. However, that might be the start of a really bad day. Start with vetting fuel, ignition, and air.

[zinner]

you can just pull off the maf sensor cable and that will eliminate the intake configuration/maf reading, but that really shouldn't cause a misfire. If all the plugs/coils/injectors were replaced, it's time to start leakdown/exhaust gases in the coolant type tests.

[thejeremyman9]

Originally Posted by f30jadyn

I feel like the stock motor isn’t holding the boost from the intake .

Im not sure what this is even supposed to mean...?

Anyways, the intake is going to make basically zero difference on a stock car (and even a tuned one frankly), and CTS is one of the best in terms of not affecting MAF readings.

https://f30.bimmerpost.com/forums/sh....php?t=1765289

You can try swapping back to OEM intake but its unlikely CTS is the problem

[f30jadyn]

Originally Posted by thejeremyman9

Im not sure what this is even supposed to mean...?

Anyways, the intake is going to make basically zero difference on a stock car (and even a tuned one frankly), and CTS is one of the best in terms of not affecting MAF readings.

https://f30.bimmerpost.com/forums/sh....php?t=1765289

You can try swapping back to OEM intake but its unlikely CTS is the problem

I know the thing is me and my mechanic who literally specializes in n55/n54 can not figure out where tf this misfire is coming from. And also at high rpm the intake makes a weird noise so I’m thinking it could be a boost leak or something.

[f30jadyn]

Originally Posted by krith

It sounds like this new engine may not have been "new." It may have been rather new to the car in question. Find what cylinder is misfiring, then swap parts (coil, plugs, injector) to another cylinder. Does the issue follow the parts? If yes, replace the bad part; if not, something is amiss with this engine. My expertise is not significant enough to say more than that.

To answer your title posting, a cold air intake may 1. Increase the sound of the turbo, as the stock air box is referred to as a muffler. 2. If not a closed box design, it may result in a slight loss in throttle response and pressure.

Eventually, this car will throw a code. However, that might be the start of a really bad day. Start with vetting fuel, ignition, and air.

The thing is, the car is not throwing any codes and he literally showed me how the spark plugs, coils, injectors, and even change the fuel pump. I’m truly running out of ideas of what it can be and me and my mechanic have been losing sleep over it.

[thejeremyman9]

Can you describe the misfire? The word can mean different things to different people. Is it a rough idle? surging? only happens at WOT? does it backfire? does it smell like fuel or anything else? if it was really misfiring as defined by the DME there would be codes

[f30jadyn]

Originally Posted by thejeremyman9

Can you describe the misfire? The word can mean different things to different people. Is it a rough idle? surging? only happens at WOT? does it backfire? does it smell like fuel or anything else? if it was really misfiring as defined by the DME there would be codes

Basically at high RPM it chops up and just kicks aggressively then will occasionally throw a drivetrain malfunction right after.

[thejeremyman9]

Originally Posted by f30jadyn

Basically at high RPM it chops up and just kicks aggressively then will occasionally throw a drivetrain malfunction right after.

Ok so what codes go with the drivetrain malfunction...? It should call out misfires on specific cylinders and/or "multiple cylinders"

[f30jadyn]

Originally Posted by thejeremyman9

Ok so what codes go with the drivetrain malfunction...? It should call out misfires on specific cylinders and/or "multiple cylinders"

The malfunction goes away after the car turns off and it doesn’t say anything abt misfires

[thejeremyman9]

Originally Posted by f30jadyn

The malfunction goes away after the car turns off and it doesn’t say anything abt misfires

Sooo scan before you turn the car off? Even if the malfunction goes away they almost always leave a shadow code even if the active code that shows the malfunction is gone. Even a OBD dongle should tell you that, ISTA or other mechanics software should gather even more info

[f30jadyn]

Originally Posted by thejeremyman9

Sooo scan before you turn the car off? Even if the malfunction goes away they almost always leave a shadow code even if the active code that shows the malfunction is gone. Even a OBD dongle should tell you that, ISTA or other mechanics software should gather even more info

Yes, the codes I was throwing relate to fuel and ecu related issues. I have used 2 different hpfp (from old motor and new motor) and no luck. I took my car to 2 dif mechanics one was to fix an oil leak as my oil drain plug was lose. While running tests, we realized at high boost the car was losing fuel. We took the intake off and it helped a little, because obv the intake sucks more air in and wasn’t helping the matter. Where I’m at now is possibly replacing the vanos solenoids, I heard those can cause misfires like the one I’m having.

[thejeremyman9]

If you are losing fuel pressure i dont see how vanos would cause or fix that.

[f30jadyn]

Originally Posted by thejeremyman9

If you are losing fuel pressure i dont see how vanos would cause or fix that.

At this point idk what it could be cuz ive done just about everything other that that. I heard that often that may be the issue with the kind of misfire im having.