[CharlieVu]

Car: 328i X
Mods : Afe intake
Afe tune

History: oil change and spark plugs changed at 49k miles. At 55k miles my car started to hesitate around 3/4 load acceleration (sport and casual mode). 3500-5000k rpm. Reminded me of my wrx when the intake was dirty. Sunday I cleaned the intake but didn't fix the issue. Monday I fueled up n added techron injector cleaner n went on a Italian drive, 4500 rpm for ten minutes. That did not fix it. Coincidentally it started happening after warranty... I did research n found issues like, fuel pump gone bad, ignition could need replacing, maybe a vacuum leak or chargepipe needs replacing. Anyone know where I should start? I'm going to remove the tune n intake tomo n see if that fixes the issue

[mr_kay]

I'd start with looking at your CP.

[fhlh]

The charge pipe is probably cracked causing a boost leak. My car behaved like this a few weeks before the CP finally cracked off the throttle body. Even if my guess is wrong, I'd get it to the shop and have it checked out

[CharlieVu]

Which CP did you guys go with? I'll look at the cp this weekend

[PappyVR4]

I had hesitation and have one other possibility. It's an easy check without spending any money to diagnose. Nicks in the wire insulation for fuel injector wires(I think that's what they're for) on the spark plug wiring harness. The harness has wires & plugs for the ignition coils, ground wires, and then another set of 4 wires and plugs. It's the last wires I'm talking about, they're thin wires and the insulation can easily be cut through by the coil's latches during a spark plug change.

Two of my cylinders had cuts in these wires. I saw one cut during a spark plug change and temporarily wrapped it in 3M Super 33+ electrical tape until a new harness came in. My hesitation went away, and I thought it was the new spark plugs that fixed the hesitation ... Then the hesitation came back. I got in a replacement section of wiring harness and did the swap. When doing so, I noticed another one of those wires had an exposed cut. With a fresh harness in, my hesitation issue went away.

The wiring harness I'm talking about is #4 in this picture

[PappyVR4]

Also, most charge pipe problems seem to be N54/N55 related. I haven't seen too many N20 charge pipe issues with just a tune.

Oh, and one more possibility not mentioned, is you may want to try S55 spark plugs since you have the afe tune. They're colder than the N20 plugs and apparently eliminate hesitation that sometimes occurs when using stock plugs with a tune. Search the forum and you'll find out more about it.

[CharlieVu]

Thank you! I will have the shop look at the car soon. Hesitant on ordering the chargepipe. Had a mechanic look at the car and no vacuum leak was found

[CharlieVu]

Dropping car off at schomp on Wednesday. Will update when I get an update

[CharlieVu]

Dropping off my car today so they can check the charge pipe and spark plugs. Removed the scorcher and the intake. Tried to imitate the hesitation but it's gone. Took off in sport and first gear and no hesitation.


Probably is the charge pipe giving out on the extra boost. I'll keep y'all posted

[mr_kay]

Some people with N55's report werid issues like this and bucking with an intake installed...not sure if it's the same case for the N20.

[CharlieVu]

Originally Posted by mr_kay

Some people with N55's report werid issues like this and bucking with an intake installed...not sure if it's the same case for the N20.

After they look at it, i will try it without the intake and just the chip. I miss the scorcher tune already...

[CharlieVu]

Schomp was not able to replicate the issue. No error codes were found. I will reinstall the scorcher tonight and go from there. I'm happy it wasn't spark plugs or the wires.

[CharlieVu]

UPDATE:

Scorcher works fine without the AFE intake. Car drives smooth and strong again. So strange. My brother said, sometimes you have to reset the ecu when it comes to piggy back tunes. I am going to install the intake tonight and test it with the scorcher. All I know is, it's nice to have full power again. Thanks everyone for your suggestions.

[CharlieVu]

UPDATE:
Afe scorcher causes Drivetrain Malfunction during aggressive driving. Read that being a big issue- can not replicate issue when afe scorcher isn't install. Saw that a lot of other f30's are having the same problem stock.