[Spyro235]

Hi guys,
I'm having a surging issue. I Know this is a common one, but I truly haven't found anyone with my exact set of symptoms, and I simply can't keep throwing money at the problem anymore. I'm tapped out, and I'll dip into savings if it will fix the issue, but I can't just throw my savings blindly at a problem.
Let me preface that I have brand new index 12 injectors, coded appropriately. New valve cover, which was replaced after a large crack in it was found in a smoke test of the engine bay. My DME mosfets were fixed, as some were found to be faulty (a 2007 only n54 issue).

Issues I'm currently aware of-
-early stage failing turbos, wastegate rattle at 3000 rpm on engine spin down, and I pop a half engine light if I stay in boost for extended periods of time. Driving around town, you'd truly never know.
-OFHG is weeping. Needs to be done.
-Oil Pan Gasket. This also needs to be done, Matt at ZNM has told me that it's now more than weeping. I don't have any spots on my driveway, where my car spends extended periods of time though. He told me there's an ever so slight chance that this oil pan gasket is causing my issue.

My symptoms of surging:
1) Startup- cold OR hot. Doesn't matter. 90% of the time it occurs, regardless of previously running, or engine heat at startup. The car will start completely fine, barely crank, and fire right up. As soon as the idle tries to level out, it will start jumping. it'll run at 1000-1100 rpm, and basically miss, and fall to 300rpm, before sounding awful while to try to save itself. it'll fire and save itself, race up to 1100rpm, and then die out again, dropping to 300 rpm... etc. repeat, repeat, repeat. If I rev the crap out of it (3000-4000rpm) for a second or two, it'll usually stop, and settling into it's solid, steady idle at 550-700rpm, depending on if the car was run before that day. hols idle like a champ. My mechanic has set the idle from 500-1100 rpm, and it holds it steady at all of them.

2) Now we move onto the issues that affect drivability. after the idle has settled into it's steady state, if I give the throttle as tiny bit of steady throttle (think as if I'm engaging the clutch at 800-1000 rpm), it starts missing and surging again. While engaging the clutch, this is problematic, as if I'm slipping the clutch at 1000rpm and suddenly lose power, the car jerks like crazy,falling into gear as it loses power momentarily. after we're over 1000rpm, I'm NORMALLY good, but if I'm trying to inch along in traffic at 700-1500 rpm with ever so slight throttle, the jerking and missing happens again. Jerking through my morning stop and go commute traffic is NOT fun.

3) Cruising at over 2900 rpm, at steady state. Regardless of gear, true surging comes back right under 3000rpm. Feels like I'm oscillating the pedal in and out of throttle. Super annoying. In addition to steady state, if I'm accelerating lightly through any gear, right when it hits 2900 rpm, it feels like there's a huge hole in my torque, the power falls on its face. after that, it continue climbing normally, but will surge if I'm not giving it enough throttle by then.

As a side note- NONE if these issues occur at more than 1/4 throttle. If the engine is boosting, or spooling because of throttle position, it NEVER happens.

Is it true my oil pan gasket leak could be causing this issue? Matt has run countless diagnostics, cold start tests, and both of us are pretty much stumped. My fuel pumps respond great, the MAF (or whatever bmw calls it on the n54) responds instantaneously when being monitored, the throttle position sensor responds fine. I can't just drop a few hundred more into this issue without figuring out the root cause. I plan on having both gaskets fixed when I do the turbo replacement, but I need to save up some more money to comfortably be able to drop that kind of money into the car.

[Jklad]

Any codes? When my car was having issues starting (start car, idle dips to 300, jumps back up to 1000, then back down and up again before settling) it was my hpfp. Doesn't sound like your issue though. I'd be shocked if the leaking oil pan did anything to remedy what your experiencing - highly doubt it.

Could it be related to youfailing turbos? Have you checked all the vacuum lines?

[Spyro235]

I believe Matt checked the whole engine compartment with smoke for leaks. My car never has an issue starting, the issue jsut starts immediately after firing up nice and strong.
No codes, I ONCE got a misfire on cylinder 4 code, but it happened once and never again. I'm very hesitant to think it's the failing turbos, because Matt hasn't mentioned its a possibility. He knows his way around these engines.

As a side note- another symptom that occurs fairly often is that coming to a stop, slowing rapidly with the car in gear, when I take it out of gear by engaging the clutch (pushing the pedal down) it will miss and try to die out on me, as if it had forgotten that when I release the trans from the engine, it needs to hold an idle. It's actually stalled out a few times on me during this particular symptom. Pulling up to a stop sign, push in the clutch to get it into first/ come to a complete stop, and it died out as if it just forgot to idle after I disconnected the engine from the wheels. If I blip the throttle when I push in the clutch, it never, ever misses in this particular circumstance. I've simply gotten in the habit of blipping the throttle heel-toe fashion every time I push in the clutch to slow/stop.

[Spyro235]

Any ideas?

[Jaronbwall]

Probably a dumb question but have you cleaned the intake ports? My car is surging (all though not as bad) as well. I have 91K miles and I'm sure it's really bad. I have about 10 maintenance and bolt-on up grades to complete. Haha

[Spyro235]

Yep, I was walnut blasted about 2k miles ago, in hopes it would help. I found a few surging threads this morning that seem to point to ECU programming. Those who have actually solved it fixed it by having the dealer reflash their ECU's.

[insanesam]

Originally Posted by Spyro235

Hi guys,
I'm having a surging issue. I Know this is a common one, but I truly haven't found anyone with my exact set of symptoms, and I simply can't keep throwing money at the problem anymore. I'm tapped out, and I'll dip into savings if it will fix the issue, but I can't just throw my savings blindly at a problem.
Let me preface that I have brand new index 12 injectors, coded appropriately. New valve cover, which was replaced after a large crack in it was found in a smoke test of the engine bay. My DME mosfets were fixed, as some were found to be faulty (a 2007 only n54 issue).

Issues I'm currently aware of-
-early stage failing turbos, wastegate rattle at 3000 rpm on engine spin down, and I pop a half engine light if I stay in boost for extended periods of time. Driving around town, you'd truly never know.
-OFHG is weeping. Needs to be done.
-Oil Pan Gasket. This also needs to be done, Matt at ZNM has told me that it's now more than weeping. I don't have any spots on my driveway, where my car spends extended periods of time though. He told me there's an ever so slight chance that this oil pan gasket is causing my issue.

My symptoms of surging:
1) Startup- cold OR hot. Doesn't matter. 90% of the time it occurs, regardless of previously running, or engine heat at startup. The car will start completely fine, barely crank, and fire right up. As soon as the idle tries to level out, it will start jumping. it'll run at 1000-1100 rpm, and basically miss, and fall to 300rpm, before sounding awful while to try to save itself. it'll fire and save itself, race up to 1100rpm, and then die out again, dropping to 300 rpm... etc. repeat, repeat, repeat. If I rev the crap out of it (3000-4000rpm) for a second or two, it'll usually stop, and settling into it's solid, steady idle at 550-700rpm, depending on if the car was run before that day. hols idle like a champ. My mechanic has set the idle from 500-1100 rpm, and it holds it steady at all of them.

2) Now we move onto the issues that affect drivability. after the idle has settled into it's steady state, if I give the throttle as tiny bit of steady throttle (think as if I'm engaging the clutch at 800-1000 rpm), it starts missing and surging again. While engaging the clutch, this is problematic, as if I'm slipping the clutch at 1000rpm and suddenly lose power, the car jerks like crazy,falling into gear as it loses power momentarily. after we're over 1000rpm, I'm NORMALLY good, but if I'm trying to inch along in traffic at 700-1500 rpm with ever so slight throttle, the jerking and missing happens again. Jerking through my morning stop and go commute traffic is NOT fun.

3) Cruising at over 2900 rpm, at steady state. Regardless of gear, true surging comes back right under 3000rpm. Feels like I'm oscillating the pedal in and out of throttle. Super annoying. In addition to steady state, if I'm accelerating lightly through any gear, right when it hits 2900 rpm, it feels like there's a huge hole in my torque, the power falls on its face. after that, it continue climbing normally, but will surge if I'm not giving it enough throttle by then.

As a side note- NONE if these issues occur at more than 1/4 throttle. If the engine is boosting, or spooling because of throttle position, it NEVER happens.

Is it true my oil pan gasket leak could be causing this issue? Matt has run countless diagnostics, cold start tests, and both of us are pretty much stumped. My fuel pumps respond great, the MAF (or whatever bmw calls it on the n54) responds instantaneously when being monitored, the throttle position sensor responds fine. I can't just drop a few hundred more into this issue without figuring out the root cause. I plan on having both gaskets fixed when I do the turbo replacement, but I need to save up some more money to comfortably be able to drop that kind of money into the car.

Had similar issues to your first symptoms. Car would seems to choke and stutter and about to stall. If I rev it it goes away and no codes when scanned. Recently it happened again but this time I let it stall and check engine light came on. Scanned car and got VANOS codes. Cleaned the solenoids and so far its been ok. Even idles more smoother too