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Old 05-08-2016, 04:47 AM   #1
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Small hesitation under load under 1500 rpm

Hi just got my 986 with a 2.5 and the car pulls like a champ. I have this little nagging issue though, if I let the revs below 1500 while driving, when I get back on the throttle it hesitates and bucks once or twice, then it picks up the revs and it's fine. Doesn't matter if I go light or heavy on the throttle still does it. If I don't let the revs drop below 1500 it drives perfect. No other symptoms, no CEL and no pending codes when I scanned it with my OBDII.

I was thinking of running some Techron through it to see if that helps. Anyone else had this happen before?
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Old 05-08-2016, 05:33 AM   #2
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Techron can't hurt, but I guess my suggestion would be to not try and accelerate from 1,500 RPMs. I try to keep it above 2,500-3,000 RPMs at all times, as per many recommendations from this board.
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Old 05-08-2016, 06:22 AM   #3
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Here's s reference for what Joe B is talking about:
http://986forum.com/forums/general-discussions/25016-lugging-engine.html

As far as the bucking AT 1500 rpm, I'd recommend going through all of the basic tune-up stuff if it has not been addressed recently: Techron, Plugs, MAF - TB - Intake cleaning, Air Filter.
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Old 05-08-2016, 07:01 AM   #4
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Well the car shouldn't buck. But I would really suggest downshifting instead of attempting to accelerate basically from idle.


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Old 05-08-2016, 08:30 AM   #5
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Quote:
Originally Posted by BIGJake111 View Post
Well the car shouldn't buck. But I would really suggest downshifting instead of attempting to accelerate basically from idle.


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+ 1, keep th revs up.
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Old 05-08-2016, 12:23 PM   #6
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When this occurs the engine is not lugging, it's when it transitions from drop throttle to touching the accelerator, like coasting through traffic. I have just been consciously using a lower gear but it just seems odd to me. Perhaps it's just the nature of the beast.
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Old 05-20-2016, 03:35 PM   #7
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Cosmo, are you still experiencing this?

This sounds like what I'm figuring through currently. The car threw a CEL the day I put it into hibernation, so I cleaned the throttle body, figuring the rough idle I was experiencing at the end of last season was from a dirty throttle body. I probably should have pulled the fault code, but didn't.
I did the 100k service over the winter. It started right up, but I couldn't drive it until just last week.
The car idles well enough, maybe a touch less silky than previously.
I'm thinking a MAF that's on its way out. The car hesitates wickedly below 2500rpm with a noticeable lack of power, and it sounds like it is backfiring through the air box until it gets rolling. It and starts to pull at 2500+ rpm.
No CEL, though.
I unplugged it and am going for a spin later to pick up my son from work. From what I understand, if the symptoms don't manifest with the MAF unplugged, then it confirms the MAF is bad.
I'll post back with a report.
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Old 05-20-2016, 06:00 PM   #8
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Runs like a new car with the MAF unplugged.
Time to go parts shopping, dammit!
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Old 05-21-2016, 01:32 AM   #9
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Well, never try to clean a MAF. You can use some brake cleaner or so to spray on the metal string to get it a bit cleaner, but never – i mean really never touch this thing or try to clean it mechanically. If you try that in 90% the MAF is gone and you need a new one. These things are stupidly sensible.

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Old 05-21-2016, 04:28 AM   #10
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Mine has seemed to have gotten better with a bit of driving. When I bought the car it had just been taken out of winter storage and had the battery disconnected. It's happened a couple times recently but it's way better.
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Old 06-27-2017, 05:26 PM   #11
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I feel its always good to update these threads with the solution. Mine was coils, I replaced all 6 (two were soaked in oil from bad spark plug tube seals). I did all the tubes, plugs and coils. Problem is completely gone now. Was misfiring at low rpm under load enough to affect drive-ability but not enough to throw a CEL.
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Old 06-28-2017, 04:23 AM   #12
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hmmm, I would have thought misfires would be logged by an OBD scanner
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Old 06-28-2017, 08:30 AM   #13
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Nope. I also had the same problem on a 2011 BMW 328i. Would misfire under load at low rpm. No CEL. Seems that the only misfires that are recorded are complete failures, not weak spark.
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